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From: e est <mtest31@yandex.com>
Newsgroups: gnu.bash.bug
Subject: reverse-i-search, multibyte backspace problem
Date: Sat, 18 Jul 2015 22:23:19 +0200
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Hello,

I've noticed a bug with terminal usage of bash.

Steps to reproduce:
1. Press control-r to get in reverse-i-search mode
2. Enter a key outside of the ASCII character set, like the french =C3=A9=
 or the german =C3=A4.
3. Press backspace.

What to expect:
The key gets removed.

What happens:
Instead of the whole key getting removed, you can see a weird character (=
like =EF=BF=BD or =C3=83) appear.

The most likely theory:
Instead of adhering to the utf-8 multibyte specification, and removing th=
e whole multibyte codepoint encoding sequence (or perhaps the whole seque=
nce representing the "abstract character"? [1]), it just removes the last=
 byte.

Note that the bug is dependent on the terminal. I've originally discovere=
d the bug on konsole, but it has been confirmed by other users on the fre=
enode #bash channel to exist on xterm, st and rxvt, but one user couldn't=
 reproduce it with st.

Affected versions:
I've tested 4.3.30(1)-release (my distro's packaged one) and 4.3.39(2)-re=
lease, the latter coming straight from the development git repository's m=
aster branch, compiled with ./configure && make -j 4.
The operating system I use is Kubuntu, but it has been confirmed to exist=
 on Gentoo and arch linux too.=20

Thanks for answers.

Greetings
Est31.

[1]: Quoting the Unicode standard, version 7,  Section 3.4, Characters an=
d Encoding:
"A single abstract character may also be represented by a sequence of cod=
e points=E2=80=94for example, "latin capital letter g with acute" may be =
represented by the sequence <U+0047 "latin capital letter g", U+0301 "com=
bining acute accent">, rather than being mapped to a single code point."