Always autoload callables if they aren't loaded

Fixes #117

CHANGELOG.md

@@ -19,6 +19,11 @@ Added looking up C-style Lisp names.
 Set `comment-start` inside helpful buffers, to fix external packages
 relying on that variable.
 
+Helpful now always autoloads callables if they aren't already
+loaded. This is consistent with help.el (unless you've overriden
+`help-enable-auto-load`), produces more useful results, and fixes
+crashes rendering some docstrings.
+
 # v0.15
 
 Fixed a crash on formatting values.

helpful.el

@@ -1926,13 +1926,22 @@ may contain duplicates."
      (-flatten
       (-map #'helpful--callees-1 (cdr form)))))))
 
+(defun helpful--ensure-loaded ()
+  "Ensure the symbol associated with the current buffer has been loaded."
+  (when (and helpful--callable-p
+             (symbolp helpful--sym))
+    (let ((fn-obj (helpful--without-advice helpful--sym)))
+      (when (autoloadp fn-obj)
+        (autoload-do-load fn-obj)))))
+
 (defun helpful-update ()
   "Update the current *Helpful* buffer to the latest
 state of the current symbol."
   (interactive)
   (cl-assert (not (null helpful--sym)))
   (unless (buffer-live-p helpful--associated-buffer)
     (setq helpful--associated-buffer nil))
+  (helpful--ensure-loaded)
   (-let* ((val
            ;; Look at the value before setting `inhibit-read-only', so
            ;; users can see the correct value of that variable.

test/helpful-unit-test.el

@@ -880,3 +880,14 @@ find the source code."
    (helpful--convert-c-name 'Fmake_string t))
   (should-not
    (helpful--convert-c-name 'Vgc_cons_percentage nil)))
+
+(ert-deftest helpful--loads-autoload-symbol ()
+  "When asked to describe an autoloaded symbol, just load it."
+  ;; This test assumes that you haven't loaded tetris.el.gz in your
+  ;; current instance.
+  (skip-unless (autoloadp (symbol-function 'tetris)))
+  ;; This is a regression test: `tetris' has `tetris-mode-map' in its
+  ;; docstring, so we can't display the mode map unless tetris.el.gz is
+  ;; loaded.
+  ;;
+  (helpful-function #'tetris))