gnu: Add rust-block2-0.2.

* gnu/packages/crates-io.scm (rust-block2-0.2): New variable.

gnu/packages/crates-io.scm

@@ -7857,6 +7857,28 @@ storage.")
 extension of blocks.")
     (license license:expat)))
 
+(define-public rust-block2-0.2
+  (package
+    (name "rust-block2")
+    (version "0.2.0-alpha.6")
+    (source (origin
+              (method url-fetch)
+              (uri (crate-uri "block2" version))
+              (file-name (string-append name "-" version ".tar.gz"))
+              (sha256
+               (base32
+                "0hpcdl81rmwvhfni9413hrg1wd4xwf6vhch3yv15bxs42wyfdncd"))))
+    (build-system cargo-build-system)
+    (arguments
+     `(#:tests? #f  ; Tests require gcc-objc.
+       #:cargo-inputs
+       (("rust-block-sys" ,rust-block-sys-0.1)
+        ("rust-objc2-encode" ,rust-objc2-encode-2))))
+    (home-page "https://github.com/madsmtm/objc2")
+    (synopsis "Apple's C language extension of blocks")
+    (description "This package contains Apple's C language extension of blocks.")
+    (license license:expat)))
+
 (define-public rust-block-buffer-0.10
   (package
     (name "rust-block-buffer")