From c8dbb04da96dd200165690cba253c8b832bc388a Mon Sep 17 00:00:00 2001
From: zeertzjq <zeertzjq@outlook.com>
Date: Sat, 23 May 2026 08:57:36 +0800
Subject: [PATCH] vim-patch:9.2.0510: setline() mapping may trigger autoindent
 (#39961)

Problem:  setline() insert mode mapping may trigger autoindent,
          corrupting the newly inserted line content (Evgeni Chasnovski)
Solution: Only strip autoindent whitespace when the rest of the line is
          all whitespace (glepnir).

fixes:  vim/vim#19363
closes: vim/vim#20290

https://github.com/vim/vim/commit/e3dedac77b2076210e7027b14a5927622434f014

Co-authored-by: glepnir <glephunter@gmail.com>
---
 src/nvim/edit.c                | 59 ++++++++++++++++++++--------------
 test/old/testdir/test_edit.vim | 24 ++++++++++++++
 2 files changed, 58 insertions(+), 25 deletions(-)

diff --git a/src/nvim/edit.c b/src/nvim/edit.c
index 85fd450a10..dd2354b14a 100644
--- a/src/nvim/edit.c
+++ b/src/nvim/edit.c
@@ -2295,33 +2295,42 @@ static void stop_insert(pos_T *end_insert_pos, int esc, int nomove)
 
       curwin->w_cursor = *end_insert_pos;
       check_cursor_col(curwin);        // make sure it is not past the line
-      while (true) {
-        if (gchar_cursor() == NUL && curwin->w_cursor.col > 0) {
-          curwin->w_cursor.col--;
-        }
-        cc = gchar_cursor();
-        if (!ascii_iswhite(cc)) {
-          break;
-        }
-        if (del_char(true) == FAIL) {
-          break;            // should not happen
-        }
-      }
-      if (curwin->w_cursor.lnum != tpos.lnum) {
-        curwin->w_cursor = tpos;
-      } else if (curwin->w_cursor.col < prev_col) {
-        // reset tpos, could have been invalidated in the loop above
-        tpos = curwin->w_cursor;
-        tpos.col++;
-        if (cc != NUL && gchar_pos(&tpos) == NUL) {
-          curwin->w_cursor.col++;         // put cursor back on the NUL
-        }
+
+      // Where the loop would actually start (back up if NUL).
+      colnr_T strip_col = curwin->w_cursor.col;
+      if (gchar_cursor() == NUL && strip_col > 0) {
+        strip_col--;
       }
 
-      // <C-S-Right> may have started Visual mode, adjust the position for
-      // deleted characters.
-      if (VIsual_active) {
-        check_visual_pos();
+      // Don't strip if non-whitespace follows: setline() from a <Cmd>
+      // mapping or CursorHoldI autocmd may have inserted content.
+      if (*skipwhite(get_cursor_line_ptr() + strip_col) == NUL) {
+        curwin->w_cursor.col = strip_col;
+        while (true) {
+          cc = gchar_cursor();
+          if (!ascii_iswhite(cc)) {
+            break;
+          }
+          if (del_char(true) == FAIL) {
+            break;            // should not happen
+          }
+        }
+        if (curwin->w_cursor.lnum != tpos.lnum) {
+          curwin->w_cursor = tpos;
+        } else if (curwin->w_cursor.col < prev_col) {
+          // reset tpos, could have been invalidated in the loop above
+          tpos = curwin->w_cursor;
+          tpos.col++;
+          if (cc != NUL && gchar_pos(&tpos) == NUL) {
+            curwin->w_cursor.col++;         // put cursor back on the NUL
+          }
+        }
+
+        // <C-S-Right> may have started Visual mode, adjust the position for
+        // deleted characters.
+        if (VIsual_active) {
+          check_visual_pos();
+        }
       }
     }
   }
diff --git a/test/old/testdir/test_edit.vim b/test/old/testdir/test_edit.vim
index 7abae9c849..4530e2116f 100644
--- a/test/old/testdir/test_edit.vim
+++ b/test/old/testdir/test_edit.vim
@@ -2474,4 +2474,28 @@ func Test_edit_CAR_with_completion()
   bw!
 endfunc
 
+func Test_autoindent_no_strip_after_cmd_setline()
+  new
+  setlocal autoindent
+  inoremap <buffer> <F2> <Cmd>call setline('.', 'v  v')<CR><Cmd>call cursor(line('.'), 2)<CR>
+  call feedkeys("Go\<F2>\<Esc>", 'tx')
+  call assert_equal('v  v', getline(2))
+  bwipe!
+endfunc
+
+func Test_autoindent_no_strip_after_cursorholdi()
+  CheckFeature timers
+  new
+  setlocal autoindent
+  set updatetime=50
+  au CursorHoldI <buffer> call setline('.', 'v v')
+  call setline(1, ' x')
+  call cursor(1, 2)
+  call timer_start(120, {-> feedkeys("\<Esc>", 't')})
+  call feedkeys("o", 'tx!')
+  call assert_equal('v v', getline(2))
+  set updatetime&
+  bwipe!
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab