core: add package keyword :protected

A protected package cannot be uninstalled nor excluded.

core/core-configuration-layer.el

@@ -124,6 +124,11 @@
          :initform nil
          :type (satisfies (lambda (x) (member x '(nil pre))))
          :documentation "Initialization step.")
+   (protected :initarg :protected
+              :initform nil
+              :type boolean
+              :documentation
+              "If non-nil then this package cannot be excluded.")
    (excluded :initarg :excluded
              :initform nil
              :type boolean
@@ -247,10 +252,17 @@ Properties that can be copied are `:location', `:step' and `:excluded'."
          (location (when (listp pkg) (plist-get (cdr pkg) :location)))
          (step (when (listp pkg) (plist-get (cdr pkg) :step)))
          (excluded (when (listp pkg) (plist-get (cdr pkg) :excluded)))
+         (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 location (oset obj :location location))
     (when step (oset obj :step step))
     (oset obj :excluded excluded)
+    ;; cannot override protected packages
+    (unless copyp
+      (oset obj :protected protected)
+      (when protected
+        (push name-sym configuration-layer--protected-packages)))
     obj))
 
 (defun configuration-layer/get-packages (layers &optional dotfile)
@@ -756,7 +768,8 @@ path."
     (spacemacs-buffer/loading-animation)
     (let ((pkg-name (oref pkg :name)))
       (cond
-       ((oref pkg :excluded)
+       ((and (oref pkg :excluded)
+             (not (oref pkg :protected)))
         (spacemacs-buffer/message
          (format "%S ignored since it has been excluded." pkg-name)))
        ((null (oref pkg :owner))

layers/+distribution/spacemacs-base/packages.el

@@ -23,7 +23,7 @@
         evil-leader
         evil-surround
         evil-visualstar
-        (evil-evilified-state :location local :step pre)
+        (evil-evilified-state :location local :step pre :protected t)
         exec-path-from-shell
         fill-column-indicator
         helm

tests/core/core-configuration-layer-utest.el

@@ -609,6 +609,22 @@
       (spacemacs-buffer/loading-animation nil ((:output nil))))
      (configuration-layer//configure-packages-2 `(,pkg)))))
 
+(ert-deftest test-configure-packages-2--protected-package-is-configured()
+  (let ((pkg (cfgl-package "pkg" :name 'pkg :owner 'layer1 :protected t))
+        (mocker-mock-default-record-cls 'mocker-stub-record))
+    (mocker-let
+     ((configuration-layer//configure-package (p) ((:occur 1)))
+      (spacemacs-buffer/loading-animation nil ((:output nil))))
+     (configuration-layer//configure-packages-2 `(,pkg)))))
+
+(ert-deftest test-configure-packages-2--protected-excluded-package-is-configured()
+  (let ((pkg (cfgl-package "pkg" :name 'pkg :owner 'layer1 :excluded t :protected t))
+        (mocker-mock-default-record-cls 'mocker-stub-record))
+    (mocker-let
+     ((configuration-layer//configure-package (p) ((:occur 1)))
+      (spacemacs-buffer/loading-animation nil ((:output nil))))
+     (configuration-layer//configure-packages-2 `(,pkg)))))
+
 (ert-deftest test-configure-packages-2--excluded-package-is-not-configured()
   (let ((pkg (cfgl-package "pkg" :name 'pkg :owner 'layer1 :excluded t))
         (mocker-mock-default-record-cls 'mocker-stub-record))