From e97c32f9578861d575ca96bbbae426c76cbc9024 Mon Sep 17 00:00:00 2001
From: John McCall <rjmccall@apple.com>
Date: Tue, 2 Mar 2010 23:09:38 +0000
Subject: [PATCH] Suppress implicit member redeclarations arising from explicit
 instantiation declarations after the member has been explicitly specialized. 
 We already did this after explicit instantiation definitions;  not doing it
 for declarations meant that subsequent definitions would see a previous
 member declaration with specialization kind "explicit instantiation decl",
 which would then happily get overridden.

Fixes PR 6458.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@97605 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Sema/SemaTemplate.cpp                    |  1 +
 test/CXX/temp/temp.spec/temp.explicit/p4.cpp | 16 ++++++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/lib/Sema/SemaTemplate.cpp b/lib/Sema/SemaTemplate.cpp
index c10b12b2da..03219580f9 100644
--- a/lib/Sema/SemaTemplate.cpp
+++ b/lib/Sema/SemaTemplate.cpp
@@ -3790,6 +3790,7 @@ Sema::CheckSpecializationInstantiationRedecl(SourceLocation NewLoc,
       //   of a template appears after a declaration of an explicit 
       //   specialization for that template, the explicit instantiation has no
       //   effect.
+      SuppressNew = true;
       return false;
         
     case TSK_ExplicitInstantiationDefinition:
diff --git a/test/CXX/temp/temp.spec/temp.explicit/p4.cpp b/test/CXX/temp/temp.spec/temp.explicit/p4.cpp
index f292b5a93d..2b852136f3 100644
--- a/test/CXX/temp/temp.spec/temp.explicit/p4.cpp
+++ b/test/CXX/temp/temp.spec/temp.explicit/p4.cpp
@@ -30,3 +30,19 @@ template long X0<long>::value;
 
 template<> struct X0<double>;
 template struct X0<double>;
+
+// PR 6458
+namespace test0 {
+  template <class T> class foo {
+    int compare(T x, T y);
+  };
+
+  template <> int foo<char>::compare(char x, char y);
+  template <class T> int foo<T>::compare(T x, T y) {
+    // invalid at T=char; if we get a diagnostic here, we're
+    // inappropriately instantiating this template.
+    void *ptr = x;
+  }
+  extern template class foo<char>;
+  template class foo<char>;
+}
-- 
2.40.0