clang-tools  4.0.0
TwineLocalCheck.cpp
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1 //===--- TwineLocalCheck.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 "TwineLocalCheck.h"
11 #include "clang/AST/ASTContext.h"
12 #include "clang/ASTMatchers/ASTMatchers.h"
13 #include "clang/Lex/Lexer.h"
14 
15 using namespace clang::ast_matchers;
16 
17 namespace clang {
18 namespace tidy {
19 namespace llvm {
20 
21 void TwineLocalCheck::registerMatchers(MatchFinder *Finder) {
22  auto TwineType =
23  qualType(hasDeclaration(recordDecl(hasName("::llvm::Twine"))));
24  Finder->addMatcher(varDecl(hasType(TwineType)).bind("variable"), this);
25 }
26 
27 void TwineLocalCheck::check(const MatchFinder::MatchResult &Result) {
28  const auto *VD = Result.Nodes.getNodeAs<VarDecl>("variable");
29  auto Diag = diag(VD->getLocation(),
30  "twine variables are prone to use-after-free bugs");
31 
32  // If this VarDecl has an initializer try to fix it.
33  if (VD->hasInit()) {
34  // Peel away implicit constructors and casts so we can see the actual type
35  // of the initializer.
36  const Expr *C = VD->getInit()->IgnoreImplicit();
37 
38  while (isa<CXXConstructExpr>(C))
39  C = cast<CXXConstructExpr>(C)->getArg(0)->IgnoreParenImpCasts();
40 
41  SourceRange TypeRange =
42  VD->getTypeSourceInfo()->getTypeLoc().getSourceRange();
43 
44  // A real Twine, turn it into a std::string.
45  if (VD->getType()->getCanonicalTypeUnqualified() ==
46  C->getType()->getCanonicalTypeUnqualified()) {
47  SourceLocation EndLoc = Lexer::getLocForEndOfToken(
48  VD->getInit()->getLocEnd(), 0, *Result.SourceManager, getLangOpts());
49  Diag << FixItHint::CreateReplacement(TypeRange, "std::string")
50  << FixItHint::CreateInsertion(VD->getInit()->getLocStart(), "(")
51  << FixItHint::CreateInsertion(EndLoc, ").str()");
52  } else {
53  // Just an implicit conversion. Insert the real type.
54  Diag << FixItHint::CreateReplacement(
55  TypeRange,
56  C->getType().getAsString(Result.Context->getPrintingPolicy()));
57  }
58  }
59 }
60 
61 } // namespace llvm
62 } // namespace tidy
63 } // namespace clang
std::unique_ptr< ast_matchers::MatchFinder > Finder
Definition: ClangTidy.cpp:262
const NamedDecl * Result
Definition: USRFinder.cpp:162