bug#32917: 27.0.50; read-hide-char documentation

[charles@aurox.ch (Charles A. Roelli)]

  read-hide-char is a variable defined in ‘C source code’.
  Its value is nil

  Documentation:
  Whether to hide input characters in noninteractive mode.
  It must be a character, which will be used to mask the input
  characters.  This variable should never be set globally.

First, the scope of 'read-hide-char' seems wider than what the
documentation claims (for example, it is used in read-passwd,
interactively -- not just in "noninteractive mode").

Second, it can clearly also be nil instead of a character.


Here's a suggested change for emacs-26:

diff --git a/src/minibuf.c b/src/minibuf.c
index 691fad0..f1bde91 100644
--- a/src/minibuf.c
+++ b/src/minibuf.c
@@ -2107,8 +2107,11 @@ properties.  */);
 
   DEFVAR_LISP ("read-hide-char", Vread_hide_char,
 	       doc: /* Whether to hide input characters in noninteractive mode.
-It must be a character, which will be used to mask the input
-characters.  This variable should never be set globally.  */);
+If non-nil, it must be a character, which will be used to mask the
+input characters.  This variable should never be set globally.
+
+This variable also overrides the default character that `read-passwd'
+uses to hide passwords.  */);
   Vread_hide_char = Qnil;
 
   defsubr (&Sactive_minibuffer_window);