clang-tools  5.0.0
UnusedAliasDeclsCheck.cpp
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1 //===--- UnusedAliasDeclsCheck.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 "UnusedAliasDeclsCheck.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 misc {
20 
21 void UnusedAliasDeclsCheck::registerMatchers(MatchFinder *Finder) {
22  // Only register the matchers for C++11; the functionality currently does not
23  // provide any benefit to other languages, despite being benign.
24  if (!getLangOpts().CPlusPlus11)
25  return;
26 
27  // We cannot do anything about headers (yet), as the alias declarations
28  // used in one header could be used by some other translation unit.
29  Finder->addMatcher(namespaceAliasDecl(isExpansionInMainFile()).bind("alias"),
30  this);
31  Finder->addMatcher(nestedNameSpecifier().bind("nns"), this);
32 }
33 
34 void UnusedAliasDeclsCheck::check(const MatchFinder::MatchResult &Result) {
35  if (const auto *AliasDecl = Result.Nodes.getNodeAs<NamedDecl>("alias")) {
36  FoundDecls[AliasDecl] = CharSourceRange::getCharRange(
37  AliasDecl->getLocStart(),
38  Lexer::findLocationAfterToken(
39  AliasDecl->getLocEnd(), tok::semi, *Result.SourceManager,
40  getLangOpts(),
41  /*SkipTrailingWhitespaceAndNewLine=*/true));
42  return;
43  }
44 
45  if (const auto *NestedName =
46  Result.Nodes.getNodeAs<NestedNameSpecifier>("nns")) {
47  if (const auto *AliasDecl = NestedName->getAsNamespaceAlias()) {
48  FoundDecls[AliasDecl] = CharSourceRange();
49  }
50  }
51 }
52 
53 void UnusedAliasDeclsCheck::onEndOfTranslationUnit() {
54  for (const auto &FoundDecl : FoundDecls) {
55  if (!FoundDecl.second.isValid())
56  continue;
57  diag(FoundDecl.first->getLocation(), "namespace alias decl %0 is unused")
58  << FoundDecl.first << FixItHint::CreateRemoval(FoundDecl.second);
59  }
60 }
61 
62 } // namespace misc
63 } // namespace tidy
64 } // namespace clang
std::unique_ptr< ast_matchers::MatchFinder > Finder
Definition: ClangTidy.cpp:275