Re: Rust

[ludo@gnu.org (Ludovic Courtès)]

Eric Le Bihan <eric.le.bihan.dev@free.fr> skribis:

> Le Fri, 29 Jul 2016 17:16:29 +0200,
> ludo@gnu.org (Ludovic Courtès) a écrit :

[...]

>> > Some questions, though:
>> >
>> > 1. I can compile a sample program in a guix environment created
>> > using `guix environment gcc glibc binutils rust`, but the program
>> > generated fails to run because libgcc_s.so.1 can not be found. How
>> > can it be added to the environment?  
>> 
>> As Andreas notes, ‘gcc-toolchain’, which includes ‘ld-wrapper’, should
>> fix this.
>
> Yes. It solved my problem.
>  
>> Does Rust use GCC, or just ld?
>
> It only uses the linker, i.e. ld on GNU/Linux.

Then it should be enough to add ‘ld-wrapper’ to the inputs (no need for
‘gcc-toolchain’ or ‘gcc’.)  Just make sure Rust captures the absolute
file name of ‘ld’.

> IIUC, to provide a Guix package for Cargo, the following should be done:
>
> 1. write a crate importer.
> 2. list all the crates needed by Cargo to build itself.
> 3. package each crate with the importer.
> 4. add a Cargo package which depends on the newly-imported crates and
> uses a binary version of Cargo to bootstrap itself (though this is not
> the best option in terms of auditing/reproducibility).
>
> Unlike Rust, Cargo still uses an "anonymous" binary version of itself
> for bootstrapping. I hope this may change soon.

Something along these lines, yes.  We may also need a
‘rust-build-system’, like we did for other languages:

  https://www.gnu.org/software/guix/manual/html_node/Build-Systems.html

If that build system works without invoking Cargo, then we probably
don’t need a Cargo binary to build Cargo.

Anyway, we’re not there yet.  :-)

>> > +        (add-before 'build 'pre-build
>> > +                    (lambda _
>> > +                      (let* ((bindir (string-append (getcwd)
>> > "/bin"))
>> > +                             (cc (string-append bindir "/cc")))
>> > +                        (mkdir bindir)
>> > +                        (call-with-output-file cc
>> > +                          (lambda (port)
>> > +                            (format port
>> > +                                    "#!~a\n\nexec gcc
>> > \"$@\"\n" (which "sh"))))
>> > +                        (chmod cc #o755))))  
>> 
>> Can we avoid this trick using a configure flag
>> (--with-compiler=/path/to/gcc) or a configure or environment variable
>> (CC=gcc)?  If not, that’s fine.
>
> To build the Rust standard library, only the linker is needed. The
> default value is "cc". I thought this could be overridden using the
> "--default-linker=" of the ./configure script, but it looks like it is
> not properly handled. Hence the need for the wrapper. 

OK, makes sense.  Please leave this explanation as a comment in the
code.

>> > +      #:tests? #f))  
>> 
>> We normally run test suites, unless we have a good reason not to do
>> so. :-)  Any ideas why “make check” fails?
>
> Out of laziness, I skipped the tests. I'll give it a look.

Let us know how it goes, even if the outcome is “too painful, giving
up”.  :-)

Thanks,
Ludo’.