1 //===--- UseUsingCheck.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 "UseUsingCheck.h"
11 #include "clang/AST/ASTContext.h"
12 #include "clang/Lex/Lexer.h"
13 
14 using namespace clang::ast_matchers;
15 
16 namespace clang {
17 namespace tidy {
18 namespace modernize {
19 
20 void UseUsingCheck::registerMatchers(MatchFinder *Finder) {
21   if (!getLangOpts().CPlusPlus11)
22     return;
23   Finder->addMatcher(typedefDecl().bind("typedef"), this);
24 }
25 
26 // Checks if 'typedef' keyword can be removed - we do it only if
27 // it is the only declaration in a declaration chain.
28 static bool CheckRemoval(SourceManager &SM, const SourceLocation &LocStart,
29                          const SourceLocation &LocEnd, ASTContext &Context,
30                          SourceRange &ResultRange) {
31   FileID FID = SM.getFileID(LocEnd);
32   llvm::MemoryBuffer *Buffer = SM.getBuffer(FID, LocEnd);
33   Lexer DeclLexer(SM.getLocForStartOfFile(FID), Context.getLangOpts(),
34                   Buffer->getBufferStart(), SM.getCharacterData(LocStart),
35                   Buffer->getBufferEnd());
36   Token DeclToken;
37   bool result = false;
38   int parenthesisLevel = 0;
39 
40   while (!DeclLexer.LexFromRawLexer(DeclToken)) {
41     if (DeclToken.getKind() == tok::TokenKind::l_paren)
42       parenthesisLevel++;
43     if (DeclToken.getKind() == tok::TokenKind::r_paren)
44       parenthesisLevel--;
45     if (DeclToken.getKind() == tok::TokenKind::semi)
46       break;
47     // if there is comma and we are not between open parenthesis then it is
48     // two or more declatarions in this chain
49     if (parenthesisLevel == 0 && DeclToken.getKind() == tok::TokenKind::comma)
50       return false;
51 
52     if (DeclToken.isOneOf(tok::TokenKind::identifier,
53                           tok::TokenKind::raw_identifier)) {
54       auto TokenStr = DeclToken.getRawIdentifier().str();
55 
56       if (TokenStr == "typedef") {
57         ResultRange =
58             SourceRange(DeclToken.getLocation(), DeclToken.getEndLoc());
59         result = true;
60       }
61     }
62   }
63   // assert if there was keyword 'typedef' in declaration
64   assert(result && "No typedef found");
65 
66   return result;
67 }
68 
69 void UseUsingCheck::check(const MatchFinder::MatchResult &Result) {
70   const auto *MatchedDecl = Result.Nodes.getNodeAs<TypedefDecl>("typedef");
71   if (MatchedDecl->getLocation().isInvalid())
72     return;
73 
74   auto &Context = *Result.Context;
75   auto &SM = *Result.SourceManager;
76 
77   auto Diag =
78       diag(MatchedDecl->getLocStart(), "use 'using' instead of 'typedef'");
79   if (MatchedDecl->getLocStart().isMacroID()) {
80     return;
81   }
82   SourceRange RemovalRange;
83   if (CheckRemoval(SM, MatchedDecl->getLocStart(), MatchedDecl->getLocEnd(),
84                    Context, RemovalRange)) {
85     Diag << FixItHint::CreateReplacement(
86         MatchedDecl->getSourceRange(),
87         "using " + MatchedDecl->getNameAsString() + " = " +
88             MatchedDecl->getUnderlyingType().getAsString(getLangOpts()));
89   }
90 }
91 
92 } // namespace modernize
93 } // namespace tidy
94 } // namespace clang
95