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

[Doug Evans <dje@google.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.]