Subject: [PATCH] Add a way to disable substitution of command keys in help strings
From: Clément Pit-Claudel <[email-masked]>
To: bug-gnu-emacs <[email-masked]>
Date: Wed, 16 Oct 2019 21:41:27 -0400
List-Id: <debbugs-submit.debbugs.gnu.org>

Hi all,

On 2019-10-05 04:13, Eli Zaretskii wrote (on emacs-devel):
> I guess we need to add some feature to control whether help-echo gets
> run through substitute-command-keys, or add an alternative to
> help-echo that works exactly like it, but without substitutions.
> Patches welcome.
[…]
> I'd prefer a property like help-echo-inhibit-substitution that is
> non-nil, to inhibit the call to substitute-command-keys.  A value of
> nil is easy to confuse with no property at all.

Here is a first cut at a patch implementing this feature.  I hope this tracker is the right place to post it.  I'm also not quite sure I got the Changelog format right.

Cheers,
Clément.
From 8092b19d819182c91e6066d24f243dc7d7d8641e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cl=C3=A9ment=20Pit-Claudel?= <[email-masked]>
Date: Wed, 16 Oct 2019 21:28:47 -0400
Subject: [PATCH] Add a way to disable substitution of command keys in help
 strings

* src/keyboard.c (show_help_substitute_command_keys): New function
(show_help_echo, parse_menu_item): Use it
(syms_of_keyboard): Define Qshow_help_inhibit_substitution

* doc/lispref/text.texi (Special Properties), etc/NEWS: Document
the effect of 'show-help-inhibit-substitution'
---
 doc/lispref/text.texi |  8 +++++---
 etc/NEWS              |  5 +++++
 src/keyboard.c        | 23 ++++++++++++++++++++---
 3 files changed, 30 insertions(+), 6 deletions(-)

diff --git a/doc/lispref/text.texi b/doc/lispref/text.texi
index d7b04d2934..4f7e480443 100644
--- a/doc/lispref/text.texi
+++ b/doc/lispref/text.texi
@@ -3736,9 +3736,11 @@ Special Properties
 @pxref{Extended Menu Items}), or tool bar help strings (@pxref{Tool
 Bar}).  The specified function is called with one argument, the help
 string to display, which is passed through
-@code{substitute-command-keys} before being given to the function; see
-@ref{Keys in Documentation}.  Tooltip mode (@pxref{Tooltips,,, emacs,
-The GNU Emacs Manual}) provides an example.
+@code{substitute-command-keys} before being given to the function,
+unless the help string has a non-nil
+@code{show-help-inhibit-substitution} property on its first character;
+see @ref{Keys in Documentation}.  Tooltip mode (@pxref{Tooltips,,,
+emacs, The GNU Emacs Manual}) provides an example.
 @end defvar
 
 @defvar face-filters-always-match
diff --git a/etc/NEWS b/etc/NEWS
index 4b693aaaa1..6089515daf 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -439,6 +439,11 @@ RGB triplets with a single hexadecimal digit per component.
 ---
 ** The toolbar now shows the equivalent key binding in its tooltips.
 
++++
+** Adding a non-nil 'show-help-inhibit-substitution' text property on
+the first character of a help string disables conversion via
+'substitute-command-keys'.
+
 
 * Editing Changes in Emacs 27.1
 
diff --git a/src/keyboard.c b/src/keyboard.c
index a16d13cc7b..864c9789c5 100644
--- a/src/keyboard.c
+++ b/src/keyboard.c
@@ -2019,6 +2019,22 @@ make_ctrl_char (int c)
   return c;
 }
 
+/* Substitute key descriptions and quotes in HELP, unless its first
+   character has a non-nil show-help-inhibit-substitution property. */
+
+static Lisp_Object
+show_help_substitute_command_keys (Lisp_Object help)
+{
+  if (STRINGP (help) &&
+      SCHARS (help) > 0 &&
+      !NILP (Fget_text_property (make_fixnum(0),
+                                 Qshow_help_inhibit_substitution,
+                                 help)))
+    return help;
+
+  return Fsubstitute_command_keys(help);
+}
+
 /* Display the help-echo property of the character after the mouse pointer.
    Either show it in the echo area, or call show-help-function to display
    it by other means (maybe in a tooltip).
@@ -2078,7 +2094,7 @@ show_help_echo (Lisp_Object help, Lisp_Object window, Lisp_Object object,
   if (STRINGP (help) || NILP (help))
     {
       if (!NILP (Vshow_help_function))
-	call1 (Vshow_help_function, Fsubstitute_command_keys (help));
+	call1 (Vshow_help_function, show_help_substitute_command_keys (help));
       help_echo_showing_p = STRINGP (help);
     }
 }
@@ -7652,7 +7668,7 @@ parse_menu_item (Lisp_Object item, int inmenubar)
       if (CONSP (item) && STRINGP (XCAR (item)))
 	{
 	  ASET (item_properties, ITEM_PROPERTY_HELP,
-		Fsubstitute_command_keys (XCAR (item)));
+		show_help_substitute_command_keys (XCAR (item)));
 	  start = item;
 	  item = XCDR (item);
 	}
@@ -7716,7 +7732,7 @@ parse_menu_item (Lisp_Object item, int inmenubar)
 		{
 		  Lisp_Object help = XCAR (item);
 		  if (STRINGP (help))
-		    help = Fsubstitute_command_keys (help);
+		    help = show_help_substitute_command_keys (help);
 		  ASET (item_properties, ITEM_PROPERTY_HELP, help);
 		}
 	      else if (EQ (tem, QCfilter))
@@ -11052,6 +11068,7 @@ syms_of_keyboard (void)
   /* Tool-bars.  */
   DEFSYM (QCimage, ":image");
   DEFSYM (Qhelp_echo, "help-echo");
+  DEFSYM (Qshow_help_inhibit_substitution, "show-help-inhibit-substitution");
   DEFSYM (QCrtl, ":rtl");
 
   staticpro (&item_properties);
-- 
2.17.1