emacs-build-system: Byte compile the autoload files.

* guix/build/emacs-build-system.scm (enable-autoloads-compilation)
(validate-compiled-autoloads): Add procedures.
(%standard-phases): Register the new procedures.
* gnu/packages/aux-files/emacs/guix-emacs.el (guix-emacs-find-autoloads):
Remove duplicates in the list of autoload files found.
* guix/build/emacs-utils.scm (expr->string): Add procedure.
(emacs-batch-eval, emacs-batch-edit-file): Use it.

gnu/packages/aux-files/emacs/guix-emacs.el

@@ -35,8 +35,9 @@
   "Return a list of Emacs 'autoloads' files in DIRECTORY.
 The files in the list do not have extensions (.el, .elc)."
   ;; `directory-files' doesn't honor group in regexp.
-  (mapcar #'file-name-sans-extension
+  (delete-dups (mapcar #'file-name-sans-extension
-          (directory-files directory 'full-name guix-emacs-autoloads-regexp)))
+                       (directory-files directory 'full-name
+                                        guix-emacs-autoloads-regexp))))
 
 ;;;###autoload
 (defun guix-emacs-autoload-packages ()

guix/build/emacs-build-system.scm

@@ -225,6 +225,21 @@ parallel. PARALLEL-TESTS? is ignored when using a non-make TEST-COMMAND."
     (parameterize ((%emacs emacs))
       (emacs-generate-autoloads elpa-name site-lisp))))
 
+(define* (enable-autoloads-compilation #:key outputs #:allow-other-keys)
+  "Remove the NO-BYTE-COMPILATION local variable embedded in the generated
+autoload files."
+  (let* ((out (assoc-ref outputs "out"))
+         (autoloads (find-files out "-autoloads.el$")))
+    (substitute* autoloads
+      ((";; no-byte-compile.*") ""))
+    #t))
+
+(define* (validate-compiled-autoloads #:key outputs #:allow-other-keys)
+  "Verify whether the byte compiled autoloads load fine."
+  (let* ((out (assoc-ref outputs "out"))
+         (autoloads (find-files out "-autoloads.elc$")))
+    (emacs-batch-eval (format #f "(mapc #'load '~s)" autoloads))))
+
 (define (emacs-package? name)
   "Check if NAME correspond to the name of an Emacs package."
   (string-prefix? "emacs-" name))
@@ -253,10 +268,13 @@ second hyphen.  This corresponds to 'name-version' as used in ELPA packages."
     (replace 'check check)
     (replace 'install install)
     (add-after 'install 'make-autoloads make-autoloads)
-    (add-after 'make-autoloads 'patch-el-files patch-el-files)
+    (add-after 'make-autoloads 'enable-autoloads-compilation
+      enable-autoloads-compilation)
+    (add-after 'enable-autoloads-compilation 'patch-el-files patch-el-files)
     ;; The .el files are byte compiled directly in the store.
     (add-after 'patch-el-files 'build build)
-    (add-after 'build 'move-doc move-doc)))
+    (add-after 'build 'validate-compiled-autoloads validate-compiled-autoloads)
+    (add-after 'validate-compiled-autoloads 'move-doc move-doc)))
 
 (define* (emacs-build #:key inputs (phases %standard-phases)
                       #:allow-other-keys #:rest args)

guix/build/emacs-utils.scm

@@ -41,16 +41,22 @@
   ;; The `emacs' command.
   (make-parameter "emacs"))
 
+(define (expr->string expr)
+  "Converts EXPR, an expression, into a string."
+  (if (string? expr)
+      expr
+      (format #f "~s" expr)))
+
 (define (emacs-batch-eval expr)
   "Run Emacs in batch mode, and execute the elisp code EXPR."
   (invoke (%emacs) "--quick" "--batch"
-          (format #f "--eval=~S" expr)))
+          (string-append "--eval=" (expr->string expr))))
 
 (define (emacs-batch-edit-file file expr)
   "Load FILE in Emacs using batch mode, and execute the elisp code EXPR."
   (invoke (%emacs) "--quick" "--batch"
           (string-append "--visit=" file)
-          (format #f "--eval=~S" expr)))
+          (string-append "--eval=" (expr->string expr))))
 
 (define (emacs-batch-disable-compilation file)
   (emacs-batch-edit-file file