Revert "[clang-tidy] Don't replace typedefs in extern c scope (#69102)"

This reverts commit 9dcc665.

Author: PiotrZSL

clang-tools-extra/clang-tidy/modernize/UseUsingCheck.cpp

@@ -11,39 +11,26 @@
 #include "clang/Lex/Lexer.h"
 
 using namespace clang::ast_matchers;
-namespace {
-
-AST_MATCHER(clang::LinkageSpecDecl, isExternCLinkage) {
-  return Node.getLanguage() == clang::LinkageSpecDecl::lang_c;
-}
-} // namespace
 
 namespace clang::tidy::modernize {
 
-static constexpr llvm::StringLiteral ExternCDeclName = "extern-c-decl";
 static constexpr llvm::StringLiteral ParentDeclName = "parent-decl";
 static constexpr llvm::StringLiteral TagDeclName = "tag-decl";
 static constexpr llvm::StringLiteral TypedefName = "typedef";
 
 UseUsingCheck::UseUsingCheck(StringRef Name, ClangTidyContext *Context)
     : ClangTidyCheck(Name, Context),
-      IgnoreMacros(Options.getLocalOrGlobal("IgnoreMacros", true)),
-      IgnoreExternC(Options.get("IgnoreExternC", false)) {}
+      IgnoreMacros(Options.getLocalOrGlobal("IgnoreMacros", true)) {}
 
 void UseUsingCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
   Options.store(Opts, "IgnoreMacros", IgnoreMacros);
-  Options.store(Opts, "IgnoreExternC", IgnoreExternC);
 }
 
 void UseUsingCheck::registerMatchers(MatchFinder *Finder) {
-  Finder->addMatcher(
-      typedefDecl(
-          unless(isInstantiated()),
-          optionally(hasAncestor(
-              linkageSpecDecl(isExternCLinkage()).bind(ExternCDeclName))),
-          hasParent(decl().bind(ParentDeclName)))
-          .bind(TypedefName),
-      this);
+  Finder->addMatcher(typedefDecl(unless(isInstantiated()),
+                                 hasParent(decl().bind(ParentDeclName)))
+                         .bind(TypedefName),
+                     this);
 
   // This matcher is used to find tag declarations in source code within
   // typedefs. They appear in the AST just *prior* to the typedefs.
@@ -83,11 +70,6 @@ void UseUsingCheck::check(const MatchFinder::MatchResult &Result) {
   if (MatchedDecl->getLocation().isInvalid())
     return;
 
-  const auto *ExternCDecl =
-      Result.Nodes.getNodeAs<LinkageSpecDecl>(ExternCDeclName);
-  if (ExternCDecl && IgnoreExternC)
-    return;
-
   SourceLocation StartLoc = MatchedDecl->getBeginLoc();
 
   if (StartLoc.isMacroID() && IgnoreMacros)
@@ -140,8 +122,7 @@ void UseUsingCheck::check(const MatchFinder::MatchResult &Result) {
       Type = FirstTypedefName + Type.substr(FirstTypedefType.size() + 1);
   }
   if (!ReplaceRange.getEnd().isMacroID()) {
-    const SourceLocation::IntTy Offset =
-        MatchedDecl->getFunctionType() ? 0 : Name.size();
+    const SourceLocation::IntTy Offset = MatchedDecl->getFunctionType() ? 0 : Name.size();
     LastReplacementEnd = ReplaceRange.getEnd().getLocWithOffset(Offset);
   }
 

clang-tools-extra/clang-tidy/modernize/UseUsingCheck.h

@@ -20,7 +20,6 @@ namespace clang::tidy::modernize {
 class UseUsingCheck : public ClangTidyCheck {
 
   const bool IgnoreMacros;
-  const bool IgnoreExternC;
   SourceLocation LastReplacementEnd;
   llvm::DenseMap<const Decl *, SourceRange> LastTagDeclRanges;
 

clang-tools-extra/docs/ReleaseNotes.rst

@@ -408,8 +408,7 @@ Changes in existing checks
 
 - Improved :doc:`modernize-use-using
   <clang-tidy/checks/modernize/use-using>` check to fix function pointer and
-  forward declared ``typedef`` correctly. Added option `IgnoreExternC` to ignore ``typedef``
-  declaration in ``extern "C"`` scope.
+  forward declared ``typedef`` correctly.
 
 - Improved :doc:`performance-faster-string-find
   <clang-tidy/checks/performance/faster-string-find>` check to properly escape

clang-tools-extra/docs/clang-tidy/checks/modernize/use-using.rst

@@ -28,14 +28,6 @@ After:
   using R_t = struct { int a; };
   using R_p = R_t*;
 
-The checker ignores `typedef` within `extern "C" { ... }` blocks.
-
-.. code-block:: c++
-
-  extern "C" {
-    typedef int InExternC; // Left intact.
-  }
-
 This check requires using C++11 or higher to run.
 
 Options
@@ -45,8 +37,3 @@ Options
 
    If set to `true`, the check will not give warnings inside macros. Default
    is `true`.
-
-.. option:: IgnoreExternC
-
-   If set to `true`, the check will not give warning inside `extern "C"`scope.
-   Default is `false`

clang-tools-extra/test/clang-tidy/checkers/modernize/use-using-ignore-extern-c.cpp

@@ -325,20 +325,3 @@ typedef bool (*ISSUE_65055_2)(int);
 typedef class ISSUE_67529_1 *ISSUE_67529;
 // CHECK-MESSAGES: :[[@LINE-1]]:1: warning: use 'using' instead of 'typedef'
 // CHECK-FIXES: using ISSUE_67529 = class ISSUE_67529_1 *;
-
-// Some Header
-extern "C" {
-
-typedef int InExternC;
-// CHECK-MESSAGES: :[[@LINE-1]]:1: warning: use 'using' instead of 'typedef' [modernize-use-using]
-// CHECK-FIXES: using InExternC = int;
-
-}
-
-extern "C++" {
-
-typedef int InExternCPP;
-// CHECK-MESSAGES: :[[@LINE-1]]:1: warning: use 'using' instead of 'typedef' [modernize-use-using]
-// CHECK-FIXES: using InExternCPP = int;
-
-}