com.google.errorprone.bugpatterns.IsInstanceIncompatibleType Maven / Gradle / Ivy
/*
* Copyright 2017 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.
*/
package com.google.errorprone.bugpatterns;
import static com.google.common.collect.Iterables.getOnlyElement;
import static com.google.errorprone.BugPattern.SeverityLevel.ERROR;
import static com.google.errorprone.matchers.Description.NO_MATCH;
import static com.google.errorprone.matchers.Matchers.instanceMethod;
import static com.google.errorprone.util.ASTHelpers.getReceiver;
import static com.google.errorprone.util.ASTHelpers.getType;
import static com.google.errorprone.util.ASTHelpers.isCastable;
import static com.google.errorprone.util.Signatures.prettyType;
import com.google.errorprone.BugPattern;
import com.google.errorprone.VisitorState;
import com.google.errorprone.bugpatterns.BugChecker.MemberReferenceTreeMatcher;
import com.google.errorprone.bugpatterns.BugChecker.MethodInvocationTreeMatcher;
import com.google.errorprone.matchers.Description;
import com.google.errorprone.matchers.Matcher;
import com.google.errorprone.util.ASTHelpers;
import com.sun.source.tree.ExpressionTree;
import com.sun.source.tree.MemberReferenceTree;
import com.sun.source.tree.MethodInvocationTree;
import com.sun.source.tree.Tree;
import com.sun.tools.javac.code.Type;
import java.util.List;
import org.checkerframework.checker.nullness.qual.Nullable;
/**
* @author [email protected] (Liam Miller-Cushon)
* @author [email protected] (Eleanor Harris)
*/
@BugPattern(summary = "This use of isInstance will always evaluate to false.", severity = ERROR)
public final class IsInstanceIncompatibleType extends BugChecker
implements MethodInvocationTreeMatcher, MemberReferenceTreeMatcher {
private static final Matcher IS_INSTANCE =
instanceMethod().onExactClass("java.lang.Class").named("isInstance");
@Override
public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
if (!IS_INSTANCE.matches(tree, state)) {
return NO_MATCH;
}
Type receiverType = classTypeArgument(tree);
if (receiverType == null) {
return NO_MATCH;
}
Type argumentType = getType(tree.getArguments().get(0));
return isCastable(argumentType, receiverType, state)
? NO_MATCH
: buildMessage(argumentType, receiverType, tree, state);
}
@Override
public Description matchMemberReference(MemberReferenceTree tree, VisitorState state) {
if (!IS_INSTANCE.matches(tree, state)) {
return NO_MATCH;
}
Type type = state.getTypes().findDescriptorType(getType(tree));
Type receiverType = classTypeArgument(tree);
if (receiverType == null) {
return NO_MATCH;
}
Type argumentType = ASTHelpers.getUpperBound(type.getParameterTypes().get(0), state.getTypes());
return isCastable(argumentType, receiverType, state)
? NO_MATCH
: buildMessage(argumentType, receiverType, tree, state);
}
private static @Nullable Type classTypeArgument(ExpressionTree tree) {
ExpressionTree receiver = getReceiver(tree);
if (receiver == null) {
return null;
}
List receiverTypeArguments = getType(receiver).getTypeArguments();
return !receiverTypeArguments.isEmpty() ? getOnlyElement(receiverTypeArguments) : null;
}
private Description buildMessage(Type type1, Type type2, Tree tree, VisitorState state) {
return buildDescription(tree)
.setMessage(
String.format(
"This expression will always evaluate to false because %s cannot be cast to %s",
prettyType(state.getTypes().erasure(type1)),
prettyType(state.getTypes().erasure(type2))))
.build();
}
}