Re: [PATCH] [gdb/symtab] Error out for .debug_types section in dwz file

[Tom de Vries <tdevries@suse.de>]

On 9/20/23 11:18, Guinevere Larsen wrote:
> On 12/09/2023 10:43, Tom de Vries via Gdb-patches wrote:
>> There are two methods to factor out type information in a dwarf4 
>> executable:
>> - use -fdebug-info-types to generate type units in a .debug_types 
>> section, and
>> - use dwz to create partial units.
>>
>> The dwz method has an extra benefit: it also allows to factor out 
>> information
>> between executables into a newly created .dwz file, pointed to by a
>> .gnu_debugaltlink section.
>>
>> There is nothing prohibiting a .gnu_debugaltlink file to contain a
>> .debug_types section.
>>
>> It's just not generated by dwz or any other tool atm, and consequently 
>> gdb has
>> no support for it.  Enhancement PR symtab/30838 is open about the lack of
>> support.
>>
>> Make the current situation explicit by emitting a dwarf error:
>> ...
>> (gdb) file struct-with-sig-2^M
>> Reading symbols from struct-with-sig-2...^M
>> Dwarf Error: .debug_types section not supported in dwz file^M
>> ...
>> and add an assert in write_gdbindex:
>> ...
>> +      /* See enhancement PR symtab/30838.  */
>> +      gdb_assert (!(per_cu->is_dwz && per_cu->is_debug_types));
>> ...
>> to clarify why we can use:
>> ...
>>        data_buf &cu_list = (per_cu->is_debug_types
>>                             ? types_cu_list
>>                             : per_cu->is_dwz ? dwz_cu_list : 
>> objfile_cu_list);
>> ...
>>
>> The test-case is a modified copy from gdb.dwarf2/struct-with-sig.exp, 
>> so it
>> keeps the copyright years range.
>>
>> Tested on x86_64-linux.
>>
>> Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30838
>> ---
> 
> Hi! I tested this patch and it does not add any regression, and properly 
> detects the situation.
> 

Hi,

Thanks for testing this, committed.

- Tom

> Tested-By: Guinevere Larsen <blarsen@redhat.com>
>