Re: [C++ Patch] PR 37087

[Paolo Carlini <paolo dot carlini at oracle dot com>]

Hi,
> I guess I think we should try to leave the permerror in place, unless 
> there's a fundamental reason we can't make it work, and add a test 
> (with -fpermissive) for this to the testsuite so that we keep it working.
Ok, thanks for your feedback.

My point, inspired by this PR of course, was essentially that every time 
we have a permerror we don't know if an error occurs or not, I would say 
the front-end becomes a tad more complex, because must tolerate rather 
special situations (so special that are errors by default) and proceed 
anyway.

By the way, I tested alternate fixes for this issue, which just detects 
the problem with ::a in the parser, thus much earlier. In this case the 
error message doesn't mention anymore specializations... I'm attaching a 
draft here, FYI

Thanks,
Paolo.

/////////////////

Index: testsuite/g++.dg/template/crash80.C
===================================================================
*** testsuite/g++.dg/template/crash80.C	(revision 0)
--- testsuite/g++.dg/template/crash80.C	(revision 0)
***************
*** 0 ****
--- 1,9 ----
+ // PR c++/37087
+ 
+ namespace a {
+   template <typename T> class Foo;
+ }
+ 
+ namespace b {
+   template <> class ::a::Foo<double> {}; // { dg-error "global qualification" }
+ }
Index: cp/parser.c
===================================================================
*** cp/parser.c	(revision 138953)
--- cp/parser.c	(working copy)
*************** cp_parser_class_head (cp_parser* parser,
*** 14981,14988 ****
    cp_parser_commit_to_tentative_parse (parser);
    /* Issue the error about the overly-qualified name now.  */
    if (qualified_p)
!     cp_parser_error (parser,
! 		     "global qualification of class name is invalid");
    else if (invalid_nested_name_p)
      cp_parser_error (parser,
  		     "qualified name does not name a class");
--- 14981,14991 ----
    cp_parser_commit_to_tentative_parse (parser);
    /* Issue the error about the overly-qualified name now.  */
    if (qualified_p)
!     {
!       cp_parser_error (parser,
! 		       "global qualification of class name is invalid");
!       return error_mark_node;
!     }
    else if (invalid_nested_name_p)
      cp_parser_error (parser,
  		     "qualified name does not name a class");