gnu: Add rust-cexpr-0.2.

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

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

gnu/packages/crates-io.scm

@@ -1789,6 +1789,37 @@ archive to be linked into Rustcode.")
      "This package provides a C expression parser and evaluator.")
     (license (list license:asl2.0 license:expat))))
 
+(define-public rust-cexpr-0.2
+  (package
+    (inherit rust-cexpr-0.3)
+    (name "rust-cexpr")
+    (version "0.2.3")
+    (source
+     (origin
+       (method url-fetch)
+       (uri (crate-uri "cexpr" version))
+       (file-name
+        (string-append name "-" version ".tar.gz"))
+       (sha256
+        (base32
+         "0v1xa3758czmj8h97gh548mr8g0v13ixxvrlm1s79nb7jmgc9aj2"))))
+    (build-system cargo-build-system)
+    (arguments
+     `(#:cargo-inputs
+       (("rust-nom" ,rust-nom-3))
+       #:cargo-development-inputs
+       (("rust-clang-sys" ,rust-clang-sys-0.11))
+       #:phases
+       (modify-phases %standard-phases
+         (add-after 'unpack 'set-environmental-variable
+           (lambda* (#:key inputs #:allow-other-keys)
+             (let ((clang (assoc-ref inputs "libclang")))
+               (setenv "LIBCLANG_PATH"
+                       (string-append clang "/lib")))
+             #t)))))
+    (inputs
+     `(("libclang" ,clang)))))
+
 (define-public rust-chrono-0.4
   (package
     (name "rust-chrono")