build-system/go: Build with a filesystem union of Go dependencies.

This basically changes (guix build-system go) so that instead of looking
up its dependencies in a list of directories in $GOPATH, all the
Go dependencies are symlinked into a single directory.

Fixes <https://bugs.gnu.org/33620>.

* guix/build/go-build-system.scm (setup-go-environment): New variable.
(setup-environment, install-source): Remove variables.
(unpack): Unpack the source relative to $GOPATH.
(install): Do not install the compiled objects in the 'pkg' directory.
Install the source code in this phase, and only install the source of
the package named by IMPORT-PATH.
* doc/guix.texi (Build Systems): Adjust accordingly.
* gnu/packages/docker.scm (docker): Import (guix build union) on the build side
and adjust to build phase name changes in (guix build-system go).
* gnu/packages/shellutils.scm (direnv): Likewise.
* gnu/packages/databases.scm (mongo-tools)[arguments]:
Set '#:install-source #f'.
* gnu/packages/music.scm (demlo)[arguments]: Move the 'install-scripts'
phase after the 'install' phase.

4 files changed, 10 insertions, 7 deletions

diff --git a/gnu/packages/databases.scm b/gnu/packages/databases.scm
index be02b79efa..921304ef2a 100644
--- a/gnu/packages/databases.scm
+++ b/gnu/packages/databases.scm
@@ -2610,6 +2610,7 @@ transforms idiomatic python function calls to well-formed SQL queries.")
        #:modules ((srfi srfi-1)
                   (guix build go-build-system)
                   (guix build utils))
+       #:install-source? #f
        #:phases
        (let ((all-tools
               '("bsondump" "mongodump" "mongoexport" "mongofiles"
@@ -2629,8 +2630,6 @@ transforms idiomatic python function calls to well-formed SQL queries.")
                  (("skipping restore of system.profile collection\", db)")
                   "skipping restore of system.profile collection\")"))
                #t))
-           ;; We don't need to install the source code for end-user applications
-           (delete 'install-source)
            (replace 'build
              (lambda _
                (for-each (lambda (tool)
diff --git a/gnu/packages/docker.scm b/gnu/packages/docker.scm
index 7cb8f96258..4b6d04fe91 100644
--- a/gnu/packages/docker.scm
+++ b/gnu/packages/docker.scm
@@ -249,9 +249,11 @@ network attachments.")
      `(#:modules
        ((guix build gnu-build-system)
         ((guix build go-build-system) #:prefix go:)
+        (guix build union)
         (guix build utils))
        #:imported-modules
        (,@%gnu-build-system-modules
+        (guix build union)
         (guix build go-build-system))
        #:phases
        (modify-phases %standard-phases
@@ -412,8 +414,8 @@ network attachments.")
              ;; Make build faster
              (setenv "GOCACHE" "/tmp")
              #t))
-         (add-before 'build 'setup-environment
-           (assoc-ref go:%standard-phases 'setup-environment))
+         (add-before 'build 'setup-go-environment
+           (assoc-ref go:%standard-phases 'setup-go-environment))
          (replace 'build
            (lambda _
              ;; Our LD doesn't like the statically linked relocatable things
diff --git a/gnu/packages/music.scm b/gnu/packages/music.scm
index 05fdc1428f..54c7798472 100644
--- a/gnu/packages/music.scm
+++ b/gnu/packages/music.scm
@@ -4361,7 +4361,7 @@ console music players.")
                                             dir "/sbin"))
                            (list ffmpeg chromaprint))))
                  #t)))
-           (add-after 'install-source 'install-scripts
+           (add-after 'install 'install-scripts
              (lambda* (#:key outputs #:allow-other-keys)
                (let* ((out (assoc-ref outputs "out"))
                       (root (string-append out "/src/gitlab.com/ambrevar/demlo"))
diff --git a/gnu/packages/shellutils.scm b/gnu/packages/shellutils.scm
index a672aa041a..88c0f32e99 100644
--- a/gnu/packages/shellutils.scm
+++ b/gnu/packages/shellutils.scm
@@ -118,15 +118,17 @@ are already there.")
        #:make-flags (list (string-append "DESTDIR=" (assoc-ref %outputs "out")))
        #:modules ((guix build gnu-build-system)
                   ((guix build go-build-system) #:prefix go:)
+                  (guix build union)
                   (guix build utils))
        #:imported-modules (,@%gnu-build-system-modules
+                            (guix build union)
                             (guix build go-build-system))
        #:phases
        (modify-phases %standard-phases
          (delete 'configure)
          ;; Help the build scripts find the Go language dependencies.
-         (add-after 'unpack 'setup-go-environment
-           (assoc-ref go:%standard-phases 'setup-environment)))))
+         (add-before 'unpack 'setup-go-environment
+           (assoc-ref go:%standard-phases 'setup-go-environment)))))
     (inputs
      `(("go" ,go)
        ("go-github-com-burntsushi-toml" ,go-github-com-burntsushi-toml)