gnu: Add rust-ref-cast-impl-0.2.

* gnu/packages/crates-io.scm (rust-ref-cast-impl-0.2): New variable.

Signed-off-by: Efraim Flashner <efraim@flashner.co.il>

gnu/packages/crates-io.scm

@@ -7897,6 +7897,32 @@ system calls.")
      "Safely cast &T to &U where the struct U contains a single field of type T.")
     (license (list license:asl2.0 license:expat))))
 
+(define-public rust-ref-cast-impl-0.2
+  (package
+    (name "rust-ref-cast-impl")
+    (version "0.2.6")
+    (source
+     (origin
+       (method url-fetch)
+       (uri (crate-uri "ref-cast-impl" version))
+       (file-name
+        (string-append name "-" version ".tar.gz"))
+       (sha256
+        (base32
+         "0hw0frpzna5rf5szix56zyzd0vackcb3svj94ndj629xi75dkb32"))))
+    (build-system cargo-build-system)
+    (arguments
+     `(#:skip-build? #t
+       #:cargo-inputs
+       (("rust-proc-macro2" ,rust-proc-macro2-0.4)
+        ("rust-quote" ,rust-quote-1.0)
+        ("rust-syn" ,rust-syn-0.15))))
+    (home-page "https://github.com/dtolnay/ref-cast")
+    (synopsis "Derive implementation for @code{ref_cast::RefCast}")
+    (description
+     "Derive implementation for ref_cast::RefCast.")
+    (license (list license:asl2.0 license:expat))))
+
 (define-public rust-regex-1.1
   (package
     (name "rust-regex")