[bug#63631] [PATCH] import: go: Handle subpackage versioning correctly.

[Timo Wilken <guix@twilken.net>]

Some Go source repositories (notably the Google Cloud SDK) contain multiple
submodules and use a `refs/tags/<submodule>/<version>' tagging scheme.

Fixes <https://bugs.gnu.org/54097>.

* guix/import/go.scm (vcs->origin): Accept a module-path-suffix.
(go-module->guix-package): Use the new parameter.
---
Here's a patch that fixes the reported issue (bug#54097) for me. I've only
tested this on the github.com/googleapis/google-cloud-go/compute package so
far, though it seems to work there. Perhaps others have more testcases?

I don't know enough about Go tooling to use it, so I've just patched the Guile
logic of the importer. (I don't write Go, I just want to package stuff written
in it.) In terms of performance, at least the repo contents are apparently
cached by the first `git-checkout-hash' call, even if it fails, so the second
call doesn't have to redownload them.

 guix/import/go.scm | 56 +++++++++++++++++++++++++++++++++++-----------
 1 file changed, 43 insertions(+), 13 deletions(-)

diff --git a/guix/import/go.scm b/guix/import/go.scm
index 0357e6a1eb..652ac58b6f 100644
--- a/guix/import/go.scm
+++ b/guix/import/go.scm
@@ -7,6 +7,7 @@
 ;;; Copyright © 2021 Xinglu Chen <public@yoctocell.xyz>
 ;;; Copyright © 2021 Sarah Morgensen <iskarian@mgsn.dev>
 ;;; Copyright © 2021 Simon Tournier <zimon.toutoune@gmail.com>
+;;; Copyright © 2023 Timo Wilken <guix@twilken.net>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -89,6 +90,7 @@ (define-module (guix import go)
 
 ;;; TODO list
 ;;; - get correct hash in vcs->origin for Mercurial and Subversion
+;;; - handle subdir/vX.Y versioning in vcs->origin for Mercurial and Subversion
 
 ;;; Code:
 
@@ -513,29 +515,54 @@ (define* (git-checkout-hash url reference algorithm)
                                           `(tag-or-commit . ,reference)))))
     (file-hash* checkout #:algorithm algorithm #:recursive? #true)))
 
-(define (vcs->origin vcs-type vcs-repo-url version)
+(define (vcs->origin vcs-type vcs-repo-url module-path-suffix version)
   "Generate the `origin' block of a package depending on what type of source
 control system is being used."
   (case vcs-type
     ((git)
-     (let ((plain-version? (string=? version (go-version->git-ref version)))
-           (v-prefixed?    (string-prefix? "v" version)))
+     (let ((v-prefixed? (string-prefix? "v" version))
+           (path-prefixed? #f)
+           (trimmed-path-suffix (string-trim-both module-path-suffix #\/))
+           (checkout-hash (false-if-git-not-found
+                           (git-checkout-hash
+                            vcs-repo-url
+                            (go-version->git-ref version)
+                            (hash-algorithm sha256)))))
+       ;; If `checkout-hash' is false, that must mean that a tag named after
+       ;; the version doesn't exist.  Some repos that contain submodules use a
+       ;; <submodule>/<version> tagging scheme instead, so try that.
+       (unless checkout-hash
+         (when (string=? "" trimmed-path-suffix)
+           ;; If this isn't a submodule, <submodule>/<version> tagging makes no sense.
+           ;; Tell the user we couldn't find the original version.
+           (raise
+            (formatted-message (G_ "could not find git reference '~a' in repository '~a'")
+                               (go-version->git-ref version) vcs-repo-url)))
+         (set! path-prefixed? #t)
+         (set! checkout-hash (git-checkout-hash
+                              vcs-repo-url
+                              (go-version->git-ref
+                               (string-append trimmed-path-suffix "/" version))
+                              (hash-algorithm sha256))))
        `(origin
           (method git-fetch)
           (uri (git-reference
                 (url ,vcs-repo-url)
-                ;; This is done because the version field of the package,
-                ;; which the generated quoted expression refers to, has been
-                ;; stripped of any 'v' prefixed.
-                (commit ,(if (and plain-version? v-prefixed?)
-                             '(string-append "v" version)
-                             '(go-version->git-ref version)))))
+                ;; The 'v' is prepended again because the version field of
+                ;; the package, which the generated quoted expression refers
+                ;; to, has been stripped of any 'v' prefixed.
+                (commit (go-version->git-ref
+                         ,(cond
+                           (path-prefixed?
+                            `(string-append
+                              ,trimmed-path-suffix "/"
+                              ,@(if v-prefixed? '("v" version) '(version))))
+                           (v-prefixed? '(string-append "v" version))
+                           (else 'version))))))
           (file-name (git-file-name name version))
           (sha256
            (base32
-            ,(bytevector->nix-base32-string
-              (git-checkout-hash vcs-repo-url (go-version->git-ref version)
-                                 (hash-algorithm sha256))))))))
+            ,(bytevector->nix-base32-string checkout-hash))))))
     ((hg)
      `(origin
         (method hg-fetch)
@@ -614,6 +641,9 @@ (define* (go-module->guix-package module-path #:key
           (match:prefix (string-match "([\\./]v[0-9]+)?$" module-path)))
          (guix-name (go-module->guix-package-name module-path))
          (root-module-path (module-path->repository-root module-path))
+         (module-path-suffix  ; subdirectory inside the source repo
+          (substring module-path-sans-suffix
+                     (string-prefix-length root-module-path module-path-sans-suffix)))
          ;; The VCS type and URL are not included in goproxy information. For
          ;; this we need to fetch it from the official module page.
          (meta-data (fetch-module-meta-data root-module-path))
@@ -627,7 +657,7 @@ (define* (go-module->guix-package module-path #:key
         (name ,guix-name)
         (version ,(strip-v-prefix version*))
         (source
-         ,(vcs->origin vcs-type vcs-repo-url version*))
+         ,(vcs->origin vcs-type vcs-repo-url module-path-suffix version*))
         (build-system go-build-system)
         (arguments
          '(#:import-path ,module-path

base-commit: e499cb2c12d7f1c6d2f004364c9cc7bdb7e38cd5
-- 
2.40.1