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com.google.errorprone.bugpatterns.UnusedException Maven / Gradle / Ivy
/*
* Copyright 2018 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.getLast;
import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
import static com.google.errorprone.BugPattern.StandardTags.STYLE;
import static com.google.errorprone.util.ASTHelpers.getStartPosition;
import static com.google.errorprone.util.ASTHelpers.isSameType;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Sets;
import com.google.common.collect.Streams;
import com.google.errorprone.BugPattern;
import com.google.errorprone.VisitorState;
import com.google.errorprone.bugpatterns.BugChecker.CatchTreeMatcher;
import com.google.errorprone.fixes.SuggestedFix;
import com.google.errorprone.matchers.Description;
import com.google.errorprone.util.ASTHelpers;
import com.sun.source.tree.CatchTree;
import com.sun.source.tree.NewClassTree;
import com.sun.source.tree.VariableTree;
import com.sun.tools.javac.code.Symbol;
import com.sun.tools.javac.code.Symbol.ClassSymbol;
import com.sun.tools.javac.code.Symbol.MethodSymbol;
import com.sun.tools.javac.code.Symbol.VarSymbol;
import com.sun.tools.javac.code.Type;
import com.sun.tools.javac.tree.JCTree;
import com.sun.tools.javac.tree.JCTree.JCIdent;
import com.sun.tools.javac.tree.JCTree.JCNewClass;
import com.sun.tools.javac.tree.JCTree.JCThrow;
import com.sun.tools.javac.tree.JCTree.JCTry;
import com.sun.tools.javac.tree.TreeScanner;
import java.util.HashSet;
import java.util.List;
import java.util.Optional;
import java.util.Set;
import java.util.concurrent.atomic.AtomicBoolean;
import javax.lang.model.element.Modifier;
/**
* Bugpattern for catch blocks which catch an exception but throw another one without wrapping the
* original.
*
* @author [email protected] (Graeme Morgan)
*/
@BugPattern(
name = "UnusedException",
summary =
"This catch block catches an exception and re-throws another, but swallows the caught"
+ " exception rather than setting it as a cause. This can make debugging harder.",
severity = WARNING,
tags = STYLE,
documentSuppression = false)
public final class UnusedException extends BugChecker implements CatchTreeMatcher {
private static final ImmutableSet VISIBILITY_MODIFIERS =
ImmutableSet.of(Modifier.PRIVATE, Modifier.PROTECTED, Modifier.PUBLIC);
@Override
public Description matchCatch(CatchTree tree, VisitorState state) {
if (isSuppressed(tree.getParameter()) || isSuppressedViaName(tree.getParameter())) {
return Description.NO_MATCH;
}
VarSymbol exceptionSymbol = ASTHelpers.getSymbol(tree.getParameter());
if (isSameType(exceptionSymbol.asType(), state.getSymtab().interruptedExceptionType, state)) {
return Description.NO_MATCH;
}
AtomicBoolean symbolUsed = new AtomicBoolean(false);
((JCTree) tree)
.accept(
new TreeScanner() {
@Override
public void visitIdent(JCIdent identTree) {
if (exceptionSymbol.equals(identTree.sym)) {
symbolUsed.set(true);
}
}
});
if (symbolUsed.get()) {
return Description.NO_MATCH;
}
Set throwTrees = new HashSet<>();
((JCTree) tree)
.accept(
new TreeScanner() {
@Override
public void visitThrow(JCThrow throwTree) {
super.visitThrow(throwTree);
throwTrees.add(throwTree);
}
// Don't visit nested try blocks.
@Override
public void visitTry(JCTry tryTree) {}
});
if (throwTrees.isEmpty()) {
return Description.NO_MATCH;
}
SuggestedFix.Builder allFixes = SuggestedFix.builder();
throwTrees.stream()
.filter(badThrow -> badThrow.getExpression() instanceof NewClassTree)
.forEach(
badThrow ->
fixConstructor((NewClassTree) badThrow.getExpression(), exceptionSymbol, state)
.ifPresent(allFixes::merge));
return describeMatch(tree, allFixes.build());
}
private static boolean isSuppressedViaName(VariableTree parameter) {
return parameter.getName().toString().startsWith("unused");
}
private static Optional fixConstructor(
NewClassTree constructor, VarSymbol exception, VisitorState state) {
Symbol symbol = ASTHelpers.getSymbol(((JCNewClass) constructor).clazz);
if (!(symbol instanceof ClassSymbol)) {
return Optional.empty();
}
ImmutableList constructors = ASTHelpers.getConstructors((ClassSymbol) symbol);
MethodSymbol constructorSymbol = ASTHelpers.getSymbol(constructor);
if (constructorSymbol == null) {
return Optional.empty();
}
List types = getParameterTypes(constructorSymbol);
for (MethodSymbol proposedConstructor : constructors) {
List proposedTypes = getParameterTypes(proposedConstructor);
if (proposedTypes.size() != types.size() + 1) {
continue;
}
Set constructorVisibility =
Sets.intersection(constructorSymbol.getModifiers(), VISIBILITY_MODIFIERS);
Set replacementVisibility =
Sets.intersection(proposedConstructor.getModifiers(), VISIBILITY_MODIFIERS);
if (constructor.getClassBody() == null
&& !constructorVisibility.equals(replacementVisibility)) {
continue;
}
if (typesEqual(proposedTypes.subList(0, types.size()), types, state)
&& state.getTypes().isAssignable(exception.type, getLast(proposedTypes))) {
return Optional.of(
appendArgument(constructor, exception.getSimpleName().toString(), state, types));
}
}
return Optional.empty();
}
private static boolean typesEqual(List typesA, List typesB, VisitorState state) {
return Streams.zip(
typesA.stream(), typesB.stream(), (a, b) -> ASTHelpers.isSameType(a, b, state))
.allMatch(x -> x);
}
private static SuggestedFix appendArgument(
NewClassTree constructor, String exception, VisitorState state, List types) {
if (types.isEmpty()) {
// Skip past the opening '(' of the constructor.
String source = state.getSourceForNode(constructor);
int startPosition = getStartPosition(constructor);
int pos =
source.indexOf('(', state.getEndPosition(constructor.getIdentifier()) - startPosition)
+ startPosition
+ 1;
return SuggestedFix.replace(pos, pos, exception);
}
return SuggestedFix.postfixWith(
getLast(constructor.getArguments()), String.format(", %s", exception));
}
private static List getParameterTypes(MethodSymbol constructorSymbol) {
return constructorSymbol.type.getParameterTypes();
}
}