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/*******************************************************************************
* Copyright (c) 2013, 2014 GK Software AG and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Stephan Herrmann - initial API and implementation
*******************************************************************************/
package org.eclipse.jdt.internal.compiler.ast;
import org.eclipse.jdt.internal.compiler.classfmt.ClassFileConstants;
import org.eclipse.jdt.internal.compiler.flow.FlowContext;
import org.eclipse.jdt.internal.compiler.flow.FlowInfo;
import org.eclipse.jdt.internal.compiler.impl.CompilerOptions;
import org.eclipse.jdt.internal.compiler.lookup.ArrayBinding;
import org.eclipse.jdt.internal.compiler.lookup.BlockScope;
import org.eclipse.jdt.internal.compiler.lookup.CaptureBinding;
import org.eclipse.jdt.internal.compiler.lookup.InvocationSite;
import org.eclipse.jdt.internal.compiler.lookup.MethodBinding;
import org.eclipse.jdt.internal.compiler.lookup.ParameterizedTypeBinding;
import org.eclipse.jdt.internal.compiler.lookup.ProblemMethodBinding;
import org.eclipse.jdt.internal.compiler.lookup.ProblemReasons;
import org.eclipse.jdt.internal.compiler.lookup.RawTypeBinding;
import org.eclipse.jdt.internal.compiler.lookup.ReferenceBinding;
import org.eclipse.jdt.internal.compiler.lookup.Scope;
import org.eclipse.jdt.internal.compiler.lookup.TagBits;
import org.eclipse.jdt.internal.compiler.lookup.TypeBinding;
import org.eclipse.jdt.internal.compiler.lookup.TypeBindingVisitor;
import org.eclipse.jdt.internal.compiler.lookup.TypeIds;
import org.eclipse.jdt.internal.compiler.lookup.TypeVariableBinding;
import org.eclipse.jdt.internal.compiler.lookup.VariableBinding;
import org.eclipse.jdt.internal.compiler.lookup.WildcardBinding;
/**
* Performs matching of null type annotations.
* Instances are used to encode result from this analysis.
* @since 3.10
*/
public class NullAnnotationMatching {
public static final NullAnnotationMatching NULL_ANNOTATIONS_OK = new NullAnnotationMatching(0, null);
public static final NullAnnotationMatching NULL_ANNOTATIONS_UNCHECKED = new NullAnnotationMatching(1, null);
public static final NullAnnotationMatching NULL_ANNOTATIONS_MISMATCH = new NullAnnotationMatching(2, null);
/** 0 = OK, 1 = unchecked, 2 = definite mismatch */
public final int severity;
/** If non-null this field holds the supertype of the provided type which was used for direct matching. */
public final TypeBinding superTypeHint;
public NullAnnotationMatching(int severity, TypeBinding superTypeHint) {
this.severity = severity;
this.superTypeHint = superTypeHint;
}
public boolean isAnyMismatch() { return this.severity != 0; }
public boolean isUnchecked() { return this.severity == 1; }
public boolean isDefiniteMismatch() { return this.severity == 2; }
public String superTypeHintName(CompilerOptions options, boolean shortNames) {
return String.valueOf(this.superTypeHint.nullAnnotatedReadableName(options, shortNames));
}
/** Check null-ness of 'var' against a possible null annotation */
public static int checkAssignment(BlockScope currentScope, FlowContext flowContext,
VariableBinding var, int nullStatus, Expression expression, TypeBinding providedType)
{
long lhsTagBits = 0L;
boolean hasReported = false;
if (currentScope.compilerOptions().sourceLevel < ClassFileConstants.JDK1_8) {
lhsTagBits = var.tagBits & TagBits.AnnotationNullMASK;
} else {
if (expression instanceof ConditionalExpression && expression.isPolyExpression()) {
// drill into both branches:
ConditionalExpression ce = ((ConditionalExpression) expression);
int status1 = NullAnnotationMatching.checkAssignment(currentScope, flowContext, var, ce.ifTrueNullStatus, ce.valueIfTrue, ce.valueIfTrue.resolvedType);
int status2 = NullAnnotationMatching.checkAssignment(currentScope, flowContext, var, ce.ifFalseNullStatus, ce.valueIfFalse, ce.valueIfFalse.resolvedType);
if (status1 == status2)
return status1;
return nullStatus; // if both branches disagree use the precomputed & merged nullStatus
}
lhsTagBits = var.type.tagBits & TagBits.AnnotationNullMASK;
NullAnnotationMatching annotationStatus = analyse(var.type, providedType, nullStatus);
if (annotationStatus.isDefiniteMismatch()) {
currentScope.problemReporter().nullityMismatchingTypeAnnotation(expression, providedType, var.type, annotationStatus);
hasReported = true;
} else if (annotationStatus.isUnchecked()) {
flowContext.recordNullityMismatch(currentScope, expression, providedType, var.type, nullStatus);
hasReported = true;
}
}
if (lhsTagBits == TagBits.AnnotationNonNull && nullStatus != FlowInfo.NON_NULL) {
if (!hasReported)
flowContext.recordNullityMismatch(currentScope, expression, providedType, var.type, nullStatus);
return FlowInfo.NON_NULL;
} else if (lhsTagBits == TagBits.AnnotationNullable && nullStatus == FlowInfo.UNKNOWN) { // provided a legacy type?
return FlowInfo.POTENTIALLY_NULL; // -> use more specific info from the annotation
}
return nullStatus;
}
/**
* Find any mismatches between the two given types, which are caused by null type annotations.
* @param requiredType
* @param providedType
* @param nullStatus we are only interested in NULL or NON_NULL, -1 indicates that we are in a recursion, where flow info is ignored
* @return a status object representing the severity of mismatching plus optionally a supertype hint
*/
public static NullAnnotationMatching analyse(TypeBinding requiredType, TypeBinding providedType, int nullStatus) {
return analyse(requiredType, providedType, nullStatus, false);
}
// additional parameter strict: if true we do not tolerate incompatibly missing annotations on type parameters (for overriding analysis)
public static NullAnnotationMatching analyse(TypeBinding requiredType, TypeBinding providedType, int nullStatus, boolean strict) {
int severity = 0;
TypeBinding superTypeHint = null;
if (requiredType instanceof ArrayBinding) {
long[] requiredDimsTagBits = ((ArrayBinding)requiredType).nullTagBitsPerDimension;
if (requiredDimsTagBits != null) {
int dims = requiredType.dimensions();
if (requiredType.dimensions() == providedType.dimensions()) {
long[] providedDimsTagBits = ((ArrayBinding)providedType).nullTagBitsPerDimension;
if (providedDimsTagBits == null) {
severity = 1; // required is annotated, provided not, need unchecked conversion
} else {
for (int i=0; i<=dims; i++) {
long requiredBits = validNullTagBits(requiredDimsTagBits[i]);
long providedBits = validNullTagBits(providedDimsTagBits[i]);
if (i > 0)
nullStatus = -1; // don't use beyond the outermost dimension
severity = Math.max(severity, computeNullProblemSeverity(requiredBits, providedBits, nullStatus, strict));
if (severity == 2)
return NullAnnotationMatching.NULL_ANNOTATIONS_MISMATCH;
}
}
} else if (providedType.id == TypeIds.T_null) {
if (dims > 0 && requiredDimsTagBits[0] == TagBits.AnnotationNonNull)
return NullAnnotationMatching.NULL_ANNOTATIONS_MISMATCH;
}
}
} else if (requiredType.hasNullTypeAnnotations() || providedType.hasNullTypeAnnotations()) {
long requiredBits = requiredNullTagBits(requiredType);
if (requiredBits != TagBits.AnnotationNullable // nullable lhs accepts everything, ...
|| nullStatus == -1) // only at detail/recursion even nullable must be matched exactly
{
long providedBits = providedNullTagBits(providedType);
severity = computeNullProblemSeverity(requiredBits, providedBits, nullStatus, strict && nullStatus == -1);
}
if (severity < 2) {
TypeBinding providedSuper = providedType.findSuperTypeOriginatingFrom(requiredType);
if (providedSuper != providedType) //$IDENTITY-COMPARISON$
superTypeHint = providedSuper;
if (requiredType.isParameterizedType() && providedSuper instanceof ParameterizedTypeBinding) { // TODO(stephan): handle providedType.isRaw()
TypeBinding[] requiredArguments = ((ParameterizedTypeBinding) requiredType).arguments;
TypeBinding[] providedArguments = ((ParameterizedTypeBinding) providedSuper).arguments;
if (requiredArguments != null && providedArguments != null && requiredArguments.length == providedArguments.length) {
for (int i = 0; i < requiredArguments.length; i++) {
NullAnnotationMatching status = analyse(requiredArguments[i], providedArguments[i], -1, strict);
severity = Math.max(severity, status.severity);
if (severity == 2)
return new NullAnnotationMatching(severity, superTypeHint);
}
}
}
TypeBinding requiredEnclosing = requiredType.enclosingType();
TypeBinding providedEnclosing = providedType.enclosingType();
if (requiredEnclosing != null && providedEnclosing != null) {
NullAnnotationMatching status = analyse(requiredEnclosing, providedEnclosing, -1, strict);
severity = Math.max(severity, status.severity);
}
}
}
if (severity == 0)
return NullAnnotationMatching.NULL_ANNOTATIONS_OK;
return new NullAnnotationMatching(severity, superTypeHint);
}
// interpreting 'type' as a required type, compute the required null bits
// we inspect the main type plus bounds of type variables and wildcards
static long requiredNullTagBits(TypeBinding type) {
long tagBits = type.tagBits & TagBits.AnnotationNullMASK;
if (tagBits != 0)
return validNullTagBits(tagBits);
if (type.isWildcard()) {
WildcardBinding wildcard = (WildcardBinding)type;
if (wildcard.boundKind == Wildcard.UNBOUND)
return 0;
tagBits = wildcard.bound.tagBits & TagBits.AnnotationNullMASK;
if (tagBits == 0)
return 0;
switch (wildcard.boundKind) {
case Wildcard.EXTENDS :
if (tagBits == TagBits.AnnotationNonNull)
return TagBits.AnnotationNonNull;
return TagBits.AnnotationNullMASK; // wildcard accepts @Nullable or better
case Wildcard.SUPER :
if (tagBits == TagBits.AnnotationNullable)
return TagBits.AnnotationNullable;
return TagBits.AnnotationNullMASK; // wildcard accepts @NonNull or worse
}
return 0;
}
if (type.isTypeVariable()) {
// assume we must require @NonNull, unless: (1) lower @Nullable bound, or (2) no nullness specified
TypeVariableBinding typeVariable = (TypeVariableBinding)type;
boolean haveNullBits = false;
if (type.isCapture()) {
TypeBinding lowerBound = ((CaptureBinding) type).lowerBound;
if (lowerBound != null) {
tagBits = lowerBound.tagBits & TagBits.AnnotationNullMASK;
if (tagBits == TagBits.AnnotationNullable)
return TagBits.AnnotationNullable; // (1) type cannot require @NonNull
haveNullBits = tagBits != 0;
}
}
if (typeVariable.firstBound != null)
haveNullBits |= (typeVariable.firstBound.tagBits & TagBits.AnnotationNullMASK) != 0;
if (haveNullBits)
return TagBits.AnnotationNonNull; // could require @NonNull (unless (2) unspecified nullness)
}
return 0;
}
// interpreting 'type' as a provided type, compute the provide null bits
// we inspect the main type plus bounds of type variables and wildcards
static long providedNullTagBits(TypeBinding type) {
long tagBits = type.tagBits & TagBits.AnnotationNullMASK;
if (tagBits != 0)
return validNullTagBits(tagBits);
if (type.isWildcard()) { // wildcard can be 'provided' during inheritance checks
WildcardBinding wildcard = (WildcardBinding)type;
if (wildcard.boundKind == Wildcard.UNBOUND)
return 0;
tagBits = wildcard.bound.tagBits & TagBits.AnnotationNullMASK;
if (tagBits == 0)
return 0;
switch (wildcard.boundKind) {
case Wildcard.EXTENDS :
if (tagBits == TagBits.AnnotationNonNull)
return TagBits.AnnotationNonNull;
return TagBits.AnnotationNullMASK; // @Nullable or better
case Wildcard.SUPER :
if (tagBits == TagBits.AnnotationNullable)
return TagBits.AnnotationNullable;
return TagBits.AnnotationNullMASK; // @NonNull or worse
}
return 0;
}
if (type.isTypeVariable()) { // incl. captures
TypeVariableBinding typeVariable = (TypeVariableBinding)type;
boolean haveNullBits = false;
if (typeVariable.isCapture()) {
TypeBinding lowerBound = ((CaptureBinding) typeVariable).lowerBound;
if (lowerBound != null) {
tagBits = lowerBound.tagBits & TagBits.AnnotationNullMASK;
if (tagBits == TagBits.AnnotationNullable)
return TagBits.AnnotationNullable; // cannot be @NonNull
haveNullBits |= (tagBits != 0);
}
}
if (typeVariable.firstBound != null) {
long boundBits = typeVariable.firstBound.tagBits & TagBits.AnnotationNullMASK;
if (boundBits == TagBits.AnnotationNonNull)
return TagBits.AnnotationNonNull; // cannot be @Nullable
haveNullBits |= (boundBits != 0);
}
if (haveNullBits)
return TagBits.AnnotationNullMASK; // could be either, can only match to a wildcard accepting both
}
return 0;
}
public static long validNullTagBits(long bits) {
bits &= TagBits.AnnotationNullMASK;
return bits == TagBits.AnnotationNullMASK ? 0 : bits;
}
/** Provided that both types are {@link TypeBinding#equalsEquals}, return the one that is more likely to show null at runtime. */
public static TypeBinding moreDangerousType(TypeBinding one, TypeBinding two) {
if (one == null) return null;
long oneNullBits = validNullTagBits(one.tagBits);
long twoNullBits = validNullTagBits(two.tagBits);
if (oneNullBits != twoNullBits) {
if (oneNullBits == TagBits.AnnotationNullable)
return one; // nullable is dangerous
if (twoNullBits == TagBits.AnnotationNullable)
return two; // nullable is dangerous
// below this point we have unknown vs. nonnull, which is which?
if (oneNullBits == 0)
return one; // unknown is more dangerous than nonnull
return two; // unknown is more dangerous than nonnull
} else if (one != two) { //$IDENTITY-COMPARISON$
if (analyse(one, two, -1).isAnyMismatch())
return two; // two doesn't snugly fit into one, so it must be more dangerous
}
return one;
}
private static int computeNullProblemSeverity(long requiredBits, long providedBits, int nullStatus, boolean strict) {
if ((requiredBits != 0 || strict) && requiredBits != providedBits) {
if (requiredBits == TagBits.AnnotationNonNull && nullStatus == FlowInfo.NON_NULL) {
return 0; // OK by flow analysis
}
if (requiredBits == TagBits.AnnotationNullMASK)
return 0; // OK since LHS accepts either
if (providedBits != 0) {
return 2; // mismatching annotations
} else {
return 1; // need unchecked conversion regarding type detail
}
}
return 0; // OK by tagBits
}
/**
* After a method has substituted type parameters, check if this resulted in any contradictory null annotations.
* Problems are either reported directly (if scope != null) or by returning a ProblemMethodBinding.
*/
public static MethodBinding checkForContraditions(
final MethodBinding method, final InvocationSite invocationSite, final Scope scope) {
class SearchContradictions extends TypeBindingVisitor {
ReferenceBinding typeWithContradiction;
@Override
public boolean visit(ReferenceBinding referenceBinding) {
if ((referenceBinding.tagBits & TagBits.AnnotationNullMASK) == TagBits.AnnotationNullMASK) {
this.typeWithContradiction = referenceBinding;
return false;
}
return true;
}
@Override
public boolean visit(TypeVariableBinding typeVariable) {
return visit((ReferenceBinding)typeVariable);
}
@Override
public boolean visit(RawTypeBinding rawType) {
return visit((ReferenceBinding)rawType);
}
}
SearchContradictions searchContradiction = new SearchContradictions();
TypeBindingVisitor.visit(searchContradiction, method.returnType);
if (searchContradiction.typeWithContradiction != null) {
if (scope == null)
return new ProblemMethodBinding(method, method.selector, method.parameters, ProblemReasons.ContradictoryNullAnnotations);
scope.problemReporter().contradictoryNullAnnotationsInferred(method, invocationSite);
// note: if needed, we might want to update the method by removing the contradictory annotations??
return method;
}
Expression[] arguments = null;
if (invocationSite instanceof Invocation)
arguments = ((Invocation)invocationSite).arguments();
for (int i = 0; i < method.parameters.length; i++) {
TypeBindingVisitor.visit(searchContradiction, method.parameters[i]);
if (searchContradiction.typeWithContradiction != null) {
if (scope == null)
return new ProblemMethodBinding(method, method.selector, method.parameters, ProblemReasons.ContradictoryNullAnnotations);
if (arguments != null && i < arguments.length)
scope.problemReporter().contradictoryNullAnnotationsInferred(method, arguments[i]);
else
scope.problemReporter().contradictoryNullAnnotationsInferred(method, invocationSite);
return method;
}
}
return method;
}
}
