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//===--- SignedBitwiseCheck.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 "SignedBitwiseCheck.h"
#include "clang/AST/ASTContext.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
using namespace clang::ast_matchers;
using namespace clang::ast_matchers::internal;
namespace clang {
namespace tidy {
namespace hicpp {
SignedBitwiseCheck::SignedBitwiseCheck(StringRef Name,
ClangTidyContext *Context)
: ClangTidyCheck(Name, Context),
IgnorePositiveIntegerLiterals(
Options.get("IgnorePositiveIntegerLiterals", false)) {}
void SignedBitwiseCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
Options.store(Opts, "IgnorePositiveIntegerLiterals",
IgnorePositiveIntegerLiterals);
}
void SignedBitwiseCheck::registerMatchers(MatchFinder *Finder) {
const auto SignedIntegerOperand =
(IgnorePositiveIntegerLiterals
? expr(ignoringImpCasts(hasType(isSignedInteger())),
unless(integerLiteral()))
: expr(ignoringImpCasts(hasType(isSignedInteger()))))
.bind("signed-operand");
// The standard [bitmask.types] allows some integral types to be implemented
// as signed types. Exclude these types from diagnosing for bitwise or(|) and
// bitwise and(&). Shifting and complementing such values is still not
// allowed.
const auto BitmaskType = namedDecl(
hasAnyName("::std::locale::category", "::std::ctype_base::mask",
"::std::ios_base::fmtflags", "::std::ios_base::iostate",
"::std::ios_base::openmode"));
const auto IsStdBitmask = ignoringImpCasts(declRefExpr(hasType(BitmaskType)));
// Match binary bitwise operations on signed integer arguments.
Finder->addMatcher(
binaryOperator(hasAnyOperatorName("^", "|", "&", "^=", "|=", "&="),
unless(allOf(hasLHS(IsStdBitmask), hasRHS(IsStdBitmask))),
hasEitherOperand(SignedIntegerOperand),
hasLHS(hasType(isInteger())), hasRHS(hasType(isInteger())))
.bind("binary-no-sign-interference"),
this);
// Shifting and complement is not allowed for any signed integer type because
// the sign bit may corrupt the result.
Finder->addMatcher(
binaryOperator(hasAnyOperatorName("<<", ">>", "<<=", ">>="),
hasEitherOperand(SignedIntegerOperand),
hasLHS(hasType(isInteger())), hasRHS(hasType(isInteger())))
.bind("binary-sign-interference"),
this);
// Match unary operations on signed integer types.
Finder->addMatcher(
unaryOperator(hasOperatorName("~"), hasUnaryOperand(SignedIntegerOperand))
.bind("unary-signed"),
this);
}
void SignedBitwiseCheck::check(const MatchFinder::MatchResult &Result) {
const ast_matchers::BoundNodes &N = Result.Nodes;
const auto *SignedOperand = N.getNodeAs<Expr>("signed-operand");
assert(SignedOperand &&
"No signed operand found in problematic bitwise operations");
bool IsUnary = false;
SourceLocation Location;
if (const auto *UnaryOp = N.getNodeAs<UnaryOperator>("unary-signed")) {
IsUnary = true;
Location = UnaryOp->getBeginLoc();
} else {
if (const auto *BinaryOp =
N.getNodeAs<BinaryOperator>("binary-no-sign-interference"))
Location = BinaryOp->getBeginLoc();
else if (const auto *BinaryOp =
N.getNodeAs<BinaryOperator>("binary-sign-interference"))
Location = BinaryOp->getBeginLoc();
else
llvm_unreachable("unexpected matcher result");
}
diag(Location, "use of a signed integer operand with a "
"%select{binary|unary}0 bitwise operator")
<< IsUnary << SignedOperand->getSourceRange();
}
} // namespace hicpp
} // namespace tidy
} // namespace clang
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