com.google.errorprone.bugpatterns.UnnecessaryTypeArgument Maven / Gradle / Ivy
/*
* Copyright 2015 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.base.Verify.verify;
import static com.google.errorprone.BugPattern.SeverityLevel.ERROR;
import static com.google.errorprone.util.ASTHelpers.getStartPosition;
import com.google.errorprone.BugPattern;
import com.google.errorprone.VisitorState;
import com.google.errorprone.bugpatterns.BugChecker.MethodInvocationTreeMatcher;
import com.google.errorprone.bugpatterns.BugChecker.NewClassTreeMatcher;
import com.google.errorprone.fixes.Fix;
import com.google.errorprone.fixes.SuggestedFix;
import com.google.errorprone.matchers.Description;
import com.google.errorprone.util.ASTHelpers;
import com.sun.source.tree.MethodInvocationTree;
import com.sun.source.tree.NewClassTree;
import com.sun.source.tree.Tree;
import com.sun.tools.javac.code.Symbol;
import com.sun.tools.javac.code.Symbol.MethodSymbol;
import com.sun.tools.javac.tree.JCTree;
import java.util.List;
/** A {@link BugChecker}; see the associated {@link BugPattern} annotation for details. */
@BugPattern(
summary = "Non-generic methods should not be invoked with type arguments",
severity = ERROR)
public class UnnecessaryTypeArgument extends BugChecker
implements MethodInvocationTreeMatcher, NewClassTreeMatcher {
@Override
public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
return check(tree, tree.getTypeArguments(), state);
}
@Override
public Description matchNewClass(NewClassTree tree, VisitorState state) {
return check(tree, tree.getTypeArguments(), state);
}
private Description check(Tree tree, List arguments, VisitorState state) {
Symbol sym = ASTHelpers.getSymbol(tree);
if (!(sym instanceof MethodSymbol)) {
return Description.NO_MATCH;
}
MethodSymbol methodSymbol = (MethodSymbol) sym;
int expected = methodSymbol.getTypeParameters().size();
int actual = arguments.size();
if (actual <= expected) {
return Description.NO_MATCH;
}
for (MethodSymbol superMethod : ASTHelpers.findSuperMethods(methodSymbol, state.getTypes())) {
if (!superMethod.getTypeParameters().isEmpty()) {
// Exempt methods that override generic methods to preserve the substitutability of the
// two types.
return Description.NO_MATCH;
}
}
return describeMatch(tree, buildFix(tree, arguments, state));
}
/** Constructor a fix that deletes the set of type arguments. */
private static Fix buildFix(Tree tree, List arguments, VisitorState state) {
JCTree node = (JCTree) tree;
int startAbsolute = node.getStartPosition();
int lower = getStartPosition(arguments.get(0)) - startAbsolute;
int upper = state.getEndPosition(arguments.get(arguments.size() - 1)) - startAbsolute;
CharSequence source = state.getSourceForNode(node);
while (lower >= 0 && source.charAt(lower) != '<') {
lower--;
}
while (upper < source.length() && source.charAt(upper) != '>') {
upper++;
}
// There's a small chance that the fix will be incorrect because there's a '<' or '>' in
// a comment (e.g. `this.*/>f()`), it should never be the case that we don't find
// any angle brackets.
verify(source.charAt(lower) == '<' && source.charAt(upper) == '>');
Fix fix = SuggestedFix.replace(startAbsolute + lower, startAbsolute + upper + 1, "");
return fix;
}
}