allow to pin packages to specific archive

core/core-configuration-layer.el

@@ -186,7 +186,8 @@ LAYER has to be installed for this method to work properly."
 (defvar configuration-layer--elpa-archives
   '(("melpa" . "melpa.org/packages/")
     ("org"   . "orgmode.org/elpa/")
-    ("gnu"   . "elpa.gnu.org/packages/"))
+    ("gnu"   . "elpa.gnu.org/packages/")
+    ("melpa-stable" . "stable.melpa.org/packages/"))
   "List of ELPA archives required by Spacemacs.")
 
 (defvar configuration-layer-no-layer nil
@@ -486,13 +487,16 @@ If TOGGLEP is nil then `:toggle' parameter is ignored."
   (let* ((name-sym (if (listp pkg) (car pkg) pkg))
          (name-str (symbol-name name-sym))
          (location (when (listp pkg) (plist-get (cdr pkg) :location)))
+         (archive (when (listp pkg) (plist-get (cdr pkg) :archive)))
          (min-version (when (listp pkg) (plist-get (cdr pkg) :min-version)))
          (step (when (listp pkg) (plist-get (cdr pkg) :step)))
          (excluded (when (listp pkg) (plist-get (cdr pkg) :excluded)))
          (toggle (when (and togglep (listp pkg)) (plist-get (cdr pkg) :toggle)))
          (protected (when (listp pkg) (plist-get (cdr pkg) :protected)))
          (copyp (not (null obj)))
          (obj (if obj obj (cfgl-package name-str :name name-sym))))
+    (when archive
+      (configuration-layer/pin-package name-sym archive))
     (when location (oset obj :location location))
     (when min-version (oset obj :min-version (version-to-list min-version)))
     (when step (oset obj :step step))
@@ -1866,7 +1870,18 @@ FILE-TO-LOAD is an explicit file to load after the installation."
             (1+ configuration-layer-error-count))
     (setq configuration-layer-error-count 1)))
 
+(defun configuration-layer/pin-package (package archive)
+  "Pin PACKAGE to ARCHIVE.
+
+When PACKAGE is pinned to specific ARCHIVE, it is installed
+exactly from that ARCHIVE.
+
+ARCHIVE must be one of the following symbols: melpa, org, gnu,
+melpa-stable."
+  (unless (memq archive '(melpa org gnu melpa-stable))
+    (error "Archive '%s' is not supported." archive))
+  (push `(,package . ,(symbol-name archive)) package-pinned-packages))
+
 (provide 'core-configuration-layer)
 
 ;;; core-configuration-layer.el ends here
-