Re: [PATCH] gdb/testsuite/lib/future.exp: follow dejagnu default_target_compile

[Simon Marchi <simark@simark.ca>]

On 2022-09-05 14:26, Lancelot SIX via Gdb-patches wrote:
> GDB's testsuite can override dejagnu's default_target_compile if the
> system provided dejagnu installation does not provide support to compile
> languages GDB needs.
> 
> Recent version of dejagnu (1.6.3, installed on REHL-9) includes ba60272
> "Establish a default C compiler by evaluating [find_gcc] if no other
> compiler is given."[1].  This commit removed calls such as
> `set_board_info compiler  "[find_gcc]"` from the various baseboards
> and has default_target_compile call `find_gcc` itself to find a compiler
> if none was specified by the board description.
> 
> On systems with dejagnu-1.6.3, if GDB's overrides is needed to support
> languages still unknown to dejagnu, we end up in the following
> situation:
>   - The system board files do not set the C compiler anymore,
>   - GDB's replacement for default_target_compile assumes that the
>     compiler should have been set up by the board file.
> 
> In this situation, no one sets the C compiler for the board and as a
> result many test are not compiled and not executed:
> 
>     [...]
>     Running .../gdb/testsuite/gdb.base/bt-on-error-and-warning.exp ...
>     gdb compile failed, default_target_compile: No compiler to compile with
>     Running .../gdb/testsuite/gdb.base/dprintf-non-stop.exp ...
>     gdb compile failed, default_target_compile: No compiler to compile with
>     Running .../gdb/testsuite/gdb.base/structs3.exp ...
>     gdb compile failed, default_target_compile: No compiler to compile with
>     [...]
> 
> We are observing this error with ROCgdb[2], a downstream port of GDB
> supporting AMD GPUs.  This port needs to use GDB's override of
> default_target_compile to compile HIP programs since dejagnu does not
> provide support for this language yet.
> 
> This patch changes gdb_default_target_compile_1 in a similar way
> default_target_compile has been updated so both implementations remain
> compatible.  Even if this is not strictly required by GDB just yet,
> I believe keeping both implementations in sync desirable.
> 
> Using board files provided with dejagnu <=1.6.2 is still supported: if
> the compiler is set by the board file, gdb_default_target_compile_1 uses
> it and does not need `find_gcc`.
> 
> Patch tested on x86_64 REHL-9 and ubuntu-20.04 on top of GDB and ROCgdb.
> 
> [1] http://git.savannah.gnu.org/gitweb/?p=dejagnu.git;a=commit;h=ba60272a5ac6f6a7012acca03f596a6ed003f044
> [2] https://github.com/ROCm-Developer-Tools/ROCgdb

Thanks, this is ok.

OOC, does this mean we can remove the "find_gcc" calls in our own
boards?  The override in future.exp does not systematically get used
when running on a system with an older DejaGNU, so I would guess not.

Simon