Re: [PATCH] gdb: tighten assertions in set_type_vptr_*

[Simon Marchi <simark@simark.ca>]

On 2026-02-02 12:38, Kevin Buettner wrote:
> On Mon, 26 Jan 2026 10:54:00 -0500
> Simon Marchi <simon.marchi@efficios.com> wrote:
> 
>> From: Simon Marchi <simon.marchi@efficios.com>
>> To: gdb-patches@sourceware.org
>> Cc: Simon Marchi <simon.marchi@polymtl.ca>
>> Subject: [PATCH] gdb: tighten assertions in set_type_vptr_*
>> Date: Mon, 26 Jan 2026 10:54:00 -0500
>>
>> From: Simon Marchi <simon.marchi@polymtl.ca>
>>
>> In C++, only structures and classes (represented by TYPE_CODE_STRUCT)
>> can participate in inheritance.  I therefore think it does not make
>> sense to allow for TYPE_CODE_UNION in set_type_vptr_basetype and
>> set_type_vptr_fieldno.  Remove the possibility for the type to be a
>> union in these functions.
>>
>> Also, for the same reason, add an assertion that checks the type of
>> basetype in set_type_vptr_basetype.
>>
>> I did not change the getters (internal_type_vptr_fieldno and
>> internal_type_vptr_basetype), because it seems like they are called by
>> code that handles similarly both structures and unions.  Making those
>> stricter would require adding conditions in those callers, which doesn't
>> look like an improvement.  For unions, they will correctly return an
>> "invalid" value.
>>
>> Change allocate_cplus_struct_type to not use set_type_vptr_fieldno to
>> initialize the field to -1, otherwise it would trip the assertion when
>> initializing for a union type.
> 
> Makes sense to me...
> 
> Approved-by: Kevin Buettner <kevinb@redhat.com>
> 

Pushed, thanks!

Simon