clang-tools-extra/clang-tidy/readability/RedundantDeclarationCheck.cpp

   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 {
  17 namespace tidy {
  18 namespace readability {
  19
  20 AST_MATCHER(FunctionDecl, doesDeclarationForceExternallyVisibleDefinition) {
  21   return Node.doesDeclarationForceExternallyVisibleDefinition();
  22 }
  23
  24 RedundantDeclarationCheck::RedundantDeclarationCheck(StringRef Name,
  25                                                      ClangTidyContext *Context)
  26     : ClangTidyCheck(Name, Context),
  27       IgnoreMacros(Options.getLocalOrGlobal("IgnoreMacros", true)) {}
  28
  29 void RedundantDeclarationCheck::storeOptions(
  30     ClangTidyOptions::OptionMap &Opts) {
  31   Options.store(Opts, "IgnoreMacros", IgnoreMacros);
  32 }
  33
  34 void RedundantDeclarationCheck::registerMatchers(MatchFinder *Finder) {
  35   Finder->addMatcher(
  36       namedDecl(anyOf(varDecl(unless(isDefinition())),
  37                       functionDecl(unless(anyOf(
  38                           isDefinition(), isDefaulted(),
  39                           doesDeclarationForceExternallyVisibleDefinition(),
  40                           hasAncestor(friendDecl()))))))
  41           .bind("Decl"),
  42       this);
  43 }
  44
  45 void RedundantDeclarationCheck::check(const MatchFinder::MatchResult &Result) {
  46   const auto *D = Result.Nodes.getNodeAs<NamedDecl>("Decl");
  47   const auto *Prev = D->getPreviousDecl();
  48   if (!Prev)
  49     return;
  50   if (!Prev->getLocation().isValid())
  51     return;
  52   if (Prev->getLocation() == D->getLocation())
  53     return;
  54   if (IgnoreMacros &&
  55       (D->getLocation().isMacroID() || Prev->getLocation().isMacroID()))
  56     return;
  57   // Don't complain when the previous declaration is a friend declaration.
  58   for (const auto &Parent : Result.Context->getParents(*Prev))
  59     if (Parent.get<FriendDecl>())
  60       return;
  61
  62   const SourceManager &SM = *Result.SourceManager;
  63
  64   const bool DifferentHeaders =
  65       !SM.isInMainFile(D->getLocation()) &&
  66       !SM.isWrittenInSameFile(Prev->getLocation(), D->getLocation());
  67
  68   bool MultiVar = false;
  69   if (const auto *VD = dyn_cast<VarDecl>(D)) {
  70     // Is this a multivariable declaration?
  71     for (const auto *Other : VD->getDeclContext()->decls()) {
  72       if (Other != D && Other->getBeginLoc() == VD->getBeginLoc()) {
  73         MultiVar = true;
  74         break;
  75       }
  76     }
  77   }
  78
  79   SourceLocation EndLoc = Lexer::getLocForEndOfToken(
  80       D->getSourceRange().getEnd(), 0, SM, Result.Context->getLangOpts());
  81   {
  82     auto Diag = diag(D->getLocation(), "redundant %0 declaration") << D;
  83     if (!MultiVar && !DifferentHeaders)
  84       Diag << FixItHint::CreateRemoval(
  85           SourceRange(D->getSourceRange().getBegin(), EndLoc));
  86   }
  87   diag(Prev->getLocation(), "previously declared here", DiagnosticIDs::Note);
  88 }
  89 } // namespace readability
  90 } // namespace tidy
  91 } // namespace clang