* lisp/custom.el: Avoid adding vars to load-history multiple times

Avoid the abuse of (eval `(defvar ...)) which tends to end up
adding redundant entries in `load-history`, as discussed in
https://lists.gnu.org/r/help-gnu-emacs/2019-03/msg00237.html

(custom-initialize-default): Don't add to load-history.
(custom-declare-variable): Use internal--define-uninitialized-variable
and only add the var to load-history once.  Do it before calling
`initialize` so the special-variable-p flag is set.

* src/eval.c (Finternal__define_uninitialized_variable): New function.
(Fdefvar, Fdefconst): Use it.
(syms_of_eval): Defsubr' it.

1 files changed, 11 insertions, 10 deletions

diff --git a/lisp/custom.el b/lisp/custom.el
index 53b8045f058..29bf9e570a8 100644
--- a/lisp/custom.el
+++ b/lisp/custom.el
@@ -56,8 +56,14 @@ Otherwise, if symbol has a `saved-value' property, it will evaluate
 the car of that and use it as the default binding for symbol.
 Otherwise, EXP will be evaluated and used as the default binding for
 symbol."
-  (eval `(defvar ,symbol ,(let ((sv (get symbol 'saved-value)))
-                            (if sv (car sv) exp)))))
+  (condition-case nil
+      (default-toplevel-value symbol)   ;Test presence of default value.
+    (void-variable
+     ;; The var is not initialized yet.
+     (set-default-toplevel-value
+      symbol (eval (let ((sv (get symbol 'saved-value)))
+                     (if sv (car sv) exp))
+                   t)))))
 
 (defun custom-initialize-set (symbol exp)
   "Initialize SYMBOL based on EXP.
@@ -188,18 +194,13 @@ set to nil, as the value is no longer rogue."
 		(t
 		 (custom-handle-keyword symbol keyword value
 					'custom-variable))))))
+    ;; Set the docstring, record the var on load-history, as well
+    ;; as set the special-variable-p flag.
+    (internal--define-uninitialized-variable symbol doc)
     (put symbol 'custom-requests requests)
     ;; Do the actual initialization.
     (unless custom-dont-initialize
       (funcall initialize symbol default)))
-  ;; Use defvar to set the docstring as well as the special-variable-p flag.
-  ;; FIXME: We should reproduce more of `defvar's behavior, such as the warning
-  ;; when the var is currently let-bound.
-  (if (not (default-boundp symbol))
-      ;; Don't use defvar to avoid setting a default-value when undesired.
-      (when doc (put symbol 'variable-documentation doc))
-    (eval `(defvar ,symbol nil ,@(when doc (list doc)))))
-  (push symbol current-load-list)
   (run-hooks 'custom-define-hook)
   symbol)