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//===--- ComparisonInTempFailureRetryCheck.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 "../utils/Matchers.h"
#include "ComparisonInTempFailureRetryCheck.h"
#include "clang/AST/ASTContext.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
#include "clang/Lex/Lexer.h"
using namespace clang::ast_matchers;
namespace clang {
namespace tidy {
namespace android {
namespace {
AST_MATCHER(BinaryOperator, isRHSATempFailureRetryArg) {
if (!Node.getBeginLoc().isMacroID())
return false;
const SourceManager &SM = Finder->getASTContext().getSourceManager();
if (!SM.isMacroArgExpansion(Node.getRHS()->IgnoreParenCasts()->getBeginLoc()))
return false;
const LangOptions &Opts = Finder->getASTContext().getLangOpts();
SourceLocation LocStart = Node.getBeginLoc();
while (LocStart.isMacroID()) {
SourceLocation Invocation = SM.getImmediateMacroCallerLoc(LocStart);
Token Tok;
if (!Lexer::getRawToken(SM.getSpellingLoc(Invocation), Tok, SM, Opts,
/*IgnoreWhiteSpace=*/true)) {
if (Tok.getKind() == tok::raw_identifier &&
Tok.getRawIdentifier() == "TEMP_FAILURE_RETRY")
return true;
}
LocStart = Invocation;
}
return false;
}
} // namespace
void ComparisonInTempFailureRetryCheck::registerMatchers(MatchFinder *Finder) {
// Both glibc's and Bionic's TEMP_FAILURE_RETRY macros structurally look like:
//
// #define TEMP_FAILURE_RETRY(x) ({ \
// typeof(x) y; \
// do y = (x); \
// while (y == -1 && errno == EINTR); \
// y; \
// })
//
// (glibc uses `long int` instead of `typeof(x)` for the type of y).
//
// It's unclear how to walk up the AST from inside the expansion of `x`, and
// we need to not complain about things like TEMP_FAILURE_RETRY(foo(x == 1)),
// so we just match the assignment of `y = (x)` and inspect `x` from there.
Finder->addMatcher(
binaryOperator(
hasOperatorName("="),
hasRHS(ignoringParenCasts(
binaryOperator(matchers::isComparisonOperator()).bind("binop"))),
isRHSATempFailureRetryArg()),
this);
}
void ComparisonInTempFailureRetryCheck::check(
const MatchFinder::MatchResult &Result) {
const auto &BinOp = *Result.Nodes.getNodeAs<BinaryOperator>("binop");
diag(BinOp.getOperatorLoc(), "top-level comparison in TEMP_FAILURE_RETRY");
// FIXME: FixIts would be nice, but potentially nontrivial when nested macros
// happen, e.g. `TEMP_FAILURE_RETRY(IS_ZERO(foo()))`
}
} // namespace android
} // namespace tidy
} // namespace clang
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