From 33636e66c7a7744b044117d904fb08e0abcc6bb2 Mon Sep 17 00:00:00 2001
From: Douglas Gregor <dgregor@apple.com>
Date: Thu, 24 Dec 2009 20:56:24 +0000
Subject: [PATCH] Egregious, disgusting workaround for PR5866. We need to
 rework how we keep track of friends within templates, which will provide a
 real for PR5866. For now, this makes sure we don't do something entirely
 stupid with friends of specializations.

llvm-svn: 92143
---
 clang/include/clang/AST/DeclCXX.h              | 10 +++++++++-
 clang/lib/Sema/SemaDeclCXX.cpp                 |  3 +++
 clang/lib/Sema/SemaTemplateInstantiateDecl.cpp |  7 +++++--
 3 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/clang/include/clang/AST/DeclCXX.h b/clang/include/clang/AST/DeclCXX.h
index c1975505372b..02581c1241a4 100644
--- a/clang/include/clang/AST/DeclCXX.h
+++ b/clang/include/clang/AST/DeclCXX.h
@@ -1338,11 +1338,16 @@ private:
   // Location of the 'friend' specifier.
   SourceLocation FriendLoc;
 
+  // FIXME: Hack to keep track of whether this was a friend function
+  // template specialization.
+  bool WasSpecialization;
+
   FriendDecl(DeclContext *DC, SourceLocation L, FriendUnion Friend,
              SourceLocation FriendL)
     : Decl(Decl::Friend, DC, L),
       Friend(Friend),
-      FriendLoc(FriendL) {
+      FriendLoc(FriendL),
+      WasSpecialization(false) {
   }
 
 public:
@@ -1369,6 +1374,9 @@ public:
     return FriendLoc;
   }
 
+  bool wasSpecialization() const { return WasSpecialization; }
+  void setSpecialization(bool WS) { WasSpecialization = WS; }
+
   // Implement isa/cast/dyncast/etc.
   static bool classof(const Decl *D) {
     return D->getKind() == Decl::Friend;
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index 2e4ee63ebdb5..b70b0dccb75e 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -5380,6 +5380,9 @@ Sema::ActOnFriendFunctionDecl(Scope *S,
   FrD->setAccess(AS_public);
   CurContext->addDecl(FrD);
 
+  if (D.getName().getKind() == UnqualifiedId::IK_TemplateId)
+    FrD->setSpecialization(true);
+
   return DeclPtrTy::make(ND);
 }
 
diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index 18a73250a529..1ec91bd55ec3 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -401,7 +401,10 @@ Decl *TemplateDeclInstantiator::VisitFriendDecl(FriendDecl *D) {
     // Hack to make this work almost well pending a rewrite.
     if (ND->getDeclContext()->isRecord())
       NewND = SemaRef.FindInstantiatedDecl(ND, TemplateArgs);
-    else
+    else if (D->wasSpecialization()) {
+      // Totally egregious hack to work around PR5866
+      return 0;
+    } else
       NewND = Visit(ND);
     if (!NewND) return 0;
 
@@ -687,7 +690,7 @@ Decl *TemplateDeclInstantiator::VisitCXXRecordDecl(CXXRecordDecl *D) {
 ///   1) instantiating function templates
 ///   2) substituting friend declarations
 /// FIXME: preserve function definitions in case #2
-  Decl *TemplateDeclInstantiator::VisitFunctionDecl(FunctionDecl *D,
+Decl *TemplateDeclInstantiator::VisitFunctionDecl(FunctionDecl *D,
                                        TemplateParameterList *TemplateParams) {
   // Check whether there is already a function template specialization for
   // this declaration.