emacs-29 f8c95d1a76: Fix xt-mouse on terminals that report UTF-8 encoded coordinates

[Eli Zaretskii]

branch: emacs-29
commit f8c95d1a7681e861fc22d2a040cda0ddfe23eff4
Author: Eli Zaretskii <eliz@gnu.org>
Commit: Eli Zaretskii <eliz@gnu.org>

    Fix xt-mouse on terminals that report UTF-8 encoded coordinates
    
    * lisp/xt-mouse.el (xterm-mouse--read-coordinate): Fix conversion
    of mouse coordinates in rxvt-unicode.  Patches by Vladimir
    Panteleev <git@cy.md> and Jared Finder <jared@finder.org>.
    (Bug#61022)
---
 lisp/xt-mouse.el | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/lisp/xt-mouse.el b/lisp/xt-mouse.el
index adfa480bc0..4ccd35d527 100644
--- a/lisp/xt-mouse.el
+++ b/lisp/xt-mouse.el
@@ -151,16 +151,22 @@ If `xterm-mouse-utf-8' was non-nil when
 `turn-on-xterm-mouse-tracking-on-terminal' was called, reads the
 coordinate as an UTF-8 code unit sequence; otherwise, reads a
 single byte."
-  (let ((previous-keyboard-coding-system (keyboard-coding-system)))
+  (let ((previous-keyboard-coding-system (keyboard-coding-system))
+        (utf-8-p (terminal-parameter nil 'xterm-mouse-utf-8))
+        ;; Prevent conversions inside 'read-char' due to input method,
+        ;; when we call 'read-char' below with 2nd argument non-nil.
+        (input-method-function nil))
     (unwind-protect
         (progn
-          (set-keyboard-coding-system
-           (if (terminal-parameter nil 'xterm-mouse-utf-8)
-               'utf-8-unix
-             'no-conversion))
-          ;; Wait only a little; we assume that the entire escape sequence
-          ;; has already been sent when this function is called.
-          (read-char nil nil 0.1))
+          (set-keyboard-coding-system (if utf-8-p 'utf-8-unix 'no-conversion))
+          (read-char nil
+                     ;; Force 'read-char' to decode UTF-8 sequences if
+                     ;; 'xterm-mouse-utf-8' is non-nil.
+                     utf-8-p
+                     ;; Wait only a little; we assume that the entire
+                     ;; escape sequence has already been sent when
+                     ;; this function is called.
+                     0.1))
       (set-keyboard-coding-system previous-keyboard-coding-system))))
 
 ;; In default mode, each numeric parameter of XTerm's mouse report is