bug#81487: problem rendering thai text from a utf8 input file

The same problem appears. 
Invocation setup: prepend C:\msys64\mingw64\bin;C:\emacs\bin; to PATH
Invocation shell: cmd.exe
Invocation: emacs -Q -nw UTF-8-demo.txt
Result: after hitting 5 PgDn keys to reach the bottom of the file, some Thai text now appears in the right side of the screen. With each PgUp key, this text appears at the same place in the screen, though it is not present in the input file. Attached file thai-render-artifact.png shows what I see at the first point an error could be detected, with artifact circled in red.  FYI: The executable was built from source code on Jan-13-2026 using mingw-W64-mingw32-gcc toolchain, with the ./configure arguments shown in the original email.

-----Original Message-----
From: Eli Zaretskii <[email protected]> 
Sent: Monday, July 27, 2026 8:17 AM
To: Keith Hill <[email protected]>
Cc: [email protected]
Subject: Re: bug#81487: problem rendering thai text from a utf8 input file

[Please always use Reply To All, to keep the bug tracker CC'ed.]

> From: Keith Hill <[email protected]>
> Date: Mon, 27 Jul 2026 01:00:24 +0000
> 
> The problem I saw was with a TTY frame; it was invoked from an Msys2 
> MINGW64 shell via "emacs -nw". The code page was already 65001 & I 
> think there's evidence of that in the mail I sent.  FWIW: cat and less 
> both render this file as intended. I'll can't tell which font is used, but it looks the same as what one sees via cat the file.  The file is rendering fine until the Thai block is reached.  Originally, I saw this using Microsoft Terminal.
> Now I also can see it using Msys2's mingw64.exe shell launcher. 

Please try starting Emacs in Command Prompt window, not in MSYS Bash window.

Also, please use "emacs -Q -nw", to disable any customizations you might have that could affect this.

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