clang-tools  7.0.0
ComparisonInTempFailureRetryCheck.cpp
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1 //===--- ComparisonInTempFailureRetryCheck.cpp - clang-tidy----------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "../utils/Matchers.h"
12 #include "clang/AST/ASTContext.h"
13 #include "clang/ASTMatchers/ASTMatchFinder.h"
14 #include "clang/Lex/Lexer.h"
15 
16 using namespace clang::ast_matchers;
17 
18 namespace clang {
19 namespace tidy {
20 namespace android {
21 
22 namespace {
23 AST_MATCHER(BinaryOperator, isRHSATempFailureRetryArg) {
24  if (!Node.getLocStart().isMacroID())
25  return false;
26 
27  const SourceManager &SM = Finder->getASTContext().getSourceManager();
28  if (!SM.isMacroArgExpansion(Node.getRHS()->IgnoreParenCasts()->getLocStart()))
29  return false;
30 
31  const LangOptions &Opts = Finder->getASTContext().getLangOpts();
32  SourceLocation LocStart = Node.getLocStart();
33  while (LocStart.isMacroID()) {
34  SourceLocation Invocation = SM.getImmediateMacroCallerLoc(LocStart);
35  Token Tok;
36  if (!Lexer::getRawToken(SM.getSpellingLoc(Invocation), Tok, SM, Opts,
37  /*IgnoreWhiteSpace=*/true)) {
38  if (Tok.getKind() == tok::raw_identifier &&
39  Tok.getRawIdentifier() == "TEMP_FAILURE_RETRY")
40  return true;
41  }
42 
43  LocStart = Invocation;
44  }
45  return false;
46 }
47 } // namespace
48 
49 void ComparisonInTempFailureRetryCheck::registerMatchers(MatchFinder *Finder) {
50  // Both glibc's and Bionic's TEMP_FAILURE_RETRY macros structurally look like:
51  //
52  // #define TEMP_FAILURE_RETRY(x) ({ \
53  // typeof(x) y; \
54  // do y = (x); \
55  // while (y == -1 && errno == EINTR); \
56  // y; \
57  // })
58  //
59  // (glibc uses `long int` instead of `typeof(x)` for the type of y).
60  //
61  // It's unclear how to walk up the AST from inside the expansion of `x`, and
62  // we need to not complain about things like TEMP_FAILURE_RETRY(foo(x == 1)),
63  // so we just match the assignment of `y = (x)` and inspect `x` from there.
64  Finder->addMatcher(
65  binaryOperator(
66  hasOperatorName("="),
67  hasRHS(ignoringParenCasts(
68  binaryOperator(matchers::isComparisonOperator()).bind("binop"))),
69  isRHSATempFailureRetryArg()),
70  this);
71 }
72 
73 void ComparisonInTempFailureRetryCheck::check(
74  const MatchFinder::MatchResult &Result) {
75  const auto &BinOp = *Result.Nodes.getNodeAs<BinaryOperator>("binop");
76  diag(BinOp.getOperatorLoc(), "top-level comparison in TEMP_FAILURE_RETRY");
77 
78  // FIXME: FixIts would be nice, but potentially nontrivial when nested macros
79  // happen, e.g. `TEMP_FAILURE_RETRY(IS_ZERO(foo()))`
80 }
81 
82 } // namespace android
83 } // namespace tidy
84 } // namespace clang
AST_MATCHER(BinaryOperator, isAssignmentOperator)
Definition: Matchers.h:20
===– Representation.cpp - ClangDoc Representation --------—*- C++ -*-===//