Class AbstractReturnValueIgnored

java.lang.Object

com.google.errorprone.bugpatterns.BugChecker

com.google.errorprone.bugpatterns.AbstractReturnValueIgnored

All Implemented Interfaces:

BugChecker.MemberReferenceTreeMatcher, BugChecker.MethodInvocationTreeMatcher, BugChecker.NewClassTreeMatcher, BugChecker.ReturnTreeMatcher, ResultUsePolicyAnalyzer<ExpressionTree, VisitorState>, Suppressible, Serializable

Direct Known Subclasses:

CheckReturnValue, FutureReturnValueIgnored, IgnoredPureGetter, ProtoBuilderReturnValueIgnored, RectIntersectReturnValueIgnored, ReturnValueIgnored, RxReturnValueIgnored

public abstract class AbstractReturnValueIgnored
extends BugChecker
implements BugChecker.MethodInvocationTreeMatcher, BugChecker.MemberReferenceTreeMatcher, BugChecker.ReturnTreeMatcher, BugChecker.NewClassTreeMatcher, ResultUsePolicyAnalyzer<ExpressionTree, VisitorState>

An abstract base class to match API usages in which the return value is not used.

In addition to regular contexts in which a return value isn't used (e.g.: the result of String.trim() is just ignored), this class has the capacity to determine if the result is cast in such a way as to lose important static type information.

If an analysis extending this base class chooses to care about this circumstance, they can override lostType(VisitorState) to define the type information they wish to keep.

Author:

eaftan@google.com (Eddie Aftandilian)

See Also:

• Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class BugChecker

BugChecker.AnnotatedTypeTreeMatcher, BugChecker.AnnotationTreeMatcher, BugChecker.ArrayAccessTreeMatcher, BugChecker.ArrayTypeTreeMatcher, BugChecker.AssertTreeMatcher, BugChecker.AssignmentTreeMatcher, BugChecker.BinaryTreeMatcher, BugChecker.BindingPatternTreeMatcher, BugChecker.BlockTreeMatcher, BugChecker.BreakTreeMatcher, BugChecker.CaseTreeMatcher, BugChecker.CatchTreeMatcher, BugChecker.ClassTreeMatcher, BugChecker.CompilationUnitTreeMatcher, BugChecker.CompoundAssignmentTreeMatcher, BugChecker.ConditionalExpressionTreeMatcher, BugChecker.ContinueTreeMatcher, BugChecker.DoWhileLoopTreeMatcher, BugChecker.EmptyStatementTreeMatcher, BugChecker.EnhancedForLoopTreeMatcher, BugChecker.ExportsTreeMatcher, BugChecker.ExpressionStatementTreeMatcher, BugChecker.ForLoopTreeMatcher, BugChecker.IdentifierTreeMatcher, BugChecker.IfTreeMatcher, BugChecker.ImportTreeMatcher, BugChecker.InstanceOfTreeMatcher, BugChecker.IntersectionTypeTreeMatcher, BugChecker.LabeledStatementTreeMatcher, BugChecker.LambdaExpressionTreeMatcher, BugChecker.LiteralTreeMatcher, BugChecker.MemberReferenceTreeMatcher, BugChecker.MemberSelectTreeMatcher, BugChecker.MethodInvocationTreeMatcher, BugChecker.MethodTreeMatcher, BugChecker.ModifiersTreeMatcher, BugChecker.ModuleTreeMatcher, BugChecker.NewArrayTreeMatcher, BugChecker.NewClassTreeMatcher, BugChecker.OpensTreeMatcher, BugChecker.PackageTreeMatcher, BugChecker.ParameterizedTypeTreeMatcher, BugChecker.ParenthesizedTreeMatcher, BugChecker.PrimitiveTypeTreeMatcher, BugChecker.ProvidesTreeMatcher, BugChecker.RequiresTreeMatcher, BugChecker.ReturnTreeMatcher, BugChecker.SuppressibleTreePathScanner<R,P>, BugChecker.SwitchExpressionTreeMatcher, BugChecker.SwitchTreeMatcher, BugChecker.SynchronizedTreeMatcher, BugChecker.ThrowTreeMatcher, BugChecker.TryTreeMatcher, BugChecker.TypeCastTreeMatcher, BugChecker.TypeParameterTreeMatcher, BugChecker.UnaryTreeMatcher, BugChecker.UnionTypeTreeMatcher, BugChecker.UsesTreeMatcher, BugChecker.VariableTreeMatcher, BugChecker.WhileLoopTreeMatcher, BugChecker.WildcardTreeMatcher, BugChecker.YieldTreeMatcher

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	AbstractReturnValueIgnored()
protected	AbstractReturnValueIgnored(ConstantExpressions constantExpressions)

Method Summary

Modifier and Type	Method	Description
protected boolean	allowInExceptionThrowers()	Override this to return false to forbid discarding return values in testers that are testing whether an exception is thrown.
protected Description	describeReturnValueIgnored(MemberReferenceTree memberReferenceTree, VisitorState state)	Uses the default description for results ignored via a method reference.
protected Description	describeReturnValueIgnored(MethodInvocationTree methodInvocationTree, VisitorState state)	Fixes the error by assigning the result of the call to the receiver reference, or deleting the method call.
protected Description	describeReturnValueIgnored(NewClassTree newClassTree, VisitorState state)	Uses the default description for results ignored via a constructor call.
protected String	getMessage(Name name)	Returns the diagnostic message.
ResultUsePolicy	getMethodPolicy(ExpressionTree expression, VisitorState state)	Returns the ResultUsePolicy for the method used in the given expression.
boolean	isCovered(ExpressionTree tree, VisitorState state)	Returns whether this checker makes any determination about whether the given expression's return value should be used or not.
protected Optional<com.sun.tools.javac.code.Type>	lostType(VisitorState state)	Check for occurrences of this type being lost, i.e. cast to Object.
protected String	lostTypeMessage(String returnedType, String declaredReturnType)
Description	matchMemberReference(MemberReferenceTree tree, VisitorState state)
Description	matchMethodInvocation(MethodInvocationTree methodInvocationTree, VisitorState state)
Description	matchNewClass(NewClassTree newClassTree, VisitorState state)
Description	matchReturn(ReturnTree tree, VisitorState state)	Returning a type from a lambda or method that returns Object loses the type information.
protected abstract Matcher<? super ExpressionTree>	specializedMatcher()	Match whatever additional conditions concrete subclasses want to match (a list of known side-effect-free methods, has a @CheckReturnValue annotation, etc.).

Methods inherited from class BugChecker

allNames, buildDescription, buildDescription, buildDescription, canonicalName, customSuppressionAnnotations, defaultSeverity, describeMatch, describeMatch, describeMatch, describeMatch, describeMatch, describeMatch, disableable, equals, hashCode, isSuppressed, isSuppressed, isSuppressed, isSuppressed, linkUrl, message, supportsSuppressWarnings, suppressedByAnyOf, suppressedRegions

Methods inherited from class Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface ResultUsePolicyAnalyzer

allNames, canonicalName, getMatchMetadata

Methods inherited from interface Suppressible

allNames, canonicalName, customSuppressionAnnotations, supportsSuppressWarnings, suppressedByAnyOf

Constructor Details

AbstractReturnValueIgnored

protected AbstractReturnValueIgnored()

AbstractReturnValueIgnored

protected AbstractReturnValueIgnored(ConstantExpressions constantExpressions)

Method Details

matchMethodInvocation

public Description matchMethodInvocation(MethodInvocationTree methodInvocationTree,
 VisitorState state)

Specified by:

matchMethodInvocation in interface BugChecker.MethodInvocationTreeMatcher

matchNewClass

public Description matchNewClass(NewClassTree newClassTree,
 VisitorState state)

Specified by:

matchNewClass in interface BugChecker.NewClassTreeMatcher

matchMemberReference

public Description matchMemberReference(MemberReferenceTree tree,
 VisitorState state)

Specified by:

matchMemberReference in interface BugChecker.MemberReferenceTreeMatcher

isCovered

public boolean isCovered(ExpressionTree tree,
 VisitorState state)

Description copied from interface: ResultUsePolicyAnalyzer

Returns whether this checker makes any determination about whether the given expression's return value should be used or not. Most checkers either determine that an expression is CRV or make no determination.

Specified by:

isCovered in interface ResultUsePolicyAnalyzer<ExpressionTree, VisitorState>

getMethodPolicy

public ResultUsePolicy getMethodPolicy(ExpressionTree expression,
 VisitorState state)

Description copied from interface: ResultUsePolicyAnalyzer

Returns the ResultUsePolicy for the method used in the given expression.

Specified by:

getMethodPolicy in interface ResultUsePolicyAnalyzer<ExpressionTree, VisitorState>

specializedMatcher

protected abstract Matcher<? super ExpressionTree> specializedMatcher()

Match whatever additional conditions concrete subclasses want to match (a list of known side-effect-free methods, has a @CheckReturnValue annotation, etc.).

lostType

protected Optional<com.sun.tools.javac.code.Type> lostType(VisitorState state)

Check for occurrences of this type being lost, i.e. cast to Object.

lostTypeMessage

protected String lostTypeMessage(String returnedType,
 String declaredReturnType)

allowInExceptionThrowers

protected boolean allowInExceptionThrowers()

Override this to return false to forbid discarding return values in testers that are testing whether an exception is thrown.

describeReturnValueIgnored

protected Description describeReturnValueIgnored(MethodInvocationTree methodInvocationTree,
 VisitorState state)

Fixes the error by assigning the result of the call to the receiver reference, or deleting the method call. Subclasses may override if they prefer a different description.

describeReturnValueIgnored

protected Description describeReturnValueIgnored(MemberReferenceTree memberReferenceTree,
 VisitorState state)

Uses the default description for results ignored via a method reference. Subclasses may override if they prefer a different description.

describeReturnValueIgnored

protected Description describeReturnValueIgnored(NewClassTree newClassTree,
 VisitorState state)

Uses the default description for results ignored via a constructor call. Subclasses may override if they prefer a different description.

getMessage

protected String getMessage(Name name)

Returns the diagnostic message. Can be overridden by subclasses to provide a customized diagnostic that includes the name of the invoked method.

matchReturn

public Description matchReturn(ReturnTree tree,
 VisitorState state)

Returning a type from a lambda or method that returns Object loses the type information.

Specified by:

matchReturn in interface BugChecker.ReturnTreeMatcher