Some long UTF8 characters causing cursor to drift

Neovim:

NVIM v0.4.3
Build type: Release
LuaJIT 2.0.5
Compilation: /usr/local/Homebrew/Library/Homebrew/shims/mac/super/clang -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=1 -DNDEBUG -DMIN_LOG_LEVEL=3 -Wall -Wextra -pedantic -Wno-unused-parameter -Wstrict-prototypes -std=gnu99 -Wshadow -Wconversion -Wmissing-prototypes -Wimplicit-fallthrough -Wvla -fstack-protector-strong -fdiagnostics-color=auto -DINCLUDE_GENERATED_DECLARATIONS -D_GNU_SOURCE -DNVIM_MSGPACK_HAS_FLOAT32 -DNVIM_UNIBI_HAS_VAR_FROM -I/tmp/neovim-20191107-13403-1or2rj3/neovim-0.4.3/build/config -I/tmp/neovim-20191107-13403-1or2rj3/neovim-0.4.3/src -I/usr/local/include -I/tmp/neovim-20191107-13403-1or2rj3/neovim-0.4.3/deps-build/include -I/usr/local/opt/gettext/include -I/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.15.sdk/usr/include -I/tmp/neovim-20191107-13403-1or2rj3/neovim-0.4.3/build/src/nvim/auto -I/tmp/neovim-20191107-13403-1or2rj3/neovim-0.4.3/build/include
Compiled by [e-mail]

Features: +acl +iconv +tui
See ":help feature-compile"

   system vimrc file: "$VIM/sysinit.vim"
  fall-back for $VIM: "/usr/local/Cellar/neovim/0.4.3/share/nvim"

Code:

Version: 1.41.1
Commit: 26076a4de974ead31f97692a0d32f90d735645c0
Date: 2019-12-18T14:57:51.166Z
Electron: 6.1.5
Chrome: 76.0.3809.146
Node.js: 12.4.0
V8: 7.6.303.31-electron.0
OS: Darwin x64 18.7.0

The problem is quite subtle but when the editor encounters UTF8 characters longer than 2*8bits, the cursor is drifted forward by 1 position. Here character ᵩ has UTF8 code E1 B5 A9. This drift affects x and D operations in normal mode also.

Plain nvim seems to be fine with that so I suppose it’s a problem with the plugin? (2*8bits-characters like φ(CF 86) works also fine.)

[xrq-phys]

Thanks for explanation and the fix!

[asvetliakov]

Didn’t test esc at the end of the line, as you said, didn’t work.