Re: GCC/Rust libgrust-v2/to-submit branch

[Arthur Cohen <arthur.cohen@embecosm.com>]

Hi Thomas!

A newer version of the library has been force-pushed to the branch 
`libgrust-v2/to-submit`.

On 11/20/23 15:55, Thomas Schwinge wrote:
> Hi!
> 
> Arthur and Pierre-Emmanuel have prepared a GCC/Rust libgrust-v2/to-submit
> branch: <https://github.com/Rust-GCC/gccrs/tree/libgrust-v2/to-submit>.
> In that one, most of the issues raised have been addressed, and which
> I've now successfully "tested" in my different GCC configurations,
> requiring just one additional change (see end of this email).  I'm using
> "tested" in quotes here, as libgrust currently is still missing its
> eventual content, and still is without actual users, so we may still be
> up for surprises later on.  ;-)
> 
> On 2023-10-27T22:41:52+0200, I wrote:
>> On 2023-09-27T00:25:16+0200, I wrote:
>>> don't we also directly need to
>>> incorporate here a few GCC/Rust master branch follow-on commits, like:
>>>
>>>    - commit 171ea4e2b3e202067c50f9c206974fbe1da691c0 "fixup: Fix bootstrap build"
>>>    - commit 61cbe201029658c32e5c360823b9a1a17d21b03c "fixup: Fix missing build dependency"
>>
>> I've not yet run into the need for these two.  Let's please leave these
>> out of the upstream submission for now, until we understand what exactly
>> these are necessary for.
> 
> (Still the same.)

Do you mean that we should remove the content of these commits from the 
submission? If so, I believe it's now done.

> 
>> However:
>>
>>>    - commit 6a8b207b9ef7f9038e0cae7766117428783825d8 "libgrust: Add dependency to libstdc++"
>>
>> ... this one definitely is necessary right now; see discussion in
>> <https://inbox.sourceware.org/8734xv24dd.fsf@euler.schwinge.homeip.net>
>> "Disable target libgrust if we're not building target libstdc++".
> 
> This one still isn't in the GCC/Rust libgrust-v2/to-submit branch -- but
> having now tested that branch, I'm now no longer seeing the respective
> build failure.  Isn't that change "libgrust: Add dependency to libstdc++"
> still necessary, conceptually?  (Maybe we're just lucky, currently?)
> I'll be sure to re-test in my different GCC configurations once libgrust
> gains actual content and use.  (..., which might then re-expose the
> original problem?)

This commit was integrated into another one:

fb31093105e build: Add libgrust as compilation modules

(on libgrust-v2/to-submit as of 2 minutes ago)

> 
>> And:
>>
>>> (Not sure if all of these are necessary and/or if that's the complete
>>> list; haven't looked up the corresponding GCC/Rust GitHub PRs.)
>>>
>>>> --- a/gcc/rust/config-lang.in
>>>> +++ b/gcc/rust/config-lang.in
>>>
>>>> +target_libs="target-libffi target-libbacktrace target-libgrust"
>>>
>>> Please don't add back 'target-libffi' and 'target-libbacktrace' here;
>>> just 'target-libgrust'.  (As is present in GCC/Rust master branch, and
>>> per commit 7411eca498beb13729cc2acec77e68250940aa81
>>> "Rust: Don't depend on unused 'target-libffi', 'target-libbacktrace'".)
>>
>> ... that change is necessary, too.
> 
> That's still unchanged in the GCC/Rust libgrust-v2/to-submit branch;
> please apply to 'gcc/rust/config-lang.in':
> 
>      -target_libs="target-libffi target-libbacktrace target-libgrust"
>      +target_libs=target-libgrust
> 
> Then, still should re-order the commits so that (re)generation of
> auto-generated files comes before use of libgrust (so that later
> bisection doesn't break), and move the 'contrib/gcc_update' update into
> the commit that adds the auto-generated files.

Do you mean that the regeneration should happen before the commit adding 
the proc_macro library? Or that when we keep going and adding more 
commits on top of this, we need to make sure the regeneration commit 
happens before any code starts using/depending on libgrust/?

And alright, we'll move the changes to contrib/gcc_update into the 
regeneration commit.

All the best, and thanks again for testing :)

Arthur

> 
> 
> Grüße
>   Thomas
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