Improve documentation of 'read-hide-char'

* src/minibuf.c (syms_of_minibuf) <Vread_hide_char>: Clarify
documentation and mention where else the variable is used.
* doc/lispref/minibuf.texi (Reading a Password): Add an index
entry for 'read-hide-char'.

2 files changed, 6 insertions, 2 deletions

diff --git a/doc/lispref/minibuf.texi b/doc/lispref/minibuf.texi
index 2951ef5aaec..97797d00096 100644
--- a/doc/lispref/minibuf.texi
+++ b/doc/lispref/minibuf.texi
@@ -2236,6 +2236,7 @@ Here is an example of using this function:
   To read a password to pass to another program, you can use the
 function @code{read-passwd}.
 
+@vindex read-hide-char
 @defun read-passwd prompt &optional confirm default
 This function reads a password, prompting with @var{prompt}.  It does
 not echo the password as the user types it; instead, it echoes
diff --git a/src/minibuf.c b/src/minibuf.c
index 691fad07b79..f1bde913fc9 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);