clang-tools-extra/clang-tidy/misc/UnusedAliasDeclsCheck.cpp

   1 //===--- UnusedAliasDeclsCheck.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 "UnusedAliasDeclsCheck.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::misc {
  17
  18 void UnusedAliasDeclsCheck::registerMatchers(MatchFinder *Finder) {
  19   // We cannot do anything about headers (yet), as the alias declarations
  20   // used in one header could be used by some other translation unit.
  21   Finder->addMatcher(namespaceAliasDecl(isExpansionInMainFile()).bind("alias"),
  22                      this);
  23   Finder->addMatcher(nestedNameSpecifier().bind("nns"), this);
  24 }
  25
  26 void UnusedAliasDeclsCheck::check(const MatchFinder::MatchResult &Result) {
  27   if (const auto *AliasDecl = Result.Nodes.getNodeAs<NamedDecl>("alias")) {
  28     FoundDecls[AliasDecl] = CharSourceRange::getCharRange(
  29         AliasDecl->getBeginLoc(),
  30         Lexer::findLocationAfterToken(
  31             AliasDecl->getEndLoc(), tok::semi, *Result.SourceManager,
  32             getLangOpts(),
  33             /*SkipTrailingWhitespaceAndNewLine=*/true));
  34     return;
  35   }
  36
  37   if (const auto *NestedName =
  38           Result.Nodes.getNodeAs<NestedNameSpecifier>("nns")) {
  39     if (const auto *AliasDecl = NestedName->getAsNamespaceAlias()) {
  40       FoundDecls[AliasDecl] = CharSourceRange();
  41     }
  42   }
  43 }
  44
  45 void UnusedAliasDeclsCheck::onEndOfTranslationUnit() {
  46   for (const auto &FoundDecl : FoundDecls) {
  47     if (!FoundDecl.second.isValid())
  48       continue;
  49     diag(FoundDecl.first->getLocation(), "namespace alias decl %0 is unused")
  50         << FoundDecl.first << FixItHint::CreateRemoval(FoundDecl.second);
  51   }
  52 }
  53
  54 } // namespace clang::tidy::misc