# Checker Framework changelog (release history)

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## Version 4.2.2 (2026-08-06)

### Implementation details

Renamed `CFAbstractValue.validateSet()` to `hasAnnotationFromEveryHierarchy()`.

### Closed issues

\#7723, #7784, #7806.

## Version 4.2.1 (2026-07-01)

### Closed issues

\#7726.

## Version 4.2.0 (2026-06-01)

### User-visible changes

Renamed error message key "createsmustcallfor.target.unparseable" to "createsmustcallfor.target.unparsable".

### Implementation details

In `AnnotatedTypeFactory`:

* new overload `canonicalAnnotation(AnnotationMirror, TypeMirror)`.

In `TypeHierarchy`:

* new methods `equalsShallowEffective()`.

### Closed issues

\#7676, #7679, #7680, #7695, #7697, #7699, #7700, #7727.

## Version 4.1.0 (2026-05-01)

### User-visible changes

Removed deprecated script `checker/bin-devel/build.sh`; use `./gradlew assemble`
instead.

Removed deprecated names "builder", "object.construction", and
"objectconstruction" for the Called Methods Checker.

### Implementation details

New method annotation `@DoesNotUnrefineReceiver`.

In `AnnotatedTypeFactory`:

* new method `hasDoesNotUnrefineReceiver()`.
* `isAliasedTypeAnnotation()` is now protected rather than public.

### Closed issues

\#6890, #7364, #7488.

## Version 4.0.0 (2026-04-07)

### User-visible changes

To run the Checker Framework, you need to use a JDK 17 or later version of
javac.  That is, you need to use JDK 17 or later when compiling your code.

The Checker Framework can type-check any Java project, including projects that
compile to Java 8 or 11 bytecodes and run on JRE versions 8 or 11.  That is,
your code can run under any release of Java, from Java 8 onward.

The type qualifiers and utility libraries in `checker-qual.jar` and
`checker-util.jar` still use Java 11 bytecode.  Thus, they may be used in
projects that run under Java 11 or later.

### Changes since version 3.0.0

Since version 3.0.0, 91 authors have made over 4500 commits and closed over 600
issues.  Thanks to everyone who contributed!

New checkers include:

* The [Index Checker](https://checkerframework.org/manual/#index-checker) warns
  about out-of-bounds accesses to arrays and strings.
* The [Initialized Fields
  Checker](https://checkerframework.org/manual/#initialized-fields-checker)
  warns if a constructor does not initialize a field.
* The [Resource Leak
  Checker](https://checkerframework.org/manual/#resource-leak-checker)
  guarantees that every resource is closed rather than leaked.  Examples of
  resources are a channel, executor, `ExecutionControl`, file, `FileLock`,
  `Formatter`, reader, `Scanner`, socket, stream, writer, etc.
* The [SQL Quotes
  Checker](https://checkerframework.org/manual/#sql-quotes-checker) helps
  prevent SQL injection vulnerabilities.

New command-line arguments include:

* `-AskipFiles`, `-AonlyFiles`
* `-AassumeSideEffectFree`, `-AassumeDeterministic`, `-AassumePure`, `-AassumePureGetters`
* `-AuseConservativeDefaultsForUncheckedCode`
* `-AignoreRawTypeArguments`
* `-AwarnRedundantAnnotations`
* `-Ainfer=ajava`, `-AinferOutputDirectory`, `-AinferOutputOriginal`, `-AshowWpiFailedInferences`
* `-AshowSuppressWarningsStrings`, `-AwarnUnneededSuppressionsExceptions`
* `-AshowPrefixInWarningMessages`
* `-AstubNoWarnIfNotFound`, `-AstubWarnNote`, `-AmergeStubsWithSource`
* `-Aonelinemsg`, `-AdumpOnErrors`, `-AexceptionLineSeparator`
* `-ApermitMissingJdk`, `-AparseAllJdk`
* `-AslowTypecheckingSeconds`
* `-Aversion`, `-AprintGitProperties`
* You can pass an option to only a particular checker (not all checkers) by
  using an underscore prefix.

Other improvements include thousands of enhancements and bug fixes -- too many
to list here.

### Implementation details

All previously-deprecated methods and classes have been removed.  If your
project builds upon the Checker Framework, we suggest that you upgrade to
version 3.55.1, resolve all the deprecation warnings, then upgrade to version
4.0.0.

## Version 3.55.1 (2026-04-03)

No user-visible changes.

## Version 3.55.0 (2026-04-02)

### User-visible changes

The Checker Framework runs under JDK 26 -- that is, it runs on a version 26 JVM.

Removed deprecated command-line option `-AskipDirs`; use `-AskipFiles`.

### Implementation details

In `AnnotatedTypeMirror`:

* Renamed `getEffectiveAnnotation*()` to `getAnnotation*()`.
* Renamed `hasEffectiveAnnotation*()` to `hasAnnotation*()`.

Removed deprecated method `ObjectCreationNode.getConstructor()`; use
`getTypeToInstantiate()`.

### Closed issues

\#7079, #7489, #7539.

## Version 3.54.0 (2026-03-02)

### User-visible changes

Command-line arguments:

* Added `-AinferOutputDirectory`.
* Removed long-deprecated `-Alint=forbidnonnullarraycomponents`.

New command-line argument `-Aonelinemsg` puts error messages on a single line.
This is useful when using a tool that only shows the first line of the error.

The command-line argument `-Anomsgtext` surrounds the error key with brackets
instead of parenthesis. This matches Java error messages.

### Implementation details

In `AnnotatedTypeFactory`, `canonicalAnnotation()` returns a non-null value.

In `AnnotationClassLoader`:

* Renamed `hasWellDefinedTargetMetaAnnotation()` to `isTypeQualifierAnnotation()`.
  The method now returns `true` for annotations bearing `@InvisibleQualifier`
  or `@SubtypeOf`, in addition to the existing `@Target(TYPE_USE)` check.

In `TestDiagnostic`:

* Renamed field `message` to `key`.
* Added new nullable field `message` for the full message without the key.

Removed classes and methods that have been deprecated for more than two years.

### Closed issues

\#6874, #7471, #7475, #7486.

## Version 3.53.1 (2026-02-02)

### Closed issues

\#4858, #6141, #6620, #7360, #7388.

## Version 3.53.0 (2026-01-06)

### Implementation details

In `AbstractAnalysis`, added `getStoreBefore(Tree)`, `getStoreBefore(Node)`,
`getStoreAfter(Tree)`, and `getStoreAfter(Node)`.

In `GenericAnnotatedTypeFactory`, removed `getStoreBefore(Set<Node>)` and `getStoreAfter(Set<Node>)`.

### Closed issues

\#2358.

## Version 3.52.1 (2025-12-02)

### User-visible changes

Added `Opt.ifPresentOrElse()` method.

### Closed issues

\#7243, #7398.

## Version 3.52.0 (2025-11-04)

### Implementation details

In `CFAbstractAnalysis`, renamed `defaultCreateAbstractValue` to `getCfValue`

In `GenericAnnotatedTypeFactory`:

* renamed `performFlowAnalysis` to `performFlowAnalysisForClass`
* renamed `checkAndPerformFlowAnalysis` to `performFlowAnalysisForClassOnce`

### Closed issues

\#6629, #7341, #7346.

## Version 3.51.1 (2025-10-01)

### Closed issues

\#6623, #7250.

## Version 3.51.0 (2025-09-10)

### Implementation details

In `CFGVisualizeOptions`:

* renamed `isPDF()` to `isPdfOutput()`
* renamed `isString()` to `isStringOutput()`

Dataflow Framework:

* In `playground` package, renamed `*Playground.java` to `*Pdf.java`

### Closed issues

\#7229, #7241, #7248, #7258.

## Version 3.50.0 (2025-08-28)

### User-visible changes

If you supply `--add-exports` flags when you run the Checker Framework,
you need to add:
`--add-exports=jdk.compiler/com.sun.tools.javac.parser=ALL-UNNAMED`.

### Implementation details

Moved the Annotation File Utilities code into the Checker Framework repository
as a subproject.

## Version 3.49.5 (June 30, 2025)

### User-visible changes

The Checker Framework runs under JDK 25 -- that is, it runs on a version 25 JVM.

### Closed issues

\#7093.

## Version 3.49.4 (June 2, 2025)

### Closed issues

\#6740, #7013, #7038, #7070, #7082.

## Version 3.49.3 (May 2, 2025)

### User-visible changes

The Checker Framework runs under JDK 24 -- that is, it runs on a version 24 JVM.

### Closed issues

\#6520, #6671, #6750, #6762, #6887, #7001, #7019, #7024, #7029, #7053.

## Version 3.49.2 (April 1, 2025)

### Closed issues

\#6747, #6755, #6789, #6891, #6963, #6996, #7001, #7008, #7014.

## Version 3.49.1 (March 3, 2025)

### Closed issues

\#6970, #6974.

## Version 3.49.0 (February 3, 2025)

### User-visible changes

The Optional Checker is more precise for `Optional` values resulting from
operations on container types (e.g., `List`, `Map`, `Iterable`).  It supports
two new annotations:

* `@NonEmpty`
* `@UnknownNonEmpty`

The Signature Checker no longer supports `@BinaryNameWithoutPackage` because
it is equivalent to `@Identifier`; use `@Identifier` instead.

The JavaStubifier implementation now appears in package `org.checkerframework.framework.stubifier.JavaStubifier`.

### Closed issues

\#6935, #6936, #6939.

## Version 3.48.4 (January 2, 2025)

### Closed issues

\#6919, #6630.

## Version 3.48.3 (December 2, 2024)

### Closed issues

\#6886.

## Version 3.48.2 (November 1, 2024)

### Closed issues

\#6371, #6867.

## Version 3.48.1 (October 11, 2024)

### User-visible changes

The Returns Receiver sub-checker is now disabled by default when running the
Resource Leak Checker, as usually it is not needed and it adds overhead. To
enable it, use the new `-AenableReturnsReceiverForRlc` command-line argument.

### Closed issues

\#6434, #6810, #6839, #6842, #6856.

## Version 3.48.0 (October 2, 2024)

### User-visible changes

The new SQL Quotes Checker prevents errors in quoting in SQL queries.  It
prevents injection attacks that exploit quoting errors.

Aggregate Checkers now interleave error messages so that all errors about a line
of code appear together.

### Closed issues

\#3568, #6725, #6753, #6769, #6770, #6780, #6785, #6795, #6804, #6811, #6825.

## Version 3.47.0 (September 3, 2024)

### User-visible changes

The Checker Framework runs under JDK 22 -- that is, it runs on a version 22 JVM.
The Checker Framework runs under JDK 23 -- that is, it runs on a version 23 JVM.

The Optional Checker no longer supports the `@OptionalBottom` annotation.

### Implementation details

Removed annotations:

* `@OptionalBottom`

### Closed issues

\#6510, #6704, #6743, #6749, #6760, #6761.

## Version 3.46.0 (August 1, 2024)

### User-visible changes

The new SqlQuotesChecker prevents errors in quoting in SQL queries.  It prevents
injection attacks that exploit quoting errors.

Renamed `@EnsuresCalledMethodsVarArgs`to `@EnsuresCalledMethodsVarargs`.

### Closed issues

\#4923, #6420, #6469, #6652, #6664.

## Version 3.45.0 (July 1, 2024)

### Implementation details

Added a `Tree` argument to `AnnotatedTypes.adaptParameters()`

Deprecated methods:

* `TreeUtils.isVarArgs()` => `isVarargsCall()`
* `TreeUtils.isVarArgMethodCall()` => `isVarargsCall()`

### Closed issues

\#152, #5575, #6630, #6641, #6648, #6676.

## Version 3.44.0 (June 3, 2024)

### Implementation details

Removed methods:

* `AbstractAnalysis.readFromStore()`:  use `Map.get()`

Renamed methods:

* `CFAbstractStore.methodValues()` => `methodCallExpressions()`
* `AbstractCFGVisualizer.format()` => `escapeString()`

Renamed fields:

* `AnalysisResult.stores` => `inputs`

Deprecated methods:

* `AbstractAnalysis.getContainingMethod()` => `getEnclosingMethod()`
* `AbstractAnalysis.getContainingClass()` => `getEnclosingMethod()`
* `ControlFlowGraph.getContainingMethod()` => `getEnclosingMethod()`
* `ControlFlowGraph.getContainingClass()` => `getEnclosingClass()`
* `JavaExpression.isUnassignableByOtherCode()` => `isAssignableByOtherCode()`
* `JavaExpression.isUnmodifiableByOtherCode()` => `isModifiableByOtherCode()`

`BaseTypeVisitor#visitMethod(MethodTree, Void)` is now `final`.
Subclasses should override `BaseTypeVisitor#processMethodTree(MethodTree)`.

### Closed issues

\#802, #2676, #2780, #2926, #3378, #3612, #3764, #4007, #4964, #5070, #5176,
\#5237, #5541, #6046, #6382, #6388, #6566, #6568, #6570, #6576, #6577, #6631,
\#6635, #6636, #6644.

## Version 3.43.0 (May 1, 2024)

### User-visible changes

Method, constructor, lambda, and method reference type inference has been
greatly improved.  The `-AconservativeUninferredTypeArguments` option is
no longer necessary and has been removed.

Renamed command-line arguments:

* `-AskipDirs` has been renamed to `-AskipFiles`.
   `-AskipDirs` will continue to work for the time being.

New command-line arguments:

* `-AonlyFiles` complements `-AskipFiles`

A specialized inference algorithm for the Resource Leak Checker runs
automatically as part of whole-program inference.

### Implementation details

Deprecated `ObjectCreationNode#getConstructor` in favor of new
`ObjectCreationNode#getTypeToInstantiate()`.

Renamed `AbstractCFGVisualizer.visualizeBlockHelper()` to
`visualizeBlockWithSeparator()`.

Moved methods from `TreeUtils` to subclasses of `TreeUtilsAfterJava11`:

* isConstantCaseLabelTree
* isDefaultCaseLabelTree
* isPatternCaseLabelTree

Renamed `BaseTypeVisitor.checkForPolymorphicQualifiers()` to
`warnInvalidPolymorphicQualifier()`.

### Closed issues

\#979, #4559, #4593, #5058, #5734, #5781, #6071, #6093, #6239, #6297, #6317,
\#6322, #6346, #6373, #6376, #6378, #6379, #6380, #6389, #6393, #6396, #6402,
\#6406, #6407, #6417, #6421, #6430, #6433, #6438, #6442, #6473, #6480, #6507,
\#6531, #6535.

## Version 3.42.0 (December 15, 2023)

### User-visible changes

Method annotation `@AssertMethod` indicates that a method checks a value and
possibly throws an assertion.  Using it can make flow-sensitive type refinement
more effective.

In `org.checkerframework.common.util.debug`, renamed `EmptyProcessor` to `DoNothingProcessor`.
Removed `org.checkerframework.common.util.report.DoNothingChecker`; use `DoNothingProcessor`.
Moved `ReportChecker` from `org.checkerframework.common.util.report` to `org.checkerframework.common.util.count.report`.

## Version 3.41.0 (December 4, 2023)

### User-visible changes

New command-line options:

* `-AassumePureGetters` Unsoundly assume that every getter method is pure

### Implementation details

Added method `isDeterministic()` to the `AnnotationProvider` interface.

`CFAbstractValue#leastUpperBound` and `CFAbstractValue#widenUpperBound` are now
final.  Subclasses should override method `CFAbstractValue#upperBound(V,
TypeMirror, boolean)` instead.

### Closed issues

\#1497, #3345, #6037, #6204, #6276, #6282, #6290, #6296, #6319, #6327.

## Version 3.40.0 (November 1, 2023)

### User-visible changes

Optional Checker:  `checker-util.jar` defines `OptionalUtil.castPresent()` for
suppressing false positive warnings from the Optional Checker.

### Closed issues

\#4947, #6179, #6215, #6218, #6222, #6247, #6259, #6260.

## Version 3.39.0 (October 2, 2023)

### User-visible changes

The Checker Framework runs on a version 21 JVM.
It does not yet soundly check all new Java 21 language features, but it does not
crash when compiling them.

### Implementation details

Dataflow supports all the new Java 21 language features.

* A new node, `DeconstructorPatternNode`, was added, so any implementation of
   `NodeVisitor` must be updated.
* Method `InstanceOfNode.getBindingVariable()` is deprecated; use
   `getPatternNode()` or `getBindingVariables()` instead.

WPI uses 1-based indexing for formal parameters and arguments.

### Closed issues

\#5911, #5967, #6155, #6173, #6201.

## Version 3.38.0 (September 1, 2023)

### User-visible changes

Eliminated the `@SignedPositiveFromUnsigned` annotation, which users were
advised against using.

### Implementation details

Renamed `SourceChecker.processArg()' to`processErrorMessageArg()`.

### Closed issues

\#2156, #5672, #6110, #6111, #6116, #6125, #6129, #6136.

## Version 3.37.0 (August 1, 2023)

### User-visible changes

Removed support for deprecated option `-AuseDefaultsForUncheckedCode`.

The Signedness Checker no longer allows (nor needs) `@UnknownSignedness`
to be written on a non-integral type.

### Implementation details

`QualifierHierarchy`:

* The constructor takes an `AnnotatedTypeFactory`.
* Changes to `isSubtype()`:
  * `isSubtype()` has been renamed to `isSubypeQualifiers()` and made protected.
      Clients that are not in a qualifier hierarchy should call `isSubtypeShallow()`
      or, rarely, new method `isSubtypeQualifiersOnly()`.
  * New public method `isSubtypeShallow()' that takes two more arguments than
      `isSubypeQualifiers()`.
* Similar changes to `greatestLowerBound()` and `leastUpperBound()`.

### Closed issues

\#6076, #6077, #6078, #6098, #6100, #6104, #6113.

## Version 3.36.0 (July 3, 2023)

### User-visible changes

The Initialization Checker issues a `cast.unsafe` warning instead of an
`initialization.cast` error.

The Resource Leak Checker now issues a `required.method.not.known` error
when an expression with type `@MustCallUnknown` has a must-call obligation
(e.g., because it is a parameter annotated as `@Owning`).

The Resource Leak Checker's default MustCall type for type variables has been
changed from `@MustCallUnknown` to `@MustCall({})`.  This change reduces the
number of false positive warnings in code that uses type variables but not
resources.  However, it makes some code that uses type variables and resources
unverifiable with any annotation.

### Implementation details

Deprecated `ElementUtils.getSimpleNameOrDescription()` in favor of `getSimpleDescription()`.

Renamed methods in `AnnotatedTypeMirror`.
The old versions are deprecated.  Because the `*PrimaryAnnotation*` methods
might not return an annotation of a type variable or wildcard, it is better to
call `getEffectiveAnnotation*` or `hasEffectiveAnnotation*` instead.

* `clearAnnotations*()` => `clearPrimaryAnnotations()`
* `getAnnotation*()` => `getPrimaryAnnotation*()`.
* `hasAnnotation*()` => `hasPrimaryAnnotation()`.
* `removeAnnotation*()` => `removePrimaryAnnotation*()`.
* `isAnnotatedInHierarchy()` => `hasPrimaryAnnotationInHierarchy()`
* `removeNonTopAnnotationInHierarchy()` should not be used.

Dataflow Framework:

* New `ExpressionStatementNode` marks an expression that is used as a statement.
* Removed class `StringConcatenateAssignmentNode`, which is now desugared.

`GenericAnnotatedTypeFactory`:

* Renamed `getTypeFactoryOfSubchecker()` to `getTypeFactoryOfSubcheckerOrNull`.
* Added new `getTypeFactoryOfSubchecker()` that never returns null.

Return types changed:

* `GenericAnnotatedTypeFactory.getFinalLocalValues()` return type changed to
   `Map`, though the returned value is still a `HashMap`.
* `BaseTypeChecker.getImmediateSubcheckerClasses()` return type changed to
   `Set`, though the returned value is still a `LinkedHashSet`.

Renamed methods in `CFAbstractValue`:

* `combineOneAnnotation()` => `combineAnnotationWithTypeVar()`
* `combineNoAnnotations()` => `combineTwoTypeVars()`

### Closed issues

\#5908, #5936, #5971, #6019, #6025, #6028, #6030, #6039, #6053, #6060, #6069.

## Version 3.35.0 (June 1, 2023)

### User-visible changes

The Checker Framework no longer issues `type.checking.not.run` errors.
This reduces clutter in the output.

Signedness Checker:

* The receiver type of `Object.hashCode()` is now `@UnknownSignedness`.

### Implementation details

Instead of overriding `isRelevant()`, a type factory implementation should
override `isRelevantImpl()`.  Clients should continue to call `isRelevant()`;
never call `isRelevantImpl()` except as `super.isRelevantImpl()`.

Methods that now return a `boolean` rather than `void`:

* `commonAssignmentCheck()`
* `checkArrayInitialization()`
* `checkLock()`
* `checkLockOfThisOrTree()`
* `ensureExpressionIsEffectivelyFinal()`

Methods that now return `AnnotationMirrorSet` instead of `Set<? extends AnnotationMirror>`:

* `getTopAnnotations()`
* `getBottomAnnotations()`
* `getDefaultTypeDeclarationBounds()`
* `getExceptionParameterLowerBoundAnnotations()`

Renamed `BaseTypeVisitor.checkExtendsImplements()` to `checkExtendsAndImplements()`.

Class `FieldInvariants`:

* constructor now takes an `AnnotatedTypeFactory`
* `isSuperInvariant()` has been renamed to `isStrongerThan()` and
   no longer takes an `AnnotatedTypeFactory`

`CFAbstractValue.validateSet()` takes a type factory rather than a `QualifierHierarchy`.

Removed methods that have been deprecated for over two years.

### Closed issues

\#4170, #5722, #5777, #5807, #5821, #5826, #5829, #5837, #5930.

## Version 3.34.0 (May 2, 2023)

### User-visible changes

The Checker Framework runs under JDK 20 -- that is, it runs on a version 20 JVM.

Explicit lambda parameters are defaulted the same as method parameters.  For
example, in `(String s) -> {...}` the type of `s` is `@NonNull String`.

### Implementation details

Renamings in `AnnotatedTypeFactory`:

* `prepareCompilationUnitForWriting()` => `wpiPrepareCompilationUnitForWriting()`
* `prepareClassForWriting()` => `wpiPrepareClassForWriting()`
* `prepareMethodForWriting()` => `wpiPrepareMethodForWriting()`
   and changed its signature by adding two formal parameters

### Closed issues

\#803, #5739, #5749, #5767, #5781, #5787.

## Version 3.33.0 (April 3, 2023)

### User-visible changes

The new command-line argument `-AwarnRedundantAnnotations` warns about redundant
annotations.  With this flag, a warning is issued if an explicitly written
annotation on a type is the same as the default annotation.  This feature does
not warn about all redundant annotations, only some.

The Value Checker is cognizant of signedness annotations.  This eliminates some
false positive warnings.

### Implementation details

The Checker Framework no longer builds under JDK 8.
However, you can still run the Checker Framework under JDK 8.

### Closed issues

\#3785, #5436, #5708, #5717, #5720, #5721, #5727, #5732.

## Version 3.32.0 (March 2, 2023)

### User-visible changes

Fixed a bug in the Nullness Checker where a call to a side-effecting method did
not make some formal parameters possibly-null.  The Nullness Checker is likely
to issue more warnings for your code.  For ways to eliminate the new warnings,
see <https://checkerframework.org/manual/#type-refinement-side-effects>.

If you supply the `-AinvocationPreservesArgumentNullness` command-line
option, the Nullness Checker unsoundly assumes that arguments passed to
non-null parameters in an invocation remain non-null after the invocation.
This assumption is unsound in general, but it holds for most code.

### Implementation details

Moved `TreeUtils.isAutoGeneratedRecordMember(Element)` to `ElementUtils`.

Renamed `TreeUtils.instanceOfGetPattern()` to `TreeUtils.instanceOfTreeGetPattern()`.

Deprecated `AnnotatedTypes#isExplicitlySuperBounded` and `AnnotatedTypes#isExplicitlyExtendsBounded`
because they are duplicates of `#hasExplicitSuperBound` and `#hasExplicitExtendsBound`.

## Version 3.31.0 (February 17, 2023)

### User-visible changes

Command-line argument `-AshowPrefixInWarningMessages` puts the checker name
on the first line of each warning and error message.

Signedness Checker changes:

* Cast expressions are not subject to type refinement.  When a programmer
   writes a cast such as `(@Signed int) 2`, it is not refined to
   `@SignednessGlb` and cannot be used in an unsigned context.
* When incompatible arguments are passed to `@PolySigned` formal parameters,
   the error is expressed in terms of `@SignednessBottom` rather than the
   greatest lower bound of the argument types.

### Implementation details

Moved `AnnotationMirrorSet` and `AnnotationMirrorMap` from
`org.checkerframework.framework.util` to `org.checkerframework.javacutil`.
Changed uses of `Set<AnnotationMirror>` to `AnnotationMirrorSet` including in APIs.
Removed methods from AnnotationUtils that are no longer useful:
`createAnnotationMap`, `createAnnotationSet`, `createUnmodifiableAnnotationSet`.

### Closed issues

\#5597.

## Version 3.30.0 (February 2, 2023)

### Implementation details

`getQualifierKind()` throws an exception rather than returning null.

Renamed Gradle task `copyJarsToDist` to `assembleForJavac`.

### Closed issues

\#5402, #5486, #5489, #5519, #5524, #5526.

## Version 3.29.0 (January 5, 2023)

### User-visible changes

Dropped support for `-ApermitUnsupportedJdkVersion` command-line argument.
You can now run the Checker Framework under any JDK version, without a warning.

Pass `-Astubs=permit-nullness-assertion-exception.astub` to not be warned about
null pointer exceptions within nullness assertion methods like
`Objects.requireNonNull`.

Pass `-Astubs=sometimes-nullable.astub` to unsoundly permit passing null to
calls if null is sometimes but not always permitted.

### Closed issues

\#5412, #5431, #5435, #5438, #5447, #5450, #5453, #5471, #5472, #5487.

## Version 3.28.0 (December 1, 2022)

### User-visible changes

The Checker Framework runs under JDK 19 -- that is, it runs on a version 19 JVM.

### Implementation details

Renamed `TryFinallyScopeCell` to `LabelCell`.

Renamed `TreeUtils.isEnumSuper` to `isEnumSuperCall`.

### Closed issues

\#5390, #5399, #5390.

## Version 3.27.0 (November 1, 2022)

### User-visible changes

The Constant Value Checker supports new annotation `@DoesNotMatchRegex`.

### Closed issues

\#5238, #5360, #5362, #5387.

## Version 3.26.0 (October 3, 2022)

### User-visible changes

The Checker Framework runs under JDK 18 -- that is, it runs on a version 18 JVM.
(It worked before, but gave a warning that it was not tested.)

Annotations are available for some new JDK 17 APIs (some of those
introduced since JDK 11).

Added `-AnoWarnMemoryConstraints` to change the "Memory constraints are impeding
performance; please increase max heap size" message from a warning to a note.

'unneeded.suppression' warnings can now themselves be suppressed.

### Implementation details

Deprecated `TreeUtils.constructor()` in favor of `TreeUtils.elementFromUse()`.

Added method `isSideEffectFree()` to the `AnnotationProvider` interface.

Deprecated `CFAbstractStore.isSideEffectFree()` in favor of new method
`AnnotationProvider.isSideEffectFree()`.  Note the different contracts of
`PurityUtils.isSideEffectFree()` and `AnnotationProvider.isSideEffectFree()`.

Use `TreeUtils.elementFromDeclaration` and `TreeUtils.elementFromUse` in
preference to `TreeUtils.elementFromTree`, when possible.

For code formatting, use `./gradlew spotlessCheck` and `./gradlew spotlessApply`.
The `checkFormat` and `reformat` Gradle tasks have been removed.

Removed variable `BaseTypeVisitor.inferPurity`.

### Closed issues

\#5081, #5159, #5245, #5302, #5319, #5323.

## Version 3.25.0 (September 1, 2022)

### User-visible changes

Make `mustcall.not.inheritable` a warning rather than an error.

The Property File Checker, Internationalization Checker, and Compiler
Message Checker use `File.pathSeparator` to separate property file paths in
`-Apropfiles`, rather than ':'.

Added `DoNothingChecker` that does nothing.

### Closed issues

\#5216, #5240, #5256, #5273.

## Version 3.24.0 (August 3, 2022)

### User-visible changes

Performance improvements.

Minor bug fixes and enhancements.

### Implementation details

Prefer `SystemUtil.jreVersion` to `SystemUtil.getJreVersion()`.

### Closed issues

\#5200, #5216.

## Version 3.23.0 (July 11, 2022)

### User-visible changes

By default, command-line argument `-AstubWarnIfNotFound` is treated as true
for stub files provided on the command line and false for built-in stub
files.  Use `-AstubWarnIfNotFound` to enable it for all stub files, and use
new `-AstubNoWarnIfNotFound` to disable it for all stub files.

New command-line argument `-ApermitStaticOwning` suppresses Resource Leak
Checker warnings related to static owning fields.

New command-line argument `-ApermitInitializationLeak` suppresses Resource Leak
Checker warnings related to field initialization.

### Closed issues

\#4855, #5151, #5166, #5172, #5175, #5181, #5189.

## Version 3.22.2 (June 14, 2022)

### Implementation details

Expose CFG APIs to allow inserting jumps and throws.

## Version 3.22.1 (June 1, 2022)

### Closed issues

\#58, #5136, #5138, #5142, #5143.

## Version 3.22.0 (May 2, 2022)

### User-visible changes

The Signedness Checker now checks calls to `equals()` as well as to `==`.  When
two formal parameter types are annotated with @PolySigned, the two arguments at
a call site must have the same signedness type annotation. (This differs from
the standard rule for polymorphic qualifiers.)

### Implementation details

When passed a NewClassTree that creates an anonymous constructor,
AnnotatedTypeFactory#constructorFormUse now returns the type of the anonymous
constructor rather than the type of the super constructor invoked in the
anonymous classes constructor.  If the super constructor has explicit
annotations, they are copied to the anonymous classes constructor.

### Closed issues

\#5113.

## Version 3.21.4 (April 1, 2022)

### Closed issues

\#5086.

## Version 3.21.3 (March 1, 2022)

### Closed issues

\#2847, #4965, #5039, #5042, #5047.

## Version 3.21.2 (February 1, 2022)

### User-visible changes

The `wpi.sh` script supports non-standard names for build system compile targets
via the new `-c` command-line option.

The Checker Framework now more precisely computes and checks the type of the
pattern variable in a pattern match instanceof.

### Implementation details

Deprecated CFGLambda.getMethod{Name} in favor of getEnclosingMethod{Name}.

### Closed issues

\#4615, #4993, #5006, #5007, #5008, #5013, #5016, #5021.

## Version 3.21.1 (January 7, 2022)

### User-visible changes

The Checker Framework Gradle Plugin now works incrementally:  if you change just
one source file, then Gradle will recompile just that file rather than all
files.

### Closed issues

\#2401, #4994, #4995, #4996.

## Version 3.21.0 (December 17, 2021)

### User-visible changes

The Checker Framework now more precisely computes the type of a switch expression.

### Implementation details

The Dataflow Framework now analyzes switch expressions and switch statements
that use the new `->` case syntax. To do so, a new node, SwitchExpressionNode,
was added.

### Closed issues

\#2373, #4934, #4977, #4979, #4987.

## Version 3.20.0 (December 6, 2021)

### User-visible changes

The Checker Framework now runs on code that contains switch expressions and
switch statements that use the new `->` case syntax, but treats them
conservatively. A future version will improve precision.

### Implementation details

The Dataflow Framework can be run on code that contains switch expressions and
switch statements that use the new `->` case syntax, but it does not yet
analyze the cases in a switch expression and it treats `->` as `:`. A future
version will do so.

Removed methods and classes that have been deprecated for more than one year:

* Old way of constructing qualifier hierarchies
* `@SuppressWarningsKeys`
* `RegularBlock.getContents()`
* `TestUtilities.testBooleanProperty()`
* `CFAbstractTransfer.getValueWithSameAnnotations()`

### Closed issues

\#4911, #4948, #4965.

## Version 3.19.0 (November 1, 2021)

### User-visible changes

The Checker Framework runs under JDK 17 -- that is, it runs on a version 17 JVM.
The Checker Framework also continues to run under JDK 8 and JDK 11.  New
command-line argument `-ApermitUnsupportedJdkVersion` lets you run the Checker
Framework on any JDK (version 8 or greater) without a warning about an
unsupported JDK version.  The Checker Framework does not yet run on code that
contains switch expressions.

### Implementation details

Removed `org.checkerframework.framework.type.VisitorState`
Removed `AnnotatedTypeFactory#postTypeVarSubstitution`

Deprecated methods in AnnotatedTypeFactory:

* `getCurrentClassTree`
* `getCurrentMethodReceiver`

### Closed issues

\#4932, #4924, #4908, #3014.

## Version 3.18.1 (October 4, 2021)

### Closed issues

\#4902 and #4903.

## Version 3.18.0 (September 1, 2021)

### User-visible changes

Java records are type-checked.  Thanks to Neil Brown.

### Closed issues

\#4838, #4843, #4852, #4853, #4861, #4876, #4877, #4878, #4878, #4889, #4889.

## Version 3.17.0 (August 3, 2021)

### User-visible changes

`-Ainfer` can now infer postcondition annotations that reference formal parameters
(e.g. `"#1"`, `"#2"`) and the receiver (`"this"`).

### Implementation details

Method renamings and signature changes (old methods are removed) in `GenericAnnotatedTypeFactory`:

<!-- markdownlint-disable line-length -->

* `getPreconditionAnnotation(VariableElement, AnnotatedTypeMirror)` => `getPreconditionAnnotations(String, AnnotatedTypeMirror, AnnotatedTypeMirror)`
* `getPostconditionAnnotation(VariableElement, AnnotatedTypeMirror, List<AnnotationMirror>)` => `getPostconditionAnnotations(String, AnnotatedTypeMirror, AnnotatedTypeMirror, List<AnnotationMirror>)`
* `getPreOrPostconditionAnnotation(VariableElement, AnnotatedTypeMirror, Analysis.BeforeOrAfter, List<AnnotationMirror>)` => `getPreOrPostconditionAnnotations(String, AnnotatedTypeMirror, AnnotatedTypeMirror, Analysis.BeforeOrAfter, List<AnnotationMirror>)`
* `requiresOrEnsuresQualifierAnno(VariableElement, AnnotationMirror, Analysis.BeforeOrAfter)` => `createRequiresOrEnsuresQualifier(String, AnnotationMirror, AnnotatedTypeMirror, Analysis.BeforeOrAfter, List<AnnotationMirror>)`

Method renamings and signature changes (old method is removed) in `WholeProgramInferenceStorage`:

* `getPreOrPostconditionsForField(Analysis.BeforeOrAfter, ExecutableElement, VariableElement, AnnotatedTypeFactory)` =>  `getPreOrPostconditions(Analysis.BeforeOrAfter, ExecutableElement, String, AnnotatedTypeMirror, AnnotatedTypeFactory)`

<!-- markdownlint-enable line-length -->

Method renamings:

* `CFAbstractAnalysis.getFieldValues` => `getFieldInitialValues`

The following methods no longer take a `fieldValues` parameter:

* `GenericAnnotatedTypeFactory#createFlowAnalysis`
* `CFAnalysis` constructor
* `CFAbstractAnalysis#performAnalysis`
* `CFAbstractAnalysis` constructors

### Closed issues

\#4685, #4689, #4785, #4805, #4806, #4815, #4829, #4849.

## Version 3.16.0 (July 13, 2021)

### User-visible changes

You can run the Checker Framework on a JDK 16 JVM.  You can pass the `--release
16` command-line argument to the compiler.  You may need to add additional
command-line options, such as `--add-opens`; see the Checker Framework manual.
New syntax, such as records and switch expressions, is not yet supported or
type-checked; that will be added in a future release.  Thanks to Neil Brown for
the JDK 16 support.

The Lock Checker supports a new type, `@NewObject`, for the result of a
constructor invocation.

The `-Ainfer` command-line argument now outputs purity annotations even if
neither `-AsuggestPureMethods` nor `-AcheckPurityAnnotations` is supplied
on the command line.

### Implementation details

Method renamings (the old methods remain but are deprecated):

* `AnnotationFileElementTypes.getDeclAnnotation` => `getDeclAnnotations`

Method renamings (the old methods were removed):

* `AnnotatedTypeMirror.clearAnnotations =>`clearPrimaryAnnotations`

Method renamings in `DefaultTypeHierarchy` (the old methods were removed):

* `visitIntersectionSupertype` => `visitIntersectionSupertype`
* `visitIntersectionSubtype` => `visitIntersection_Type`
* `visitUnionSubtype` => `visitUnion_Type`
* `visitTypevarSubtype` => `visitTypevar_Type`
* `visitTypevarSupertype` => `visitType_Typevar`
* `visitWildcardSubtype` => `visitWildcard_Type`
* `visitWildcardSupertype` => `visitType_Wildcard`

Method renamings in `AnnotatedTypes` (the old methods were removed):

* `expandVarArgs` => `expandVarArgsParameters`
* `expandVarArgsFromTypes` => `expandVarArgsParametersFromTypes`

### Closed issues

\#3013, #3754, #3791, #3845, #4523, #4767.

## Version 3.15.0 (June 18, 2021)

### User-visible changes

The Resource Leak Checker ensures that certain methods are called on an
object before it is de-allocated. By default, it enforces that `close()` is
called on any expression whose compile-time type implements `java.io.Closeable`.

### Implementation details

Method renamings (the old methods remain but are deprecated):

* `AnnotatedDeclaredType#wasRaw` => `isUnderlyingTypeRaw`
* `AnnotatedDeclaredType#setWasRaw` => `setIsUnderlyingTypeRaw`

### Closed issues

\#4549, #4646, #4684, and #4699.

## Version 3.14.0 (June 1, 2021)

### User-visible changes

The Units Checker supports new qualifiers (thanks to Rene Kraneis):

* `@Volume`, `@m3`, `@mm3`, `@km3`
* `@Force`, `@N`, `@kN`
* `@t` (metric ton, a unit of mass)

Stub files can now override declaration annotations in the annotated JDK.
Previously, stub files only overrode type annotations in the annotated JDK.

Command-line argument `-AstubWarnIfNotFound` is treated as true for stub
files provided on the command line.

### Implementation details

Method `SourceChecker.getProperties` takes a third formal parameter `permitNonExisting`.

Method `TreeUtils.getMethodName()` returns a `String` rather than a `Name`.

Removed CheckerDevelMain.

### Closed issues

\#3993, #4116, #4586, #4598, #4612, #4614.

## Version 3.13.0 (May 3, 2021)

### Survey

If you use the Checker Framework, please answer a 3-question survey about what
version of Java you use.  It will take less than 1 minute to complete.  Please
answer it at
<https://docs.google.com/forms/d/1Bbt34c_3nDItHsBnmEfumoyrR-Zxhvo3VTHucXwfMcQ>.
Thanks!

### User-visible changes

Command-line argument -AassumeKeyFor makes the Nullness Checker and Map Key
Checker unsoundly assume that the argument to `Map.get` is a key for the
receiver map.

Warning message keys are shorter.  This reduces clutter in error messages and in
`@SuppressWarnings` annotations.  Most ".type.invalid", ".type.incompatible",
".invalid", and ".not.satisfied" suffixes and "type.invalid." prefixes have been
removed, and most ".invalid." substrings have been changed to ".".

The Checker Framework no longer crashes on code that contains binding
variables (introduced in Java 14 for `instanceof` pattern matching), and
such variables are reflected in the control flow graph (CFG).  Thanks to
Chris Day for this change.  However, note that the Checker Framework only
has full support for Java 8 and Java 11.

New command-line argument `-AstubWarnNote` makes stub file warnings notes
rather than warnings.

Removed the StubGenerator section from the manual, because changes in JDK 11
have broken the StubGenerator program.

### Implementation details

Method renamings:

* `DependentTypesHelper.atReturnType` => `atMethodBody`

### Closed issues

\#1268, #3039, #4410, #4550, #4558, #4563, #4566, #4567, #4571, #4584, #4591,
\#4594, #4600.

## Version 3.12.0 (April 1, 2021)

### User-visible changes

New FAQ item "How should I annotate code that uses generics?" gives
examples of annotations on type variables, together with their meaning.

`-Ainfer=ajava` uses ajava files (rather than jaif files or stub files)
internally during whole-program inference.

The Optional Checker supports a new annotation `@OptionalBottom` that
stands for (only) the `null` value.

The `value` element/argument to `@EnumVal` is now required.  Previously it
defaulted to an empty array.

### Implementation details

A precondition or normal postcondition annotation's `value` element must have
type `String[]`, not `String`.  A conditional postcondition annotation's
`expression` element must have type `String[]`, not `String`.  These changes
will not affect users (any programmer-written annotation that was legal before
will still be legal), but it may affect checker implementations.

`JavaExpressionParseUtil`:
`JavaExpressionParseUtil#parse` no longer viewpoint-adapts Java expressions. It
just converts the expression `String` to a `JavaExpression`.  To that end,
`JavaExpressionParseUtil.JavaExpressionContext` has been removed and
`JavaExpressionParseUtil#parse` no longer takes a context object.  Most calls to
`JavaExpressionParseUtil#parse` should be replaced with a call to one of the
methods in `StringToJavaExpressions`.

Renamed `AnnotatedTypeComparer` to `DoubleAnnotatedTypeScanner`. In the new
class, the method `compare` was renamed `defaultAction`. The method `combineRs`
was replaced by `reduce`.

Removed methods:

* `AnnotationUtils.getElementValueArrayOrSingleton`
* `DependentTypesHelper.standardizeNewClassTree`: use `atExpression` instead
* `DependentTypesHelper.standardizeString`: override one of the methods
   explained in the Javadoc of `convertAnnotationMirror`

Method renamings:

* `DefaultQualifierForUseTypeAnnotator.getSupportAnnosFromDefaultQualifierForUses`
  => `getDefaultQualifierForUses`
* In `DependentTypesHelper`:
  * `check*` => `check*ForErrorExpressions`
  * `viewpointAdaptConstructor` => `atConstructorInvocation`
  * `viewpointAdaptMethod` => `atMethodInvocation`
  * `viewpointAdaptTypeVariableBounds` => `atParameterizedTypeUse`
  * `standardizeClass` =>  `atTypeDecl`
  * `standardizeExpression` => `atExpression`
  * `standardizeFieldAccess` => `atFieldAccess`
  * `standardizeReturnType` => `atReturnType`
  * `standardizeVariable` => `atVariableDeclaration`

Deprecated some overloads in `AnnotationUtils` that take a `CharSequence`
(use an overload that takes an `ExecutablElement`):

* `getElementValueArray`
* `getElementValueClassName`
* `getElementValueClassNames`
* `getElementValueEnumArray`
* `getElementValueEnum`
* `getElementValue`
* `getElementValuesWithDefaults`

Deprecated methods in `AnnotationUtils`:

* `areSameByClass`: use `areSameByName`
* `getElementValuesWithDefaults`: use a `getElementValue*` method

Removed deprecated `PluginUtil` class.

### Closed issues

\#1376, #3740, #3970, #4041, #4254, #4346, #4355, #4358, #4372, #4381, #4384,
\#4417, #4449, #4452, #4480.

## Version 3.11.0 (March 1, 2021)

### User-visible changes

In a stub file for a class C, you may write a declaration for a method that is
inherited by C but not defined by it.  Previously, such stub declarations were
ignored.  For more information, see the manual's documentation of "fake
overrides".

Nullness Checker error message key changes:

* `known.nonnull` => `nulltest.redundant`
* `initialization.static.fields.uninitialized` => `initialization.static.field.uninitialized`,
   and it is now issued on the field rather than on the class
* new `initialization.field.uninitialized` is issued on the field instead of
   `initialization.fields.uninitialized` on the class, if there is no
   explicitly-written constructor.

Signature Checker supports two new type qualifiers:

* `@CanonicalNameAndBinaryName`
* `@CanonicalNameOrPrimitiveType`

### Implementation details

You can make a variable's default type depend on its name, or a method
return type default depend on the method's name.  To support this feature,
`@DefaultFor` has new elements `names` and `namesExceptions`.

Changes to protected fields in `OverrideChecker`:

* Removed `overriderMeth`, `overriderTyp`, `overriddenMeth`, `overriddenTyp`
* Renamed `methodReference` => `isMethodReference`
* Renamed `overridingType` => `overriderType`
* Renamed `overridingReturnType` => `overriderReturnType`

Changes to JavaExpression parsing:

* The signatures of these methods changed; see Javadoc.
  * `JavaExpressionParseUtil#parse`
  * `DependentTypesHelper#standardizeString`
* These methods moved:
  * `GenericAnnotatedTypeFactory#standardizeAnnotationFromContract` => `DependentTypesHelper`
  * `JavaExpressionParseUtil#fromVariableTree` => `JavaExpression`

Changes to JavaExpressionContext:

* New method
  JavaExpressionContext#buildContextForMethodDeclaration(MethodTree, SourceChecker)
  replaces all overloads of buildContextForMethodDeclaration.

Parsing a Java expression no longer requires the formal parameters
`AnnotationProvider provider` or `boolean allowNonDeterministic`.  Methods
in `JavaExpression` with simplified signatures include

* `fromArrayAccess`
* `fromNodeFieldAccess`
* `fromNode`
* `fromTree`
* `getParametersOfEnclosingMethod`
* `getReceiver`

`CFAbstractStore.insertValue` does nothing if passed a nondeterministic
expression.  Use new method `CFAbstractStore.insertValuePermitNondeterministic`
to map a nondeterministic expression to a value.

### Closed issues

\#862, #3631, #3991, #4031, #4206, #4207, #4226, #4231, #4248, #4263, #4265,
\#4279, #4286, #4289.

## Version 3.10.0 (February 1, 2021)

### User-visible changes

Moved utility classes from `checker-qual.jar` to the new `checker-util.jar`.
Also, added `util` to the end of all the packages of the utility classes.

In Maven Central, `checker.jar` no longer contains duplicates of qualifiers in
`checker-qual.jar`, but rather uses a Maven dependency. A fat jar file with all
the dependencies (like the old `checker.jar`) is available in Maven Central with
the classifier "all".

When supplying the `-Ainfer=...` command-line argument, you must also supply `-Awarns`.

Replaced several error message keys:

* `contracts.precondition.expression.parameter.name`
* `contracts.postcondition.expression.parameter.name`
* `contracts.conditional.postcondition.expression.parameter.name`
* `method.declaration.expression.parameter.name`
by new message keys:
* `expression.parameter.name`
* `expression.parameter.name.shadows.field`

### Implementation details

Deprecated `ElementUtils.enclosingClass`; use `ElementUtils.enclosingTypeElement`.

Removed classes (use `SourceChecker` instead):

* `BaseTypeContext`
* `CFContext`
* `BaseContext`

Removed methods:

* `SourceChecker.getContext()`: it returned the receiver
* `SourceChecker.getChecker()`: it returned the receiver
* `AnnotatedTypeFactory.getContext()`: use `getChecker()`
* methods on `TreePath`s from class 'TreeUtils`; use the versions in`TreePathUtil`.

Moved class:

* org.checkerframework.framework.util.PurityUnqualified to
   org.checkerframework.framework.qual.PurityUnqualified

Renamed methods:

* `AnnotatedTypeMirror.directSuperTypes` => `directSupertypes` (note
   capitalization) for consistency with `javax.lang.model.util.Types`
* `AnnotatedTypeMirror.removeAnnotation(Class)` => `removeAnnotationByClass`
* `MethodCall.getParameters` => `getArguments`
* `MethodCall.containsSyntacticEqualParameter` => `containsSyntacticEqualArgument`
* `ArrayAccess.getReceiver` => `getArray`

### Closed issues

\#3325 , #3474.

## Version 3.9.1 (January 13, 2021)

### Implementation details

Copied methods on `TreePath`s from class 'TreeUtils` to new class `TreePathUtil`.
(The methods in TreePath will be deleted in the next release.)

* `TreeUtils.enclosingClass` => `TreePathUtil.enclosingClass`
* `TreeUtils.enclosingMethod` => `TreePathUtil.enclosingMethod`
* `TreeUtils.enclosingMethodOrLambda` => `TreePathUtil.enclosingMethodOrLambda`
* `TreeUtils.enclosingNonParen` => `TreePathUtil.enclosingNonParen`
* `TreeUtils.enclosingOfClass` => `TreePathUtil.enclosingOfClass`
* `TreeUtils.enclosingOfKind` => `TreePathUtil.enclosingOfKind`
* `TreeUtils.enclosingTopLevelBlock` => `TreePathUtil.enclosingTopLevelBlock`
* `TreeUtils.enclosingVariable` => `TreePathUtil.enclosingVariable`
* `TreeUtils.getAssignmentContext` => `TreePathUtil.getAssignmentContext`
* `TreeUtils.inConstructor` => `TreePathUtil.inConstructor`
* `TreeUtils.isTreeInStaticScope` => `TreePathUtil.isTreeInStaticScope`
* `TreeUtils.pathTillClass` => `TreePathUtil.pathTillClass`
* `TreeUtils.pathTillOfKind` => `TreePathUtil.pathTillOfKind`

### Closed issues

\#789, #3202, #4071, #4083, #4114, #4115.

## Version 3.9.0 (January 4, 2021)

### User-visible changes

New scripts `checker/bin/wpi.sh` and `checker/bin/wpi-many.sh` run whole-program
inference, without modifying the source code of the target programs.

The `-Ainfer` command-line argument now infers

* method preconditions (`@RequiresQualifiers`, `@RequiresNonNull`)
* method postconditions (`@EnsuresQualifiers`, `@EnsuresNonNull`)
* `@MonotonicNonNull`

The Called Methods Checker supports the -AdisableReturnsReceiver command-line option.

The Format String Checker recognizes Error Prone's `@FormatMethod` annotation.

Use of `@SuppressWarnings("fbc")` to suppress initialization warnings is deprecated.

### Implementation details

Class renamings:

* `StubParser` => `AnnotationFileParser`
* `Receiver` => `JavaExpression`
   Also related class and method renamings, such as
  * `FlowExpressions.internalReprOf` => `JavaExpressions.fromNode`
* In the Dataflow Framework:
  * `ThisLiteralNode` => `ThisNode`
  * `ExplicitThisLiteralNode` => `ExplicitThisNode`
  * `ImplicitThisLiteralNode` => `ImplicitThisNode`

Method deprecations:

* Deprecated `AnnotatedTypeFactory.addAliasedAnnotation`; use `addAliasedTypeAnnotation`

### Closed issues

\#765, #2452, #2953, #3377, #3496, #3499, #3826, #3956, #3971, #3974, #3994,
\#4004, #4005, #4018, #4032, #4068, #4070.

## Version 3.8.0 (December 1, 2020)

### User-visible changes

The Initialized Fields Checker warns when a field is not initialized by a
constructor.  This is more general than the Initialization Checker, which
only checks that `@NonNull` fields are initialized.

The manual describes how to modify an sbt build file to run the Checker
Framework.

The -AwarnUnneededSuppressions command-line option warns only about
suppression strings that contain a checker name.

The -AwarnUnneededSuppressionsExceptions=REGEX command-line option
partially disables -AwarnUnneededSuppressions.  Most users don't need this.

### Implementation details

Added classes `SubtypeIsSubsetQualifierHierarchy` and
`SubtypeIsSupersetQualifierHierarchy`.

Moved the `contractsUtils` field from the visitor to the type factory.

Class renamings:

* `ContractsUtils` => `ContractsFromMethod`

Method renamings:

* `ElementUtils.getVerboseName` => `ElementUtils.getQualifiedName`
* `ElementUtils.getSimpleName` => `ElementUtils.getSimpleSignature`

Field renamings:

* `AnnotatedTypeMirror.actualType` => `AnnotatedTypeMirror.underlyingType`

Added a formal parameter to methods in `MostlyNoElementQualifierHierarchy`:

* `leastUpperBoundWithElements`
* `greatestLowerBoundWithElements`

Removed a formal parameter from methods in `BaseTypeVisitor`:

* `checkPostcondition`
* `checkConditionalPostcondition`

In `Analysis.runAnalysisFor()`, changed `boolean` parameter to enum `BeforeOrAfter`.

Removed `org.checkerframework.framework.util.AnnotatedTypes#getIteratedType`; use
`AnnotatedTypeFactory#getIterableElementType(ExpressionTree)` instead.

### Closed issues

\#3287, #3390, #3681, #3839, #3850, #3851, #3862, #3871, #3884, #3888, #3908,
\#3929, #3932, #3935.

## Version 3.7.1 (November 2, 2020)

### User-visible changes

The Constant Value Checker supports two new annotations: @EnumVal and @MatchesRegex.

The Nullness Checker supports annotation org.jspecify.annotations.NullnessUnspecified.

### Implementation details

AnnotatedIntersectionType#directSuperTypes now returns
List<? extends AnnotatedTypeMirror>.

The @RelevantJavaTypes annotation is now enforced:  a checker issues a warning
if the programmer writes a type annotation on a type that is not listed.

Deprecated CFAbstractTransfer.getValueWithSameAnnotations(), which is no
longer used.  Added new methods getWidenedValue() and getNarrowedValue().

Renamed TestUtilities.assertResultsAreValid() to TestUtilities.assertTestDidNotFail().

Renamed BaseTypeValidator.isValidType() to BaseTypeValidator.isValidStructurally().

New method BaseTypeVisitor#visitAnnotatedType(List, Tree) centralizes checking
of user-written type annotations, even when parsed in declaration locations.

### Closed issues

\#868, #1908, #2075, #3349, #3362, #3569, #3614, #3637, #3709, #3710, #3711,
\#3720, #3730, #3742, #3760, #3770, #3775, #3776, #3792, #3793, #3794, #3819,
\#3831.

## Version 3.7.0 (October 1, 2020)

### User-visible changes

The new Called Methods Checker tracks methods that have definitely been
called on an object. It automatically supports detecting mis-uses of the
builder pattern in code that uses Lombok or AutoValue.

Accumulation analysis is now supported via a generic Accumulation Checker.
An accumulation analysis is a restricted form of typestate analysis that does
not require a precise alias analysis for soundness. The Called Methods Checker
is an accumulation analysis.

The Nullness Checker supports annotations
org.codehaus.commons.nullanalysis.NotNull,
org.codehaus.commons.nullanalysis.Nullable, and
org.jspecify.annotations.Nullable.

The Signature Checker supports annotations `@CanonicalName` and
`@CanonicalNameOrEmpty`.
The Signature Checker treats `jdk.jfr.Unsigned` as an alias for its own
`@Unsigned` annotation.

The shorthand syntax for the -processor command-line argument applies to
utility checkers, such as the Constant Value Checker.

### Implementation details

A checker implementation may override AnnotatedTypeFactory.getWidenedAnnotations
to provide special behavior for primitive widening conversions.

Deprecated org.checkerframework.framework.util.MultiGraphQualifierHierarchy and
org.checkerframework.framework.util.GraphQualifierHierarchy.  Removed
AnnotatedTypeFactory#createQualifierHierarchy(MultiGraphFactory) and
AnnotatedTypeFactory#createQualifierHierarchyFactory.  See Javadoc of
MultiGraphQualifierHierarchy for instructions on how to use the new classes and
methods.

Renamed methods:

* NumberUtils.isFloatingPoint => TypesUtils.isFloatingPoint
* NumberUtils.isIntegral => TypesUtils.isIntegralPrimitiveOrBoxed
* NumberUtils.isPrimitiveFloatingPoint => TypeKindUtils.isFloatingPoint
* NumberUtils.isPrimitiveIntegral => TypeKindUtils.isIntegral
* NumberUtils.unboxPrimitive => TypeKindUtils.primitiveOrBoxedToTypeKind
* TypeKindUtils.widenedNumericType => TypeKindUtils.widenedNumericType
* TypesUtils.isFloating => TypesUtils.isFloatingPrimitive
* TypesUtils.isIntegral => TypesUtils.isIntegralPrimitive

The CFStore copy constructor now takes only one argument.

### Closed issues

\#352, #354, #553, #722, #762, #2208, #2239, #3033, #3105, #3266, #3275, #3408,
\#3561, #3616, #3619, #3622, #3625, #3630, #3632, #3648, #3650, #3667, #3668,
\#3669, #3700, #3701.

## Version 3.6.1 (September 2, 2020)

Documented that the Checker Framework can issue false positive warnings in
dead code.

Documented when the Signedness Checker permits right shift operations.

### Closed issues

\#3484, #3562, #3565, #3566, #3570, #3584, #3594, #3597, #3598.

## Version 3.6.0 (August 3, 2020)

### User-visible changes

The Interning Checker supports method annotations @EqualsMethod and
@CompareToMethod.  Place them on methods like equals(), compareTo(), and
compare() to permit certain uses of == on non-interned values.

Added an overloaded version of NullnessUtil.castNonNull that takes an error message.

Added a new option `-Aversion` to print the version of the Checker Framework.

New CFGVisualizeLauncher command-line arguments:

* `--outputdir`: directory in which to write output files
* `--string`: print the control flow graph in the terminal
All CFGVisualizeLauncher command-line arguments now start with `--` instead of `-`.

### Implementation details

`commonAssignmentCheck()` now takes an additional argument.  Type system
authors must update their overriding implementations.

Renamed methods:

* GenericAnnotatedTypeFactory#addAnnotationsFromDefaultQualifierForUse => #addAnnotationsFromDefaultForType
* BaseTypeValidator#shouldCheckTopLevelDeclaredType => #shouldCheckTopLevelDeclaredOrPrimitiveType

Removed org.checkerframework.framework.test.FrameworkPer(Directory/File)Test classes.
Use CheckerFrameworkPer(Directory/File)Test instead.

### Closed issues

\#1395, #2483, #3207, #3223, #3224, #3313, #3381, #3422, #3424, #3428, #3429,
\#3438, #3442, #3443, #3447, #3449, #3461, #3482, #3485, #3495, #3500, #3528.

## Version 3.5.0 (July 1, 2020)

### User-visible changes

Use "allcheckers:" instead of "all:" as a prefix in a warning suppression string.
Writing `@SuppressWarnings("allcheckers")` means the same thing as
`@SuppressWarnings("all")`, unless the `-ArequirePrefixInWarningSuppressions`
command-line argument is supplied.  See the manual for details.

It is no longer necessary to pass -Astubs=checker.jar/javadoc.astub when
compiling a program that uses Javadoc classes.

Renamed command-line arguments:

* -AshowSuppressWarningKeys to -AshowSuppressWarningsStrings

The Signature Checker no longer considers Java keywords to be identifiers.
Renamed Signature Checker annotations:

* @BinaryNameInUnnamedPackage => @BinaryNameWithoutPackage
* @FieldDescriptorForPrimitiveOrArrayInUnnamedPackage => @FieldDescriptorWithoutPackage
* @IdentifierOrArray => @ArrayWithoutPackage
Added new Signature Checker annotations:
* @BinaryNameOrPrimitiveType
* @DotSeparatedIdentifiersOrPrimitiveType
* @IdentifierOrPrimitiveType

The Nullness Checker now treats `System.getProperty()` soundly.  Use
`-Alint=permitClearProperty` to disable special treatment of
`System.getProperty()` and to permit undefining built-in system properties.

Class qualifier parameters:  When a generic class represents a collection,
a user can write a type qualifier on the type argument, as in
`List<@Tainted Character>` versus `List<@Untainted Character>`.  When a
non-generic class represents a collection with a hard-coded type (as
`StringBuffer` hard-codes `Character`), you can use the new class qualifier
parameter feature to distinguish `StringBuffer`s that contain different
types of characters.

The Dataflow Framework supports backward analysis.  See its manual.

### Implementation details

Changed the types of some fields and methods from array to List:

* QualifierDefaults.validLocationsForUncheckedCodeDefaults()
* QualifierDefaults.STANDARD_CLIMB_DEFAULTS_TOP
* QualifierDefaults.STANDARD_CLIMB_DEFAULTS_BOTTOM
* QualifierDefaults.STANDARD_UNCHECKED_DEFAULTS_TOP
* QualifierDefaults.STANDARD_UNCHECKED_DEFAULTS_BOTTOM

Dataflow Framework: Analysis is now an interface.  Added AbstractAnalysis,
ForwardAnalysis, ForwardTransferFunction, ForwardAnalysisImpl,
BackwardAnalysis, BackwardTransferFunction, and BackwardAnalysisImpl.
To adapt existing code:

* `extends Analysis<V, S, T>` => `extends ForwardAnalysisImpl<V, S, T>`
* `implements TransferFunction<V, S>`
  => `implements ForwardTransferFunction<V, S>`

In AbstractQualifierPolymorphism, use AnnotationMirrors instead of sets of
annotation mirrors.

Renamed meta-annotation SuppressWarningsKeys to SuppressWarningsPrefix.
Renamed SourceChecker#getSuppressWarningsKeys(...) to getSuppressWarningsPrefixes.
Renamed SubtypingChecker#getSuppressWarningsKeys to getSuppressWarningsPrefixes.

Added GenericAnnotatedTypeFactory#postAnalyze, changed signature of
GenericAnnotatedTypeFactory#handleCFGViz, and removed CFAbstractAnalysis#visualizeCFG.

Removed methods and classes marked deprecated in release 3.3.0 or earlier.

### Closed issues

\#1362, #1727, #2632, #3249, #3296, #3300, #3356, #3357, #3358, #3359, #3380.

## Version 3.4.1 (June 1, 2020)

-Ainfer now takes an argument:

* -Ainfer=jaifs uses .jaif files to store the results of whole-program inference.
* -Ainfer=stubs uses .astub files to store the results of whole-program inference.
* -Ainfer is deprecated but is the same as -Ainfer=jaifs, for backwards compatibility.

New command-line option:

* `-AmergeStubsWithSource` If both a stub file and a source file are available,
  use both.

### Closed issues

\#2893, #3021, #3128, #3160, #3232, #3277, #3285, #3289, #3295, #3302, #3305,
\#3307, #3310, #3316, #3318, #3329.

## Version 3.4.0 (May 3, 2020)

The annotated jdk8.jar is no longer used.  You should remove any occurrence of
  -Xbootclasspath/p:.../jdk8.jar
from your build scripts.  Annotations for JDK 8 are included in checker.jar.

The Returns Receiver Checker enables documenting and checking that a method
returns its receiver (i.e., the `this` parameter).

### Closed issues

\#3267, #3263, #3217, #3212, #3201, #3111, #3010, #2943, #2930.

## Version 3.3.0 (April 1, 2020)

### User-visible changes

New command-line options:

* `-Alint=trustArrayLenZero` trust `@ArrayLen(0)` annotations when determining
  the type of Collections.toArray.

Renamings:

* `-AuseDefaultsForUncheckedCode` to `-AuseConservativeDefaultsForUncheckedCode`
    The old name works temporarily but will be removed in a future release.

For collection methods with `Object` formal parameter type, such as
contains, indexOf, and remove, the annotated JDK now forbids null as an
argument.  To make the Nullness Checker permit null, pass
`-Astubs=collection-object-parameters-may-be-null.astub`.

The argument to @SuppressWarnings can be a substring of a message key that
extends at each end to a period or an end of the key.  (Previously, any
substring worked, including the empty string which suppressed all warnings.
Use "all" to suppress all warnings.)

All postcondition annotations are repeatable (e.g., `@EnsuresNonNull`,
`@EnsuresNonNullIf`, ...).

Renamed wrapper annotations (which users should not write):

* `@DefaultQualifiers` => `@DefaultQualifier.List`
* `@EnsuresQualifiersIf` => `@EnsuresQualifierIf.List`
* `@EnsuresQualifiers` => `@EnsuresQualifier.List`
* `@RequiresQualifiers` => `@RequiresQualifier.List`

### Implementation details

Removed `@DefaultInUncheckedCodeFor` and
`@DefaultQualifierInHierarchyInUncheckedCode`.

Renamings:

* applyUncheckedCodeDefaults() to applyConservativeDefaults()
* useUncheckedCodeDefault() to useConservativeDefault()
* AnnotatedTypeReplacer to AnnotatedTypeCopierWithReplacement
* AnnotatedTypeMerger to AnnotatedTypeReplacer

Deprecated the `framework.source.Result` class; use `DiagMessage` or
`List<DiagMessage>` instead.  If you were creating a `Result` just to
pass it to `report`, then call new methods `reportError` and
`reportWarning` instead.

AbstractTypeProcessor#typeProcessingOver() always gets called.

### Closed issues

\#1307, #1881, #1929, #2432, #2793, #3040, #3046, #3050, #3056, #3083, #3124,
\#3126, #3129, #3132, #3139, #3149, #3150, #3167, #3189.

## Version 3.2.0 (March 2, 2020)

@SuppressWarnings("initialization") suppresses only warnings whose key
contains "initialization".  Previously, it suppressed all warnings issued
by the Nullness Checker or the Initialization Checker.

### Closed issues

\#2719, #3001, #3020, #3069, #3093, #3120.

## Version 3.1.1 (February 3, 2020)

New command-line options:

* -AassumeDeterministic Unsoundly assume that every method is deterministic
* -AassumePure Unsoundly assume that every method is pure

Renamed -Anocheckjdk to -ApermitMissingJdk.
The old version still works, for backward compatibility.

Renamed -Alint=forbidnonnullarraycomponents to
-Alint=soundArrayCreationNullness.  The old version still works, for
backward compatibility.

Implementation details:

* Deprecated QualifierHierarchy#getTypeQualifiers.
* Deprecated Analysis#Analysis(ProcessingEnvironment) and Analysis#Analysis(T,
   int, ProcessingEnvironment); use Analysis#Analysis(), Analysis#Analysis(int),
   Analysis#Analysis(T), and Analysis#Analysis(T, int) instead.
* Renamed SourceChecker#getMessages to getMessagesProperties.
* Renamed one overload of SourceChecker.printMessages to printOrStoreMessage.

### Closed issues

\#2181, #2975, #3018, #3022, #3032, #3036, #3037, #3038, #3041, #3049, #3055,
\#3076.

## Version 3.1.0 (January 3, 2020)

Command-line option -AprintGitProperties prints information about the git
repository from which the Checker Framework was compiled.

### Implementation details

* Removed static cache in AnnotationUtils#areSameByClass and added
   AnnotatedTypeFactory#areSameByClass that uses an instance cache.
* Removed static cache in AnnotationBuilder#fromName and #fromClass.
* ContractsUtils#getPreconditions takes an ExecutableElement as an argument.
* ContractsUtils#getContracts returns a Set.
* Moved ContractUtils.Contract to outer level.
* Renamed ConditionalPostcondition#annoResult to ConditionalPostcondition#resultValue.

### Closed issues

\#2867, #2897, #2972.

## Version 3.0.1 (December 2, 2019)

New command-line option for the Constant Value Checker
`-AnoNullStringsConcatenation` unsoundly assumes that every operand of a String
concatenation is non-null.

### Implementation details

* Moved AnnotatedTypes#hasTypeQualifierElementTypes to AnnotationUtils.
* Deprecated AnnotatedTypes#isTypeAnnotation and AnnotatedTypes#hasTypeQualifierElementTypes.

### Closed issues

\#945, #1224, #2024, #2744, #2809, #2815, #2818, #2830, #2840, #2853, #2854,
\#2865, #2873, #2874, #2878, #2880, #2886, #2888, #2900, #2905, #2919, #2923.

## Version 3.0.0 (November 1, 2019)

The Checker Framework works on both JDK 8 and JDK 11.

* Type annotations for JDK 8 remain in jdk8.jar.
* Type annotations for JDK 11 appear in stub files in checker.jar.

Removed the @PolyAll annotation.

### Implementation details

* Removed all previously deprecated methods.
* AnnotatedTypeFactory#getFnInterfaceFromTree now returns an AnnotatedExecutableType.
* AnnotationUtils#areSame and #areSameByName now only accept non-null
   AnnotationMirrors

### Closed issues

\#1169, #1654, #2081, #2703, #2739, #2749, #2779, #2781, #2798, #2820, #2824,
\#2829, #2842, #2845, #2848.

## Version 2.11.1 (October 1, 2019)

The manual links to the Object Construction Checker.

### Closed issues

\#1635, #2718, #2767.

## Version 2.11.0 (August 30, 2019)

The Checker Framework now uses the Java 9 javac API. The manual describes
how to satisfy this dependency, in a way that works on a Java 8 JVM.
Running the Checker Framework on a Java 9 JVM is not yet supported.

## Version 2.10.1 (August 22, 2019)

### Closed issues

\#1152, #1614, #2031, #2482, #2543, #2587, #2678, #2686, #2690, #2712, #2717,
\#2713, #2721, #2725, #2729.

## Version 2.10.0 (August 1, 2019)

Removed the NullnessRawnessChecker.  Use the NullnessChecker instead.

### Closed issues

\#435, #939, #1430, #1687, #1771, #1902, #2173, #2345, #2470, #2534, #2606,
\#2613, #2619, #2633, #2638.

## Version 2.9.0 (July 3, 2019)

Renamed the Signedness Checker's @Constant annotation to @SignednessGlb.
Introduced an alias, @SignedPositive, for use by programmers.

Annotated the first argument of Opt.get and Opt.orElseThrow as @NonNull.

Removed meta-annotation @ImplicitFor:

* Use the new meta-annotation @QualifierForLiteral to replace
   @ImplicitFor(literals, stringpatterns).
* Use the meta-annotation @DefaultFor to replace @ImplicitFor(typeKinds,
   types).
* Use the new meta-annotation @UpperBoundFor to specify a qualifier upper
   bound for certain types.
* You can completely remove
     @ImplicitFor(typeNames = Void.class, literals = LiteralKind.NULL)
   on bottom qualifiers.
     @DefaultFor(types = Void.class)
   and
     @QualifierForLiterals(literals = LiteralKind.NULL)
   are added to the bottom qualifier by default.

Add @DefaultQualifierOnUse and @NoDefaultQualifierOnUse type declaration annotations

New/changed error message keys:

* initialization.static.fields.uninitialized for uninitialized static fields
* unary.increment and unary.decrement
   replace some occurrences of compound.assignment

### Implementation details

* Renamed QualifierPolymorphism#annotate methods to resolve
* Renamed ImplicitsTreeAnnotator to LiteralTreeAnnotator
* Renamed ImplicitsTypeAnnotator to DefaultForTypeAnnotator
* Removed TypeUseLocation.TYPE_DECLARATION
* Removed InheritedFromClassAnnotator, replace with DefaultQualifierForUseTypeAnnotator
* Rename TreeUtils.isSuperCall and TreeUtils.isThisCall to
 isSuperConstructorCall and isThisConstructorCall

### Closed issues

\#2247, #2391, #2409, #2434, #2451, #2457, #2468, #2484, #2485, #2493, #2505,
\#2536, #2537, #2540, #2541, #2564, #2565, #2585.

## Version 2.8.2 (June 3, 2019)

The Signature Checker supports a new type, @FqBinaryName.

Added a template for a repository that you can use to write a custom checker.

Linked to the Checker Framework Gradle plugin, which makes it easy to run
a checker on a project that is built using the Gradle build tool.

Implementation detail: deprecated TreeUtils.skipParens in favor of
TreeUtils.withoutParens which has the same specification.

### Closed issues

\#2291, #2406, #2469, #2477, #2479, #2480, #2494, #2499.

## Version 2.8.1 (May 1, 2019)

Moved text about the Purity Checker into its own chapter in the manual.

### Closed issues

\#660, #2030, #2223, #2240, #2244, #2375, #2407, #2410, #2415, #2420, #2421,
\#2446, #2447, #2460, #2462.

## Version 2.8.0 (April 3, 2019)

Support `androidx.annotation.RecentlyNonNull` and `RecentlyNullable` (as of
2.6.0, but not previously documented).

The following qualifiers are now repeatable:  `@DefaultQualifier`
`@EnsuresQualifierIf` `@EnsuresQualifier` `@RequiresQualifier`.  Therefore,
users generally do not need to write the following wrapper annotations:
`@DefaultQualifiers` `@EnsuresQualifiersIf` `@EnsuresQualifiers`
`@RequiresQualifiers`.

New command-line option `-ArequirePrefixInWarningSuppressions` makes
`@SuppressWarnings` recognize warning keys of the form
"checkername:key.about.problem" but ignore warning keys of the form
"key.about.problem" without the checker name as a prefix.

New CONSTRUCTOR_RESULT enum constant in TypeUseLocation makes it possible to
set default annotations for constructor results.

Clarified the semantics of annotations on class and constructor declarations.
See Section 25.5 "Annotations on classes and constructors" in the manual.

Interface changes:

* Added protected methods to BaseTypeVisitor so that checkers can change the
   checks for annotations on classes, constructor declarations, and constructor
   invocations.
* Removed BaseTypeVisitor#checkAssignability and BaseTypeVisitor#isAssignable
   methods.
* Renamed AnnotatedTypeFactory#getEnclosingMethod to
   AnnotatedTypeFactory#getEnclosingElementForArtificialTree

### Closed issues

\#2159, #2230, #2318, #2324, #2330, #2334, #2343, #2344, #2353, #2366, #2367,
\#2370, #2371, #2385.

## Version 2.7.0 (March 1, 2019)

The manual links to the AWS crypto policy compliance checker, which enforces
that no weak cipher algorithms are used with the Java crypto API.

The Nullness Checker supports RxJava annotations
io.reactivex.annotations.NonNull and io.reactivex.annotations.Nullable.

The checker-qual artifact (jar file) contains an OSGi manifest.

New TYPE_DECLARATION enum constant in TypeUseLocation makes it possible to
(for example) set defaults annotations for class/interface definitions.

Interface changes:

* Renamed the "value" element of the @HasSubsequence annotation to
   "subsequence".
* Renamed @PolySignedness to @PolySigned.
* Renamed AnnotatedTypeFactory.ParameterizedMethodType to
   ParameterizedExecutableType.

Added missing checks regarding annotations on classes, constructor
declarations, and constructor invocations.  You may see new warnings.

### Closed issues

\#788, #1751, #2147, #2163, #2186, #2235, #2243, #2263, #2264, #2286, #2302,
\#2326, #2327.

## Version 2.6.0 (February 3, 2019)

The manual includes a section about how to use Lombok and the Checker
Framework simultaneously.

Commons CSV has been added to the annotated libraries on Maven Central.

Some error messages have been changed to improve comprehensibility,
such as by adjusting wording or adding additional information.

Relevant to type system implementers:
Renamed method areSameIgnoringValues to areSameByName.

### Closed issues

\#2008, #2166, #2185, #2187, #2221, #2224, #2229, #2234, #2248.
Also fixed false negatives in handling of Map.get().

## Version 2.5.8 (December 5, 2018)

The manual now links to the AWS KMS compliance checker, which enforces
that calls to AWS KMS only generate 256-bit keys.

### Closed issues

\#372, #1678, #2207, #2212, #2217.

## Version 2.5.7 (November 4, 2018)

New @EnsuresKeyFor and @EnsuresKeyForIf method annotations permit
specifying the postcondition that a method gives some value a @KeyFor type.

The manual links to the Rx Thread & Effect Checker, which enforces
UI Thread safety properties for stream-based Android applications.

### Closed issues

\#1014, #2151, #2178, #2180, #2183, #2188, #2190, #2195, #2196, #2198, #2199.

## Version 2.5.6 (October 3, 2018)

Introduce checker-qual-android artifact that is just like the checker-qual
artifact, but the qualifiers have classfile retention.  This is useful for
Android projects.

Removed the code for the checker-compat-qual artifact.  It was only useful
for Java 7, which the Checker Framework no longer supports.  The
checker-compat-qual artifact remains available on Maven Central, with
versions 2.5.5 and earlier.

### Closed issues

\#2135, #2157, #2158, #2164, #2171.

## Version 2.5.5 (August 30, 2018)

Implicit imports (deprecated in November 2014) are no longer supported.

Renamed the testlib Maven artifact to framework-test.

Removed command-line option -AprintErrorStack, which is now the default.
Added -AnoPrintErrorStack to disable it (which should be rare).

Replaced ErrorReporter class with BugInCF and UserError exceptions.

### Closed issues

\#1999, #2008, #2023, #2029, #2074, #2088, #2098, #2099, #2102, #2107.

## Version 2.5.4 (August 1, 2018)

### Closed issues

\#2030, #2048, #2052, #2059, #2065, #2067, #2073, #2082.

## Version 2.5.3 (July 2, 2018)

### Closed issues

\#266, #1248, #1678, #2010, #2011, #2018, #2020, #2046, #2047, #2054.

## Version 2.5.2 (June 1, 2018)

In the Map Key Checker, null is now @UnknownKeyFor.  See the "Map Key Checker"
chapter in the manual for more details.

### Closed issues

\#370, #469, #1701, #1916, #1922, #1959, #1976, #1978, #1981, #1983, #1984,
\#1991, #1992.

## Version 2.5.1 (May 1, 2018)

Added a Maven artifact of the Checker Framework testing library, testlib.

### Closed issues

\#849, #1739, #1838, #1847, #1890, #1901, #1911, #1912, #1913, #1934, #1936,
\#1941, #1942, #1945, #1946, #1948, #1949, #1952, #1953, #1956, #1958.

## Version 2.5.0 (April 2, 2018)

Declaration annotations that are aliases for type annotations are now treated
as if they apply to the top-level type.  See "Declaration annotations" section
in the "Warnings" chapter in the manual for more details.

Ended support for annotations in comments.  See "Migrating away from
annotations in comments" section in the "Handling legacy code" chapter in the
manual for instructions on how to remove annotations from comments.

### Closed issues

\#515, #1667, #1739, #1776, #1819, #1863, #1864, #1865, #1866, #1867, #1870,
\#1876, #1879, #1882, #1898, #1903, #1905, #1906, #1910, #1914, #1915, #1920.

## Version 2.4.0 (March 1, 2018)

Added the Index Checker, which eliminates ArrayIndexOutOfBoundsException.

Added the Optional Checker, which verifies uses of Java 8's Optional class.

Removed the Linear Checker, whose implementation was inconsistent with its
documentation.

Added a @QualifierArgument annotation to be used on pre- and postcondition
  annotations created by @PreconditionAnnotation, @PostconditionAnnotation,
  and @ConditionalPostconditionAnnotation. This allows qualifiers with
  arguments to be used in pre- and postconditions.

Added new type @InternalFormForNonArray to the Signature Checker

Moved annotated libraries from checker/lib/*.jar to the Maven Central Repository:
<https://central.sonatype.com/search?q=org.checkerframework.annotatedlib>

Moved the Javadoc stub file from checker/lib/javadoc.astub to
checker/resources/javadoc.astub.

Simplified the instructions for running the Checker Framework with Gradle.

The Checker Framework Eclipse plugin is no longer released nor supported.

### Closed issues

\#65, #66, #100, #108, #175, #184, #190, #194, #209, #239, #260, #270, #274,
\#293, #302, #303, #306, #321, #325, #341, #356, #360, #361, #371, #383, #385,
\#391, #397, #398, #410, #423, #424, #431, #430, #432, #548, #1131, #1148,
\#1213, #1455, #1504, #1642, #1685, #1770, #1796, #1797, #1801, #1809, #1810,
\#1815, #1817, #1818, #1823, #1831, #1837, #1839, #1850, #1851, #1852, #1861.

## Version 2.3.2 (February 1, 2018)

### Closed issues

\#946, #1133, #1232, #1319, #1625, #1633, #1696, #1709, #1712, #1734, #1738,
\#1749, #1754, #1760, #1761, #1768, #1769, #1781.

## Version 2.3.1 (January 2, 2018)

### Closed issues

\#1695, #1696, #1697, #1698, #1705, #1708, #1711, #1714, #1715, #1724.

## Version 2.3.0 (December 1, 2017)

Removed the deprecated @LazyNonNull type qualifier.
Deprecated most methods in InternalUtils and moved them to either
TreeUtils or TypesUtils. Adapted a few method names and parameter
orders for consistency.

### Closed issues

\#951, #1356, #1495, #1602, #1605, #1623, #1628, #1636, #1641, #1653, #1655,
\#1664, #1665, #1681, #1684, #1688, #1690.

## Version 2.2.2 (November 2, 2017)

The Interning Checker supports a new annotation, @InternedDistinct, which
indicates that the value is not equals() to any other value.

An annotated version of the Commons IO library appears in checker/lib/ .

Closed issue #1586, which required re-opening issues 293 and 341 until
proper fixes for those are implemented.

### Closed issues

\#1386, #1389, #1423, #1520, #1529, #1530, #1531, #1546, #1553, #1555, #1565,
\#1570, #1579, #1580, #1582, #1585, #1586, #1587, #1598, #1609, #1615, #1617.

## Version 2.2.1 (September 29, 2017)

Deprecated some methods in AnnotatedTypeMirror and AnnotationUtils, to
be removed after the 2.2.1 release.

The qualifiers and utility classes in checker-qual.jar are compiled to Java 8
byte code. A new jar, checker-qual7.jar, includes the qualifiers and utility
classes compiled to Java 7 byte code.

### Closed issues

\#724, #1431, #1442, #1459, #1464, #1482, #1496, #1499, #1500, #1506, #1507,
\#1510, #1512, #1522, #1526, #1528, #1532, #1535, #1542, #1543.

## Version 2.2.0 (September 5, 2017)

A Java 8 JVM is required to run the Checker Framework.
You can still typecheck and compile Java 7 (or earlier) code.
With the "-target 7" flag, the resulting .class files still run with JDK 7.

The stub file format has changed to be more similar to regular Java syntax.
Most notably, receiver annotations are written using standard Java 8 syntax
(a special first formal parameter named "this") and inner classes are written
using standard Java syntax (rather than at the top level using a name that
contains "$". You need to update your stub files to conform to the new syntax.

### Closed issues

\#220, #293, #297, #341, #375, #407, #536, #571, #798, #867, #1180, #1214, #1218,
\#1371, #1411, #1427, #1428, #1435, #1438, #1450, #1456, #1460, #1466, #1473,
\#1474.

## Version 2.1.14 (3 August 2017)

Nullness Checker change to annotated JDK:  The type argument to the Class,
Constructor, and Optional classes may now be annotated as @Nullable or
@NonNull.  The nullness of the type argument doesn't matter, but this
enables easier integration with generic clients.

Many crashes and false positives associated with uninferred method type
arguments have been correct. By default, uninferred method type arguments,
which can happen with Java 8 style target type contexts, are silently ignored.
Use the option -AconservativeUninferredTypeArguments to see warnings about
method calls where the Checker Framework fails to infer type arguments.

### Closed issues

\#753, #804, #961, #1032, #1062, #1066, #1098, #1209, #1280, #1316, #1329, #1355,
\#1365, #1366, #1367, #1377, #1379, #1382, #1384, #1397, #1398, #1399, #1402,
\#1404, #1406, #1407.

## Version 2.1.13 (3 July 2017)

Verified that the Checker Framework builds from source on Windows Subsystem
for Linux, on Windows 10 Creators Edition.

The manual explains how to configure Android projects that use Android Studio
3.0 and Android Gradle Plugin 3.0.0, which support type annotations.

### Closed issues

\#146, #1264, #1275, #1290, #1303, #1308, #1310, #1312, #1313, #1315, #1323,
\#1324, #1331, #1332, #1333, #1334, #1347, #1357, #1372.

## Version 2.1.12 (1 June 2017)

The manual links to Glacier, a class immutability checker.

The stubparser license has been updated.  You can now use stubparser under
either the LGPL or the Apache license, whichever you prefer.

### Closed issues

\#254, #1201, #1229, #1236, #1239, #1240, #1257, #1265, #1270, #1271, #1272,
\#1274, #1288, #1291, #1299, #1304, #1305.

## Version 2.1.11 (1 May 2017)

The manual contains new FAQ (frequently asked questions) sections about
false positive warnings and about inference for field types.

### Closed issues

\#989, #1096, #1136, #1228.

## Version 2.1.10 (3 April 2017)

The Constant Value Checker, which performs constant propagation, has been
extended to perform interval analysis -- that is, it determines, for each
expression, a statically-known lower and upper bound.  Use the new
@IntRange annotation to express this.  Thanks to Jiasen (Jason) Xu for this
feature.

### Closed issues

\#134, #216, #227, #307, #334, #437, #445, #718, #1044, #1045, #1051, #1052,
\#1054, #1055, #1059, #1077, #1087, #1102, #1108, #1110, #1111, #1120, #1124,
\#1127, #1132.

## Version 2.1.9 (1 March 2017)

By default, uninferred method type arguments, which can happen with Java 8
style target type contexts, are silently ignored, removing many false
positives.  The new option -AconservativeUninferredTypeArguments can be used to
get the conservative behavior.

### Closed issues

\#1006, #1011, #1015, #1027, #1035, #1036, #1037, #1039, #1043, #1046, #1049,
\#1053, #1072, #1084.

## Version 2.1.8 (20 January 2017)

The Checker Framework webpage has moved to <https://checkerframework.org/>.
Old URLs should redirect to the new one, but please update your links
and let us know if any old links are broken rather than redirecting.

The documentation has been reorganized in the Checker Framework repository.
The manual, tutorial, and webpages now appear under checker-framework/docs/.

### Closed issues

\#770, #1003, #1012.

## Version 2.1.7 (3 January 2017)

Manual improvements:

* Added a link to jOOQ's SQL checker.
* Documented the `-AprintVerboseGenerics` command-line option.
* Better explanation of relationship between Fake Enum and Subtyping Checkers.

### Closed issues

\#154, #322, #402, #404, #433, #531, #578, #720, #795, #916, #953, #973, #974,
\#975, #976, #980, #988, #1000.

## Version 2.1.6 (1 December 2016)

### Closed issues

\#412, #475.

## Version 2.1.5 (2 November 2016)

The new class org.checkerframework.checker.nullness.Opt provides every
method in Java 8's java.util.Optional class, but written for possibly-null
references rather than for the Optional type.  This can shorten code that
manipulates possibly-null references.

In bytecode, type variable upper bounds of type Object may or may not have
been explicitly written.  The Checker Framework now assumes they were not
written explicitly in source code and defaults them as implicit upper bounds.

The manual describes how to run a checker within the NetBeans IDE.

The manual describes two approaches to creating a type alias or typedef.

### Closed issues

\#643, #775, #887, #906, #941.

## Version 2.1.4 (3 October 2016)

### Closed issues

\#885, #886, #919.

## Version 2.1.3 (16 September 2016)

### Closed issues

\#122, #488, #495, #580, #618, #647, #713, #764, #818, #872, #893, #894, #901,
\#902, #903, #905, #913.

## Version 2.1.2 (1 September 2016)

### Closed issues

\#182, #367, #712, #811, #846, #857, #858, #863, #870, #871, #878, #883, #888.

## Version 2.1.1 (1 August 2016)

The codebase conforms to a consistent coding style, which is enforced by
a git pre-commit hook.

AnnotatedTypeFactory#createSupportedTypeQualifiers() must now return a mutable
list.  Checkers that override this method will have to be changed.

### Closed issues

\#384, #590, #681, #790, #805, #809, #810, #820, #824, #826, #829, #838, #845,
\#850, #856.

## Version 2.1.0 (1 July 2016)

The new Signedness Checker prevents mixing of unsigned and signed
values and prevents meaningless operations on unsigned values.

The Lock Checker expresses the annotated variable as `<self>`;
previously it used `itself`, which may conflict with an identifier.

### Closed issues

\#166, #273, #358, #408, #471, #484, #594, #625, #692, #700, #701, #711, #717,
\#752, #756, #759, #763, #767, #779, #783, #794, #807, #808.

## Version 2.0.1 (1 June 2016)

We renamed method annotateImplicit to addComputedTypeAnnotations.  If you
have implemented a checker, you need to change occurrences of
annotateImplicit to addComputedTypeAnnotations.

The Checker Framework (checker.jar) is now placed on the processorpath
during compilation.  Previously, it was placed on the classpath.  The
qualifiers (checker-qual.jar) remain on the classpath.  This change should
reduce conflicts between your code and the Checker Framework.  If your code
depends on classes in the Checker Framework, then you should add those
classes to the classpath when you run the compiler.

### Closed issues

\#171, #250, #291, #523, #577, #672, #680, #688, #689, #690, #691, #695, #696,
\#698, #702, #704, #705, #706, #707, #720, #721, #723, #728, #736, #738, #740.

## Version 2.0.0 (2 May 2016)

Inference:

* The infer-and-annotate.sh script infers annotations and inserts them in
  your source code.  This can reduce the burden of writing annotations and
  let you get started using a type system more quickly.  See the
  "Whole-program inference" section in the manual for details.

Type systems:

* The Lock Checker has been replaced by a new implementation that provides
  a stronger guarantee.  The old Lock Checker prevented two threads from
  simultaneously using a given variable, but race conditions were still
  possible due to aliases.  The new Lock Checker prevents two threads from
  simultaneously dereferencing a given value, and thus prevents race
  conditions.  For details, see the "Lock Checker" chapter in the manual,
  which has been rewritten to describe the new semantics.

* The top type qualifier for the Signature String type system has been
  renamed from @UnannotatedString to @SignatureUnknown.  You shouldn't
  ever write this annotation, but if you perform separate compilation (for
  instance, if you do type-checking with the Signature String Checker
  against a library that is annotated with Signature String annotations),
  then you need to re-compile the library.

* The IGJ, OIGJ, and Javari Checkers are no longer distributed with the
  Checker Framework.  If you wish to use them, install version 1.9.13 of
  the Checker Framework.  The implementations have been removed because
  they were not being maintained.  The type systems are valuable, but the
  type-checkers should be rewritten from scratch.

Documentation improvements:

* New manual section "Tips for creating a checker" shows how to break down
  the implementation of a type system into small, manageable pieces.

* Improved instructions for using Maven and Gradle, including for Android
  code.

Tool changes:

* The Checker Framework Live Demo webpage lets you try the Checker
  Framework without installing it:  <https://eisop.uwaterloo.ca/live/>

* New command-line arguments -Acfgviz and -Averbosecfg enable better
  debugging of the control-flow-graph generation step of type-checking.

* New command-line argument -Ainfer is used by the infer-and-annotate.sh
  script that performs type inference.

### Closed issues

\#69, #86, #199, #299, #329, #421, #428, #557, #564, #573, #579, #665, #668,
\#669, #670, #671.

## Version 1.9.13 (1 April 2016)

Documentation:

* Clarified Maven documentation about use of annotations in comments.
* Added FAQ about annotating fully-qualified type names.

### Closed issues

\#438, #572, #579, #607, #624, #631.

## Version 1.9.12 (1 March 2016)

The Checker Framework distribution contains annotated versions
of libraries in directory checker-framework/checker/lib/.
During type-checking, you should put these versions first on your classpath,
to obtain more precise type-checking with fewer false positive warnings.

tools.jar is no longer required to be on the classpath when using
checker-qual.jar

The Signature String Checker supports two new string representations of a
Java type: @InternalForm and @ClassGetSimpleName.

The manual documents how to run a pluggable type-checker in IntelliJ IDEA.

The instructions on how to run a type-checker in Gradle have been updated to
use the artifacts in Maven Central. Examples using the instructions have been
added under checker-framework/docs/examples/GradleExamples/.

Renamed enum DefaultLocation to TypeUseLocation.

### Closed issues

\#130, #263, #345, #458, #559, #559, #574, #582, #596.

## Version 1.9.11 (1 February 2016)

Renamed and merged -AuseSafeDefaultsForUnannotatedSourceCode and
-AsafeDefaultsForUnannotatedBytecode command-line options to
-AuseDefaultsForUncheckedCode that takes arguments source and bytecode.

For type-system developers:

* The previously deprecated
  org.checkerframework.framework.qual.TypeQualifier{s} annotations
  were removed.
* Every type system uses the CLIMB-to-top defaulting scheme, unless it
  explicitly specifies a different one.  Previously a type system needed
  to explicitly request CLIMB-to-top, but now it is the default.

### Closed issues

\#524, #563, #568.

## Version 1.9.10 (4 January 2016)

The Checker Framework distribution files now contain a version number:
for example, checker-framework-1.9.9.zip rather than checker-framework.zip.

The Nullness Checker supports the org.eclipse.jgit.annotations.Nullable and
NonNull annotations.

Buildfiles do less unnecessary recomputation.

Documentation:

* Documented how to initialize circular data structures in the
  Initialization type system.
* Linked to David Bürgin's Nullness Checker tutorial at
  <https://github.com/glts/safer-spring-petclinic/wiki>
* Acknowledged more contributors in the manual.

For type-system developers:

* The org.checkerframework.framework.qual.TypeQualifier{s} annotations are
  now deprecated.  To indicate which annotations a checker supports, see
  <https://checkerframework.org/manual/#creating-indicating-supported-annotations>.
  Support for TypeQualifier{s} will be removed in the next release.
* Renamed
  `org.checkerframework.framework.qual.Default{,Qualifier}ForUnannotatedCode` to
  `DefaultInUncheckedCodeFor and DefaultQualifierInHierarchyInUncheckedCode`.

### Closed issues

\#169, #363, #448, #478, #496, #516, #529.

## Version 1.9.9 (1 December 2015)

Fixed issues:  #511, #513, #514, #455, #527.

Removed the javac_maven script and batch file,
which had been previously deprecated.

## Version 1.9.8 (9 November 2015)

Field initialization warnings can now be suppressed for a single field at a
time, by placing @SuppressWarnings("initialization") on the field declaration.

Updated Maven instructions to no longer require a script.
Added an example of how to use the instructions under
docs/examples/MavenExample.

The javac_maven script (and batch file) are deprecated and will be
removed as of December 2015.

Fixed issues:  #487, #500, #502.

## Version 1.9.7 (24 October 2015)

Fixed issues:  #291, #474.

## Version 1.9.6 (8 October 2015)

Fixed issue:  #460.

## Version 1.9.5 (1 September 2015)

Test Framework Updates:

* The test framework has been refactored to improve extensibility.
* Tests that previously extended ParameterizedCheckerTest or
  CheckerTest should extend either CheckerFrameworkTest or nothing.
* If a test used methods that were previously found on
  CheckerTest, you may find them in TestUtilities.

Fixed issues:  #438, #457, #459.

## Version 1.9.4 (4 August 2015)

Documented the notion of a compound checker, which depends on other checkers
  and automatically runs them.

Renamed -AuseConservativeDefaultsForUnannotatedSourceCode command-line
  option to -AuseSafeDefaultsForUnannotatedSourceCode

Moved the Checker Framework version control repository from Google Code to
GitHub, and from the Mercurial version control system to Git.  If you have
cloned the old repository, then discard your old clone and create a new one
using this command:

```sh
  git clone https://github.com/typetools/checker-framework.git
```

Fixed issues:  #427, #429, #434, #442, #450.

## Version 1.9.3 (1 July 2015)

New command-line options:

* -AsafeDefaultsForUnannotatedBytecode causes a checker to use conservative
  defaults for .class files that were compiled without running the given
  checker.  Without this option, type-checking is unsound (that is, there
  might be errors at run time even though the checker issues no warnings).
* -AuseConservativeDefaultsForUnannotatedSourceCode uses conservative
  annotations for unannotated type uses.  Use this when compiling a library in
  which some but not all classes are annotated.

Various bug fixes and documentation improvements.

Fixed issues: #436.

## Version 1.9.2 (1 June 2015)

Internationalization Format String Checker:
This new type-checker prevents use of incorrect internationalization
format strings.

Fixed issues: #434.

## Version 1.9.1 (1 May 2015)

New FAQ entry:
  "How does the Checker Framework compare with Eclipse's null analysis?"

## Version 1.9.0 (17 April 2015)

Bug fixes for generics, especially type parameters:

* Manual chapter 21 "Generics and polymorphism" has been expanded,
     and it gives more information on annotating type parameters.
* The qualifier on a type parameter (e.g. <@HERE T> ) only applies
     to the lower bound of that type parameter.  Previously it also
     applied to the upper bound.
* Unannotated, unbounded wildcards are now qualified with the
     annotations of the type parameter to which they are an argument.
     See the new manual section 23.3.4 for more details.
* Warning "bound" is issued if the lower bound of
     a type parameter or wildcard is a supertype of its upper bound,
     e.g.  <@Nullable T extends @NonNull Object>
* Method type argument inference has been improved. Fewer warnings
     should be issued when method invocations omit type arguments.
* Added command-line option -AprintVerboseGenerics to print more
     information about type parameters and wildcards when they appear
     in warning messages.

Reflection resolution:
If you supply the -AresolveReflection command-line option, the Checker
Framework attempts to resolve reflection.  This reduces the number of
false positive warnings caused by reflection.

The documentation for the Map Key Checker has been moved into its own
chapter in the manual.

Fixed issues: #221, #241, #313, #314, #328, #335, #337, #338, #339, #355, #369,
              #376, #378, #386, #388, #389, #393, #403, #404, #413, #414, #415,
              #417, #418, #420, #421, #422, #426.

## Version 1.8.11 (2 March 2015)

Fixed issues: #396, #400, #401.

## Version 1.8.10 (30 January 2015)

Fixed issues: #37, #127, #350, #364, #365, #387, #392, #395.

## Version 1.8.9 (19 December 2014)

Aliasing Checker:
This new type-checker ensures that an expression has no aliases.

Fixed issues: #362, #380, #382.

## Version 1.8.8 (26 November 2014)

@SuppressWarnings("all") suppresses all Checker Framework warnings.

Implicit imports are deprecated, including the jsr308_imports environment
variable and the -jsr308_imports ... and -Djsr308.imports=... command-line
options.

For checkers bundled with the Checker Framework, package names may now
be omitted when running from the command line.
E.g.
    javac -processor NullnessChecker MyFile.java

The Nullness checker supports Android annotations
android.support.annotation.NonNull and android.support.annotation.Nullable.

Fixed issues: #366, #379.

## Version 1.8.7 (30 October 2014)

Fix performance regression introduced in release 1.8.6.

Nullness Checker:

* Updated Nullness annotations in the annotated JDK.
    See issues: #336, #340, #374.
* String concatenations with null literals are now @NonNull
    rather than @Nullable.  See issue #357.

Fixed issues:  #200, #300, #332, #336, #340, #357, #359, #373, #374.

## Version 1.8.6 (25 September 2014)

Method Reference and Lambda Expression Support:
The Checker Framework now supports type-checking method references
and lambda expressions to ensure they are congruent with the
functional interface they are assigned to. The bodies of lambda expressions
are also now type-checked similarly to regular method bodies.

Dataflow:

* Handling of the following language features has been improved:
  boxed Booleans, finally blocks, switch statements, type casts, enhanced
  for loops
* Performance improvements

Annotations:
The checker-compat-qual.jar is now included with the Checker Framework
release.  It can also be found in Maven Central at the coordinates:
org.checkerframework:checker-compat-qual
Annotations in checker-compat-qual.jar do not require Java 8 but
can only be placed in annotation locations valid in Java 7.

## Version 1.8.5 (29 August 2014)

Eclipse Plugin:
All checkers in the Checker Framework manual now appear in the
Eclipse plugin by default.  Users no longer have to include
checker.jar on their classpath to run any of the built-in checkers.

Improved Java 7 compatibility and introduced Java 7 compliant
annotations for the Nullness Checker.  Please see the section on
"Class-file compatibility with Java 7" in the manual for more details.

Fixed issue #347.

## Version 1.8.4 (1 August 2014)

The new Constant Value Checker is a constant propagation analysis:  it
determines which variable values can be known at compile time.

Overriding methods now inherit declaration annotations from methods they
override, if the declaration annotation is meta-annotate with
@InheritedAnnotation.  In particular, the purity annotations @SideEffectFree,
@Deterministic, and @Pure are inherited.

Command-line options:

* Renamed the -AenablePurity command-line flag to -AcheckPurityAnnotations.
* Added a command-line option -AoutputArgsToFile to output all command-line
  options passed to the compiler to a file.  This is especially useful when
  debugging Maven compilation.

Annotations:
These changes are relevant only to people who wish to use pluggable
type-checking with a standard Java 7 toolset.  (If you are not having
trouble with your Java 7 JVM, then you don't care about them.)

* Made clean-room reimplementations of nullness-related annotations
  compatible with Java 7 JVMs, by removing TYPE_USE as a target.
* Added a new set of Java 7 compatibility annotations for the Nullness Checker
  in the org.checkerframework.checker.nullness.compatqual package. These
  annotations do not require Java 8 but can only be placed in annotation
  locations valid in Java 7.

Java 8 support:
The Checker Framework no longer crashes when type-checking code with lambda
expressions, but it does issue a lambda.unsupported warning when
type-checking code containing lambda expressions.  Full support for
type-checking lambda expressions will appear in a future release.

Fixed issue #343.

## Version 1.8.3 (1 July 2014)

Updated the Initialization Checker section in the manual with
a new introduction paragraph.

Removed the Maven plugin section from the manual as the plugin is
no longer maintained and the final release was on June 2, #2014.
The javac_maven script (and batch file) are available to use
the Checker Framework from Maven.

Fixed issue #331.

## Version 1.8.2 (2 Jun 2014)

Converted from using rt.jar to ct.sym for creating the annotated jdk.
Using the annotated jdk on the bootclasspath of a VM will cause the
vm to crash immediately.

The Lock Checker has been rewritten to support dataflow analysis.
It can now understand conditional expressions, for example, and
knows that "lock" is held in the body of statements like
"if (lock.tryLock()) { ... }"
The Lock Checker chapter in the manual has been updated accordingly
and describes the new Lock Checker features in detail.

Provided a javac_maven script (and batch file) to make it simpler
to use the Checker Framework from Maven.  The Maven plug-in is deprecated
and will be removed as of July 1, 2014. Added an explanation of how
to use the script in the Maven section of the manual.

The Checker Framework installation instructions in the manual have
been updated.

Fixed issues: #312, #315, #316, #318, #319, #324, #326, #327.

## Version 1.8.1 (1 May 2014)

Support to directly use the Java 8 javac in addition to jsr308-langtools.
Added docs/examples directory to checker-framework.zip.
New section in the manual describing the contents of checker-framework.zip.

Fixed issues: #204, #304, #320.

## Version 1.8.0 (2 April 2014)

Added the GUI Effect Checker, which prevents "invalid thread access" errors
when a background thread in a GUI attempts to access the UI.

Changed the Java package of all type-checkers and qualifiers.  The package
"checkers" has been renamed to "org.checkerframeork.checker".  This
requires you to change your import statements, such as from
  import checkers.nullness.quals.*;
to
  import org.checkerframework.checker.nullness.qual.*;
It also requires you to change command-line invocations of javac, such as from
  javac -processor checkers.nullness.NullnessChecker ...
to
  javac -processor org.checkerframework.checker.nullness.NullnessChecker ...

Restructured the Checker Framework project and package layout,
using the org.checkerframework prefix.

## Version 1.7.5 (5 March 2014)

Minor improvements to documentation and demos.
Support a few new units in the UnitsChecker.

## Version 1.7.4 (19 February 2014)

Error messages now display the error key that can be used in
SuppressWarnings annotations. Use -AshowSuppressWarningKeys to
show additional keys.

Defaulted type qualifiers are now stored in the Element and written
to the final bytecode.

Reduce special treatment of checkers.quals.Unqualified.

Fixed issues: #170, #240, #265, #281.

## Version 1.7.3 (4 February 2014)

Fixes for Issues #210, #253, #280, #288.

Manual:

* Improved discussion of checker guarantees.

Maven Plugin:

* Added option useJavacOutput to display exact compiler output.

Eclipse Plugin:

* Added the Format String Checker to the list of built-in checkers.

## Version 1.7.2 (2 January 2014)

Fixed issues: #289, #292, #295, #296, #298.

## Version 1.7.1 (9 December 2013)

Fixes for
Issues #141, #145, #257, #261, #269, #267, #275, #278, #282, #283, #284, #285.

### Implementation details

Renamed AbstractBasicAnnotatedTypeFactory to GenericAnnotatedTypeFactory

## Version 1.7.0 (23 October 2013)

Format String Checker:
This new type-checker ensures that format methods, such as
System.out.printf, are invoked with correct arguments.

Renamed the Basic Checker to the Subtyping Checker.

Reimplemented the dataflow analysis that performs flow-sensitive type
refinement.  This fixes many bugs, improves precision, and adds features.
Many more Java expressions can be written as annotation arguments.

Initialization Checker:
This new abstract type-checker verifies initialization properties.  It
needs to be combined with another type system whose proper initialization
should be checked.  This is the new default initialization checker for the
Nullness Checker.  It is based on the "Freedom Before Commitment" approach.

Renamed method annotations used by the Nullness Checker:

* @AssertNonNullAfter => @EnsuresNonNull
* @NonNullOnEntry => @RequiresNonNull
* @AssertNonNullIfTrue(...) => @IfMethodReturnsFalseEnsuresNonNull
* @AssertNonNullIfFalse(...) => @IfMethodReturnsFalseEnsuresNonNull
* @LazyNonNull => @MonotonicNonNull
* @AssertParametersNonNull => [no replacement]

Removed annotations used by the Nullness Checker:

* @AssertParametersNonNull

Renamed type annotations used by the Initialization Checker:

* @NonRaw => @Initialized
* @Raw => @UnknownInitialization
* new annotation @UnderInitialization

The old Initialization Checker (that uses @Raw and @NonRaw) can be invoked
by invoking the NullnessRawnessChecker rather than the NullnessChecker.

Purity (side effect) analysis uses new annotations @SideEffectFree,
@Deterministic, and @TerminatesExecution; @Pure means both @SideEffectFree
and @Deterministic.

Pre- and postconditions about type qualifiers are available for any type system
through @RequiresQualifier, @EnsuresQualifier and @EnsuresQualifierIf.  The
contract annotations for the Nullness Checker (e.g. @EnsuresNonNull) are now
only a special case of these general purpose annotations.
The meta-annotations @PreconditionAnnotation, @PostconditionAnnotation, and
@ConditionalPostconditionAnnotation can be used to create more special-case
annotations for other type systems.

Renamed assertion comment string used by all checkers:

* @SuppressWarnings => @AssumeAssertion

To use an assert statement to suppress warnings, the assertion message must
include the string "@AssumeAssertion(warningkey)".  Previously, just the
warning key sufficed, but the string @SuppressWarnings(warningkey) was
recommended.

New command-line options:

* -AonlyDefs and -AonlyUses complement existing -AskipDefs and -AskipUses
* -AsuppressWarnings Suppress warnings matching the given key
* -AassumeSideEffectFree Unsoundly assume that every method is side-effect-free
* -AignoreRawTypeArguments Ignore subtype tests for type arguments that
  were inferred for a raw type
* -AenablePurity Check the bodies of methods marked as pure
  (@SideEffectFree or @Deterministic)
* -AsuggestPureMethods Suggest methods that could be marked as pure
* -AassumeAssertionsAreEnabled, -AassumeAssertionsAreDisabled Whether to
  assume that assertions are enabled or disabled
* -AconcurrentSemantics Whether to assume concurrent semantics
* -Anocheckjdk Don't err if no annotated JDK can be found
* -Aflowdotdir Create an image of the control flow graph
* -AinvariantArrays replaces -Alint=arrays:invariant
* -AcheckCastElementType replaces -Alint=cast:strict

Manual:

* New manual section about array types.
* New FAQ entries:  "Which checker should I start with?", "How can I handle
  typestate, or phases of my program with different data properties?",
* "What is the meaning of a type qualifier at a class declaration?"
* Reorganized FAQ chapter into sections.
* Many other improvements.

## Version 1.6.7 (28 August 2013)

User-visible framework improvements:

* Improve the error message produced by -Adetailedmsgtext

Bug fixes:

* Fix issue #245: anonymous classes were skipped by default

## Version 1.6.6 (01 August 2013)

Documentation:

* The Checker Framework manual has been improved.  Changes include:
  more troubleshooting tips to the Checker Framework manual, an improved
  discussion on qualifier bounds, more examples, improved formatting, and more.
* An FAQ entry has been added to discuss JSR305.
* Minor clarifications have been added to the Checker Framework tutorial.

## Version 1.6.5 (01 July 2013)

User-visible framework improvements:

* Stub files now support static imports.

Maven plugin:

* Maven plugin will now issue a warning rather than quit when zero checkers
  are specified in a project's pom.xml.

Documentation:

* Improved the Maven plugin instructions in the Checker Framework manual.
* Added documentation for the -XDTA:noannotationsincomments compiler flag.

Internal framework improvements:

* Improved Maven-plugin developer documentation.

## Version 1.6.4 (01 June 2013)

User-visible framework improvements:

* StubGenerator now generates stubs that can be read by the StubParser.

Maven plugin:

* The Maven plugin no longer requires the Maven project's output directory to
  exist in order to run the Checker Framework.  However, if you ask the Checker
  Framework to generate class files then the output directory will be created.

Documentation:

* Improved the Maven plugin instructions in the Checker Framework manual.
* Improved the discussion of why to define both a bottom and a top qualifier in
  the Checker Framework manual.
* Update FAQ to discuss that some other tools incorrectly interpret array declarations.

## Version 1.6.3 (01 May 2013)

Eclipse plugin bug fixes:

* The javac argument files used by the Eclipse plugin now properly escape file
  paths.  Windows users should no longer encounter errors about missing built-in
  checkers.

Documentation:

* Add FAQ "What is the meaning of an annotation after a type?"

## Version 1.6.2 (04 Apr 2013)

Eclipse plugin:

* The "Additional compiler parameters" text field has now been replaced by a
  list.  Parameters in this list may be activated/deactivated via checkbox.

Eclipse plugin bug fixes:

* Classpaths and source files should now be correctly quoted when they contain
  spaces.

Internal framework improvements:

* Update pom files to use the same update-version code as the Checker Framework
  "web" ant task.  Remove pom specific update-version code.
* Update build ant tasks to avoid re-running targets when executing tests from
  the release script.

## Version 1.6.1 (01 Mar 2013)

User-visible framework improvements:

* A number of error messages have been clarified.
* Stub file now supports type annotations in front and after method type
  variable declarations.
* You may now specify custom paths to javac.jar and jdk7.jar on the command line
  for non-standard installations.

Internal framework improvements:

* Add shouldBeApplied method to avoid unnecessary scans in DefaultApplier and
  avoid annotating void types.
* Add createQualifierDefaults and createQualifierPolymorphism factory methods.

Maven plugin:

* Put Checker Framework jars at the beginning of classpath.
* Added option to compile code in order to support checking for multi-module
  projects.
* The plugin no longer copies the various Checker Framework maven artifacts to
  one location but instead takes advantage of the new custom path options for
  javac.jar and jdk7.jar.
* The maven plugin no longer attempts to resolve jdk6.jar

Eclipse plugin:

* Put Checker Framework jars at the beginning of classpath.
* All files selected from a single project can now be checked.  The previous
  behavior only checked the entire project or one file depending on the type of
  the first file selected.

Documentation:

* Fixed broken links and incomplete URLs in the Checker Framework Manual.
* Update FAQ to discuss that some other tools incorrectly interpret array
  declarations.

## Version 1.6.0 (1 Feb 2013)

User-visible framework improvements:

* It is possible to use enum constants in stub files without requiring the fully
  qualified name, as was previously necessary.
* Support build on a stock Java 8 OpenJDK.

Adapt to underlying jsr308-langtools changes.

* The most visible change is syntax for fully-qualified types,
  from `@A java.lang.Object` to `java.lang.@A Object`.
* JDK 7 is now required.  The Checker Framework does not build or run on JDK 6.

Documentation:

* A new tutorial is available at <https://checkerframework.org/tutorial/>

## Version 1.5.0 (14 Jan 2013)

User-visible framework improvements:

* To invoke the Checker Framework, call the main method of class CheckerMain,
  which is a drop-in replacement for javac.  This replaces all previous
  techniques for invoking the Checker Framework.  Users should no longer provide
  any Checker Framework jars on the classpath or bootclasspath.  jsr308-all.jar
  has been removed.
* The Checker Framework now works with both JDK 6 and JDK 7, without need for
  user customization.  The Checker Framework determines the appropriate
  annotated JDK to use.
* All jar files now reside in checker-framework/checkers/binary/.

Maven plugin:

* Individual pom files (and artifacts in the Maven repository) for all
  Checker Framework jar files.
* Avoid too-long command lines on Windows.
* See the Maven section of the manual for more details.

Eclipse plugin:

* Avoid too-long command lines on Windows.
* Other bug fixes and interface improvements.

Other framework improvements:

* New -Adetailedmsgtext command-line option, intended for use by IDE plugins.

## Version 1.4.4 (1 Dec 2012)

Internal framework improvements:

* Add shutdown hook mechanism and use it for -AresourceStats resource
  statistics flag.
* Add -AstubWarnIfNotFound and -AstubDebug options to improve
  warnings and debug information from the stub file parsing.
* Ignore case when comparing error suppression keys.
* Support the bottom type as subtype of any wildcard type.

Tool Integration Changes

* The Maven plugin id has been changed to reflect standard Maven
  naming conventions.
* Eclipse and Maven plugin version numbers will now
  track the Checker Framework version numbers.

Bug fixes.

## Version 1.4.3 (1 Nov 2012)

Clarify license:

* The Checker Framework is licensed under the GPL2.  More permissive
  licenses apply to annotations, tool plugins (Maven, Eclipse),
  external libraries included with the Checker Framework, and examples in
  the Checker Framework Manual.
* Replaced all third-party annotations by cleanroom implementations, to
  avoid any potential problems or confusion with licensing.

Aliased annotations:

* Clarified that there is no need to rewrite your program.  The Checker
  Framework recognizes dozens of annotations used by other tools.

Improved documentation of Units Checker and Gradle Integration.

Improved developer documentation of Eclipse and Maven plugins.

Bug fixes.

## Version 1.4.2 (16 Oct 2012)

External tool support:

* Eclipse plug-in now works properly, due to many fixes

Regex Checker:

* New CheckedPatternSyntaxException added to RegexUtil

Support new foreign annotations:
  org.eclipse.jdt.annotation.Nullable
  org.eclipse.jdt.annotation.NonNull

New FAQ: "What is a receiver?"

Make annotations use 1-based numbering for formal parameters.
Previously, due to a bug the annotations used 0-based numbering.
This change means that you need to rewrite annotations in the following ways:

```rewrites
@KeyFor("#3")  =>  @KeyFor("#4")
@AssertNonNullIfTrue("#0")  =>  @AssertNonNullIfTrue("#1")
@AssertNonNullIfTrue({"#0", "#1"})  =>  @AssertNonNullIfTrue({"#1", "#2"})
@AssertNonNullAfter("get(#2)")  =>  @AssertNonNullAfter("get(#3)")
```

This command:

```sh
  find . -type f -print | xargs perl -pi -e 's/("#)([0-9])(")/$1.($2+1).$3/eg'
```

handles the first two cases, which account for most uses.  You would need
to handle any annotations like the last two cases in a different way,
such as by running

```sh
  grep -r -n -E '\("[^"]+#[0-9][^A-Za-z]|\("#[0-9][^"]' .
```

and making manual changes to the matching lines.  (It is possible to
provide a command that handles all cases, but it would be more likely to
make undesired changes.)
Whenever making automated changes, it is wise to save a copy of your
codebase, then compare it to the modified version so you can undo any
undesired changes.  Also, avoid running the automated command over version
control files such as your .hg, .git, .svn, or CVS directory.

## Version 1.4.1 (29 Sep 2012)

User-visible framework improvements:

* Support stub files contained in .jar files.
* Support aliasing for declaration annotations.
* Updated the Maven plugin.

Code refactoring:

* Make AnnotationUtils and AnnotatedTypes into stateless utility classes.
  Instead, provide the necessary parameters for particular methods.
* Make class AnnotationBuilder independent of AnnotationUtils.
* Remove the ProcessingEnvironment from AnnotatedTypeMirror, which was
  hardly used and can be replaced easily.
* Used more consistent naming for a few more fields.
* Moved AnnotatedTypes from package checkers.types to checkers.utils.
  this required making a few methods in AnnotatedTypeFactory public,
  which might require changes in downstream code.

Internal framework improvements:

* Fixed Issues #136, #139, #142, #156.
* Bug fixes and documentation improvements.

## Version 1.4.0 (11 Sep 2012)

User-visible framework improvements:

* Defaulting:
  * @DefaultQualifier annotations now use a Class instead of a String,
    preventing simple typo errors.
  * @DefaultLocation extended with more constants.
  * TreeAnnotator propagates the least-upper-bound of the operands of
    binary/compound operations, instead of taking the default qualifier.
* Stub files now ignore the return type, allowing for files automatically
    generated from other formats.
* Type factories and type hierarchies:
  * Simplify AnnotatedTypeFactory constructors.
  * Add a GeneralAnnotatedTypeFactory that supports multiple type systems.
  * Improvements to QualifierHierarchy construction.
* Type-checking improvements:
  * Propagate annotations from the sub-expression of a cast to its result.
  * Better handling of assignment context and improved inference of
    array creation expressions.
* Optional stricter checking of casts to array and generic types using
  the new -Alint=cast:strict flag.
  This will become the default in the future.
* Code reorganization:
  * SourceChecker.initChecker no longer has a ProcessingEnvironment
    parameter. The environment can now be accessed using the standard
    processingEnv field (instead of the previous env field).
  * Classes com.sun.source.util.AbstractTypeProcessor and
    checkers.util.AggregateChecker are now in package checkers.source.
  * Move isAssignable from the BaseTypeChecker to the BaseTypeVisitor; now
    the Checker only consists of factories and logic is contained in the
    Visitor.
* Warning and error messages:
  * Issue a warning if an unsupported -Alint option is provided.
  * Improved error messages.
* Maven plugin now works.

Nullness Checker:

* Only allow creation of (implicitly) non-null objects.
* Optionally forbid creation of arrays with @NonNull component type,
    when flag -Alint=arrays:forbidnonnullcomponents is supplied.
    This will become the default in the future.

Internal framework improvements:

* Enable assertion checking.
* Improve handling of annotated type variables.
* Assignment context is now a type, not a tree.
* Fix all compiler warnings.

## Version 1.3.1 (21 Jul 2012)

Installation:

* Clarify installation instructions for Windows.  Remove javac.bat, which
* worked for running distributed checkers but not for creating new checkers.

User-visible framework improvements:

* Implement @PolyAll qualifier to vary over multiple type systems.
* The Checker Framework is unsound due to Java's covariant array subtyping.
  You can enable invariant array subtyping (for qualifiers only, not for
  base Java types) with the command-line option -Alint=arrays:invariant.
  This will become the default in the future.

Internal framework improvements:

* Improve defaulting for multiple qualifier hierarchies.
* Big refactoring of how qualifier hierarchies are built up.
* Improvements to error handling output for unexpected exceptions.
* Bug fixes and documentation improvements.

## Version 1.3.0 (3 Jul 2012)

Annotation syntax changes, as mandated by the latest Type Annotations
(JSR 308) specification.  The most important ones are:

* New receiver syntax, using "this" as a formal parameter name:
  ReturnType methodname(@ReceiverAnnotation MyClass this, ...) { ... }
* Changed @Target default to be the Java 1.5 values
* UW extension: in addition to annotations in comments, support
  special /*>>>*/ comments to hide multiple tokens.
  This is useful for the new receiver syntax and for import statements.

Framework improvements:

* Adapt to annotation storage changes in jsr308-langtools 1.3.0.
* Move type validation methods from the BaseTypeChecker to BaseTypeVisitor.

## Version 1.2.7 (14 May 2012)

Regex Checker:

* Add basic support for the concatenation of two non-regular expressions
  that produce a valid regular expression.
* Support "isRegex" in flow inference.

Framework improvements:

* New @StubFiles annotation declaratively adds stub files to a checker.

Internal bug fixes:

* Respect skipDefs and skipUses in NullnessFlow.
* Support package annotations in stub files.
* Better support for enums in annotation attributes.
* Cleanups to how implicit receivers are determined.

## Version 1.2.6 (18 Mar 2012)

Nullness Checker:

* Correctly handle unboxing in more contexts (if, switch (Issue 129),
    while loops, ...)

Regex Checker:

* Add capturing groups parameter to Regex qualifier.
  * Count groups in String literals and String concatenation.
  * Verify group number to method calls that take a capturing group
    number.
  * Update RegexUtil methods to take optional groups parameter.
  * Modify regex qualifier hierarchy to support groups parameter.
* Add special case for Pattern.compile when called with Pattern.LITERAL flag.

Internal bug fixes:

* Improve flow's support of annotations with parameters.
* Fix generics corner cases (Issues #131, #132, #133, #135).
* Support type annotations in annotations and type-check annotations.
* Improve reflective look-up of visitors and factories.
* Small cleanups.

## Version 1.2.5.1 (06 Feb 2012)

Nullness Checker:

* Correct the annotations on ThreadLocal and InheritableThreadLocal.

Internal bug fixes:

* Expand release tests.
* Compile release with JDK 6 to work on both JDK 6 and JDK 7.

## Version 1.2.5 (3 Feb 2012)

Don't put classpath on the bootclasspath when invoking javac.  This
prevents problems if, for example, android.jar is on the classpath.

New -jsr308_imports ... and -Djsr308.imports=... command-line options, for
specifying implicit imports from the command line.  This is needed by Maven.

New -Aignorejdkastub option makes the checker not load the jdk.astub
file. Files from the "stubs" option are still loaded.

Regex Checker:

* Support concatenation of PolyRegex strings.
* Improve examples of use of RegexUtil methods.

Signature Checker:

* Add new @ClassGetName annotation, for a 4th string representation of a
  class that is used by the JDK.  Add supporting annotations to make the
  type hierarchy a complete lattice.
* Add PolySignature annotation.

Internal bug fixes:

* Improve method type argument inference.
* Handle type variables whose upper bound is a type variable.
* Fix bug in least upper bound computation for anonymous classes.
* Improve handling of annotations inherited from superclasses.
* Fix design problem with Nullness Checker and primitive types.
* Ensure that overriding methods respect pre- and postconditions.
* Correctly resolve references to an enclosing this.
* Improve handling of Java source that contains compilation errors.

## Version 1.2.4 (15 Dec 2011)

All checkers:

* @Target(TYPE_USE) meta-annotation is properly handled.

Nullness Checker:

* Do not allow nullness annotations on primitive types.
* Improvements to rawness (initialization) checks.
* Special-case known keys for System.getProperty.
* The -Alint=uninitialized command-line option now defaults to off, and
  applies only to initialization of primitive and @Nullable fields.  It is
  not possible to disable, from the command line, the check that all
  @NonNull fields are initialized.  Such warnings must be suppressed
  explicitly, for example by using @SuppressWarnings.

Regex Checker:

* Improved RegexUtil class.

Manual:

* Add FAQ item "Is the Checker Framework an official part of Java?"
* Trim down README.txt; users should read the manual instead.
* Improvements throughout, especially to Nullness and Regex Checker sections.

### Implementation details

* Add a new @InvisibleQualifier meta-annotation for type qualifiers.
  Instead of special-casing @Unqualified in the AnnotatedTypeMirror it
  now looks for this meta-annotation. This also allows type systems to
  hide type qualifiers it doesn't want visible, which we now use in the
  Nullness Checker to hide the @Primitive annotation.
* Nullness Checker:  Introduce a new internal qualifier @Primitive that is
  used for primitive types.
* Be stricter about qualifiers being present on all types. If you get
  errors about missing qualifiers, check your defaulting rules.
  This helped in fixing small bugs in corner cases of the type
  hierarchy and type factory.
* Unify decoding type annotations from trees and elements.
* Improve handling of annotations on type variables and upper bounds.
* Support checkers that use multiple, disjoint qualifier hierarchies.
* Many bug fixes.

## Version 1.2.3 (1 Nov 2011)

Regex Checker:

* Add @PolyRegex polymorphic annotation
* Add more stub library annotations

### Implementation details

* Do not use "null" for unqualified types. Explicitly use @Unqualified
  and be strict about correct usage. If this causes trouble for you,
  check your @ImplicitFor and @DefaultQualifierInHierarchy
  meta-annotations and ensure correct defaulting in your
  AnnotatedTypeFactory.

Bug fixes:

* Correctly handle f-bounded polymorphism. AnnotatedTypeMirror now has
  methods to query the "effective" annotations on a type, which
  handles type variable and wildcard bounds correctly. Also, terminate
  recursions by not doing lazy-initialization of bounds during defaulting.
* Many other small bug fixes and documentation updates.

## Version 1.2.2 (1 Oct 2011)

Be less restrictive about when to start type processing when errors
already exist.

Add -AskipDefs command-line option to not type-check some class
definitions.

Documentation improvements.

## Version 1.2.1 (20 Sep 2011)

Fix issues #109, #110, #111 and various other cleanups.

Improvements to the release process.

Documentation improvements.

## Version 1.2.0.1 (4 Sep 2011)

New version number to stay in sync with JSR 308 compiler bugfix.

No significant changes.

## Version 1.2.0 (2 Sep 2011)

Updated to JDK 8. Use -source 8 (the new default) for type annotations.

Documentation improvements

Bug fixes all over

Nullness Checker:

* Correct the upper bounds of all Collection subtypes

## Version 1.1.5 (22 Jul 2011)

### User-visible changes

* Units Checker:
  Instead of conversion routines, provide unit constants, with which
  to multiply unqualified values. This is easier to type and the
  multiplication gets optimized away by the compiler.

* Fenum Checker:
  Ensure that the switch statement expression is a supertype of all
  the case expressions.

### Implementation details

* Parse declaration annotations in stub files

* Output error messages instead of raising exceptions. This change
  required us to introduce method "initChecker" in class
  SourceChecker, which should be used instead of "init". This allows
  us to handle the calls to initChecker within the framework.
  Use method "errorAbort" to output an error message and abort
  processing.

## Version 1.1.4 (8 Jul 2011)

### User-visible changes

* Units Checker (new):
  Ensures operations are performed on variables of correct units of
  measurement (e.g., miles vs. kilometers vs. kilograms).

* Changed -AskipClasses command-line option to -AskipUses

### Implementation details

* Improve support for type qualifiers with enum attributes

## Version 1.1.3 (17 Jun 2011)

### User-visible changes

Interning:

* Add @UsesObjectEquals annotation

Manual:

* Signature Checker is now documented
* Fenum Checker documentation improved
* Small improvements to other sections

### Implementation details

* Updates to the web-site build process

* The BaseTypeVisitor used to provide the same two type parameters as
  class SourceVisitor. However, all subtypes of BaseTypeVisitor were
  instantiated as <Void, Void>. We decided to directly instantiate the
  SourceVisitor as <Void, Void> and removed this complexity.
  Instead, the BaseTypeVisitor is now parameterized by the subtype of
  BaseTypeChecker that should be used. This gives a more concrete type
  to field "checker" and is similar to BasicAnnotatedTypeFactory.

* Added method AnnotatedTypeFactory.typeVariablesFromUse to allow
  type-checkers to adapt the upper bounds of a type variable depending on
  the type instantiation.

* Method type argument inference:
  Changed AnnotatedTypeFactory.methodFromUse to return a Pair consisting
  of the method and the inferred or explicit method type arguments.
  If you override this method, you will need to update your version.
  See this change set for a simple example:
  <https://github.com/typetools/checker-framework/source/detail?r=8381a213a4>

* Testing framework:
  Support for multiple expected errors using the "// :: A :: B :: C" syntax.

Many small updates and fixes.

## Version 1.1.2 (12 Jan 2011)

Fake Enum Checker (new):
  A "fake enumeration" is a set of integers rather than a proper Java enum.
  They are used in legacy code and for efficiency (e.g., in Android).  The
  Fake Enum Checker gives them the same safety guarantees as a proper Java
  enum.

Property File Checker (new):
  Ensures that valid keys are used for property files and resource bundles.
  Also includes a checker that code is properly internationalized and a
  checker for compiler message keys as used in the Checker Framework.

Signature Checker (new):
  Ensures that different string representations of a Java type (e.g.,
  `"pakkage.Outer.Inner"` vs. `"pakkage.Outer$Inner"` vs. `"Lpakkage/Outer$Inner;"`)
  are not misused.

Interning Checker enhancements:
  Issues fewer false positives for code like "a==b || a.equals(b)"

Foreign annotations:
The Checker Framework supports more non-Checker-Framework annotations.
This means that it can check already-annotated code without requiring you
to rewrite your annotations.

* Add as an alias for checkers.interning.quals.Interned:
  com.sun.istack.Interned
* Add as aliases for checkers.nullness.quals.NonNull:
  com.sun.istack.NotNull
  org.netbeans.api.annotations.common.NonNull
* Add as aliases for checkers.nullness.quals.Nullable:
  com.sun.istack.Nullable
  javax.validation.constraints.NotNull
  org.netbeans.api.annotations.common.CheckForNull
  org.netbeans.api.annotations.common.NullAllowed
  org.netbeans.api.annotations.common.NullUnknown

Manual improvements:

* Improve installation instructions
* Rewrite section on generics (thanks to Bert Fernandez and David Cok)
    Also refactor the generics section into its own chapter
* Rewrite section on @Unused and @Dependent
* New manual section: Writing Java expressions as annotation arguments
* Better explanation of warning suppression
* JSR 308 is planned for Java 8, not Java 7

Stub files:

* Support nested classes by expressing them at top level in binary form: A$B
* Improved error reporting when parsing stub files

Annotated JDK:

* New way of generating annotated JDK
* jdk.jar file no longer appears in repository
* Warning if you are not using the annotated JDK.

Miscellaneous:
  Warn if -source command-line argument does not support type annotations

Many bug fixes
  There are too many to list, but some notable ones are to local type
  inference, generics, pre- and post-conditions (e.g., @NonNullOnEntry,
  @AssertNonNull*), and map keys (@KeyFor).  In particular, preconditions
  and map key annotations are now checked, and if they cannot be verified,
  an error is raised; previously, they were not verified, just unsoundly
  trusted.

## Version 1.1.1 (18 Sep 2010)

Eclipse support:
  Removed the obsolete Eclipse plug-in from repository.  The new one uses a
  different repository
  (<https://code.google.com/a/eclipselabs.org/p/checker-plugin/>) but a user
  obtains it from the same URL as before:
  <https://checkerframework.org/eclipse/>

Property Key Checker:
  The property key checker allows multiple resource bundles and the
  simultaneous use of both resource bundles and property files.

Javari Checker:
  Added Javari stub classes for more JDK classes.

Distribution:
  Changed directory structure (top level is "checker-framework"; "checkers"
  is a under that) for consistency with version control repository.

Many documentation improvements and minor bugfixes.

## Version 1.1.0b, 16 Jun 2010

Fixed a bug related to running binary release in JDK 6

## Version 1.1.0 (13 Jun 2010)

Checkers

* Introduced a new simple mechanism for running a checker
* Added one annotated JDK for all checkers

Nullness Checker

* Fixed bugs related to map.get() and KeyFor annotation
* Fixed bugs related to AssertNonNull* and parameters
* Minor updates to the annotated JDK, especially to java.io.File

Manual

* Updated installation instructions
* Clarified section regarding fields and type inference

## Version 1.0.9 (25 May 2010)

Nullness Checker:

* Improved Javadocs and manual documentation
* Added two new annotations: AssertNonNullAfter, KeyFor
* Fixed a bug related to AssertNonNullIfFalse and assert statements
* Renamed NonNullVariable to NonNullOnEntry

Checkers:

* Interning: Skipping equality check, if either operands should be skipped
* Fixed a bug related to annotations targeting array fields found in classfile
* Fixed a bug related to method invocation generic type inference
    in static methods

Manual

* Added a section on nullness method annotations
* Revised the Nullness Checker section
* Updated Ant usage instructions

## Version 1.0.8 (15 May 2010)

Checkers

* Changed behavior of flow type refinement when annotation is explicit
* Handle array initializer trees (without explicit type)
* Handle the case of Vector.copyInto
* Include javax classes in the distributed jdk jar files

Interning Checker

* Handle interning inference of string concatenation
* Add 20+ @Interned annotations to the JDK
* Add an option, checkclass, to validate the interning
    of specific classes only

Bug fixes

* Fix a bug related to array implicit types
* Lock Checker: Treat null as a bottom type

Manual

* Added a new section about Flow inference and fields

## Version 1.0.7 (12 Apr 2010)

Checkers

* Distributed a Maven repository
* Updated stub parser project to latest version (javaparser 1.0.8)
* Fixed bugs related to iterable wildcards and type parameter types

## Version 1.0.6 (24 Feb 2009)

Nullness Checker

* Added support for new annotations:
  * Pure - indicates that the method, given the same parameters, return the
    same values
  * AssertNonNullIfFalse - indicates that a field is NonNull if the method
    returns false
* Renamed AssertNonNull to AssertParametersNonNull
* Updated the annotated jdk

Javari Checker

* Fixed many bugs:
  * handle implicit dereferencing of this (e.g. `field` in place of
    `this.field`)
  * apply default annotations to method parameters

## Version 1.0.5 (12 Jan 2009)

Checkers

* Added support for annotated jdk jars
* Improved readability of some failure messages
* Added AssertNonNullIfTrue support for method parameter references
* Fixed a bug related to LazyNonNull and array fields
* Fixed a bug related to inference and compound assignments (e.g. +=)
* nullness: permit the type of @NonNull Void

Manual

* Updated annotating-libraries chapter regarding annotated jdk

## Version 1.0.4 (19 Dec 2009)

Bug Fixes

* wildcards not recognized as subtypes of type variables
    e.g. '? extends A' and 'A'
* PolyNull methods not accepting null literal value arguments
* spurious unexpected Raw warnings

Manual

* Clarified FAQ item regarding why List's type parameter is
    "extends @NonNull Object"

## Version 1.0.3 (5 Dec 2009)

Checkers

* New location UPPER_BOUND for DefaultQualifier permits setting the default
    for upper bounds, such as Object in "? extends Object".
* @DefaultQualifier accepts simple names, like @DefaultQualifier("Nullable"),
    rather than requiring @DefaultQualifier("checkers.nullness.quals.Nullable").
* Local variable type inference has improved support for array accesses.
* The repository contains Eclipse project and launch configuration files.
    This is helpful too people who want to build a checker, not to people
    who merely want to run a checker.
* Many bug fixes, including:
    handling wildcard subtyping rules
    stub files and vararg methods being ignored
    nullness and spurious rawness errors
    uses of array clone method (e.g. String[].clone())
    multibound type parameters (e.g. <T extends @A Number & @B Cloneable>)

Manual

* Documented the behavior of annotations on type parameter declarations.
* New FAQ item:
  * How to collect warnings from multiple files
  * Why a qualifier shouldn't apply to both types and declarations

## Version 1.0.2 (16 Nov 2009)

Checkers

* Renamed Regex Checker's @ValidRegex annotation to @Regex
* Improved Collection.toArray() heuristics to be more sound

Bug fixes

* Fixed the annotated JDK to match OpenJDK 6
  * Added missing methods and corrected class hierarchy
* Fixed a crash related to intersection types

## Version 1.0.1 (1 Nov 2009)

Checkers

* Added new checkers:
  * RegEx checker to detect invalid regular expression use
  * Internationalization (I18n) checker to detect internationalization errors

Functionality

* Added more performance optimizations
* nullness: Added support for netbeans nullness annotations
* nullness: better semantics for redundant nullness tests
    related to redundant tests in assertions
* lock: Added support for JCIP annotation in the Lock Checker
* tainting: Added support for polymorphism
* Lock Checker supports the JCIP GuardedBy annotation

Bug fixes

* Fixed a crashing bug related to interaction between
    generic types and wildcards
* Fixed a bug in stub file parser related to vararg annotations
* Fixed few bugs in skeleton file generators

Manual

* Tweak installation instructions
* Reference Units Checker
* Added new sections for new checkers
  * RegEx checker (S 10)
  * Internationalization Checker (S 11)

## Version 1.0.0 (30 Sep 2009)

Functionality

* Added Linear Checker to restrict aliasing

Bug fixes

* Fixed flow errors related to loop controls and break/continue

Manual

* Adopt new term, "Declaration Annotation" instead of non-type annotations
* Added new sections:
  * Linear Checker (S 9)
  * Inexpressible types (S 14.3)
  * How to get started annotating legacy code (S 2.4.4)
* Expanded Tainting Checker section

## Version 0.9.9 (4 Sep 2009)

Functionality

* Added more optional lint checks (cast:unsafe, all)
* Nullness Checker supports @SuppressWarnings("nullness:generic.argument"),
    for suppressing warnings related to misuse of generic type arguments.
    This was already supported and documented, but had not been mentioned
    in the changelog.

Bug fixes

* Fixed many bugs related to Stub files causing parser to ignore
  * bodiless constructors
  * annotated arrays annotations
  * type parameter and wildcard bounds annotations

Manual

* Rewrote 'javac implementation survival guide' (S 13.9)
* Restructured 'Using a checker' (S 2)
* Added 'Integration with external tools' (S 14)
* Added new questions to the FAQ (S 15)

## Version 0.9.8 (21 Aug 2009)

Functionality

* Added a Tainting Checker
* Added support for conditional nonnull checking
* Added optional check for redundant nullness tests
* Updated stub parser to latest libraries

Bug fixes

* Fixed a bug related to int[] treated as Object when passed to vararg T...
* Fixed a crash related to intersection types
* Fixed a bug related to -AskipClasses not being honored
* Fixed a bug related to flow

Manual

* Added new sections
  * 8 Tainting Checker
  * 3.2.3 Conditional nullness

## Version 0.9.7 (12 Aug 2009)

Functionality

* Changed swNonNull to castNonNull
* nullness: Improved flow to infer nullness based on method invocations
* locking: Permitted @Holding to appear on constructors

Bug fixes

* Fixed a bug related to typevar and wildcard extends clauses

## Version 0.9.6 (29 Jul 2009)

Functionality

* Changed 'jsr308.skipClasses' property with '-AskipClasses' option
* Locking checker
  * Add subtype checking for Holding
  * Treat constructors as synchronized methods

Bug fixes

* Added some missing nullness annotations in the jdk
* Fixed some bugs related to reading stub files

Manual

* Added a new section
  * 2.10  Tips about writing annotations
* Updated sections of
  * 2.6   Unused fields and dependent types
  * 3.1.1 Rawness annotation hierarchy

## Version 0.9.5 (13 Jul 2009)

Functionality

* Added support for Findbugs, JSR305, and IntelliJ nullness annotations
* Added an Aggregate Checker base-class
* Added support for a form of field access control

Bug fixes

* Added check for arguments in super() calls in constructors

Manual

* Added new sections:
  * Fields access control
  * Other tools for nullness checking
  * Bundling multiple checkers

## Version 0.9.4 (30 Jun 2009)

Functionality

* Added Lock Checker

Bug fixes

* Handle more patterns for determining Map.get() return type

Manual Documentations

* Improved installation instructions
* Added the following sections
  * 2.6 Dependent types
  * 3.1 subsection for LazyNonNull
  * 10.9 When to use (and not to use) type qualifiers

## Version 0.9.3 (23 Jun 2009)

Functionality

* Added support DefaultQualifier on packages
* Added support for Dependent qualifier types
    see checkers.quals.Dependent
* Added an option to treat checker errors as warnings
* Improved flow handling of boolean logic

Manual Documentations

* Improved installation instructions
* Improved discussion of effective and implicit qualifiers and defaults
* Added a discussion about the need for bottom qualifiers
* Added sections for how-to
  * suppress Basic Checker warnings
  * troubleshoot skeleton files

## Version 0.9.2 (2 Jun 2009)

Functionality

* Added preliminary support for lazy initialization in nullness
    see LazyNonNull

Bug fixes

* Corrected method declarations in JDK skeleton files
  * bug resulted in a run-time error

Documentations

* Updated qualifier javadoc documentations
* Corrected a reference on passing qualifiers to javac

## Version 0.9.1 (19 May 2009)

Bug fixes

* Eliminated unexpected compiler errors when using checkers
* Fixed bug related to reading annotations in skeleton files

API Changes

* Renamed SourceChecker.process() to .typeProcess()

Manual

* Updated troubleshooting info
* info for annotations in skeleton files

## Version 0.9b, 22 Apr 2009

No visible changes

## Version 0.9 (16 Apr 2009)

Framework

* More space and performance optimizations
* Handle raw type with multiple type var level
    e.g. class Pair<X, Y extends X> { ... }

Manual

* Improve installation instructions
* Update references to command line arguments

## Version 0.8.9 (28 Mar 2009)

Framework

* Introduce Space (and minor performance) optimizations
* Type-check constructor invocation receiver type
* Fixed bug related to try-catch flow sensitivity analysis
* Fixed bugs when type-checking annotations and enums
  * bug results in null-pointer exception

## Version 0.8.8 (13 Mar 2009)

Nullness Checker

* Support for custom nullness assertion via @AssertNonNull
* Support for meta-annotation AssertNonNull
* Support for Collection.toArray() method
  * Infer the nullness of the returned type
* Corrected some JDK Collection API annotations

Framework

* Fixed bugs related to assignments expressions in Flow
* Fixed bugs related to enum and annotation type hierarchy
* Fixed bugs related to default annotations on wildcard bounds

## Version 0.8.7 (27 Feb 2009)

Framework

* Support annotations on type parameters
* Fixed bugs related to polymorphic types/annotations
* Fixed bugs related to stub fixes

Manual

* Specify annotation defaults settings for IGJ
* Update Known Problems section

## Version 0.8.6 (3 Feb 2009)

Framework

* Fixed bugs related to flow sensitivity analysis related to
    . for loop and do while loops
    . multiple iterations of a loop
    . complement of logical conditions
* Declarative syntax for string literal type introduction rules
* Support for specifying stub file directories

## Version 0.8.5 (17 Jan 2009)

Framework

* Fixed bugs related to flow sensitivity analysis
* Fixed bugs related to annotations on type parameters

## Version 0.8.4 (17 Dec 2008)

Distribution

* Included checkers-quals.jar which contains the qualifiers only

Framework

* Fixed bugs related to inner classes
* Fixed a bug related to resolving polymorphic qualifiers
    within static methods

Manual

* Added 'Distributing your annotated project'

## Version 0.8.3 (7 Dec 2008)

Framework

* Fixed bugs related to inner classes
* Changed cast semantics
    Unqualified casts don't change cast away (or in) any qualifiers
* Refactored AnnotationBuilder to ease building annotations
* Added support for Object += String new behavior
* Added a type validation check for method return types

Nullness

* Added inference of field initialization
    Suppress false warnings due to method invocations within constructors

IGJ

* Added proper support for AssignsFields and inner classes interactions

Manual

* Updated 'Known Problems' section

## Version 0.8.2 (14 Nov 2008)

Framework

* Included a binary distribution in the releases
* Added support for annotations on type parameters
* Fixed bugs related to casts

Nullness

* Improved error messages readability
* Added partial support for Map.get() detection

Manual

* Improved installation instructions

## Version 0.8.1 (1 Nov 2008)

Framework

* Added support for array initializers
* Fixed many bugs related to generics and generic type inference

Documentations

* Added 'Getting Started' guide

## Version 0.8 (27 Sep 2008)

Framework

* Added support for newly specified array syntax
* Refactored code for annotating supertypes
* Fixed AnnotationBuilder AnnotationMirror string representation
* Fixed AnnotatedTypeMirror hashCode

Manual

* Reorganized 'Annotating Libraries' section

## Version 0.7.9 (19 Sep 2008)

Framework

* Added support for stub files/classes
* Fixed bugs related to anonymous classes
* Fixed bugs related to qualifier polymorphism

Manual

* Updated 'Annotating Libraries' section to describe stub files

Tests

* Added support for Windows
* Fixed a bug causing IGJ tests to fail on Windows

## Version 0.7.8 (12 Sep 2008)

Framework

* Improved support for anonymous classes
* Included refactorings to ease extensibility
* Fixed some minor bugs

Nullness

* Fix some errors in annotated JDK

## Version 0.7.7 (29 Aug 2008)

Framework

* Fixed bugs related to polymorphic qualifiers
* Fixed bugs related to elements array convention
* Add implicit type arguments to raw types

Interning

* Suppress cast warnings for interned classes

Manual

* Removed discussion of non-standard array syntax alternatives

## Version 0.7.6 (12 Aug 2008)

Framework

* Changed default array syntax to ARRAYS-PRE, per the JSR 308 specification
* Added an optional check for qualifier unsafe casts
* Added support for running multiple checkers at once
* Fixed bugs related array syntax
* Fixed bugs related to accessing outer classes with-in inner classes

Manual

* Added a new subsection about Checker Auto-Discovery
  * 2.2.1 Checker Auto-discovery

## Version 0.7.5 (2 Aug 2008)

Framework

* Added support for ARRAYS-PRE and ELTS-PRE array syntax
* Added a check for unsafe casts
* Some improvements to the AnnotationBuilder API

Nullness Checker

* Added a check for synchronized objects
* Added a check for (un)boxing conversions

Javari Checker

* Fixed some JDK annotated classes

## Version 0.7.4 (11 July 2008)

Framework

* Added support for annotations found in classfiles
* Added support for the ARRAY-IN array syntax
* Added AnnotationBuilder, to create AnotationMirrors with values
* Improved the readability of recursive types string representation

Nullness Checker

* Added a check for thrown Throwable nullability

IGJ Checker

* Treat enums as mutable by default, like regular classes

Manual

* Added a new subsection about array syntax proposals:
  * 2.1.2 Annotating Arrays

## Version 0.7.3 ( 4 July 2008)

Javari Checker

* Converted JDK files into stubs

Nullness Checker

* Fixed java.lang.Number declaration in the annotated jdk

Framework

* Fixed a bug causing crashes related to primitive type boxing
* Renamed DAGQualifierHierarchy to GraphQualifierHierarchy

## Version 0.7.2 (26 June 2008)

IGJ Checker

* Supports flow-sensitive type refinement

Framework

* Renamed Default annotation to DefaultQualifier
* Added DefaultQualifiers annotation
* Fixed bugs related to flow-sensitive type refinement
* Fixed an error in the build script in Windows

Manual

* Added a new section
  * 9.2  javac implementation survival guide
* Added hyperlinks to Javadocs of the referenced classes

## Version 0.7.1 (20 June 2008)

Nullness Checker

* Made NNEL the default qualifier scheme

Basic Checker

* Moved to its own checkers.basic package

Framework

* Enhanced type-checking within qualifier-polymorphic method bodies
* Fixed a bug causing StackOverflowError when type-checking wildcards
* Fixed a bug causing a NullPointerException when type-checking
    compound assignments, in the form of +=

Class Skeleton Generator

* Distributed in compiled form (no more special installation instructions)
* Added required asmx.jar library to lib/

Manual

* Added new sections
  * 2.2.1 Ant tasks
  * 2.2.2 Eclipse plugin
  * 2.6   The effective qualifier on a type
* Rewrote section 8 on annotating libraries
  * Added reference to the new Eclipse plug-in
  * Deleted installation instructions

Javari Checker

* Fixed bugs causing a NullPointerException when type-checking
    primitive arrays

IGJ Checker

* Fixed bugs related to uses of raw types

API Changes

* Moved AnnotationFactory functionality to AnnotationUtils
* Removed .root and .inConflict from DAGQualifierHierarchy

## Version 0.7 (14 June 2008)

Installation

* New, very simple installation instructions for Linux.  For other
    operating systems, you should continue to use the old instructions.

Nullness Checker

* Renamed from "NonNull Checker" to "Nullness Checker".
  * Renamed package from checkers.nonnull to checkers.nullness.
  * The annotation names remain the same.
* Added PolyNull, a polymorphic type qualifier for nullness.

Interning Checker

* Renamed from "Interned Checker" to "Interning Checker".
  * Renamed package from checkers.interned to checkers.interning.
  * The annotation names remain the same.
* Added PolyInterned, a polymorphic type qualifier for Interning.
* Added support for @Default annotation.

Framework

* Qualifiers
  * @PolymorphicQualifier was not previously documented in the manual.
  * Moved meta-qualifiers from checkers.metaquals package to checkers.quals.
  * Removed @VariableQualifier and @RootQualifier meta-qualifiers.
* Added BasicAnnotatedTypeFactory, a factory that handles implicitFor,
    defaults, flow-sensitive type inference.
* Deprecated GraphQualifierHierarchy; DAGQualifierHierarchy replaces it.
* Renamed methods in QualifierHierarchy.

Manual

* Rewrote several manual sections, most notably:
  * 2.1.1  Writing annotations in comments for backward compatibility
      (note new -Xspacesincomments argument to javac)
  * 2.3  Checking partially-annotated programs: handling unannotated code
  * 2.6  Default qualifier for unannotated types
  * 2.7  Implicitly refined types (flow-sensitive type qualifier inference)
  * 8  Annotating libraries
  * 9  How to create a new checker plugin
* Javadoc for the Checker Framework is included in its distribution and is
    available online at <https://checkerframework.org/api/>.

## Version 0.6.4 (9 June 2008)

All Framework

* Updated the distributed JDK and examples to the new location of qualifiers

Javari Checker

* Improved documentation on polymorphism resolution
* Removed redundant code now added to the framework from JavariVisitor,
    JavariChecker and JavariAnnotatedTypeFactory
* Refactored method polymorphism into JavariAnnotatedTypeFactory
* Fixed bug on obtaining type from NewClassTree, annotations at constructor
    invocation are not ignored now
* Refactored polymorphism resolution, now all annotations on parameters and
    receivers are replaced, not only on the return type
* Refactored and renamed internal annotator classes in
    JavariAnnotatedTypeFactory
* Added more constructor tests
* Moved Javari annotations to checkers.javari.quals package

## Version 0.6.3 (6 June 2008)

Checker Framework

* Improved documentation and manual
* Treat qualifiers on extends clauses of type variables and wildcard types as
    if present on type variable itself
* Renamed AnnotationRelations to QualifierHierarchy
* Renamed GraphAnnotationRelations to GraphQualifierHierarchy
* Renamed TypeRelations to TypeHierarchy
* Added flow as a supported lint option for all checkers
* Determined the suppress warning key reflectively

Interned Checker

* Moved @Interned annotation to checkers.interned.quals package

NonNull Checker

* Moved nonnull annotations to checkers.nonnull.quals package

Miscellaneous

* Included Javadocs in the release
* Improved documentation for all checkers

## Version 0.6.2 (30 May 2008)

Checker Framework API

* Added support for @Default annotation via TreeAnnotator
* Added support for PolymorphicQualifier meta-annotation
* Disallow the use of @SupportedAnnotationTypes on checkers
* Fixed bugs related to wildcards with super clauses
* Improved flow-sensitive analysis for fields

Javari Checker

* Moved Javari qualifiers from checkers.quals to checkers.javari.quals
* Fixed bugs causing null pointer exceptions

NonNull Checker

* Fixed bugs related to nonnull flow
* Added new tests to test suite

Basic Checker

* Renamed Custom Checker to Basic Checker

## Version 0.6.1 (26 Apr 2008)

Checker Framework API

* Added support for @ImplicitFor meta-annotations via the new TypeAnnotator
    and TreeAnnotator classes
* Improved documentation and specifications
* Fixed a bug related to getting supertypes of wildcards
* Fixed a crash on class literals of primitive and array types
* Framework ignores annotations that are not part of a type system
* Fixed several minor bugs in the flow-sensitive inference implementation.

IGJ Checker

* Updated the checker to use AnnotationRelations and TypeRelations

Javari Checker

* Changing RoMaybe annotation to PolyRead
* Updated checker to use AnnotationRelations and TypeRelations
* Updated the JDK
* Fixed bugs related to QReadOnly and type argument subtyping
* Fixed bugs related to this-mutable fields in methods with @ReadOnly receiver
* Fixed bugs related to primitive type casts
* Added new tests to test suit

NonNull Checker

* Updated the annotated JDK
* Fixed bugs in which default annotations were not correctly applied
* Added @Raw types to handle partial object initialization.
* Fixed several minor bugs in the checker implementation.

Custom Checker

* Updated checker to use hierarchy meta-annotations, via -Aquals argument

## Version 0.6 (11 Apr 2008)

Checker Framework API

* Introduced AnnotationRelations and TypeRelations, more robust classes to
    represent type and annotation hierarchies, and deprecated
    SimpleSubtypeRelation
* Add support for meta-annotations to declare type qualifiers subtype relations
* Re-factored AnnotatedTypes and AnnotatedTypeFactory
* Added a default implementation of SourceChecker.getSuppressWarningsKey()
    that reads the @SuppressWarningsKey class annotation
* Improved support for multidimensional arrays and new array expressions
* Fixed a bug in which implicit annotations were not being applied to
    parenthesized expressions
* Framework ignores annotations on a type that do not have @TypeQualifier
* Moved error/warning messages into "messages.properties" files in each
    checker package
* Fixed a bug in which annotations were inferred to liberally by
    checkers.flow.Flow

Interned Checker

* Added heuristics that suppress warnings for certain comparisons (namely in
    methods that override Comparator.compareTo and Object.equals)
* The Interned checker uses flow-sensitive inference by default

IGJ Checker

* Fixed bugs related to resolving immutability variable in method invocation
* Fixed a bug related to reassignability of fields
* Add more tests

Javari Checker

* Added placeholder annotation for ThisMutable mutability
* Re-factored JavariAnnotatedTypeFactory
* Fixed self-type resolution for method receivers for readonly classes
* Fixed annotations on parameters of readonly methods
* Fixed type validation for arrays of primitives
* Added more tests
* Renamed @RoMaybe annotation to @PolyRead

NonNull Checker

* Removed deprecated checkers.nonnull.flow package
* Fixed a bug in which default annotations were not applied correctly

Miscellaneous

* Improved Javadocs
* Added FactoryTestChecker, a more modular tester for the annotated type
    factory
* Simplify error output for some types by stripping package names

## Version 0.5.1 (21 Mar 2008)

Checker Framework API

* Added support for conditional expression
* Added checks for type validity and assignability
* Added support for per-checker customization of asMemberOf
* Added support for type parameters in method invocation,
    including type inference
* Enhanced performance of AnnotatedTypeFactory
* Checkers run only when no errors are found by Javac
* Fixed bugs related AnnotationUtils.deepCopy()
* Fixed support for annotated class type parameters
* Fixed some support for annotated type variable bounds
* Added enhancements to flow-sensitive qualifier inference
* Added checks for type parameter bounds

Interned Checker

* Fixed some failing test cases
* Fixed a bug related to autoboxing/unboxing
* Added experimental flow-sensitive qualifier inference (use
    "-Alint=flow" to enable)
* Improved subtype testing, removing some spurious errors

IGJ Checker

* Deleted IGJVisitor!
* Fixed some bugs related to immutability type variable resolution

Javari Checker

* Removed redundant methods from JavariVisitor in the new framework
* Added support to constructor receivers
* Added support to parenthesized expressions
* Fixed a bug related to resolving RoMaybe constructors
* Fixed a bug related to parsing conditional expressions
* Added parsing of parenthesized expressions
* Replaced checkers.javari.VisitorState with
    checkers.types.VisitorState, present in BaseTypeVisitor
* Modified JavariVisitor type parameters (it now extends
    BaseTypeVisitor<Void, Void>, not BaseTypeVisitor<Void,
    checkers.javari.VisitorState>)
* Modified JavariAnnotatedTypeFactory TreePreAnnotator to mutate a
    AnnotatedTypeMirror parameter instead of returning a
    `List<AnnotationMirror>`, in accordance with other parts of the
    framework design
* Modified test output format
* Added tests to test suite

NonNull Checker

* Fixed a bug related to errors produced on package declarations
* Exception parameters are now treated as NonNull by default
* Added better support for complex conditionals in NonNull-specific
    flow-sensitive inference
* Fixed some failing test cases
* Improved subtype testing, removing some spurious errors

Custom Checker

* Added a new type-checker for type systems with no special semantics, for
    which annotations can be provided via the command line

Miscellaneous

* Made corrections and added more links to Javadocs
* A platform-independent binary version of the checkers and framework
    (checkers.jar) is now included in this release

## Version 0.5 (7 Mar 2008)

Checker Framework API

* Enhanced the supertype finder to take annotations on extends and
    implements clauses of a class type
* Fixed a bug related to checking an empty array initializer ("{}")
* Fixed a bug related to missing type information when multiple
    top-level classes are defined in a single file
* Fixed infinite recursion when checking expressions like `Enum<E
    extends Enum<E>>`
* Fixed a crash in checkers.flow.Flow related to multiple top-level
    classes in a single file
* Added better support for annotated wildcard type bounds
* Added AnnotatedTypeFactory.annotateImplicit() methods to replace
    overriding the getAnnotatedType() methods directly
* Fixed a bug in which constructor arguments were not checked

Interned Checker

* Fixed a bug related to auto-unboxing of classes for primitives
* Added checks for calling methods with an @Interned receiver

IGJ Checker

* Implemented the immutability inference for self-type (type of
    'this') properly
* Enhanced the implicit annotations to make an un-annotated code
    type-check
* Fixed bugs related to invoking methods based on a method's receiver
    annotations

Javari Checker

* Restored in this version, after porting to the new framework

NonNull Checker

* Fixed a bug in which primitive types were considered possibly null
* Improvements to support for @Default annotations

Miscellaneous

* Improved error message display for all checkers

## Version 0.4.1 (22 Feb 2008)

Checker Framework API

* Introduced AnnotatedTypeFactory.directSupertypes() which finds the
    supertypes as annotated types, which can be used by the framework.
* Introduced default error messages analogous to javac's error messages.
* Fixed bugs related to handling array access and enhanced-for-loop type
    testing.
* Fixed several bugs that are due AnnotationMirror not overriding .equals()
    and .hashCode().
* Improved Javadocs for various classes and methods.
* Fixed several bugs that caused crashes in the checkers.
* Fixed a bug where varargs annotations were not handled correctly.

IGJ Checker

* Restored in this version, after porting the checker to the new framework.

NonNull Checker

* Fixed a bug where static field accesses were not handled correctly.
* Improved error messages for the NonNull checker.
* Added the NNEL (NonNull Except Locals) annotation default.

Interned Checker

* Fixed a bug where annotations on type parameter bounds were not handled
    correctly.
* Improved error messages for the Interned checker.

## Version 0.4 (11 Feb 2008)

Checker Framework API

* Added checkers.flow, an improved and generalized flow-sensitive type
    qualifier inference, and removed redundant parts from
    checkers.nonnull.flow.
* Fixed a bug that prevented AnnotatedTypeMirror.removeAnnotation from working
    correctly.
* Fixed incorrect behavior in checkers.util.SimpleSubtypeRelation.

NonNull Checker

* Adopted the new checkers.flow.Flow type qualifier inference.
* Clarifications and improvements to Javadocs.

## Version 0.3.99 (20 Nov 2007)

Checker Framework API

* Deprecated AnnotatedClassType, AnnotatedMethodType, and AnnotationLocation
    in favor of AnnotatedTypeMirror (a new representation of annotated types
    based on the javax.lang.model.type hierarchy).
* Added checkers.basetype, which provides simple assignment and
    pseudo-assignment checking.
* Deprecated checkers.subtype in favor of checkers.basetype.
* Added options for debugging output from checkers: -Afilenames, -Ashowchecks

Interned Checker

* Adopted the new Checker Framework API.
* Fixed a bug in which "new" expressions had an incorrect type.

NonNull Checker

* Adopted the new Checker Framework API.

Javari Checker
IGJ Checker

* Removed in this version, to be restored in a future version pending
    completion of updates to these checkers with respect to the new framework
    API.

## Version 0.3 (1 Oct 2007)

Miscellaneous Changes

* Consolidated HTML documentation into a single user manual (see the "manual"
    directory in the distribution).

IGJ Checker

* New features:
  * Added a test suite.
  * Added annotations (skeleton files) for parts of java.util and java.lang.

NonNull Checker

* New features:
  * @SuppressWarnings("nonnull") annotation suppresses checker warnings.
  * @Default annotation can make NonNull (not Nullable) the default.
  * Added annotations (skeleton classes) for parts of java.util and java.lang.
  * NonNull checker skips no classes by default (previously skipped JDK).
  * Improved error messages: checker reports expected and found types.

* Bug fixes:
  * Fixed a null-pointer exception when checking certain array accesses.
  * Improved checking for field dereferences.

Interned Checker

* New features:
  * @SuppressWarnings("interned") annotation suppresses checker warnings.
  * The checker warns when two @Interned objects are compared with .equals

* Bug fixes:
  * The checker honors @Interned annotations on method receivers.
  * java.lang.Class types are treated as @Interned.

Checker Framework API

* New features:
  * Added support for default annotations and warning suppression in checkers

## Version 0.2.3 (30 Aug 2007)

IGJ Checker

* New features:
  * changed @W(int) annotation to @I(String) to improve readability
  * improved readability of error messages
  * added a test for validity of types (testing @Mutable String)

* Bug fixes:
  * fixed resolving of @I on fields on receiver type
  * fixed assignment checking assignment validity for enhanced for loop
  * added check for constructor invocation parameters

Interned Checker

* added the Interned checker, for verifying the absence of equality testing
    errors; see "interned-checker.html" for more information

Javari Checker

* New features:
  * added skeleton classes for parts of java.util and java.lang with Javari
      annotations

* Bug fixes:
  * fixed readonly inner class bug on Javari Checker

NonNull Checker

* New features:
  * flow-sensitive analysis for assignments from a known @NonNull type (e.g.,
      when the right-hand of an assignment is @NonNull, the left-hand is
      considered @NonNull from the assignment to the next possible
      reassignment)
  * flow-sensitive analysis within conditional checks

* Bug fixes:
  * fixed several sources of null-pointer errors in the NonNull checker
  * fixed a bug in the flow-sensitive analysis when a variable was used on
      both sides of the "=" operator

Checker Framework API

* New features:
  * added the TypesUtils.toString() method for pretty-printing annotated types
  * added AnnotationUtils, a utility class for working with annotations and
      their values
  * added SourceChecker.getDefaultSkipPattern(), so that checkers can
      individually specify which classes to skip by default
  * added preliminary support for suppressing checker warnings via
      the @SuppressWarnings annotation

* Bug fixes:
  * fixed handling of annotations of field values
  * InternalAnnotation now correctly uses defaults for annotation values
  * improved support for annotations on class type parameter bounds
  * fixed an assertion violation when compiling certain uses of arrays

## Version 0.2.2 (16 Aug 2007)

Code Changes

* checkers.igj
  * some bug fixes and improved documentation

* checkers.javari
  * fixed standard return value to be @Mutable
  * fixed generic and array handling of @ReadOnly
  * fixed @RoMaybe resolution of receivers at method invocation
  * fixed parsing of parenthesized trees and conditional trees
  * added initial support for enhanced-for loop
  * fixed constructor behavior on @ReadOnly classes
  * added checks for annotations on primitive types inside arrays

* checkers.nonnull
  * flow sensitive analysis supports System.exit, new class/array creation

* checkers.subtype
  * fixes for method overriding and other generics-related bugs

* checkers.types
  * added AnnotatedTypeMirror, a new representation for annotated types that
      might be moved to the compiler in later version
  * added AnnotatedTypeScanner and AnnotatedTypeVisitor, visitors for types
  * AnnotatedTypeFactory uses GenericsUtils for improved handing of annotated
      generic types

* checkers.util
  * added AnnotatedTypes, a utility class for AnnotatedTypeMirror
  * added GenericsUtils, a utility class for working with generic types

* tests
  * modified output to print only missing and unexpected diagnostics
  * added new test cases for the Javari Checker

Documentation Changes

* checkers/igj-checker.html
  * improvements to page

* checkers/javari-checker.html
  * examples now point to test suit files

Miscellaneous Changes

* checkers/build.xml
  * Ant script fails if it doesn't find the correct JSR 308 javac version

## Version 0.2.1 (1 Aug 2007)

Code Changes

* checkers.igj & checkers.igj.quals
  * added an initial implementation for the IGJ language

* checkers.javari
  * added a state parameter to the visitor methods
  * added tests and restructured the test suite
  * restructured and implemented RoMaybe
  * modified return type to be mutable by default
  * fixed mutability type handling for type casts and field access
  * fixed bug, ensuring no primitives can be ReadOnly
  * a method receiver type is now based on the correct annotation
  * fixed parameter type-checking for overridden methods
  * fixed bug on readonly field initialization
  * added handling for unary trees

* checkers.nonnull
  * added tests for the flow-sensitive analysis and varargs methods
  * improved flow-sensitive analysis: else statements, asserts,
      return/throw statements, instanceof checks, complex conditionals with &&
  * fixed a bug in the flow-sensitive analysis that incorrectly inferred
      @NonNull for some elements
  * removed NonnullAnnotatedClassType, moving its functionality into
      NonnullAnnotatedTypeFactory

* checkers.source
  * SourceChecker.getSupportedAnnotationTypes() returns ["*"], overriding
      AbstractProcessor.getSupportedAnnotationTypes(). This enables all
      checkers to run on unannotated code

* checkers.subtypes
  * fixed a bug pertaining to method parameter checks for overriding methods
  * fixed a bug that caused crashes when checking varargs methods

* checkers.types
  * AnnotatedTypeFactory.getClass(Element) and getMethod(Element) use the
      tree of the passed Element if one exists
  * AnnotatedClassType.includeAt, .execludeAt, .getAnnotationData were
      added and are public
  * added constructor() and skipParens() methods to InternalUtils
    renamed getTypeArgumentLocations() to getAnnotatedTypeArgumentLocations()
  * in AnnotatedClassType
    added AnnotationData to represent annotations instead of Class instances;
  * primarily allows querying annotation arguments
  * added switch for whether or not to use includes/excludes in
      AnnotatedClassType.hasAnnotationAt()

* checkers.util
  * added utility classes
  * added skeleton class generator utility for annotating external libraries

Documentation Changes

* checkers/nonnull-checker.html
  * added a note about JML
  * added a caveat about variable initialization

* checkers/README-checkers.html
  * improvements to instructions

## Version 0.2 (2 Jul 2007)

Code Changes

* checkers.subtype
  * subtype checker warns for annotated and redundant typecasts
  * SubtypeVisitor checks for invalid return and parameter types in overriding
      methods
  * added checks for compound assignments (like '+=')

* checkers.source
  * SourceChecker honors the "checkers.skipClasses" property as a regex for
      suppressing warnings from unannotated code (property is "java.*" by
      default)
  * SourceVisitor extends TreePathScanner<R,P> instead of
      TreeScanner<Void,Void>

* checkers.types
  * AnnotatedClassType.isAnnotatedWith removed
  * AnnotatedClassType.getInnerLocations renamed to getTypeArgumentLocations
  * AnnotatedClassType.include now removes from the exclude list (and
      vice-versa)
  * AnnotatedClassType.setElement and setTree methods are now public

* checkers.nonnull
  * added a flow-sensitive analysis for inferring @NonNull in "if (var !=
      null)"-style checks
  * added checks for prefix and postfix increment and decrement operations

* checkers.javari
  * added initial implementation of a type-checker for the Javari language

## Version 0.1.1 (7 Jun 2007)

Documentation Changes

* checkers/nonnull-checker.html
  * created "Tiny examples" subsection
  * created "Annotated library" subsection
  * noted where to read @NonNull-annotated source
  * moved instructions for unannotated code to README-checkers.html
  * various minor corrections and clarifications

* checkers/README-checkers.html
  * added cross-references to other Checker Framework documents
  * removed redundant text
  * moved instructions for unannotated code from nonnull-checker.html
  * various minor corrections and clarifications

* checkers/creating-a-checker.html
  * added note about getSupportedSourceVersion
  * removed line numbers from @Interned example
  * added section on SubtypeChecker/SubtypeVisitor
  * various minor corrections and clarifications

Code Changes

* checkers.subtype
  * removed deprecated getCheckedAnnotation() mechanism
  * added missing package Javadocs
  * package Javadocs reference relevant HTML documentation
  * various improvements to Javadocs
  * SubtypeVisitor and SubtypeChecker are now abstract classes
  * updated with respect to preferred usages of
      AnnotatedClassType.hasAnnotationAt and AnnotatedClassType.annotateAt

* checkers.source
  * added missing package Javadocs
  * package Javadocs reference relevant HTML documentation

* checkers.types
  * added missing package Javadocs
  * package Javadocs reference relevant HTML documentation
  * AnnotatedClassType.annotateAt now correctly handles
      AnnotationLocation.RAW argument
  * AnnotatedClassType.annotate deprecated in favor of
      AnnotatedClassType.annotateAt with AnnotationLocation.RAW as an argument
  * AnnotatedClassType.isAnnotatedWith deprecated in favor of
      AnnotatedClassType.hasAnnotationAt with AnnotationLocation.RAW as an
      argument
  * Added fromArray and fromList methods to AnnotationLocation and made
      corresponding constructors private.

* checkers.quals
  * added Javadocs and meta-annotations on annotation declarations where
      missing
  * package Javadocs reference relevant HTML documentation

* checkers.nonnull
  * various improvements to Javadocs
  * package Javadocs reference relevant HTML documentation

Miscellaneous Changes

* Improved documentation of ch examples..
* Checker Framework build file now only attempts to compile .java files.

## Version 0.1.0 (1 May 2007)

Initial release.
