com.google.errorprone.bugpatterns.ErroneousBitwiseExpression Maven / Gradle / Ivy
/*
* Copyright 2022 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.errorprone.BugPattern.SeverityLevel.WARNING;
import static com.google.errorprone.matchers.Description.NO_MATCH;
import static com.google.errorprone.util.ASTHelpers.getStartPosition;
import com.google.errorprone.BugPattern;
import com.google.errorprone.VisitorState;
import com.google.errorprone.bugpatterns.BugChecker.BinaryTreeMatcher;
import com.google.errorprone.fixes.SuggestedFix;
import com.google.errorprone.matchers.Description;
import com.google.errorprone.util.ASTHelpers;
import com.sun.source.tree.BinaryTree;
import com.sun.source.tree.Tree.Kind;
import java.util.Objects;
/** A BugPattern; see the summary. */
@BugPattern(
summary =
"This expression evaluates to 0. If this isn't an error, consider expressing it as a"
+ " literal 0.",
severity = WARNING)
public final class ErroneousBitwiseExpression extends BugChecker implements BinaryTreeMatcher {
@Override
public Description matchBinary(BinaryTree tree, VisitorState state) {
if (tree.getKind() != Kind.AND) {
return NO_MATCH;
}
Object constantValue = ASTHelpers.constValue(tree);
// Constants of the form A & B which evaluate to a literal 0 are probably trying to combine
// bitwise flags using |.
return Objects.equals(constantValue, 0) || Objects.equals(constantValue, 0L)
? describeMatch(
tree,
SuggestedFix.replace(
/* startPos= */ state.getEndPosition(tree.getLeftOperand()),
/* endPos= */ getStartPosition(tree.getRightOperand()),
" | "))
: NO_MATCH;
}
}