Incorrect handling of multiple-byte characters in double-quote string literal Rubocop quickfix

[pauljunova]

Description

Performing a quickfix on a single-quoted string literal, when a rubocop rule preferring double-quotes is active, outputs a double-quoted string with utf-8 content garbled.

Ruby LSP Information

neovim:

NVIM v0.12.3-dev-53+g0aa77cb78c
Build type: RelWithDebInfo
LuaJIT 2.1.1774638290

ruby:

ruby 3.4.7 (2025-10-08 revision 7a5688e2a2) +PRISM [x86_64-linux]

ruby-lsp: tested on 0.26.9 and 0.27.0.beta2

Reproduction steps

• Setup rubocop in project with this rule

Style/StringLiterals:
  EnforcedStyle: single_quotes

• Write a single quoted string containing multi-byte unicode characters
• Perform quickfix
• Unicode escape sequence is added and the last single-quote is not removed

recording.mp4