bug#37785: [PATCH] Add a way to disable substitution of command keys in help strings

["Clément Pit-Claudel" <cpitclaudel@gmail.com>]

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On 2019-10-17 13:18, Eli Zaretskii wrote:
>> Cc: rpluim@gmail.com, 37785@debbugs.gnu.org
>> From: Clément Pit-Claudel <cpitclaudel@gmail.com>
>> Date: Thu, 17 Oct 2019 11:53:45 -0400
>>
>> I've attached an updated patch.
> 
> Thanks, I have a few minor comments.

Wonderful, thanks a lot!  Here's an updated patch.


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From 31382178b38460a526503666ccf6f389ef0768bb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cl=C3=A9ment=20Pit-Claudel?= <clement.pitclaudel@live.com>
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 (help_echo_substitute_command_keys): New function.
(help_echo_echo, parse_menu_item): Use it.
(syms_of_keyboard): Define Qhelp_echo_inhibit_substitution.

* doc/lispref/text.texi (Special Properties), etc/NEWS: Document
the effect of 'help-echo-inhibit-substitution'.
---
 doc/lispref/text.texi | 19 +++++++++++++++----
 etc/NEWS              |  5 +++++
 src/keyboard.c        | 23 ++++++++++++++++++++---
 3 files changed, 40 insertions(+), 7 deletions(-)

diff --git a/doc/lispref/text.texi b/doc/lispref/text.texi
index d7b04d2934..f2eaca1b71 100644
--- a/doc/lispref/text.texi
+++ b/doc/lispref/text.texi
@@ -3399,7 +3399,8 @@ Special Properties
 @anchor{Text help-echo}
 If text has a string as its @code{help-echo} property, then when you
 move the mouse onto that text, Emacs displays that string in the echo
-area, or in the tooltip window (@pxref{Tooltips}).
+area, or in the tooltip window (@pxref{Tooltips}), after passing it
+through @code{substitute-command-keys}.
 
 If the value of the @code{help-echo} property is a function, that
 function is called with three arguments, @var{window}, @var{object} and
@@ -3429,6 +3430,14 @@ Special Properties
 
 This feature is used in the mode line and for other active text.
 
+@item help-echo-inhibit-substitution
+@cindex help-echo text, avoid command-key substitution
+@kindex help-echo-inhibit-substitution @r{(text property)}
+If the first character of a @code{help-echo} string has a
+non-@code{nil} @code{help-echo-inhibit-substitution} property, then it
+is displayed as-is by @code{show-help-function}, without being passed
+through @code{substitute-command-keys}.
+
 @item keymap
 @cindex keymap of character
 @kindex keymap @r{(text property)}
@@ -3736,9 +3745,11 @@ 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-@code{nil}
+@code{help-echo-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..f008bf27fb 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -2752,6 +2752,11 @@ in other packages are now obsolete aliases of 'xor'.
 +++
 ** 'define-globalized-minor-mode' now takes BODY forms.
 
++++
+** New text property 'help-echo-inhibit-substitution'.
+Setting this on the first character of a help string disables
+conversions via 'substitute-command-keys'.
+
 \f
 * Changes in Emacs 27.1 on Non-Free Operating Systems
 
diff --git a/src/keyboard.c b/src/keyboard.c
index a16d13cc7b..8a149d1a3c 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 help-echo-inhibit-substitution property.  */
+
+static Lisp_Object
+help_echo_substitute_command_keys (Lisp_Object help)
+{
+  if (STRINGP (help)
+      && SCHARS (help) > 0
+      && !NILP (Fget_text_property (make_fixnum(0),
+                                    Qhelp_echo_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, help_echo_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)));
+		help_echo_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 = help_echo_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 (Qhelp_echo_inhibit_substitution, "help-echo-inhibit-substitution");
   DEFSYM (QCrtl, ":rtl");
 
   staticpro (&item_properties);
-- 
2.17.1