Readline 8.3 regression: Prompt corruption with multibyte characters

Configuration Information: Machine: x86_64 OS: linux-gnu Compiler: gcc Comp=
ilation CFLAGS: -march=3Dx86-64 -mtune=3Dgeneric -O2 -pipe -fno-plt -fexcep=
tions -Wp,-D_FORTIFY_SOURCE=3D3 -Wformat -Werror=3Dformat-security -fstack-=
clash-protection -fcf-protection -fno-omit-frame-pointer -mno-omit-leaf-fra=
me-pointer -flto=3Dauto -DDEFAULT_PATH_VALUE=3D'/usr/local/sbin:/usr/local/=
bin:/usr/bin' -DSTANDARD_UTILS_PATH=3D'/usr/bin' -DSYS_BASHRC=3D'/etc/bash.=
bashrc' -DSYS_BASH_LOGOUT=3D'/etc/bash.bash_logout' -DNON_INTERACTIVE_LOGIN=
_SHELLS -std=3Dgnu17 uname output: Linux mylaptop 6.12.94-1-MANJARO #1 SMP =
PREEMPT_DYNAMIC Fri, 19 Jun 2026 12:26:13 +0000 x86_64 GNU/Linux Machine Ty=
pe: x86_64-pc-linux-gnu
Bash Version: 5.3 Patch Level: 15 Release Status: release
Hi everyone,
I believe I=92ve found a prompt display error in Readline 8.3: the prompt g=
ets shoved into the start of the line during a redraw when the previous com=
mand=92s output lacks a trailing newline.
This occurs only when two conditions are met simultaneously:

  1.
PS1 contains a visible multibyte character (like U+2A2F).
  2.
The prompt includes an escape sequence (like a color code) enclosed in \[ \=
] markers.

If I use ASCII instead of the multibyte character, or remove the enclosed e=
scape sequence, the redraw works perfectly. The bug only happens when both =
elements are combined. I've verified this isn't a locale/width (UTF-8) issu=
e. You can reproduce it interactively with:
```
PS1=3D$'\[\e[38;5;226m\] \u2a2f \[\e[0m\]'
printf '%s' "$(seq -s/ 1 300)"

```


When the prompt is redrawn, the cursor backtracks improperly, causing text =
corruption. To isolate this, I built Bash 5.2.21 (Readline 8.2) from source=
 on the same machine; it passes cleanly. The issue only appears after upgra=
ding to Readline 8.3.
I noticed this entry in the changes file talking about multiline prompts. D=
oes that fix cases where the visible region contains a multibyte character?=
 If this is already resolved in development, please feel free to disregard =
this. I want to archive a minimal reproducer on the mailing list just in ca=
se. It was driving me insane
Thanks for your  work on Bash.
groetjes!
>JMN