com.google.errorprone.bugpatterns.NullOptional 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.fixes.SuggestedFixes.qualifyType;
import static com.google.errorprone.matchers.Description.NO_MATCH;
import static com.google.errorprone.matchers.Matchers.methodCallInDeclarationOfThrowingRunnable;
import static com.google.errorprone.predicates.TypePredicates.anyOf;
import static com.google.errorprone.predicates.TypePredicates.isDescendantOf;
import static com.google.errorprone.util.ASTHelpers.getSymbol;
import static com.google.errorprone.util.ASTHelpers.hasDirectAnnotationWithSimpleName;
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.SuggestedFix;
import com.google.errorprone.matchers.Description;
import com.google.errorprone.predicates.TypePredicate;
import com.sun.source.tree.ExpressionTree;
import com.sun.source.tree.MethodInvocationTree;
import com.sun.source.tree.NewClassTree;
import com.sun.source.tree.Tree.Kind;
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.code.Type.ArrayType;
import java.util.Iterator;
import java.util.List;
import javax.annotation.Nullable;
/** Flags passing literal null to {@code Optional}-accepting APIs. */
@BugPattern(
name = "NullOptional",
summary =
"Passing a literal null to an Optional parameter is almost certainly a mistake. Did you"
+ " mean to provide an empty Optional?",
severity = WARNING)
public final class NullOptional extends BugChecker
implements MethodInvocationTreeMatcher, NewClassTreeMatcher {
private static final TypePredicate GUAVA_OPTIONAL =
isDescendantOf("com.google.common.base.Optional");
private static final TypePredicate OPTIONAL =
anyOf(GUAVA_OPTIONAL, isDescendantOf("java.util.Optional"));
@Override
public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
handleMethodInvocation(getSymbol(tree), tree.getArguments(), state);
return NO_MATCH;
}
@Override
public Description matchNewClass(NewClassTree tree, VisitorState state) {
handleMethodInvocation(getSymbol(tree), tree.getArguments(), state);
return NO_MATCH;
}
private void handleMethodInvocation(
@Nullable MethodSymbol symbol, List arguments, VisitorState state) {
if (symbol == null) {
return;
}
Iterator parameters = symbol.getParameters().iterator();
VarSymbol parameter = null;
Type parameterType = null;
for (ExpressionTree argument : arguments) {
parameter = parameters.hasNext() ? parameters.next() : parameter;
parameterType = parameter.type;
if (symbol.isVarArgs() && !parameters.hasNext()) {
parameterType = ((ArrayType) parameter.type).elemtype;
}
if (argument.getKind() == Kind.NULL_LITERAL
&& OPTIONAL.apply(parameterType, state)
&& !hasDirectAnnotationWithSimpleName(parameter, "Nullable")) {
if (methodCallInDeclarationOfThrowingRunnable(state)) {
return;
}
SuggestedFix.Builder fix = SuggestedFix.builder();
fix.replace(
argument,
String.format(
"%s.%s()",
qualifyType(state, fix, parameterType.tsym),
GUAVA_OPTIONAL.apply(parameterType, state) ? "absent" : "empty"));
state.reportMatch(describeMatch(argument, fix.build()));
}
}
}
}