From 37574f55cd637340f651330f5cfda69742880d36 Mon Sep 17 00:00:00 2001
From: Nick Lewycky <nicholas@mxc.ca>
Date: Mon, 8 Nov 2010 23:29:42 +0000
Subject: [PATCH] Don't lose track of previous-declarations when instantiating
 a class template. Fixes PR8001.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@118454 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Sema/SemaTemplateInstantiateDecl.cpp  | 12 +++++++++++-
 test/SemaTemplate/class-template-decl.cpp | 18 ++++++++++++++++++
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/lib/Sema/SemaTemplateInstantiateDecl.cpp b/lib/Sema/SemaTemplateInstantiateDecl.cpp
index c4bcc1e7d9..aea25c8dad 100644
--- a/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -722,6 +722,15 @@ Decl *TemplateDeclInstantiator::VisitClassTemplateDecl(ClassTemplateDecl *D) {
   CXXRecordDecl *PrevDecl = 0;
   ClassTemplateDecl *PrevClassTemplate = 0;
 
+  if (!isFriend && Pattern->getPreviousDeclaration()) {
+    DeclContext::lookup_result Found = Owner->lookup(Pattern->getDeclName());
+    if (Found.first != Found.second) {
+      PrevClassTemplate = dyn_cast<ClassTemplateDecl>(*Found.first);
+      if (PrevClassTemplate)
+        PrevDecl = PrevClassTemplate->getTemplatedDecl();
+    }
+  }
+
   // If this isn't a friend, then it's a member template, in which
   // case we just want to build the instantiation in the
   // specialization.  If it is a friend, we want to build it in
@@ -836,7 +845,8 @@ Decl *TemplateDeclInstantiator::VisitClassTemplateDecl(ClassTemplateDecl *D) {
     // friend target decl?
   } else {
     Inst->setAccess(D->getAccess());
-    Inst->setInstantiatedFromMemberTemplate(D);
+    if (!PrevClassTemplate)
+      Inst->setInstantiatedFromMemberTemplate(D);
   }
   
   // Trigger creation of the type for the instantiation.
diff --git a/test/SemaTemplate/class-template-decl.cpp b/test/SemaTemplate/class-template-decl.cpp
index 1be1bc070a..e7722123f9 100644
--- a/test/SemaTemplate/class-template-decl.cpp
+++ b/test/SemaTemplate/class-template-decl.cpp
@@ -56,3 +56,21 @@ namespace M {
 }
 
 template<typename T> class M::C3 { }; // expected-error{{out-of-line definition of 'C3' does not match any declaration in namespace 'M'}}
+
+namespace PR8001 {
+  template<typename T1>
+  struct Foo {
+    template<typename T2> class Bar;
+    typedef Bar<T1> Baz;
+
+   template<typename T2>
+   struct Bar {
+     Bar() {}
+   };
+  };
+
+  void pr8001() {
+    Foo<int>::Baz x;
+    Foo<int>::Bar<int> y(x);
+  }
+}
-- 
2.50.1