From f4fe843aac730e2202b3c9c6c52649ee186ba788 Mon Sep 17 00:00:00 2001
From: Richard Smith <richard-llvm@metafoo.co.uk>
Date: Fri, 8 Jun 2012 01:30:54 +0000
Subject: [PATCH] Allow friend declarations of defaulted special member
 functions. Only definitions of such members are prohibited, not mere
 declarations.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@158186 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Sema/SemaDecl.cpp                      | 2 +-
 test/SemaCXX/cxx0x-defaulted-functions.cpp | 6 ++++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index fdda9014dc..68f7469457 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -2039,7 +2039,7 @@ bool Sema::MergeFunctionDecl(FunctionDecl *New, Decl *OldD, Scope *S) {
             << New << getSpecialMember(OldMethod);
           return true;
         }
-      } else if (OldMethod->isExplicitlyDefaulted()) {
+      } else if (OldMethod->isExplicitlyDefaulted() && !isFriend) {
         Diag(NewMethod->getLocation(),
              diag::err_definition_of_explicitly_defaulted_member)
           << getSpecialMember(OldMethod);
diff --git a/test/SemaCXX/cxx0x-defaulted-functions.cpp b/test/SemaCXX/cxx0x-defaulted-functions.cpp
index 2ab0f73eae..595d428806 100644
--- a/test/SemaCXX/cxx0x-defaulted-functions.cpp
+++ b/test/SemaCXX/cxx0x-defaulted-functions.cpp
@@ -51,3 +51,9 @@ template<typename T> struct S : T {
 struct lit { constexpr lit() {} };
 S<lit> s_lit; // ok
 S<bar> s_bar; // ok
+
+struct Friends {
+  friend S<bar>::S();
+  friend S<bar>::S(const S&);
+  friend S<bar>::S(S&&);
+};
-- 
2.40.0