Re: 05/06: gnu: rust: Don't build for "native" arch on ARM.

Re: 05/06: gnu: rust: Don't build for "native" arch on ARM.

[Mark H Weaver]

Hi Efraim and Danny,

dannym@scratchpost.org (Danny Milosavljevic) writes:

> dannym pushed a commit to branch master
> in repository guix.
>
> commit 67ca98ec7818f5b63fe041bfee4ef10826635685
> Author: Efraim Flashner <efraim@flashner.co.il>
> Date:   Thu Mar 22 09:14:53 2018 +0200
>
>     gnu: rust: Don't build for "native" arch on ARM.
>     
>     * gnu/packages/rust.scm (rust-1.23)<#:phases>[dont-build-native]: New phase.
> ---
>  gnu/packages/rust.scm | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/gnu/packages/rust.scm b/gnu/packages/rust.scm
> index 8c5abfc..0df649c 100644
> --- a/gnu/packages/rust.scm
> +++ b/gnu/packages/rust.scm
> @@ -351,6 +351,12 @@ safety and thread safety guarantees.")
>       (substitute-keyword-arguments (package-arguments rust-1.19)
>         ((#:phases phases)
>          `(modify-phases ,phases
> +           (add-after 'unpack 'dont-build-native
> +             (lambda _
> +               ;; XXX: Revisit this when we use gcc 6.
> +               (substitute* "src/binaryen/CMakeLists.txt"
> +                 (("ADD_COMPILE_FLAG\\(\\\"-march=native\\\"\\)") ""))
> +               #t))
>             (add-after 'patch-tests 'patch-cargo-tests
>               (lambda _
>                 (substitute* "src/tools/cargo/tests/build.rs"

If it would be beneficial, you might consider using gcc-7 to compile
'rust', by adding 'gcc-7' to native-inputs.  We're already using gcc-7
to compile a few other packages, including linux-libre on x86_64.

       Mark

Re: 05/06: gnu: rust: Don't build for "native" arch on ARM.

[Danny Milosavljevic]

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Hi Mark,

On Mon, 16 Apr 2018 16:05:04 -0400
Mark H Weaver <mhw@netris.org> wrote:

> If it would be beneficial, you might consider using gcc-7 to compile
> 'rust', by adding 'gcc-7' to native-inputs.  We're already using gcc-7
> to compile a few other packages, including linux-libre on x86_64.

Yeah, it would be possible.

Rust right now has only limited C++ FFI - so I guess the risk of having
a gcc-7 Rust dlopen'ing a gcc-4 library with incompatible C++ classes/
templates in it is low.  (that stuff has been a nightmare to debug in
my working life and I'd rather not repeat it)

I had no compatibility problems with C FFI - so we are covered here.

So all in all we can do it - and let's do it.  But I've just pushed
a large update for Rust.  Let's have it built and see what else
breaks on other architectures first - before we change more.

Also, AFAIK "-march=native" autodetects the CPU in the build machine
and then optimizes for exactly that CPU.  Arguably that's not what
we want in general.

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Re: 05/06: gnu: rust: Don't build for "native" arch on ARM.

[Efraim Flashner]

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On Tue, Apr 17, 2018 at 09:17:12AM +0200, Danny Milosavljevic wrote:
> Hi Mark,
> 
> On Mon, 16 Apr 2018 16:05:04 -0400
> Mark H Weaver <mhw@netris.org> wrote:
> 
> > If it would be beneficial, you might consider using gcc-7 to compile
> > 'rust', by adding 'gcc-7' to native-inputs.  We're already using gcc-7
> > to compile a few other packages, including linux-libre on x86_64.
> 
> Yeah, it would be possible.
> 
<snip>
> 
> Also, AFAIK "-march=native" autodetects the CPU in the build machine
> and then optimizes for exactly that CPU.  Arguably that's not what
> we want in general.

This was my original intent with commenting out the '-march=native', it
just seemed that it cropped up as a build error more often with arm*
processors.

As far as aarch64 goes, it doesn't build fully in either case, but the
error I experienced with '-march=native' is gone when I add gcc-7 as a
native-input.

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Re: 05/06: gnu: rust: Don't build for "native" arch on ARM.

[Joshua Branson]

Mark H Weaver <mhw@netris.org> writes:

> Hi Efraim and Danny,
>
> dannym@scratchpost.org (Danny Milosavljevic) writes:
>
>> dannym pushed a commit to branch master
>> in repository guix.
>>
>> commit 67ca98ec7818f5b63fe041bfee4ef10826635685
>> Author: Efraim Flashner <efraim@flashner.co.il>
>> Date:   Thu Mar 22 09:14:53 2018 +0200
>>
>>     gnu: rust: Don't build for "native" arch on ARM.
>>     
>>     * gnu/packages/rust.scm (rust-1.23)<#:phases>[dont-build-native]: New phase.
>> ---
>>  gnu/packages/rust.scm | 6 ++++++
>>  1 file changed, 6 insertions(+)
>>
>> diff --git a/gnu/packages/rust.scm b/gnu/packages/rust.scm
>> index 8c5abfc..0df649c 100644
>> --- a/gnu/packages/rust.scm
>> +++ b/gnu/packages/rust.scm
>> @@ -351,6 +351,12 @@ safety and thread safety guarantees.")
>>       (substitute-keyword-arguments (package-arguments rust-1.19)
>>         ((#:phases phases)
>>          `(modify-phases ,phases
>> +           (add-after 'unpack 'dont-build-native
>> +             (lambda _
>> +               ;; XXX: Revisit this when we use gcc 6.
>> +               (substitute* "src/binaryen/CMakeLists.txt"
>> +                 (("ADD_COMPILE_FLAG\\(\\\"-march=native\\\"\\)") ""))
>> +               #t))
>>             (add-after 'patch-tests 'patch-cargo-tests
>>               (lambda _
>>                 (substitute* "src/tools/cargo/tests/build.rs"
>
> If it would be beneficial, you might consider using gcc-7 to compile
> 'rust', by adding 'gcc-7' to native-inputs.  We're already using gcc-7
> to compile a few other packages, including linux-libre on x86_64.

Maybe this is a silly question, but I thought that gcc couldn't compile
rust code?  I thought LLVM was the only compiler that could compile rust?

>
>        Mark