bug#26166: [PATCH] gnu: cargo: Simplify unpacking.

[Danny Milosavljevic]

* gnu/packages/rust.scm (cargo): Simplify unpacking.
---
 gnu/packages/rust.scm | 60 +++++++++++++++++++++++++++++++++------------------
 1 file changed, 39 insertions(+), 21 deletions(-)

diff --git a/gnu/packages/rust.scm b/gnu/packages/rust.scm
index 2dedef837..9a6f25c82 100644
--- a/gnu/packages/rust.scm
+++ b/gnu/packages/rust.scm
@@ -285,6 +285,8 @@ safety and thread safety guarantees.")
     ;; Dual licensed.
     (license (list license:asl2.0 license:expat))))
 
+;; This tries very hard not to get into a cyclic dependency like this:
+;;   cargo <- cargo-build-system <- cargo.
 (define-public cargo
   (package
     (name "cargo")
@@ -788,6 +790,11 @@ safety and thread safety guarantees.")
     (arguments
      `(#:cargo ,cargo-bootstrap
        #:tests? #f ; FIXME
+       #:modules
+       ((ice-9 match)
+        (srfi srfi-1) ; 'every
+        (guix build utils)
+        (guix build cargo-build-system))
        #:phases
        (modify-phases %standard-phases
          ;; Avoid cargo complaining about missmatched checksums.
@@ -796,30 +803,40 @@ safety and thread safety guarantees.")
          (delete 'patch-usr-bin-file)
          (add-after 'unpack 'unpack-submodule-sources
            (lambda* (#:key inputs #:allow-other-keys)
-             (let ((unpack (lambda (source target)
-                             (mkdir-p target)
-                             (with-directory-excursion target
-                               (zero? (system* "tar" "xf"
-                                               source
-                                               "--strip-components=1"))))))
+             (let* ((unpack
+                      (lambda (source target)
+                        (mkdir-p target)
+                        (with-directory-excursion target
+                          (zero? (system* "tar" "xf"
+                                          source
+                                          "--strip-components=1")))))
+                    (touch
+                      (lambda (file-name)
+                        (call-with-output-file file-name (const #t))))
+                    (install-rust-library
+                      (lambda (entry)
+                        (match entry
+                          ((name . src)
+                           (if (string-prefix? "rust-" name)
+                             (let* ((rust-length (string-length "rust-"))
+                                    (rust-name (string-drop name
+                                                            rust-length))
+                                    (rsrc (string-append "vendor/"
+                                                         rust-name))
+                                    (unpack-status (unpack src rsrc)))
+                               (touch (string-append rsrc "/.cargo-ok"))
+                               (generate-checksums rsrc src)
+                               unpack-status)))
+                           (_ #t)))))
                (mkdir "vendor")
-               (for-each (lambda (p)
-                           (let ((name (car p)))
-                             (if (string-prefix? "rust-" name)
-                               (let ((rsrc (string-append "vendor/"
-                                                           (string-drop name
-                                                                        
(string-length "rust-")))))
-                                 (unpack (assoc-ref inputs name) rsrc)
-                                 (system* "touch" (string-append rsrc 
"/.cargo-ok"))
-                                 (generate-checksums rsrc (assoc-ref inputs 
name)))))) inputs))))
-         ;; Set CARGO_HOME to use the vendored dependencies.
-         (add-after 'unpack 'set-cargo-home
+               (every install-rust-library inputs))))
+         (add-after 'unpack 'set-environment-up
            (lambda* (#:key inputs #:allow-other-keys)
              (let* ((gcc (assoc-ref inputs "gcc"))
                     (cc (string-append gcc "/bin/gcc")))
-               (mkdir "cargohome")
-               (setenv "CARGO_HOME" (string-append (getcwd) "/cargohome"))
-               (call-with-output-file "cargohome/config"
+               (mkdir ".cargo")
+               ;(setenv "CARGO_HOME" (string-append (getcwd) "/cargohome"))
+               (call-with-output-file ".cargo/config"
                  (lambda (p)
                    (format p "
 [source.crates-io]
@@ -831,7 +848,8 @@ directory = 'vendor'
 ")))
                (setenv "CMAKE_C_COMPILER" cc)
                (setenv "CC" cc))
-             #t)))))
+             #t))
+         (delete 'configure))))
     (home-page "https://github.com/rust-lang/cargo";)
     (synopsis "Build tool and package manager for Rust")
     (description "Cargo is a tool that allows Rust projects to declare their