From 27e2ff964fc3e18c27488e15dc74b44ef32d2fe0 Mon Sep 17 00:00:00 2001
From: Yaron Keren <yaron.keren@gmail.com>
Date: Mon, 17 Apr 2017 08:51:20 +0000
Subject: Address http://bugs.llvm.org/pr30994 so that a non-friend can
 properly replace a friend, and a visible friend can properly replace an
 invisible friend but not vice verse, and definitions are not replaced. This
 fixes the two FIXME in SemaTemplate/friend-template.cpp.

The code implements Richard Smith suggestion in comment 3 of the PR.

reviewer: Vassil Vassilev

Differential Revision: https://reviews.llvm.org/D31540

llvm-svn: 300443
---
 clang/lib/AST/Decl.cpp     |  4 ++++
 clang/lib/AST/DeclBase.cpp | 15 +++++++++++++++
 2 files changed, 19 insertions(+)

(limited to 'clang/lib')

diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index 2b22e5bb50a..6a288cdb21f 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -1536,6 +1536,10 @@ bool NamedDecl::declarationReplaces(NamedDecl *OldD, bool IsKnownNewer) const {
   if (isa<ObjCMethodDecl>(this))
     return false;
 
+  if (getFriendObjectKind() > OldD->getFriendObjectKind() &&
+      !isThisDeclarationADefinition())
+    return false;
+
   // For parameters, pick the newer one. This is either an error or (in
   // Objective-C) permitted as an extension.
   if (isa<ParmVarDecl>(this))
diff --git a/clang/lib/AST/DeclBase.cpp b/clang/lib/AST/DeclBase.cpp
index cda70c5edcd..ae7444579b0 100644
--- a/clang/lib/AST/DeclBase.cpp
+++ b/clang/lib/AST/DeclBase.cpp
@@ -861,6 +861,21 @@ const FunctionType *Decl::getFunctionType(bool BlocksToo) const {
   return Ty->getAs<FunctionType>();
 }
 
+bool Decl::isThisDeclarationADefinition() const {
+  if (auto *TD = dyn_cast<TagDecl>(this))
+    return TD->isThisDeclarationADefinition();
+  if (auto *FD = dyn_cast<FunctionDecl>(this))
+    return FD->isThisDeclarationADefinition();
+  if (auto *VD = dyn_cast<VarDecl>(this))
+    return VD->isThisDeclarationADefinition();
+  if (auto *CTD = dyn_cast<ClassTemplateDecl>(this))
+    return CTD->isThisDeclarationADefinition();
+  if (auto *FTD = dyn_cast<FunctionTemplateDecl>(this))
+    return FTD->isThisDeclarationADefinition();
+  if (auto *VTD = dyn_cast<VarTemplateDecl>(this))
+    return VTD->isThisDeclarationADefinition();
+  return false;
+}
 
 /// Starting at a given context (a Decl or DeclContext), look for a
 /// code context that is not a closure (a lambda, block, etc.).
-- 
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