Re: C++ error

[Fredrik Salomonsson <plattfot@posteo.net>]

Hi,

Laurent Gatto <laurent.gatto@gmail.com> writes:

> On Sat, 16 Nov 2024 at 11:56, Laurent Gatto <laurent.gatto@gmail.com> wrote:
>>
>> Hi Fredrik,
>>
>> Excellent advice, and I was able to identify the culprit.

Awesome!

>> Here's a simple reproducible example
>>
>> $ guix shell --container gcc-toolchain
>> [env]$ g++ main.cpp
>> [env]$ exit
>>
>> $ guix shell --container gcc-toolchain gfortran-toolchain
>> [env]$ g++ main.cpp
>> In file included from
>> /gnu/store/68l504nyvms77jzfg9yf4njiyfbi8gm2-profile/include/c++/bits/move.h:57,
>>                  from
>> /gnu/store/68l504nyvms77jzfg9yf4njiyfbi8gm2-profile/include/c++/bits/exception_ptr.h:43,
>>                  from
>> /gnu/store/68l504nyvms77jzfg9yf4njiyfbi8gm2-profile/include/c++/exception:153,
>>                  from
>> /gnu/store/68l504nyvms77jzfg9yf4njiyfbi8gm2-profile/include/c++/ios:39,
>>                  from
>> /gnu/store/68l504nyvms77jzfg9yf4njiyfbi8gm2-profile/include/c++/ostream:38,
>>                  from
>> /gnu/store/68l504nyvms77jzfg9yf4njiyfbi8gm2-profile/include/c++/iostream:39,
>>                  from main.cpp:1:
>> /gnu/store/68l504nyvms77jzfg9yf4njiyfbi8gm2-profile/include/c++/type_traits:732:26:
>> error: expected identifier before '(' token
>>   732 |     _GLIBCXX20_DEPRECATED("use is_standard_layout &&
>> is_trivial instead")
>>       |                          ^
>> /gnu/store/68l504nyvms77jzfg9yf4njiyfbi8gm2-profile/include/c++/type_traits:732:27:
>> error: expected unqualified-id before string constant
>>   732 |     _GLIBCXX20_DEPRECATED("use is_standard_layout &&
>> is_trivial instead")
>>       |                           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> /gnu/store/68l504nyvms77jzfg9yf4njiyfbi8gm2-profile/include/c++/type_traits:732:27:
>> error: expected ')' before string constant
>>   732 |     _GLIBCXX20_DEPRECATED("use is_standard_layout &&
>> is_trivial instead")
>>       |                          ~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>       |                           )
>> /gnu/store/68l504nyvms77jzfg9yf4njiyfbi8gm2-profile/include/c++/type_traits:3154:25:
>> error: expected unqualified-id before string constant
>>  3154 |   _GLIBCXX20_DEPRECATED("use is_standard_layout_v &&
>> is_trivial_v instead")
>>       |
>> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> /gnu/store/68l504nyvms77jzfg9yf4njiyfbi8gm2-profile/include/c++/type_traits:3154:25:
>> error: expected ')' before string constant
>>  3154 |   _GLIBCXX20_DEPRECATED("use is_standard_layout_v &&
>> is_trivial_v instead")
>>       |
>> ~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>       |                         )
>
> The order of the packages does matter. The above fails, but if I pass
> gfortran-toolchain before gcc-toolchain, it works:
>
> $ guix shell --container gfortran-toolchain gcc-toolchain
> [env]$ g++ main.cpp
> [env]$ ./a.out
> 201703
>
> Is this really expected?

This sounds like a bug.  Especially if it is order dependent if it works
or not.  And I can confirm that I can reproduce it on my end as well.

>> I also confirmed that I was able to compile that source code by simply
>> commenting gfortran-toolchain in my system manifest.
>>
>> Isn't this weird though? What if I need both?

It should work to have both in the same context.  Probably some issue
with how they are package up — I haven't checked the packaging for them.
But I have built gcc from source with both g++ and gfortran without any
issues.  That was gcc-9 and gcc-11 so maybe something broke in upstream
with gcc-14?  Although I find that unlikely.

Anyway, best is to send in a bug report to guix now that you have a
small reproducible test that show case the issue.

-- 
s/Fred[re]+i[ck]+/Fredrik/g