Re: wcwidth broken with gcc 16

 On Tue, Jun 2, 2026 at 1:46 AM Thomas Wolff via Cygwin <[email protected]>
wrote:

Thomas Wolff, et. al.,

I have been carefully following this discussion of technical issues, API
conformance, and related issues,.

There has been no significant discussion of the user experience that
depends on the resolution of this problem.

Will non-BMP Unicode code points display correctly in terminal windows
(that use an appropriate font), e.g. mintty?

Non-BMP Unicode code points include emojis, mathematical script glyphs, and
many others.

For me, I care if a small Python script like:

$ type main.py
print("U+01D49E ‹𝒞›  GC=Lu    MATHEMATICAL SCRIPT CAPITAL C")

outputs:
U+01D49E ‹𝒞›  GC=Lu    MATHEMATICAL SCRIPT CAPITAL C

on Windows Terminal, as expected

and when running cygwin in a mintty window:

$ uname -a
CYGWIN_NT-10.0-26200 mercury 3.6.9-1.x86_64 2026-04-21 15:46 UTC x86_64
Cygwin
$ mintty --version
mintty 3.8.2 (Cygwin-x86_64)
$ date
Jun  2, 2026 11:36:33
$ python3 -V
Python 3.12.12
$ cat main.py
print("U+01D49E ‹𝒞›  GC=Lu    MATHEMATICAL SCRIPT CAPITAL C")
$ python3 main.py
U+01D49E ‹𝒞›  GC=Lu    MATHEMATICAL SCRIPT CAPITAL C

correctly displays the Mathematical Script Capital C glyph as seen in the
attached screen capture.

If the resolution of this problem changes "our" user experience, that will
be another problem.

As an after thought, I may be seeing success due to the byte stream
containing UTF-8 4-byte sequences all the way through Windows 11 APIs,
without any conversions to UTF-16 or UTF-32.

I am not so up-to-date with C as to rattle off a demo in seconds, as I can
in Python. I would like to see such a minimal C demo program that I can try
with cmd in WT, with MINGW64 in mintty, and with cygwin in mintty. The demo
should send UTF-8 4-byte, UTF-16 2-short, and UTF-32 1-long characters, if
possible. TIA.

Just my take,
Doug

-- Doug Henderson, Calgary, Alberta, Canada - from gmail.com


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