Subject: [bug#70985] [PATCH v2 5/6] gnu: rust: Guard against cross-libc returning #f.

From: Efraim Flashner <[email-masked]>
Date: Sun, 7 Jul 2024 19:26:35 +0300

On Fri, Jul 05, 2024 at 06:06:02PM +0200, Christopher Baines wrote:
> * gnu/packages/rust.scm (make-rust-sysroot/implementation): Guard against
> cross-libc returning #f.
> 
> Change-Id: Ia0d5c889c6f5cd3478ad985c79feb9ba1c472c29
> ---
>  gnu/packages/rust.scm | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/gnu/packages/rust.scm b/gnu/packages/rust.scm
> index a385344473..f1de34b277 100644
> --- a/gnu/packages/rust.scm
> +++ b/gnu/packages/rust.scm
> @@ -73,7 +73,9 @@ (define-module (gnu packages rust)
>    #:use-module (ice-9 match)
>    #:use-module (ice-9 optargs)
>    #:use-module (srfi srfi-1)
> -  #:use-module (srfi srfi-26))
> +  #:use-module (srfi srfi-26)
> +  #:use-module (srfi srfi-34)
> +  #:use-module (srfi srfi-35))
>  
>  ;; This is the hash for the empty file, and the reason it's relevant is not
>  ;; the most obvious.
> @@ -1464,7 +1466,11 @@ (define make-rust-sysroot/implementation
>           (modify-inputs (package-native-inputs base-rust)
>                          (prepend (cross-gcc target
>                                              #:libc (cross-libc target))
> -                                 (cross-libc target)
> +                                 (or (cross-libc target) ; could be #f
> +                                     (raise (condition
> +                                             (&package-unsupported-target-error
> +                                              (package (libc-for-target target))
> +                                              (target target)))))
>                                   (cross-binutils target)))))
>        (properties
>         `((hidden? . #t)
> -- 
> 2.45.2

rust does support architectures without a libc, for example the mingw
targets a few lines above this snippet. I think it would make more sense
to only include (cross-libc target) and not if not.

I just tried building zoxide for powerpc-linux-gnu without (cross-libc
target) and it tried to link with the x86_64 libc, so it looks like it
is necessary where it is available.

How about we make this section even worse with:
(if (false-if-exception (cross-libc target))
    (modify-inputs ...
                   (cross-libc target)
                   ...)
    (modify-inputs ...))    ; no (cross-libc target)

In the meantime, I'll try to figure something out for actually putting
everything inside one modify-inputs so we don't have an ever expanding
number of them.

-- 
Efraim Flashner   <[email-masked]>   רנשלפ םירפא
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