Re: [PATCH] Fix PRs 52080, 52097 and 48124, rewrite bitfield expansion, enable the C++ memory model wrt bitfields everywhere

[Eric Botcazou]

> But it's only ever computed for RECORD_TYPEs where DECL_QUALIFIER is
> unused.

OK, that could work indeed.

> For now giving up seems to be easiest (just give up when
> DECL_FIELD_OFFSET is not equal for all of the bitfield members).
> That will at most get you the miscompiles for the PRs back, for
> languages with funny structure layout.

I have another variant of the DECL_FIELD_OFFSET problem:

FAIL: gnat.dg/specs/pack8.ads (test for excess errors)
Excess errors:
+===========================GNAT BUG DETECTED==============================+
| 4.8.0 20120314 (experimental) [trunk revision 185395] (i586-suse-linux) GCC 
error:|
| in finish_bitfield_representative, at stor-layout.c:1762                 |
| Error detected at pack8.ads:17:4                   

Testcase attached:

  gnat.dg/specs/pack8.ads
  gnat.dg/specs/pack8_pkg.ads

I agree that giving up (for now) is a sensible option.  Thanks.

-- 
Eric Botcazou

with Pack8_Pkg;

package Pack8 is

   subtype Index_Type is Integer range 1 .. Pack8_Pkg.N;

   subtype Str is String( Index_Type);

   subtype Str2 is String (1 .. 11);

   type Rec is record
      S1 : Str;
      S2 : Str;
      B  : Boolean;
      S3 : Str2;
   end record;
   pragma Pack (Rec);

end Pack8;

package Pack8_Pkg is

   N : Natural := 1;

end Pack8_Pkg;