🚀 go-pugleaf

A loop like the following has the nice feature that Emacs echoes the
keystrokes in the echo area, just like when a multi-keystroke key
sequence is being entered.  But I've noticed a few bugs relating to
this feature that only show up when a loop like this is used.

	(while (/= (read-char) ?a))     ; wait for "a" to be pressed

First, M-RET and M-TAB are echoed as "M-^M" and "M-        ", despite
the efforts of push_key_description in keymap.c to do otherwise.
I think this is because EchoThem passes KeyBuf[i], a char (which
will be a signed char on my machine) to an unsigned int parameter
of push_key_description.  The result is a huge integer which, being
greater than 0200, causes "M-" to be displayed.  But the function
uses c -= 0200 instead of c &= 0177 to mask off the low 7 bits, so
the special formats for RET and TAB aren't used.

The other problem is that echobuf is declared in keyboard.c to be
char[100] and KeyBuf is a char[40]; echobuf is not large enough.
I think 240 is big enough, if KeyBuf contains 40 M-TABs (assuming
the above bug is fixed).  Actually, since the prompt figures into
the size of echobuf and its size is unconstrained by Fread_key_sequence,
no fixed size is really enough.  Anyway, if I run the above program
and type TABs, Emacs mysteriously beeps as if I had typed C-g on
the 24th one.  And (read-key-sequence (make-string 1000 ?a)) blows
Emacs right out of the water.

(I discovered these bugs while using the looping commands of my
Emacs calculator.  Calc users, take note!)

								-- Dave