clang-tools-extra/clang-tidy/llvmlibc/ImplementationInNamespaceCheck.cpp

   1 //===--- ImplementationInNamespaceCheck.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 "ImplementationInNamespaceCheck.h"
  10 #include "NamespaceConstants.h"
  11 #include "clang/AST/ASTContext.h"
  12 #include "clang/ASTMatchers/ASTMatchFinder.h"
  13
  14 using namespace clang::ast_matchers;
  15
  16 namespace clang::tidy::llvm_libc {
  17
  18 void ImplementationInNamespaceCheck::registerMatchers(MatchFinder *Finder) {
  19   Finder->addMatcher(
  20       translationUnitDecl(
  21           forEach(decl(isExpansionInMainFile(), unless(linkageSpecDecl()),
  22                        // anonymous namespaces generate usingDirective
  23                        unless(usingDirectiveDecl(isImplicit())))
  24                       .bind("child_of_translation_unit"))),
  25       this);
  26 }
  27
  28 void ImplementationInNamespaceCheck::check(
  29     const MatchFinder::MatchResult &Result) {
  30   const auto *MatchedDecl =
  31       Result.Nodes.getNodeAs<Decl>("child_of_translation_unit");
  32   const auto *NS = dyn_cast<NamespaceDecl>(MatchedDecl);
  33
  34   // LLVM libc declarations should be inside of a non-anonymous namespace.
  35   if (NS == nullptr || NS->isAnonymousNamespace()) {
  36     diag(MatchedDecl->getLocation(),
  37          "declaration must be enclosed within the '%0' namespace")
  38         << RequiredNamespaceDeclMacroName;
  39     return;
  40   }
  41
  42   // Enforce that the namespace is the result of macro expansion
  43   if (Result.SourceManager->isMacroBodyExpansion(NS->getLocation()) == false) {
  44     diag(NS->getLocation(), "the outermost namespace should be the '%0' macro")
  45         << RequiredNamespaceDeclMacroName;
  46     return;
  47   }
  48
  49   // We want the macro to have [[gnu::visibility("hidden")]] as a prefix, but
  50   // visibility is just an attribute in the AST construct, so we check that
  51   // instead.
  52   if (NS->getVisibility() != Visibility::HiddenVisibility) {
  53     diag(NS->getLocation(), "the '%0' macro should start with '%1'")
  54         << RequiredNamespaceDeclMacroName << RequiredNamespaceDeclStart;
  55     return;
  56   }
  57
  58   // Lastly, make sure the namespace name actually has the __llvm_libc prefix
  59   if (NS->getName().starts_with(RequiredNamespaceRefStart) == false) {
  60     diag(NS->getLocation(), "the '%0' macro expansion should start with '%1'")
  61         << RequiredNamespaceDeclMacroName << RequiredNamespaceRefStart;
  62     return;
  63   }
  64 }
  65
  66 } // namespace clang::tidy::llvm_libc