Variable: replace-char-fold
replace-char-fold is a customizable variable defined in replace.el.gz.
Value
nil
Documentation
Non-nil means replacement commands should do character folding in matches.
This means, for instance, that ' will match a large variety of
Unicode quotes.
This variable affects query-replace and replace-string, but not
replace-regexp.
This variable was added, or its default value changed, in Emacs 25.1.
Probably introduced at or before Emacs version 25.1.
Source Code
;; Defined in /usr/src/emacs/lisp/replace.el.gz
(defcustom replace-char-fold nil
"Non-nil means replacement commands should do character folding in matches.
This means, for instance, that \\=' will match a large variety of
Unicode quotes.
This variable affects `query-replace' and `replace-string', but not
`replace-regexp'."
:type 'boolean
:group 'matching
:version "25.1")