xref: /llvm-project/clang-tools-extra/clang-tidy/google/UsingNamespaceDirectiveCheck.cpp (revision 76bbbcb41bcf4a1d7a26bb11b78cf97b60ea7d4b)
1 //===--- UsingNamespaceDirectiveCheck.cpp - clang-tidy ----------*- C++ -*-===//
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 "UsingNamespaceDirectiveCheck.h"
10 #include "clang/AST/ASTContext.h"
11 #include "clang/ASTMatchers/ASTMatchFinder.h"
12 #include "clang/ASTMatchers/ASTMatchers.h"
13 
14 using namespace clang::ast_matchers;
15 
16 namespace clang::tidy::google::build {
17 
registerMatchers(ast_matchers::MatchFinder * Finder)18 void UsingNamespaceDirectiveCheck::registerMatchers(
19     ast_matchers::MatchFinder *Finder) {
20     Finder->addMatcher(usingDirectiveDecl().bind("usingNamespace"), this);
21 }
22 
check(const MatchFinder::MatchResult & Result)23 void UsingNamespaceDirectiveCheck::check(
24     const MatchFinder::MatchResult &Result) {
25   const auto *U = Result.Nodes.getNodeAs<UsingDirectiveDecl>("usingNamespace");
26   SourceLocation Loc = U->getBeginLoc();
27   if (U->isImplicit() || !Loc.isValid())
28     return;
29 
30   // Do not warn if namespace is a std namespace with user-defined literals. The
31   // user-defined literals can only be used with a using directive.
32   if (isStdLiteralsNamespace(U->getNominatedNamespace()))
33     return;
34 
35   diag(Loc, "do not use namespace using-directives; "
36             "use using-declarations instead");
37   // TODO: We could suggest a list of using directives replacing the using
38   //       namespace directive.
39 }
40 
isStdLiteralsNamespace(const NamespaceDecl * NS)41 bool UsingNamespaceDirectiveCheck::isStdLiteralsNamespace(
42     const NamespaceDecl *NS) {
43   if (!NS->getName().ends_with("literals"))
44     return false;
45 
46   const auto *Parent = dyn_cast_or_null<NamespaceDecl>(NS->getParent());
47   if (!Parent)
48     return false;
49 
50   if (Parent->isStdNamespace())
51     return true;
52 
53   return Parent->getName() == "literals" && Parent->getParent() &&
54          Parent->getParent()->isStdNamespace();
55 }
56 } // namespace clang::tidy::google::build
57