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Improve handling of type annotations and type parameter bounds
- handle explicit type annotations on method results - interpret annotations on type variables as bound and look for explicit bound first - inherit annotations for wildcards - handle intersection bounds Also centralize annotation interpretation methods in a single class and merge two methods previously introduced to handle annotations for method results back into a single method. RELNOTES: None. ------------- Created by MOE: https://github.com/google/moe MOE_MIGRATED_REVID=231288208
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...src/main/java/com/google/errorprone/dataflow/nullnesspropagation/NullnessAnnotations.java
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| /* | ||
| * Copyright 2014 The Error Prone Authors. | ||
| * | ||
| * Licensed under the Apache License, Version 2.0 (the "License"); | ||
| * you may not use this file except in compliance with the License. | ||
| * You may obtain a copy of the License at | ||
| * | ||
| * http://www.apache.org/licenses/LICENSE-2.0 | ||
| * | ||
| * Unless required by applicable law or agreed to in writing, software | ||
| * distributed under the License is distributed on an "AS IS" BASIS, | ||
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| * See the License for the specific language governing permissions and | ||
| * limitations under the License. | ||
| */ | ||
|
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| package com.google.errorprone.dataflow.nullnesspropagation; | ||
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| import static javax.lang.model.element.ElementKind.TYPE_PARAMETER; | ||
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| import com.google.errorprone.util.MoreAnnotations; | ||
| import com.sun.tools.javac.code.Symbol; | ||
| import com.sun.tools.javac.code.Type; | ||
| import java.util.Collection; | ||
| import java.util.List; | ||
| import java.util.Optional; | ||
| import java.util.function.Predicate; | ||
| import java.util.regex.Pattern; | ||
| import java.util.stream.Stream; | ||
| import javax.annotation.Nullable; | ||
| import javax.lang.model.element.Element; | ||
| import javax.lang.model.element.ElementKind; | ||
| import javax.lang.model.element.Parameterizable; | ||
| import javax.lang.model.element.TypeParameterElement; | ||
| import javax.lang.model.type.IntersectionType; | ||
| import javax.lang.model.type.TypeKind; | ||
| import javax.lang.model.type.TypeMirror; | ||
| import javax.lang.model.type.TypeVariable; | ||
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| /** Utilities to extract {@link Nullness} from annotations. */ | ||
| public class NullnessAnnotations { | ||
| // TODO(kmb): Correctly handle JSR 305 @Nonnull(NEVER) etc. | ||
| private static final Predicate<String> ANNOTATION_RELEVANT_TO_NULLNESS = | ||
| Pattern.compile( | ||
| ".*\\.((Recently)?Nullable(Decl)?|(Recently)?NotNull(Decl)?|NonNull(Decl)?|Nonnull|" | ||
| + "CheckForNull)$") | ||
| .asPredicate(); | ||
| private static final Predicate<String> NULLABLE_ANNOTATION = | ||
| Pattern.compile(".*\\.((Recently)?Nullable(Decl)?|CheckForNull)$").asPredicate(); | ||
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| private NullnessAnnotations() {} // static methods only | ||
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| public static Optional<Nullness> fromAnnotations(Collection<String> annotations) { | ||
| return fromAnnotationStream(annotations.stream()); | ||
| } | ||
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| public static Optional<Nullness> fromAnnotationsOn(@Nullable Symbol sym) { | ||
| if (sym != null) { | ||
| return fromAnnotationStream( | ||
| MoreAnnotations.getDeclarationAndTypeAttributes(sym).map(Object::toString)); | ||
| } | ||
| return Optional.empty(); | ||
| } | ||
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| public static Optional<Nullness> fromAnnotationsOn(@Nullable TypeMirror type) { | ||
| if (type != null) { | ||
| return fromAnnotationList(type.getAnnotationMirrors()); | ||
| } | ||
| return Optional.empty(); | ||
| } | ||
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| public static Optional<Nullness> getUpperBound(@Nullable Type type) { | ||
| if (type != null && type.getKind() == TypeKind.TYPEVAR) { | ||
| return getUpperBound((TypeVariable) type); | ||
| } | ||
| return Optional.empty(); | ||
| } | ||
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| private static Optional<Nullness> getUpperBound(TypeVariable typeVar) { | ||
| // Annotations on bounds at type variable declaration | ||
| Optional<Nullness> result; | ||
| if (typeVar.getUpperBound() instanceof IntersectionType) { | ||
| // For intersection types, use the lower bound of any annotations on the individual bounds | ||
| result = | ||
| fromAnnotationStream( | ||
| ((IntersectionType) typeVar.getUpperBound()) | ||
| .getBounds().stream() | ||
| .map(TypeMirror::getAnnotationMirrors) | ||
| .map(Object::toString)); | ||
| } else { | ||
| result = fromAnnotationsOn(typeVar.getUpperBound()); | ||
| } | ||
| if (result.isPresent()) { | ||
| // If upper bound is annotated, return that, ignoring annotations on the type variable itself. | ||
| // This gets the upper bound for <T extends @Nullable Object> whether T is annotated or not. | ||
| return result; | ||
| } | ||
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| // Only if the bound isn't annotated, look for an annotation on the type variable itself and | ||
| // treat that as the upper bound. This handles "interface I<@NonNull|@Nullable T>" as a bound. | ||
| if (typeVar.asElement().getKind() == TYPE_PARAMETER) { | ||
| Element genericElt = ((TypeParameterElement) typeVar.asElement()).getGenericElement(); | ||
| if (genericElt.getKind().isClass() | ||
| || genericElt.getKind().isInterface() | ||
| || genericElt.getKind() == ElementKind.METHOD) { | ||
| return ((Parameterizable) genericElt) | ||
| .getTypeParameters().stream() | ||
| .filter( | ||
| typeParam -> | ||
| typeParam.getSimpleName().equals(typeVar.asElement().getSimpleName())) | ||
| .findFirst() | ||
| // Annotations at class/interface/method type variable declaration | ||
| .flatMap(decl -> fromAnnotationList(decl.getAnnotationMirrors())); | ||
| } | ||
| } | ||
| return Optional.empty(); | ||
| } | ||
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| private static Optional<Nullness> fromAnnotationList(List<?> annotations) { | ||
| return fromAnnotationStream(annotations.stream().map(Object::toString)); | ||
| } | ||
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| private static Optional<Nullness> fromAnnotationStream(Stream<String> annotations) { | ||
| return annotations | ||
| .filter(ANNOTATION_RELEVANT_TO_NULLNESS) | ||
| .map(annot -> NULLABLE_ANNOTATION.test(annot) ? Nullness.NULLABLE : Nullness.NONNULL) | ||
| .reduce(Nullness::greatestLowerBound); | ||
| } | ||
| } |
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