import: hackage: Handle Hackage revisions.

Hackage packages can have metadata revisions (Cabal file only) that are
not reflected in the source archive.  The Haskell build system has
support for this, but until now the Hackage importer would create a
package based on the revised Cabal file which would then build using the
old Cabal file.

Fixes <https://bugs.gnu.org/35750>.

* guix/import/cabal.scm (<cabal-package>): Add 'revision' field.
(eval-cabal): Parse 'x-revision:' property.
* guix/import/hackage.scm (read-cabal-and-hash): New procedure.
(hackage-fetch-and-hash): New procedure.
(hackage-fetch): Rewrite using 'hackage-fetch-and-hash'.
(hackage-module->sexp): Add 'cabal-hash' argument and use it to populate
the '#:cabal-revision' argument.
(hackage->guix-package): Use the new '-and-hash' functions to get the
hash of the Cabal file and pass it to 'hackage-module->sexp'.
* guix/tests/hackage.scm: Test import of Cabal file revision.

Signed-off-by: Timothy Sample <samplet@ngyro.com>

2 files changed, 49 insertions, 20 deletions

diff --git a/guix/import/cabal.scm b/guix/import/cabal.scm
index 1a87be0b00..7dfe771e41 100644
--- a/guix/import/cabal.scm
+++ b/guix/import/cabal.scm
@@ -40,6 +40,7 @@
             cabal-package?
             cabal-package-name
             cabal-package-version
+            cabal-package-revision
             cabal-package-license
             cabal-package-home-page
             cabal-package-source-repository
@@ -638,13 +639,14 @@ If #f use the function 'port-filename' to obtain it."
 ;; information of the Cabal file, but only the ones we currently are
 ;; interested in.
 (define-record-type <cabal-package>
-  (make-cabal-package name version license home-page source-repository
+  (make-cabal-package name version revision license home-page source-repository
                       synopsis description
                       executables lib test-suites
                       flags eval-environment custom-setup)
   cabal-package?
   (name   cabal-package-name)
   (version cabal-package-version)
+  (revision cabal-package-revision)
   (license cabal-package-license)
   (home-page cabal-package-home-page)
   (source-repository cabal-package-source-repository)
@@ -838,6 +840,7 @@ See the manual for limitations.")))))))
   (define (cabal-evaluated-sexp->package evaluated-sexp)
     (let* ((name (lookup-join evaluated-sexp "name"))
            (version (lookup-join evaluated-sexp "version"))
+           (revision (lookup-join evaluated-sexp "x-revision"))
            (license (lookup-join evaluated-sexp "license"))
            (home-page (lookup-join evaluated-sexp "homepage"))
            (home-page-or-hackage
@@ -856,7 +859,7 @@ See the manual for limitations.")))))))
            (custom-setup (match (make-cabal-section evaluated-sexp 'custom-setup)
                            ((x) x)
                            (_ #f))))
-      (make-cabal-package name version license home-page-or-hackage
+      (make-cabal-package name version revision license home-page-or-hackage
                           source-repository synopsis description executables lib
                           test-suites flags eval-environment custom-setup)))
 
diff --git a/guix/import/hackage.scm b/guix/import/hackage.scm
index 366256b40d..6f426af900 100644
--- a/guix/import/hackage.scm
+++ b/guix/import/hackage.scm
@@ -117,19 +117,34 @@ version is returned."
           (#f name)
           (m (match:substring m 1)))))))
 
+(define (read-cabal-and-hash port)
+  "Read a Cabal file from PORT and return it and its hash in nix-base32
+format as two values."
+  (let-values (((port get-hash) (open-sha256-input-port port)))
+    (values (read-cabal (canonical-newline-port port))
+            (bytevector->nix-base32-string (get-hash)))))
+
+(define (hackage-fetch-and-hash name-version)
+  "Fetch the latest Cabal revision for the package NAME-VERSION, and return
+two values: the parsed Cabal file and its hash in nix-base32 format.  If the
+version part is omitted from the package name, then fetch the latest
+version.  On failure, both return values will be #f."
+  (guard (c ((and (http-get-error? c)
+                  (= 404 (http-get-error-code c)))
+             (values #f #f)))           ;"expected" if package is unknown
+    (let*-values (((name version) (package-name->name+version name-version))
+                  ((url)          (hackage-cabal-url name version))
+                  ((port _)       (http-fetch url))
+                  ((cabal hash)   (read-cabal-and-hash port)))
+      (close-port port)
+      (values cabal hash))))
+
 (define (hackage-fetch name-version)
   "Return the Cabal file for the package NAME-VERSION, or #f on failure.  If
 the version part is omitted from the package name, then return the latest
 version."
-  (guard (c ((and (http-get-error? c)
-                  (= 404 (http-get-error-code c)))
-             #f))                       ;"expected" if package is unknown
-    (let-values (((name version) (package-name->name+version name-version)))
-      (let* ((url (hackage-cabal-url name version))
-             (port (http-fetch url))
-             (result (read-cabal (canonical-newline-port port))))
-        (close-port port)
-        result))))
+  (let-values (((cabal hash) (hackage-fetch-and-hash name-version)))
+    cabal))
 
 (define string->license
   ;; List of valid values from
@@ -198,15 +213,20 @@ package being processed and is used to filter references to itself."
                                    (cons own-name ghc-standard-libraries))))
           dependencies))
 
-(define* (hackage-module->sexp cabal #:key (include-test-dependencies? #t))
+(define* (hackage-module->sexp cabal cabal-hash
+                               #:key (include-test-dependencies? #t))
   "Return the `package' S-expression for a Cabal package.  CABAL is the
-representation of a Cabal file as produced by 'read-cabal'."
+representation of a Cabal file as produced by 'read-cabal'.  CABAL-HASH is
+the hash of the Cabal file."
 
   (define name
     (cabal-package-name cabal))
 
   (define version
     (cabal-package-version cabal))
+
+  (define revision
+    (cabal-package-revision cabal))
   
   (define source-url
     (hackage-source-url name version))
@@ -252,9 +272,14 @@ representation of a Cabal file as produced by 'read-cabal'."
                    (list 'quasiquote inputs))))))
   
   (define (maybe-arguments)
-    (if (not include-test-dependencies?)
-        '((arguments `(#:tests? #f)))
-        '()))
+    (match (append (if (not include-test-dependencies?)
+                       '(#:tests? #f)
+                       '())
+                   (if (not (string-null? revision))
+                       `(#:cabal-revision (,revision ,cabal-hash))
+                       '()))
+      (() '())
+      (args `((arguments (,'quasiquote ,args))))))
 
   (let ((tarball (with-store store
                    (download-to-store store source-url))))
@@ -294,10 +319,11 @@ symbol 'true' or 'false'.  The value associated with other keys has to conform
 to the Cabal file format definition.  The default value associated with the
 keys \"os\", \"arch\" and \"impl\" is \"linux\", \"x86_64\" and \"ghc\"
 respectively."
-  (let ((cabal-meta (if port
-                        (read-cabal (canonical-newline-port port))
-                        (hackage-fetch package-name))))
-    (and=> cabal-meta (compose (cut hackage-module->sexp <>
+  (let-values (((cabal-meta cabal-hash)
+                (if port
+                    (read-cabal-and-hash port)
+                    (hackage-fetch-and-hash package-name))))
+    (and=> cabal-meta (compose (cut hackage-module->sexp <> cabal-hash
                                     #:include-test-dependencies?
                                     include-test-dependencies?)
                                (cut eval-cabal <> cabal-environment)))))