Re: [PATCH] [gdb/tui] Handle unicode chars in prompt

[Tom Tromey <tom@tromey.com>]

>> In TUI, the prompt is written out by tui_puts_internal, which outputs one byte
>> at a time using waddch, which apparantly breaks multi-byte char support.
>> Fix this by detecting multi-byte chars in tui_puts_internal, and
>> printing them using
>> waddnstr.

> FWIW, I just came across this commit, which seems relevant:

Tom> Note that tui_puts_internal remains.  It is needed to handle computing
Tom> the start line of the readline prompt, which is difficult to do
Tom> properly in the case where redisplaying can also cause the command
Tom> window to scroll.  This might be possible to implement by reverting to
Tom> single "character" output, by using mbsrtowcs for its side effects to
Tom> find character boundaries in the input.  I have not attempted this.
Tom> ...

I no longer remember what made this difficult.  I wonder if it's
possible to simply emit as many characters as possible in a single call,
and then use getyx to figure out the length of the prompt after it has
been fully displayed.  If the prompt wraps or if it takes multiple
lines, offhand it seems fine to just pick whatever the final column
happens to be.


Using wchar functions in gdb is a pain; at least in the past,
gdb_wchar.h was written to support systems that don't support these at
all (DJGPP - not sure if that host even builds any more).

Some characters may take multiple columns (see 'wcwidth').  I'd hope
that the display-and-getyx approach would avoid having to have gdb
understand this; though I suppose gdb's pager probably already gets this
wrong.

Tom