1 //===--- RedundantDeclarationCheck.cpp - clang-tidy------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8
9 #include "RedundantDeclarationCheck.h"
10 #include "clang/AST/ASTContext.h"
11 #include "clang/ASTMatchers/ASTMatchFinder.h"
12 #include "clang/Lex/Lexer.h"
13
14 using namespace clang::ast_matchers;
15
16 namespace clang::tidy::readability {
17
AST_MATCHER(FunctionDecl,doesDeclarationForceExternallyVisibleDefinition)18 AST_MATCHER(FunctionDecl, doesDeclarationForceExternallyVisibleDefinition) {
19 return Node.doesDeclarationForceExternallyVisibleDefinition();
20 }
21
RedundantDeclarationCheck(StringRef Name,ClangTidyContext * Context)22 RedundantDeclarationCheck::RedundantDeclarationCheck(StringRef Name,
23 ClangTidyContext *Context)
24 : ClangTidyCheck(Name, Context),
25 IgnoreMacros(Options.getLocalOrGlobal("IgnoreMacros", true)) {}
26
storeOptions(ClangTidyOptions::OptionMap & Opts)27 void RedundantDeclarationCheck::storeOptions(
28 ClangTidyOptions::OptionMap &Opts) {
29 Options.store(Opts, "IgnoreMacros", IgnoreMacros);
30 }
31
registerMatchers(MatchFinder * Finder)32 void RedundantDeclarationCheck::registerMatchers(MatchFinder *Finder) {
33 Finder->addMatcher(
34 namedDecl(anyOf(varDecl(unless(isDefinition())),
35 functionDecl(unless(anyOf(
36 isDefinition(), isDefaulted(),
37 doesDeclarationForceExternallyVisibleDefinition(),
38 hasAncestor(friendDecl()))))),
39 optionally(hasParent(linkageSpecDecl().bind("extern"))))
40 .bind("Decl"),
41 this);
42 }
43
check(const MatchFinder::MatchResult & Result)44 void RedundantDeclarationCheck::check(const MatchFinder::MatchResult &Result) {
45 const auto *D = Result.Nodes.getNodeAs<NamedDecl>("Decl");
46 const auto *Prev = D->getPreviousDecl();
47 if (!Prev)
48 return;
49 if (!Prev->getLocation().isValid())
50 return;
51 if (Prev->getLocation() == D->getLocation())
52 return;
53 if (IgnoreMacros &&
54 (D->getLocation().isMacroID() || Prev->getLocation().isMacroID()))
55 return;
56 // Don't complain when the previous declaration is a friend declaration.
57 for (const auto &Parent : Result.Context->getParents(*Prev))
58 if (Parent.get<FriendDecl>())
59 return;
60
61 const SourceManager &SM = *Result.SourceManager;
62
63 const bool DifferentHeaders =
64 !SM.isInMainFile(D->getLocation()) &&
65 !SM.isWrittenInSameFile(Prev->getLocation(), D->getLocation());
66
67 bool MultiVar = false;
68 if (const auto *VD = dyn_cast<VarDecl>(D)) {
69 // Is this a multivariable declaration?
70 for (const auto *Other : VD->getDeclContext()->decls()) {
71 if (Other != D && Other->getBeginLoc() == VD->getBeginLoc()) {
72 MultiVar = true;
73 break;
74 }
75 }
76 }
77
78 SourceLocation EndLoc = Lexer::getLocForEndOfToken(
79 D->getSourceRange().getEnd(), 0, SM, Result.Context->getLangOpts());
80 {
81 auto Diag = diag(D->getLocation(), "redundant %0 declaration") << D;
82 if (!MultiVar && !DifferentHeaders) {
83 SourceLocation BeginLoc;
84 if (const auto *Extern =
85 Result.Nodes.getNodeAs<LinkageSpecDecl>("extern");
86 Extern && !Extern->hasBraces())
87 BeginLoc = Extern->getExternLoc();
88 else
89 BeginLoc = D->getSourceRange().getBegin();
90
91 Diag << FixItHint::CreateRemoval(SourceRange(BeginLoc, EndLoc));
92 }
93 }
94 diag(Prev->getLocation(), "previously declared here", DiagnosticIDs::Note);
95 }
96 } // namespace clang::tidy::readability
97