From: Alp Toker <alp@nuanti.com>
Date: Sat, 18 Jan 2014 00:59:32 +0000 (+0000)
Subject: Restrict redeclaration of tags introduced by using decls to MSVCCompat
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=1ee6ed2aed0f076a7144df8fdd503b84702b7190;p=clang

Restrict redeclaration of tags introduced by using decls to MSVCCompat

This limits the facility added in r199490 while we seek clarification on the
standard.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@199531 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 62fedbf969..f71540c204 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -10681,8 +10681,9 @@ Decl *Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK,
   }
 
   if (!Previous.empty()) {
-    NamedDecl *DirectPrevDecl = *Previous.begin();
-    NamedDecl *PrevDecl = DirectPrevDecl->getUnderlyingDecl();
+    NamedDecl *PrevDecl = Previous.getFoundDecl();
+    NamedDecl *DirectPrevDecl =
+        getLangOpts().MSVCCompat ? *Previous.begin() : PrevDecl;
 
     // It's okay to have a tag decl in the same scope as a typedef
     // which hides a tag decl in the same scope.  Finding this
diff --git a/test/SemaCXX/MicrosoftCompatibility.cpp b/test/SemaCXX/MicrosoftCompatibility.cpp
index 1f27deb0ee..0971646e73 100644
--- a/test/SemaCXX/MicrosoftCompatibility.cpp
+++ b/test/SemaCXX/MicrosoftCompatibility.cpp
@@ -120,6 +120,27 @@ private:
 
 }
 
+namespace using_tag_redeclaration
+{
+  struct S;
+  namespace N {
+    using ::using_tag_redeclaration::S;
+    struct S {}; // expected-note {{previous definition is here}}
+  }
+  void f() {
+    N::S s1;
+    S s2;
+  }
+  void g() {
+    struct S; // expected-note {{forward declaration of 'S'}}
+    S s3; // expected-error {{variable has incomplete type 'S'}}
+  }
+  void h() {
+    using ::using_tag_redeclaration::S;
+    struct S {}; // expected-error {{redefinition of 'S'}}
+  }
+}
+
 
 namespace MissingTypename {
 
diff --git a/test/SemaCXX/using-decl-1.cpp b/test/SemaCXX/using-decl-1.cpp
index ed5cce7c97..24d92f175c 100644
--- a/test/SemaCXX/using-decl-1.cpp
+++ b/test/SemaCXX/using-decl-1.cpp
@@ -119,27 +119,6 @@ namespace foo
   };
 }
 
-namespace using_tag_redeclaration
-{
-  struct S;
-  namespace N {
-    using ::using_tag_redeclaration::S;
-    struct S {}; // expected-note {{previous definition is here}}
-  }
-  void f() {
-    N::S s1;
-    S s2;
-  }
-  void g() {
-    struct S; // expected-note {{forward declaration of 'S'}}
-    S s3; // expected-error {{variable has incomplete type 'S'}}
-  }
-  void h() {
-    using ::using_tag_redeclaration::S;
-    struct S {}; // expected-error {{redefinition of 'S'}}
-  }
-}
-
 // Don't suggest non-typenames for positions requiring typenames.
 namespace using_suggestion_tyname_val {
 namespace N { void FFF() {} }