Re: [C++ PATCH] Friend class and DR 180 (take 2)

[Kriang Lerdsuwanakij <lerdsuwa at users dot sourceforge dot net>]

Jason Merrill wrote:

> On Wed, 27 Nov 2002 20:54:00 +0700, Kriang Lerdsuwanakij <lerdsuwa@users.sourceforge.net> wrote:
>
>  
> > This is a revised version of the friend patch submitted yesterday.
> > The diagnostic character string is cleaned up and the redundant
> > TYPE_IDENTIFIER macro is removed.
> >    
> I think the other TYPE_IDENTIFIER is also redundant.  With that change,
> this is OK.
I'd disagree here.  'type' is a TYPENAME_TYPE node.  Calling pedwarn with
simply 'type' would output entire type, i.e. 'typename A::B'.  But we want
to instruct user the correct syntax with the above 'typename' keyword
replaced by 'class'.

I think the suggested TYPE_IDENTIFIER should be replaced by
TYPENAME_TYPE_FULLNAME instead.  The TYPE_IDENTIFIER does not work correctly
with the error code like 'friend typename T::C<int>;'.  The diagnostic 
suggests
user with 'friend class T::C' but should output 'friend class T::C<int>'
instead.  The corrected patch appears below.  OK for main trunk?

--Kriang

2002-11-28  Kriang Lerdsuwanakij  <lerdsuwa@users.sourceforge.net>

	DR 180
	* decl.c (grokdeclarator): Require class-key for all friend class.
	Output the correct type and context in the error message.

2002-11-28  Kriang Lerdsuwanakij  <lerdsuwa@users.sourceforge.net>

	DR 180
	* g++.old-deja/g++.pt/crash32.C: Expect error.


diff -cprN gcc-main-save2/gcc/cp/decl.c gcc-main-new2/gcc/cp/decl.c
*** gcc-main-save2/gcc/cp/decl.c	Tue Nov 26 19:46:40 2002
--- gcc-main-new2/gcc/cp/decl.c	Thu Nov 28 19:02:33 2002
*************** grokdeclarator (declarator, declspecs, d
*** 11635,11656 ****
 	      inlinep = 0;
 	    }
 
! 	  /* Until core issue 180 is resolved, allow 'friend typename A::B'.
! 	     But don't allow implicit typenames except with a class-key.  */
! 	  if (!current_aggr && (TREE_CODE (type) != TYPENAME_TYPE
! 				|| IMPLICIT_TYPENAME_P (type)))
 	    {
 	      if (TREE_CODE (type) == TEMPLATE_TYPE_PARM)
! 	        pedwarn ("template parameters cannot be friends");
 	      else if (TREE_CODE (type) == TYPENAME_TYPE)
! 	        pedwarn ("\
! friend declaration requires class-key, i.e. `friend class %T::%T'",
! 			    constructor_name (current_class_type),
! 			    TYPE_IDENTIFIER (type));
 	      else
! 	        pedwarn ("\
! friend declaration requires class-key, i.e. `friend %#T'",
! 			    type);
 	    }
 
 	  /* Only try to do this stuff if we didn't already give up.  */
--- 11635,11653 ----
 	      inlinep = 0;
 	    }
 
! 	  if (!current_aggr)
 	    {
+ 	      /* Don't allow friend declaration without a class-key.  */
 	      if (TREE_CODE (type) == TEMPLATE_TYPE_PARM)
! 		pedwarn ("template parameters cannot be friends");
 	      else if (TREE_CODE (type) == TYPENAME_TYPE)
! 	        pedwarn ("friend declaration requires class-key, "
! 			 "i.e. `friend class %T::%D'",
! 			 TYPE_CONTEXT (type), TYPENAME_TYPE_FULLNAME (type));
 	      else
! 	        pedwarn ("friend declaration requires class-key, "
! 			 "i.e. `friend %#T'",
! 			 type);
 	    }
 
 	  /* Only try to do this stuff if we didn't already give up.  */
diff -cprN gcc-main-save2/gcc/testsuite/g++.old-deja/g++.pt/crash32.C gcc-main-new2/gcc/testsuite/g++.old-deja/g++.pt/crash32.C
*** gcc-main-save2/gcc/testsuite/g++.old-deja/g++.pt/crash32.C	Tue Nov 26 19:45:46 2002
--- gcc-main-new2/gcc/testsuite/g++.old-deja/g++.pt/crash32.C	Tue Nov 26 14:01:57 2002
*************** template <class T> struct A
*** 8,13 ****
 
 template<class T> struct C
 {
!   friend typename A<T>::B;
 };
 
--- 8,13 ----
 
 template<class T> struct C
 {
!   friend typename A<T>::B; // ERROR - struct is required
 };