platforms: Raise an exception when no suitable platform is found.

This was motivated by #60786, which produced a cryptic, hard to understand
backtrace.

Given the following reproducer:
    (use-modules (guix packages)
                 (gnu packages cross-base))

    (define linux-libre-headers-cross-mips64el-linux-gnuabi64
      (cross-kernel-headers "mips64el-linux-gnuabi64"))

    (package-arguments linux-libre-headers-cross-mips64el-linux-gnuabi64)

Before this change:
    ice-9/boot-9.scm:1685:16: In procedure raise-exception:
    In procedure struct-vtable: Wrong type argument in position 1 (expecting struct): #f

After this change:
    ice-9/boot-9.scm:1685:16: In procedure raise-exception:
    ERROR:
      1. &platform-not-found-error: "mips64el-linux-gnuabi64"

* guix/platform.scm (&platform-not-found-error): New condition.
(platform-not-found-error?): New predicate.
(false-if-platform-not-found): New syntax.
(lookup-platform-by-system): Raise an exception when no platform is found.
Update documentation.
(lookup-platform-by-target): Likewise.
(lookup-platform-by-target-or-system): Likewise, and guard lookup calls with
false-if-platform-not-found.
* gnu/packages/bootstrap.scm (glibc-dynamic-linker): Handle
lookup-platform-by-system call to preserve existing behavior.

Signed-off-by: Maxim Cournoyer <maxim.cournoyer@gmail.com>

0 files changed, 0 insertions, 0 deletions