com.google.errorprone.bugpatterns.FloatCast Maven / Gradle / Ivy
/*
* Copyright 2017 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.Sets.immutableEnumSet;
import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
import static com.google.errorprone.matchers.Description.NO_MATCH;
import static com.google.errorprone.matchers.method.MethodMatchers.staticMethod;
import static com.google.errorprone.util.ASTHelpers.isSameType;
import com.google.common.collect.ImmutableSet;
import com.google.errorprone.BugPattern;
import com.google.errorprone.VisitorState;
import com.google.errorprone.bugpatterns.BugChecker.TypeCastTreeMatcher;
import com.google.errorprone.fixes.SuggestedFix;
import com.google.errorprone.matchers.Description;
import com.google.errorprone.matchers.Matcher;
import com.google.errorprone.util.ASTHelpers;
import com.sun.source.tree.BinaryTree;
import com.sun.source.tree.ExpressionTree;
import com.sun.source.tree.MethodInvocationTree;
import com.sun.source.tree.Tree;
import com.sun.source.tree.Tree.Kind;
import com.sun.source.tree.TypeCastTree;
import com.sun.source.util.TreePath;
import com.sun.tools.javac.code.Symtab;
import com.sun.tools.javac.code.Type;
import javax.lang.model.type.TypeKind;
/** A {@link BugChecker}; see the associated {@link BugPattern} annotation for details. */
@BugPattern(summary = "Use parentheses to make the precedence explicit", severity = WARNING)
public class FloatCast extends BugChecker implements TypeCastTreeMatcher {
private static final ImmutableSet INTEGRAL =
immutableEnumSet(TypeKind.LONG, TypeKind.INT);
private static final Matcher IGNORED_METHODS =
staticMethod().onClass("java.lang.Math").namedAnyOf("floor", "ceil", "signum", "rint");
private static final Matcher POW =
staticMethod().onClass("java.lang.Math").named("pow");
@Override
public Description matchTypeCast(TypeCastTree tree, VisitorState state) {
Tree parent = state.getPath().getParentPath().getLeaf();
if (!(parent instanceof BinaryTree)) {
return NO_MATCH;
}
BinaryTree binop = (BinaryTree) parent;
if (!binop.getLeftOperand().equals(tree)) {
// the precedence is unambiguous for e.g. `i + (int) f`
return NO_MATCH;
}
if (binop.getKind() != Kind.MULTIPLY) {
// there's a bound on the imprecision for +, -, /
return NO_MATCH;
}
Type castType = ASTHelpers.getType(tree.getType());
Type operandType = ASTHelpers.getType(tree.getExpression());
if (castType == null || operandType == null) {
return NO_MATCH;
}
Symtab symtab = state.getSymtab();
if (isSameType(ASTHelpers.getType(parent), symtab.stringType, state)) {
// string concatenation doesn't count
return NO_MATCH;
}
switch (castType.getKind()) {
case LONG:
case INT:
case SHORT:
case CHAR:
case BYTE:
break;
default:
return NO_MATCH;
}
switch (operandType.getKind()) {
case FLOAT:
case DOUBLE:
break;
default:
return NO_MATCH;
}
if (IGNORED_METHODS.matches(tree.getExpression(), state)) {
return NO_MATCH;
}
if (POW.matches(tree.getExpression(), state)) {
MethodInvocationTree pow = (MethodInvocationTree) tree.getExpression();
if (pow.getArguments().stream()
.map(ASTHelpers::getType)
.filter(x -> x != null)
.map(state.getTypes()::unboxedTypeOrType)
.map(Type::getKind)
.allMatch(INTEGRAL::contains)) {
return NO_MATCH;
}
}
// Find the outermost enclosing binop, to suggest e.g. `(long) (f * a * b)` instead of
// `(long) (f * a) * b`.
Tree enclosing = binop;
TreePath path = state.getPath().getParentPath().getParentPath();
while (path != null) {
if (!(path.getLeaf() instanceof BinaryTree)) {
break;
}
BinaryTree enclosingBinop = (BinaryTree) path.getLeaf();
if (!enclosingBinop.getLeftOperand().equals(enclosing)) {
break;
}
enclosing = enclosingBinop;
path = path.getParentPath();
}
return buildDescription(tree)
.addFix(
SuggestedFix.builder()
.prefixWith(tree.getExpression(), "(")
.postfixWith(enclosing, ")")
.build())
.addFix(SuggestedFix.builder().prefixWith(tree, "(").postfixWith(tree, ")").build())
.build();
}
}