Re: [RFA] Fix PR gdb/11702, printing of static const member variables

[Doug Evans <dje at google dot com>]

On Mon, Jun 28, 2010 at 4:02 AM, Jan Kratochvil
<jan.kratochvil@redhat.com> wrote:
> On Sun, 27 Jun 2010 20:24:42 +0200, Doug Evans wrote:
>> btw, the dwarf4 standard, as I read it, says static member variables are
>> identified by having DW_AT_external. ?[4.1 Data Object Entries]
>> However, dwarf2_add_field is calling die_is_declaration.
>
> echo 'class C { static const float i = 1; } c;'|g++ -c -o 1.o -Wall -g -x c++ -
> ? ?< c> ? DW_AT_producer ? ?: (indirect string, offset: 0x11): GNU C++ 4.6.0 20100628 (experimental)
> ?<2><33>: Abbrev Number: 3 (DW_TAG_member)
> ? ?<34> ? DW_AT_name ? ? ? ?: i
> ? ?<38> ? DW_AT_type ? ? ? ?: <0x45>
> ? ?<3c> ? DW_AT_external ? ?: 1
> ? ?<3d> ? DW_AT_accessibility: 3 ? ? ? (private)
> ? ?<3e> ? DW_AT_declaration : 1
> ? ?<3f> ? DW_AT_const_value : 4 byte block: 0 0 80 3f
>
> Isn't it primarily a bug in GCC? ?There is no other DIE for `i' and it is
> a complete definition so there is no place for DW_AT_declaration there.
>
> Just such GCC change will be incompatible with existing GDBs, maybe to make
> the GCC change only for -gdwarf-4 upwards which is incompatible with older
> GDBs anyway?

I'm not sure I follow.
If all the GCC versions we care about are also adding DW_AT_external
to the DIE, gdb *could* check for it instead of die_is_declaration,
right?  Or am I missing something?

> 4.4.5 20100627 uses DW_TAG_variable but 4.5.1 20100627 uses DW_TAG_member.

Ah.

> Otherwise - for the second patch - there are some needless whitespace changes.
> Also I would test also `float' const field there using LOC_CONST_BYTES; it
> works but just to test it, based on your IRC comments about LOC_CONST_BYTES.

I'll add a few more testcases.  Thanks.
[And I'll check the whitespace fix in separately.]