RE: [PATCH] gdb: ensure has dwarf info before reading DWZ file

["Six, Lancelot" <Lancelot.Six@amd.com>]

[AMD Official Use Only - General]

> Lancelot> A consequence of this change is that the per_bfd->dwz_file
> optional
> Lancelot> object can now remain empty (instead of containing a nullptr), so
> also
> Lancelot> this patch also adjusts dwarf2_get_dwz_file to account for this
> Lancelot> possibility.  This effectively reverts the changes to
> Lancelot> dwarf2_get_dwz_file done by e9b738dfbdc.
>
> I'm curious about the motivation for this change.
> Can dwarf2_get_dwz_file be called when dwarf2_has_info returns false?
>
> Tom

It can be called when doing "save gdb-index" (dwarf2/index-write.c: save_gdb_index_command).  This case is exercised by "gdb.dwarf2/gdb-index-nodebug.exp".

Maybe a better approach could be to modify save_gdb_index_command to check if there is any debug info before calling write_dwarf_index, but the current try/catch approach is the construct currently taking core of that.  Having dwarf2_get_dwz_file return nullptr in that case does made sense to me, but I can also go another direction.

Best,
Lancelot.