com.google.errorprone.bugpatterns.StaticAssignmentInConstructor Maven / Gradle / Ivy
/*
* Copyright 2020 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.getSymbol;
import static com.google.errorprone.util.ASTHelpers.isStatic;
import com.google.errorprone.BugPattern;
import com.google.errorprone.VisitorState;
import com.google.errorprone.bugpatterns.BugChecker.MethodTreeMatcher;
import com.google.errorprone.matchers.Description;
import com.sun.source.tree.AssignmentTree;
import com.sun.source.tree.ClassTree;
import com.sun.source.tree.IdentifierTree;
import com.sun.source.tree.LambdaExpressionTree;
import com.sun.source.tree.MethodTree;
import com.sun.source.util.TreeScanner;
import com.sun.tools.javac.code.Symbol;
import com.sun.tools.javac.code.Symbol.MethodSymbol;
/** Checks for static fields being assigned within constructors. */
@BugPattern(
severity = WARNING,
summary =
"This assignment is to a static field. Mutating static state from a constructor is highly"
+ " error-prone.")
public final class StaticAssignmentInConstructor extends BugChecker implements MethodTreeMatcher {
@Override
public Description matchMethod(MethodTree tree, VisitorState state) {
MethodSymbol methodSymbol = getSymbol(tree);
if (!methodSymbol.isConstructor()) {
return NO_MATCH;
}
new TreeScanner() {
@Override
public Void visitClass(ClassTree classTree, Void unused) {
return null;
}
@Override
public Void visitMethod(MethodTree methodTree, Void unused) {
return null;
}
@Override
public Void visitLambdaExpression(LambdaExpressionTree lambdaExpressionTree, Void unused) {
return null;
}
@Override
public Void visitAssignment(AssignmentTree assignmentTree, Void unused) {
Symbol symbol = getSymbol(assignmentTree.getVariable());
if (symbol != null && isStatic(symbol) && shouldEmitFinding(assignmentTree)) {
state.reportMatch(describeMatch(assignmentTree));
}
return super.visitAssignment(assignmentTree, null);
}
private boolean shouldEmitFinding(AssignmentTree assignmentTree) {
if (!(assignmentTree.getExpression() instanceof IdentifierTree)) {
return true;
}
IdentifierTree identifierTree = ((IdentifierTree) assignmentTree.getExpression());
return !identifierTree.getName().contentEquals("this");
}
}.scan(tree.getBody(), null);
return NO_MATCH;
}
}