[bug#70985] [PATCH v3 5/6] gnu: rust: Guard against unsupported rust targets.

[Christopher Baines <mail@cbaines.net>]

As cross-libc may return #f in this case, and the config.toml file
construction will also fail if the platform rust-target is #f..

* gnu/packages/rust.scm (make-rust-sysroot/implementation): Guard against
unsupported rust targets.

Change-Id: Ia0d5c889c6f5cd3478ad985c79feb9ba1c472c29
---
 gnu/packages/rust.scm | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/gnu/packages/rust.scm b/gnu/packages/rust.scm
index a385344473..8119f4560a 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.
@@ -1309,6 +1311,13 @@ (define*-public (make-rust-sysroot target)
 
 (define make-rust-sysroot/implementation
   (mlambda (target base-rust)
+    (unless (platform-rust-target (lookup-platform-by-target target))
+      (raise
+       (condition
+        (&package-unsupported-target-error
+         (package base-rust)
+         (target target)))))
+
     (package
       (inherit base-rust)
       (name (string-append "rust-sysroot-for-" target))
-- 
2.45.2