1 //===--- RedundantDeclarationCheck.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 "RedundantDeclarationCheck.h"
11 #include "clang/AST/ASTContext.h"
12 #include "clang/ASTMatchers/ASTMatchFinder.h"
13 #include "clang/Lex/Lexer.h"
14 
15 using namespace clang::ast_matchers;
16 
17 namespace clang {
18 namespace tidy {
19 namespace readability {
20 
21 RedundantDeclarationCheck::RedundantDeclarationCheck(StringRef Name,
22                                                      ClangTidyContext *Context)
23     : ClangTidyCheck(Name, Context),
24       IgnoreMacros(Options.getLocalOrGlobal("IgnoreMacros", true)) {}
25 
26 void RedundantDeclarationCheck::registerMatchers(MatchFinder *Finder) {
27   Finder->addMatcher(
28       namedDecl(anyOf(varDecl(unless(isDefinition())),
29                       functionDecl(unless(anyOf(isDefinition(), isDefaulted(),
30                                                 hasParent(friendDecl()))))))
31           .bind("Decl"),
32       this);
33 }
34 
35 void RedundantDeclarationCheck::check(const MatchFinder::MatchResult &Result) {
36   const auto *D = Result.Nodes.getNodeAs<NamedDecl>("Decl");
37   const auto *Prev = D->getPreviousDecl();
38   if (!Prev)
39     return;
40   if (!Prev->getLocation().isValid())
41     return;
42   if (Prev->getLocation() == D->getLocation())
43     return;
44   if (IgnoreMacros &&
45       (D->getLocation().isMacroID() || Prev->getLocation().isMacroID()))
46     return;
47   // Don't complain when the previous declaration is a friend declaration.
48   for (const auto &Parent : Result.Context->getParents(*Prev))
49     if (Parent.get<FriendDecl>())
50       return;
51 
52   const SourceManager &SM = *Result.SourceManager;
53 
54   const bool DifferentHeaders =
55       !SM.isInMainFile(D->getLocation()) &&
56       !SM.isWrittenInSameFile(Prev->getLocation(), D->getLocation());
57 
58   bool MultiVar = false;
59   if (const auto *VD = dyn_cast<VarDecl>(D)) {
60     // Is this a multivariable declaration?
61     for (const auto Other : VD->getDeclContext()->decls()) {
62       if (Other != D && Other->getLocStart() == VD->getLocStart()) {
63         MultiVar = true;
64         break;
65       }
66     }
67   }
68 
69   SourceLocation EndLoc = Lexer::getLocForEndOfToken(
70       D->getSourceRange().getEnd(), 0, SM, Result.Context->getLangOpts());
71   {
72     auto Diag = diag(D->getLocation(), "redundant %0 declaration") << D;
73     if (!MultiVar && !DifferentHeaders)
74       Diag << FixItHint::CreateRemoval(
75           SourceRange(D->getSourceRange().getBegin(), EndLoc));
76   }
77   diag(Prev->getLocation(), "previously declared here", DiagnosticIDs::Note);
78 }
79 
80 } // namespace readability
81 } // namespace tidy
82 } // namespace clang
83