From 1c3639351f8c252ddcc13d234cabf8780b1c235f Mon Sep 17 00:00:00 2001
From: Anders Carlsson <andersca@mac.com>
Date: Mon, 29 Mar 2010 19:49:09 +0000
Subject: [PATCH] When collecting virtual bases it's very important to use the
 canonical type of the base class. Otherwise, we might add the same virtual
 base class twice if the virtual base is an instantiated template. Fixes
 PR6251.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@99829 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/AST/DeclCXX.cpp               |  6 +++---
 test/CodeGenCXX/virtual-bases.cpp | 23 +++++++++++++++++++++++
 2 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/lib/AST/DeclCXX.cpp b/lib/AST/DeclCXX.cpp
index 3b3bf1ba44..ed02edd394 100644
--- a/lib/AST/DeclCXX.cpp
+++ b/lib/AST/DeclCXX.cpp
@@ -84,7 +84,7 @@ CXXRecordDecl::setBases(CXXBaseSpecifier const * const *Bases,
     C.Deallocate(data().Bases);
 
   // The set of seen virtual base types.
-  llvm::SmallPtrSet<QualType, 8> SeenVBaseTypes;
+  llvm::SmallPtrSet<CanQualType, 8> SeenVBaseTypes;
   
   // The virtual bases of this class.
   llvm::SmallVector<const CXXBaseSpecifier *, 8> VBases;
@@ -107,13 +107,13 @@ CXXRecordDecl::setBases(CXXBaseSpecifier const * const *Bases,
           BaseClassDecl->vbases_begin(),
          E = BaseClassDecl->vbases_end(); VBase != E; ++VBase) {
       // Add this base if it's not already in the list.
-      if (SeenVBaseTypes.insert(VBase->getType()))
+      if (SeenVBaseTypes.insert(C.getCanonicalType(VBase->getType())))
         VBases.push_back(VBase);
     }
 
     if (Base->isVirtual()) {
       // Add this base if it's not already in the list.
-      if (SeenVBaseTypes.insert(BaseType))
+      if (SeenVBaseTypes.insert(C.getCanonicalType(BaseType)))
           VBases.push_back(Base);
     }
 
diff --git a/test/CodeGenCXX/virtual-bases.cpp b/test/CodeGenCXX/virtual-bases.cpp
index 6277175763..61de3153fd 100644
--- a/test/CodeGenCXX/virtual-bases.cpp
+++ b/test/CodeGenCXX/virtual-bases.cpp
@@ -23,3 +23,26 @@ struct C : virtual A {
 // CHECK: define void @_ZN1CC1Eb(%struct.B* %this, i1 zeroext)
 // CHECK: define void @_ZN1CC2Eb(%struct.B* %this, i8** %vtt, i1 zeroext)
 C::C(bool) { }
+
+// PR6251
+namespace PR6251 {
+
+// Test that we don't call the A<char> constructor twice.
+
+template<typename T>
+struct A { A(); };
+
+struct B : virtual A<char> { };
+struct C : virtual A<char> { };
+
+struct D : B, C  {
+  D();
+};
+
+// CHECK: define void @_ZN6PR62511DC1Ev
+// CHECK: call void @_ZN6PR62511AIcEC2Ev
+// CHECK-NOT: call void @_ZN6PR62511AIcEC2Ev
+// CHECK: ret void
+D::D() { }
+
+}
-- 
2.50.1