From b7444cd11ef1f688d91f0970f2615177af63916f Mon Sep 17 00:00:00 2001
From: Nick Lewycky <nicholas@mxc.ca>
Date: Thu, 14 Feb 2013 00:55:17 +0000
Subject: [PATCH] When marking derived classes' virtual methods ODR-used in
 order to trigger instantiation in order to permit devirtualization later in
 codegen, skip over pure functions since those can't be devirtualization
 targets.

llvm-svn: 175116
---
 clang/lib/Sema/SemaExpr.cpp               |  2 +-
 clang/test/SemaCXX/undefined-internal.cpp | 17 +++++++++++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 191683d33dba..b3ba2dc4ae92 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -11179,7 +11179,7 @@ static void MarkExprReferenced(Sema &SemaRef, SourceLocation Loc,
   if (!MostDerivedClassDecl)
     return;
   CXXMethodDecl *DM = MD->getCorrespondingMethodInClass(MostDerivedClassDecl);
-  if (!DM)
+  if (!DM || DM->isPure())
     return;
   SemaRef.MarkAnyDeclReferenced(Loc, DM, OdrUse);
 } 
diff --git a/clang/test/SemaCXX/undefined-internal.cpp b/clang/test/SemaCXX/undefined-internal.cpp
index e8810adadfa5..839fdafb3418 100644
--- a/clang/test/SemaCXX/undefined-internal.cpp
+++ b/clang/test/SemaCXX/undefined-internal.cpp
@@ -306,3 +306,20 @@ namespace test12 {
     Cls2 obj1((T7()));  // expected-note {{used here}}
   }
 }
+
+namespace test13 {
+  namespace {
+    struct X {
+      virtual void f() { }
+    };
+
+    struct Y : public X {
+      virtual void f() = 0;
+
+      virtual void g() {
+        X::f();
+      }
+    };
+  }
+}
+