From 5bc5de2fc6f7783b0cd71c5945755fc98431aa60 Mon Sep 17 00:00:00 2001
From: Maxim Cournoyer <maxim.cournoyer@gmail.com>
Date: Tue, 31 Dec 2024 10:18:30 +0900
Subject: [PATCH 3/3] wip: work on solution

---
 lisp/emacs-lisp/lisp-mode.el | 33 +++++++++++++++++++++++----------
 1 file changed, 23 insertions(+), 10 deletions(-)

diff --git a/lisp/emacs-lisp/lisp-mode.el b/lisp/emacs-lisp/lisp-mode.el
index d0c32d238bc..6c6d88f73a5 100644
--- a/lisp/emacs-lisp/lisp-mode.el
+++ b/lisp/emacs-lisp/lisp-mode.el
@@ -1,6 +1,6 @@
 ;;; lisp-mode.el --- Lisp mode, and its idiosyncratic commands  -*- lexical-binding:t -*-
 
-;; Copyright (C) 1985-1986, 1999-2024 Free Software Foundation, Inc.
+;; Copyright (C) 1985-1986, 1999-2025 Free Software Foundation, Inc.
 
 ;; Maintainer: emacs-devel@gnu.org
 ;; Keywords: lisp, languages
@@ -1480,30 +1480,34 @@ lisp-fill-paragraph
                                   (derived-mode-p 'emacs-lisp-mode))
                              emacs-lisp-docstring-fill-column
                            fill-column)))
-        (let ((ppss (syntax-ppss))
-              (start (point))
-              ;; Avoid recursion if we're being called directly with
-              ;; `M-x lisp-fill-paragraph' in an `emacs-lisp-mode' buffer.
-              (fill-paragraph-function t))
+        (let* ((ppss (syntax-ppss))
+               (start (point))
+               ;; Avoid recursion if we're being called directly with
+               ;; `M-x lisp-fill-paragraph' in an `emacs-lisp-mode' buffer.
+               (fill-paragraph-function t)
+               (string-start (ppss-comment-or-string-start ppss))
+               (indent (save-excursion
+                         (goto-char string-start)
+                         (current-column))))
           (save-excursion
             (save-restriction
               ;; If we're not inside a string, then do very basic
               ;; filling.  This avoids corrupting embedded strings in
               ;; code.
-              (if (not (ppss-comment-or-string-start ppss))
+              (if (not string-start)
                   (lisp--fill-line-simple)
                 ;; If we're in a string, then narrow (roughly) to that
                 ;; string before filling.  This avoids filling Lisp
                 ;; statements that follow the string.
                 (when (ppss-string-terminator ppss)
-                  (goto-char (ppss-comment-or-string-start ppss))
+                  (goto-char string-start)
                   ;; The string may be unterminated -- in that case, don't
                   ;; narrow.
                   (when (ignore-errors
                           (progn
                             (forward-sexp 1)
                             t))
-                    (narrow-to-region (1+ (ppss-comment-or-string-start ppss))
+                    (narrow-to-region (1+ string-start)
                                       (1- (point)))))
                 ;; Move back to where we were.
                 (goto-char start)
@@ -1516,7 +1520,16 @@ lisp-fill-paragraph
                     (goto-char (point-min))
                     (forward-line 1)
                     (narrow-to-region (point) (point-max))))
-	        (fill-paragraph justify)))))))
+                ;; Insert spaces to reproduce the same leading indent
+                ;; for the string inside the narrowed region, to avoid
+                ;; bug#56197.
+                (save-excursion
+                  (goto-char (point-min))
+                  (insert (make-string indent ?\s)))
+	        (fill-paragraph justify)
+                (save-excursion         ;clean up
+                  (goto-char (point-min))
+                  (delete-char indent))))))))
   ;; Never return nil.
   t)
 
-- 
2.46.0