clang-tools  5.0.0
StringCompareCheck.cpp
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1 //===--- MiscStringCompare.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 "StringCompareCheck.h"
11 #include "../utils/FixItHintUtils.h"
12 #include "clang/AST/ASTContext.h"
13 #include "clang/ASTMatchers/ASTMatchFinder.h"
14 #include "clang/Tooling/FixIt.h"
15 
16 using namespace clang::ast_matchers;
17 
18 namespace clang {
19 namespace tidy {
20 namespace misc {
21 
22 static const StringRef CompareMessage = "do not use 'compare' to test equality "
23  "of strings; use the string equality "
24  "operator instead";
25 
26 void StringCompareCheck::registerMatchers(MatchFinder *Finder) {
27  if (!getLangOpts().CPlusPlus)
28  return;
29 
30  const auto StrCompare = cxxMemberCallExpr(
31  callee(cxxMethodDecl(hasName("compare"),
32  ofClass(classTemplateSpecializationDecl(
33  hasName("::std::basic_string"))))),
34  hasArgument(0, expr().bind("str2")), argumentCountIs(1),
35  callee(memberExpr().bind("str1")));
36 
37  // First and second case: cast str.compare(str) to boolean.
38  Finder->addMatcher(implicitCastExpr(hasImplicitDestinationType(booleanType()),
39  has(StrCompare))
40  .bind("match1"),
41  this);
42 
43  // Third and fourth case: str.compare(str) == 0 and str.compare(str) != 0.
44  Finder->addMatcher(
45  binaryOperator(anyOf(hasOperatorName("=="), hasOperatorName("!=")),
46  hasEitherOperand(StrCompare.bind("compare")),
47  hasEitherOperand(integerLiteral(equals(0)).bind("zero")))
48  .bind("match2"),
49  this);
50 }
51 
52 void StringCompareCheck::check(const MatchFinder::MatchResult &Result) {
53  if (const auto *Matched = Result.Nodes.getNodeAs<Stmt>("match1")) {
54  diag(Matched->getLocStart(), CompareMessage);
55  return;
56  }
57 
58  if (const auto *Matched = Result.Nodes.getNodeAs<Stmt>("match2")) {
59  const ASTContext &Ctx = *Result.Context;
60 
61  if (const auto *Zero = Result.Nodes.getNodeAs<Stmt>("zero")) {
62  const auto *Str1 = Result.Nodes.getNodeAs<MemberExpr>("str1");
63  const auto *Str2 = Result.Nodes.getNodeAs<Stmt>("str2");
64  const auto *Compare = Result.Nodes.getNodeAs<Stmt>("compare");
65 
66  auto Diag = diag(Matched->getLocStart(), CompareMessage);
67 
68  if (Str1->isArrow())
69  Diag << FixItHint::CreateInsertion(Str1->getLocStart(), "*");
70 
71  Diag << tooling::fixit::createReplacement(*Zero, *Str2, Ctx)
72  << tooling::fixit::createReplacement(*Compare, *Str1->getBase(),
73  Ctx);
74  }
75  }
76 
77  // FIXME: Add fixit to fix the code for case one and two (match1).
78 }
79 
80 } // namespace misc
81 } // namespace tidy
82 } // namespace clang
static const StringRef CompareMessage
std::unique_ptr< ast_matchers::MatchFinder > Finder
Definition: ClangTidy.cpp:275