* lisp/gnus/gnus-art.el: Fix misuse of standard-value.

* lisp/custom.el (custom--standard-value): New function.

* lisp/gnus/gnus-art.el: (gnus-article-browse-html-parts)
(gnus-article-browse-html-article):
* lisp/dired-aux.el (dired-do-find-regexp-and-replace):
* lisp/emacs-lisp/package-x.el (package-upload-buffer-internal):
* lisp/startup.el (command-line): Use it.

lisp/custom.el

@@ -350,7 +350,7 @@ for more information."
   ;; if you need to recompile all the Lisp files using interpreted code.
   `(custom-declare-variable
     ',symbol
-    ,(if lexical-binding    ;FIXME: This is not reliable, but is all we have.
+    ,(if lexical-binding
          ;; The STANDARD arg should be an expression that evaluates to
          ;; the standard value.  The use of `eval' for it is spread
          ;; over many different places and hence difficult to
@@ -627,6 +627,10 @@ property, or (ii) an alias for another customizable variable."
     (or (get variable 'standard-value)
 	(get variable 'custom-autoload))))
 
+(defun custom--standard-value (variable)
+  "Return the standard value of VARIABLE."
+  (eval (car (get variable 'standard-value)) t))
+
 (define-obsolete-function-alias 'user-variable-p 'custom-variable-p "24.3")
 
 (defun custom-note-var-changed (variable)

lisp/dired-aux.el

@@ -3148,7 +3148,7 @@ REGEXP should use constructs supported by your local `grep' command."
   (with-current-buffer
       (let ((xref-show-xrefs-function
              ;; Some future-proofing (bug#44905).
-             (eval (car (get 'xref-show-xrefs-function 'standard-value)))))
+             (custom--standard-value 'xref-show-xrefs-function)))
         (dired-do-find-regexp from))
     (xref-query-replace-in-results from to)))
 

lisp/emacs-lisp/package-x.el

@@ -182,8 +182,7 @@ if it exists."
     ;; Check if `package-archive-upload-base' is valid.
     (when (or (not (stringp package-archive-upload-base))
 	      (equal package-archive-upload-base
-		     (car-safe
-		      (get 'package-archive-upload-base 'standard-value))))
+		     (custom--standard-value 'package-archive-upload-base)))
       (setq package-archive-upload-base
 	    (read-directory-name
 	     "Base directory for package archive: ")))

lisp/gnus/gnus-art.el

@@ -3010,8 +3010,7 @@ message header will be added to the bodies of the \"text/html\" parts."
 	       (when header
 		 (article-decode-encoded-words)
 		 (let ((gnus-visible-headers
-			(or (get 'gnus-visible-headers 'standard-value)
-			    gnus-visible-headers)))
+			(custom--standard-value 'gnus-visible-headers)))
 		   (article-hide-headers))
 		 (goto-char (point-min))
 		 (search-forward "\n\n" nil 'move)
@@ -3045,8 +3044,8 @@ images if any to the browser, and deletes them when exiting the group
   (interactive "P")
   (if arg
       (gnus-summary-show-article)
-    (let ((gnus-visible-headers (or (get 'gnus-visible-headers 'standard-value)
-				    gnus-visible-headers))
+    (let ((gnus-visible-headers
+	   (custom--standard-value 'gnus-visible-headers))
 	  (gnus-mime-display-attachment-buttons-in-header nil)
 	  ;; As we insert a <hr>, there's no need for the body boundary.
 	  (gnus-treat-body-boundary nil))

lisp/startup.el

@@ -1386,7 +1386,7 @@ please check its value")
 	 (equal user-mail-address
 		(let (mail-host-address)
 		  (ignore-errors
-		    (eval (car (get 'user-mail-address 'standard-value))))))
+		    (custom--standard-value 'user-mail-address))))
 	 (custom-reevaluate-setting 'user-mail-address))
 
     ;; If parameter have been changed in the init file which influence