Add online-help support to describe types

* lisp/help-fns.el (describe-symbol-backends): Move to help-mode.el.
(describe-symbol): Improve the selection of default.

* lisp/help-mode.el: Require cl-lib.
(describe-symbol-backends): Move from help-fns.el.
(help-make-xrefs): Use it.

* lisp/emacs-lisp/cl-extra.el (describe-symbol-backends): Add entry
for types.
(cl--typedef-regexp): New const.
(find-function-regexp-alist): Add entry for types.
(cl-help-type, cl-type-definition): New buttons.
(cl-find-class): New function.
(cl-describe-type): New command.
(cl--describe-class, cl--describe-class-slot)
(cl--describe-class-slots): New functions, moved from eieio-opt.el.

* lisp/emacs-lisp/cl-generic.el (cl--generic-method-documentation)
(cl--generic-all-functions, cl--generic-specializers-apply-to-type-p):
New functions.  Moved from eieio-opt.el.
(cl--generic-class-parents): New function, extracted from
cl--generic-struct-specializers.
(cl--generic-struct-specializers): Use it.

* lisp/emacs-lisp/cl-macs.el (cl-defstruct): Use pcase-dolist.
Improve constructor's docstrings.
(cl-struct-unknown-slot): New error.
(cl-struct-slot-offset): Use it.

* lisp/emacs-lisp/cl-preloaded.el (cl-struct-define): Record the type
definition in current-load-list.

* lisp/emacs-lisp/eieio-core.el (eieio--known-slot-names): New var.
(eieio--add-new-slot): Set it.
(eieio-defclass-internal): Use new name for current-load-list.
(eieio-oref): Add compiler-macro to warn about unknown slots.
* lisp/emacs-lisp/eieio.el (defclass): Update eieio--known-slot-names
as compile-time as well.  Improve constructor docstrings.

* lisp/emacs-lisp/eieio-opt.el (eieio-help-class)
(eieio--help-print-slot, eieio-help-class-slots): Move to cl-extra.el.
(eieio-class-def): Remove button.
(eieio-help-constructor): Use new name for load-history element.
(eieio--specializers-apply-to-class-p, eieio-all-generic-functions)
(eieio-method-documentation): Move to cl-generic.el.
(eieio-display-method-list): Use new names.

* lisp/emacs-lisp/lisp-mode.el (lisp-imenu-generic-expression):
Add "define-linline".
(lisp-fdefs): Remove "defsubst".
(el-fdefs): Add "defsubst", "cl-defsubst", and "define-linline".

* lisp/emacs-lisp/macroexp.el (macroexp--warned): New var.
(macroexp--warn-and-return): Use it to avoid inf-loops.
Add `compile-only' argument.

1 files changed, 15 insertions, 23 deletions

diff --git a/lisp/help-mode.el b/lisp/help-mode.el
index cdddd542532..e1fc9fd1984 100644
--- a/lisp/help-mode.el
+++ b/lisp/help-mode.el
@@ -30,6 +30,7 @@
 ;;; Code:
 
 (require 'button)
+(require 'cl-lib)
 (eval-when-compile (require 'easymenu))
 
 (defvar help-mode-map
@@ -216,7 +217,8 @@ The format is (FUNCTION ARGS...).")
                          (goto-char (point-min))
                          (if (re-search-forward
                               (format "^[ \t]*(\\(cl-\\)?define-compiler-macro[ \t]+%s"
-                                      (regexp-quote (symbol-name fun))) nil t)
+                                      (regexp-quote (symbol-name fun)))
+                              nil t)
                              (forward-line 0)
                            (message "Unable to find location in file")))
                      (message "Unable to find file")))
@@ -385,6 +387,15 @@ it does not already exist."
        (error "Current buffer is not in Help mode"))
      (current-buffer))))
 
+(defvar describe-symbol-backends
+  `((nil ,#'fboundp ,(lambda (s _b _f) (describe-function s)))
+    ("face" ,#'facep ,(lambda (s _b _f) (describe-face s)))
+    (nil
+     ,(lambda (symbol)
+        (or (and (boundp symbol) (not (keywordp symbol)))
+            (get symbol 'variable-documentation)))
+     ,#'describe-variable)))
+
 ;;;###autoload
 (defun help-make-xrefs (&optional buffer)
   "Parse and hyperlink documentation cross-references in the given BUFFER.
@@ -487,28 +498,9 @@ that."
                             ;;       (pop-to-buffer (car location))
                             ;;  (goto-char (cdr location))))
                             (help-xref-button 8 'help-function-def sym))
-                           ((and
-                             (facep sym)
-                             (save-match-data (looking-at "[ \t\n]+face\\W")))
-                            (help-xref-button 8 'help-face sym))
-                           ((and (or (boundp sym)
-                                     (get sym 'variable-documentation))
-                                 (fboundp sym))
-                            ;; We can't intuit whether to use the
-                            ;; variable or function doc -- supply both.
-                            (help-xref-button 8 'help-symbol sym))
-                           ((and
-                             (or (boundp sym)
-                                 (get sym 'variable-documentation))
-                             (or
-                              (documentation-property
-                               sym 'variable-documentation)
-                              (documentation-property
-                               (indirect-variable sym)
-                               'variable-documentation)))
-                            (help-xref-button 8 'help-variable sym))
-                           ((fboundp sym)
-                            (help-xref-button 8 'help-function sym)))))))
+                           ((cl-some (lambda (x) (funcall (nth 1 x) sym))
+                                     describe-symbol-backends)
+                            (help-xref-button 8 'help-symbol sym)))))))
                 ;; An obvious case of a key substitution:
                 (save-excursion
                   (while (re-search-forward