com.google.errorprone.bugpatterns.WrongOneof 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.common.collect.ImmutableSet.toImmutableSet;
import static com.google.common.collect.Iterables.getLast;
import static com.google.errorprone.BugPattern.SeverityLevel.ERROR;
import static com.google.errorprone.matchers.Description.NO_MATCH;
import static com.google.errorprone.predicates.TypePredicates.isDescendantOf;
import static com.google.errorprone.util.ASTHelpers.enumValues;
import static com.google.errorprone.util.ASTHelpers.getReceiver;
import static com.google.errorprone.util.ASTHelpers.getType;
import static com.google.errorprone.util.ASTHelpers.stripParentheses;
import static com.google.errorprone.util.Reachability.canCompleteNormally;
import com.google.common.base.CaseFormat;
import com.google.common.collect.ImmutableSet;
import com.google.errorprone.BugPattern;
import com.google.errorprone.VisitorState;
import com.google.errorprone.bugpatterns.BugChecker.SwitchTreeMatcher;
import com.google.errorprone.bugpatterns.threadsafety.ConstantExpressions;
import com.google.errorprone.bugpatterns.threadsafety.ConstantExpressions.ConstantExpression;
import com.google.errorprone.matchers.Description;
import com.google.errorprone.predicates.TypePredicate;
import com.sun.source.tree.CaseTree;
import com.sun.source.tree.ExpressionTree;
import com.sun.source.tree.IdentifierTree;
import com.sun.source.tree.MemberSelectTree;
import com.sun.source.tree.MethodInvocationTree;
import com.sun.source.tree.StatementTree;
import com.sun.source.tree.SwitchTree;
import com.sun.source.util.TreePath;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import javax.inject.Inject;
/** Matches always-default expressions in oneof switches. */
@BugPattern(
severity = ERROR,
summary = "This field is guaranteed not to be set given it's within a switch over a one_of.")
public final class WrongOneof extends BugChecker implements SwitchTreeMatcher {
private static final TypePredicate ONE_OF_ENUM =
isDescendantOf("com.google.protobuf.AbstractMessageLite.InternalOneOfEnum");
private final ConstantExpressions constantExpressions;
@Inject
WrongOneof(ConstantExpressions constantExpressions) {
this.constantExpressions = constantExpressions;
}
@Override
public Description matchSwitch(SwitchTree tree, VisitorState state) {
if (!ONE_OF_ENUM.apply(getType(tree.getExpression()), state)) {
return NO_MATCH;
}
ExpressionTree expression = stripParentheses(tree.getExpression());
if (!(expression instanceof MethodInvocationTree)) {
return NO_MATCH;
}
ExpressionTree receiver = getReceiver(expression);
if (receiver == null) {
return NO_MATCH;
}
constantExpressions
.constantExpression(receiver, state)
.ifPresent(constantReceiver -> processSwitch(tree, constantReceiver, state));
return NO_MATCH;
}
private void processSwitch(
SwitchTree tree, ConstantExpression constantReceiver, VisitorState state) {
ImmutableSet getters =
enumValues(getType(tree.getExpression()).tsym).stream()
.map(WrongOneof::getter)
.collect(toImmutableSet());
// Keep track of which getters might be set.
Set allowableGetters = new HashSet<>();
for (CaseTree caseTree : tree.getCases()) {
// Break out once we reach a default.
if (caseTree.getExpression() == null) {
break;
}
allowableGetters.add(
getter(((IdentifierTree) caseTree.getExpression()).getName().toString()));
scanForInvalidGetters(getters, allowableGetters, caseTree, constantReceiver, state);
List statements = caseTree.getStatements();
if (statements != null
&& !statements.isEmpty()
&& !canCompleteNormally(getLast(statements))) {
allowableGetters.clear();
}
}
}
private void scanForInvalidGetters(
Set getters,
Set allowableGetters,
CaseTree caseTree,
ConstantExpression receiverSymbolChain,
VisitorState state) {
new SuppressibleTreePathScanner(state) {
@Override
public Void visitMethodInvocation(MethodInvocationTree methodInvocationTree, Void unused) {
ExpressionTree receiver = getReceiver(methodInvocationTree);
if (receiver == null) {
return super.visitMethodInvocation(methodInvocationTree, null);
}
if (!constantExpressions
.constantExpression(receiver, state)
.map(receiverSymbolChain::equals)
.orElse(false)) {
return super.visitMethodInvocation(methodInvocationTree, null);
}
String methodName =
((MemberSelectTree) methodInvocationTree.getMethodSelect()).getIdentifier().toString();
if (!allowableGetters.contains(methodName) && getters.contains(methodName)) {
state.reportMatch(
buildDescription(methodInvocationTree)
.setMessage(
String.format(
"%s is guaranteed to return the default instance, given this is"
+ " within a switch over a one_of.",
methodName))
.build());
}
return super.visitMethodInvocation(methodInvocationTree, null);
}
}.scan(new TreePath(state.getPath(), caseTree), null);
}
private static String getter(String enumCase) {
return "get" + CaseFormat.UPPER_UNDERSCORE.to(CaseFormat.UPPER_CAMEL, enumCase);
}
}