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//===--- IncDecInConditionsCheck.cpp - clang-tidy -------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "IncDecInConditionsCheck.h"
#include "../utils/Matchers.h"
#include "clang/AST/ASTContext.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
using namespace clang::ast_matchers;
namespace clang::tidy::bugprone {
namespace {
AST_MATCHER(BinaryOperator, isLogicalOperator) { return Node.isLogicalOp(); }
AST_MATCHER(UnaryOperator, isUnaryPrePostOperator) {
return Node.isPrefix() || Node.isPostfix();
}
AST_MATCHER(CXXOperatorCallExpr, isPrePostOperator) {
return Node.getOperator() == OO_PlusPlus ||
Node.getOperator() == OO_MinusMinus;
}
} // namespace
void IncDecInConditionsCheck::registerMatchers(MatchFinder *Finder) {
auto OperatorMatcher = expr(
anyOf(binaryOperator(anyOf(isComparisonOperator(), isLogicalOperator())),
cxxOperatorCallExpr(isComparisonOperator())));
auto IsInUnevaluatedContext =
expr(anyOf(hasAncestor(expr(matchers::hasUnevaluatedContext())),
hasAncestor(typeLoc())));
Finder->addMatcher(
expr(
OperatorMatcher, unless(isExpansionInSystemHeader()),
unless(hasAncestor(OperatorMatcher)), expr().bind("parent"),
forEachDescendant(
expr(anyOf(unaryOperator(isUnaryPrePostOperator(),
hasUnaryOperand(expr().bind("operand"))),
cxxOperatorCallExpr(
isPrePostOperator(),
hasUnaryOperand(expr().bind("operand")))),
unless(IsInUnevaluatedContext),
hasAncestor(
expr(equalsBoundNode("parent"),
hasDescendant(
expr(unless(equalsBoundNode("operand")),
matchers::isStatementIdenticalToBoundNode(
"operand"),
unless(IsInUnevaluatedContext))
.bind("second")))))
.bind("operator"))),
this);
}
void IncDecInConditionsCheck::check(const MatchFinder::MatchResult &Result) {
SourceLocation ExprLoc;
bool IsIncrementOp = false;
if (const auto *MatchedDecl =
Result.Nodes.getNodeAs<CXXOperatorCallExpr>("operator")) {
ExprLoc = MatchedDecl->getExprLoc();
IsIncrementOp = (MatchedDecl->getOperator() == OO_PlusPlus);
} else if (const auto *MatchedDecl =
Result.Nodes.getNodeAs<UnaryOperator>("operator")) {
ExprLoc = MatchedDecl->getExprLoc();
IsIncrementOp = MatchedDecl->isIncrementOp();
} else
return;
diag(ExprLoc,
"%select{decrementing|incrementing}0 and referencing a variable in a "
"complex condition can cause unintended side-effects due to C++'s order "
"of evaluation, consider moving the modification outside of the "
"condition to avoid misunderstandings")
<< IsIncrementOp;
diag(Result.Nodes.getNodeAs<Expr>("second")->getExprLoc(),
"variable is referenced here", DiagnosticIDs::Note);
}
} // namespace clang::tidy::bugprone
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