Permit a class to friend its members in C++0x, without restriction.

Permit a class to friend its class members in C++ 98, as long as extensions
are enabled (and even when they aren't, only give an extwarn about it).



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@78332 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 22 insertions, 9 deletions

diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td
index ee259123b2..17bf188bf3 100644
--- a/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/include/clang/Basic/DiagnosticSemaKinds.td
@@ -299,6 +299,8 @@ def err_unexpected_friend : Error<
   "friends can only be classes or functions">;
 def err_friend_is_member : Error<
   "friends cannot be members of the declaring class">;
+def extwarn_friend_inner_class : ExtWarn<
+  "C++ 98 does not allow inner classes as friends">;
 def err_unelaborated_friend_type : Error<
   "must specify '%select{class|union}0' in a friend "
   "%select{class|union}0 declaration">;
diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index 240fcd66d9..63b0b3d83d 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -3359,12 +3359,20 @@ Sema::DeclPtrTy Sema::ActOnFriendDecl(Scope *S,
       Diag(DS.getFriendSpecLoc(), diag::err_friend_decl_defines_class)
         << RD->getSourceRange();
 
-    // C++ [class.friend]p1: A friend of a class is a function or
-    //   class that is not a member of the class . . .
-    // Definitions currently get treated in a way that causes this
-    // error, so only report it if we didn't see a definition.
-    else if (RD->getDeclContext() == CurContext)
-      Diag(DS.getFriendSpecLoc(), diag::err_friend_is_member);
+    // C++98 [class.friend]p1: A friend of a class is a function
+    //   or class that is not a member of the class . . .
+    // But that's a silly restriction which nobody implements for
+    // inner classes, and C++0x removes it anyway, so we only report
+    // this 
+    // But no-one implements it that way, and C++0x removes this
+    // restriction, so we only report it (as a warning) if we're being
+    // pedantic.  Ideally this would real -pedantic mode 
+    // 
+    // Also, definitions currently get treated in a way that causes
+    // this error, so only report it if we didn't see a definition.
+    else if (RD->getDeclContext() == CurContext &&
+             !(getLangOptions().CPlusPlus0x || getLangOptions().GNUMode))
+      Diag(DS.getFriendSpecLoc(), diag::extwarn_friend_inner_class);
 
     return DeclPtrTy::make(RD);
   }
@@ -3468,7 +3476,10 @@ Sema::DeclPtrTy Sema::ActOnFriendDecl(Scope *S,
 
     // C++ [class.friend]p1: A friend of a class is a function or
     //   class that is not a member of the class . . .
-    if (FD && DC == CurContext)
+    // C++0x changes this for both friend types and functions.
+    // Most C++ 98 compilers do seem to give an error here, so
+    // we do, too.
+    if (FD && DC == CurContext && !getLangOptions().CPlusPlus0x)
       Diag(DS.getFriendSpecLoc(), diag::err_friend_is_member);
   }
 
diff --git a/test/CXX/class/class.friend/p1.cpp b/test/CXX/class/class.friend/p1.cpp
index a9265ede5a..80afe3e7a5 100644
--- a/test/CXX/class/class.friend/p1.cpp
+++ b/test/CXX/class/class.friend/p1.cpp
@@ -32,8 +32,8 @@ class A {
   void a_member();
   friend void A::a_member(); // expected-error {{ friends cannot be members of the declaring class }}
   friend void a_member(); // okay (because we ignore class scopes when looking up friends)
-  friend class A::AInner; // expected-error {{ friends cannot be members of the declaring class }}
-  friend class AInner; // expected-error {{ friends cannot be members of the declaring class }}
+  friend class A::AInner; // this is okay as an extension
+  friend class AInner; // okay, refers to ::AInner
 
   friend void Derived::missing_member(); // expected-error {{ no function named 'missing_member' with type 'void ()' was found in the specified scope }}