vim-patch:9.1.0231: Filetype may be undetected when SwapExists sets ft in other buf (#28136)

Problem:  Filetype may be undetected when a SwapExists autocommand sets
          filetype in another buffer.
Solution: Make filetype detection state buffer-specific.  Also fix a
          similar problem for 'modified' (zeertzjq).

closes: vim/vim#14344

https://github.com/vim/vim/commit/5bf6c2117fcef85fcf046c098dd3eb72a0147859

12 files changed, 109 insertions, 32 deletions

diff --git a/src/nvim/autocmd.c b/src/nvim/autocmd.c
index 00cfef23c7..c2cc8bd9b8 100644
--- a/src/nvim/autocmd.c
+++ b/src/nvim/autocmd.c
@@ -1750,7 +1750,7 @@ bool apply_autocmds_group(event_T event, char *fname, char *fname_io, bool force
       saveRedobuff(&save_redo);
       did_save_redobuff = true;
     }
-    did_filetype = keep_filetype;
+    curbuf->b_did_filetype = curbuf->b_keep_filetype;
   }
 
   // Note that we are applying autocmds.  Some commands need to know.
@@ -1760,7 +1760,7 @@ bool apply_autocmds_group(event_T event, char *fname, char *fname_io, bool force
 
   // Remember that FileType was triggered.  Used for did_filetype().
   if (event == EVENT_FILETYPE) {
-    did_filetype = true;
+    curbuf->b_did_filetype = true;
   }
 
   char *tail = path_tail(fname);
@@ -1864,7 +1864,7 @@ bool apply_autocmds_group(event_T event, char *fname, char *fname_io, bool force
     if (did_save_redobuff) {
       restoreRedobuff(&save_redo);
     }
-    did_filetype = false;
+    curbuf->b_did_filetype = false;
     while (au_pending_free_buf != NULL) {
       buf_T *b = au_pending_free_buf->b_next;
 
@@ -1901,7 +1901,7 @@ BYPASS_AU:
   }
 
   if (retval == OK && event == EVENT_FILETYPE) {
-    au_did_filetype = true;
+    curbuf->b_au_did_filetype = true;
   }
 
   return retval;
@@ -2645,7 +2645,7 @@ void do_filetype_autocmd(buf_T *buf, bool force)
   secure = 0;
 
   ft_recursive++;
-  did_filetype = true;
+  buf->b_did_filetype = true;
   // Only pass true for "force" when it is true or
   // used recursively, to avoid endless recurrence.
   apply_autocmds(EVENT_FILETYPE, buf->b_p_ft, buf->b_fname, force || ft_recursive == 1, buf);
diff --git a/src/nvim/autocmd.h b/src/nvim/autocmd.h
index 8019cb7145..b298fbb6a1 100644
--- a/src/nvim/autocmd.h
+++ b/src/nvim/autocmd.h
@@ -15,14 +15,6 @@
 #include "nvim/pos_defs.h"
 #include "nvim/types_defs.h"
 
-// Set by the apply_autocmds_group function if the given event is equal to
-// EVENT_FILETYPE. Used by the readfile function in order to determine if
-// EVENT_BUFREADPOST triggered the EVENT_FILETYPE.
-//
-// Relying on this value requires one to reset it prior calling
-// apply_autocmds_group.
-EXTERN bool au_did_filetype INIT( = false);
-
 /// For CursorMoved event
 EXTERN win_T *last_cursormoved_win INIT( = NULL);
 /// For CursorMoved event, only used when last_cursormoved_win == curwin
@@ -31,9 +23,6 @@ EXTERN pos_T last_cursormoved INIT( = { 0, 0, 0 });
 EXTERN bool autocmd_busy INIT( = false);     ///< Is apply_autocmds() busy?
 EXTERN int autocmd_no_enter INIT( = false);  ///< Buf/WinEnter autocmds disabled
 EXTERN int autocmd_no_leave INIT( = false);  ///< Buf/WinLeave autocmds disabled
-EXTERN bool did_filetype INIT( = false);     ///< FileType event found
-/// value for did_filetype when starting to execute autocommands
-EXTERN bool keep_filetype INIT( = false);
 
 /// When deleting the current buffer, another one must be loaded.
 /// If we know which one is preferred, au_new_curbuf is set to it.
diff --git a/src/nvim/buffer.c b/src/nvim/buffer.c
index 3c2d52e6ad..39d0d24d47 100644
--- a/src/nvim/buffer.c
+++ b/src/nvim/buffer.c
@@ -267,7 +267,7 @@ int open_buffer(bool read_stdin, exarg_T *eap, int flags_arg)
   // The autocommands in readfile() may change the buffer, but only AFTER
   // reading the file.
   set_bufref(&old_curbuf, curbuf);
-  modified_was_set = false;
+  curbuf->b_modified_was_set = false;
 
   // mark cursor position as being invalid
   curwin->w_valid = 0;
@@ -350,7 +350,7 @@ int open_buffer(bool read_stdin, exarg_T *eap, int flags_arg)
   // the changed flag.  Unless in readonly mode: "ls | nvim -R -".
   // When interrupted and 'cpoptions' contains 'i' set changed flag.
   if ((got_int && vim_strchr(p_cpo, CPO_INTMOD) != NULL)
-      || modified_was_set               // ":set modified" used in autocmd
+      || curbuf->b_modified_was_set  // autocmd did ":set modified"
       || (aborting() && vim_strchr(p_cpo, CPO_INTMOD) != NULL)) {
     changed(curbuf);
   } else if (retval != FAIL && !read_stdin && !read_fifo) {
@@ -1725,7 +1725,7 @@ void enter_buffer(buf_T *buf)
     // ":ball" used in an autocommand.  If there already is a filetype we
     // might prefer to keep it.
     if (*curbuf->b_p_ft == NUL) {
-      did_filetype = false;
+      curbuf->b_did_filetype = false;
     }
 
     open_buffer(false, NULL, 0);
diff --git a/src/nvim/buffer_defs.h b/src/nvim/buffer_defs.h
index 7f7300706c..083508fe86 100644
--- a/src/nvim/buffer_defs.h
+++ b/src/nvim/buffer_defs.h
@@ -461,6 +461,19 @@ struct file_buffer {
 
   bool b_marks_read;            // Have we read ShaDa marks yet?
 
+  bool b_modified_was_set;  ///< did ":set modified"
+  bool b_did_filetype;      ///< FileType event found
+  bool b_keep_filetype;     ///< value for did_filetype when starting
+                            ///< to execute autocommands
+
+  /// Set by the apply_autocmds_group function if the given event is equal to
+  /// EVENT_FILETYPE. Used by the readfile function in order to determine if
+  /// EVENT_BUFREADPOST triggered the EVENT_FILETYPE.
+  ///
+  /// Relying on this value requires one to reset it prior calling
+  /// apply_autocmds_group().
+  bool b_au_did_filetype;
+
   // The following only used in undo.c.
   u_header_T *b_u_oldhead;     // pointer to oldest header
   u_header_T *b_u_newhead;     // pointer to newest header; may not be valid
diff --git a/src/nvim/eval/funcs.c b/src/nvim/eval/funcs.c
index 99da15ddd7..d3fe2c7e33 100644
--- a/src/nvim/eval/funcs.c
+++ b/src/nvim/eval/funcs.c
@@ -1361,7 +1361,7 @@ static void f_dictwatcherdel(typval_T *argvars, typval_T *rettv, EvalFuncData fp
 /// "did_filetype()" function
 static void f_did_filetype(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
 {
-  rettv->vval.v_number = did_filetype;
+  rettv->vval.v_number = curbuf->b_did_filetype;
 }
 
 /// "diff_filler()" function
diff --git a/src/nvim/ex_cmds.c b/src/nvim/ex_cmds.c
index dd30cdbba4..6c997b9500 100644
--- a/src/nvim/ex_cmds.c
+++ b/src/nvim/ex_cmds.c
@@ -2466,7 +2466,7 @@ int do_ecmd(int fnum, char *ffname, char *sfname, exarg_T *eap, linenr_T newlnum
   // Since we are starting to edit a file, consider the filetype to be
   // unset.  Helps for when an autocommand changes files and expects syntax
   // highlighting to work in the other file.
-  did_filetype = false;
+  curbuf->b_did_filetype = false;
 
   // other_file oldbuf
   //  false     false       re-edit same file, buffer is re-used
diff --git a/src/nvim/ex_docmd.c b/src/nvim/ex_docmd.c
index ee738d9e92..318d2e4ff2 100644
--- a/src/nvim/ex_docmd.c
+++ b/src/nvim/ex_docmd.c
@@ -7382,7 +7382,7 @@ void filetype_maybe_enable(void)
 /// ":setfiletype [FALLBACK] {name}"
 static void ex_setfiletype(exarg_T *eap)
 {
-  if (did_filetype) {
+  if (curbuf->b_did_filetype) {
     return;
   }
 
@@ -7393,7 +7393,7 @@ static void ex_setfiletype(exarg_T *eap)
 
   set_option_value_give_err(kOptFiletype, CSTR_AS_OPTVAL(arg), OPT_LOCAL);
   if (arg != eap->arg) {
-    did_filetype = false;
+    curbuf->b_did_filetype = false;
   }
 }
 
diff --git a/src/nvim/fileio.c b/src/nvim/fileio.c
index 6b50b031a3..df9c4928c9 100644
--- a/src/nvim/fileio.c
+++ b/src/nvim/fileio.c
@@ -234,7 +234,7 @@ int readfile(char *fname, char *sfname, linenr_T from, linenr_T lines_to_skip,
   int using_b_fname;
   static char *msg_is_a_directory = N_("is a directory");
 
-  au_did_filetype = false;  // reset before triggering any autocommands
+  curbuf->b_au_did_filetype = false;  // reset before triggering any autocommands
 
   curbuf->b_no_eol_lnum = 0;    // in case it was set by the previous read
 
@@ -1854,7 +1854,7 @@ failed:
     } else if (newfile || (read_buffer && sfname != NULL)) {
       apply_autocmds_exarg(EVENT_BUFREADPOST, NULL, sfname,
                            false, curbuf, eap);
-      if (!au_did_filetype && *curbuf->b_p_ft != NUL) {
+      if (!curbuf->b_au_did_filetype && *curbuf->b_p_ft != NUL) {
         // EVENT_FILETYPE was not triggered but the buffer already has a
         // filetype.  Trigger EVENT_FILETYPE using the existing filetype.
         apply_autocmds(EVENT_FILETYPE, curbuf->b_p_ft, curbuf->b_fname, true, curbuf);
@@ -3151,7 +3151,7 @@ void buf_reload(buf_T *buf, int orig_mode, bool reload_options)
 
   if (saved == OK) {
     curbuf->b_flags |= BF_CHECK_RO;           // check for RO again
-    keep_filetype = true;                     // don't detect 'filetype'
+    curbuf->b_keep_filetype = true;           // don't detect 'filetype'
     if (readfile(buf->b_ffname, buf->b_fname, 0, 0,
                  (linenr_T)MAXLNUM, &ea, flags, shortmess(SHM_FILEINFO)) != OK) {
       if (!aborting()) {
@@ -3199,7 +3199,7 @@ void buf_reload(buf_T *buf, int orig_mode, bool reload_options)
   curwin->w_cursor = old_cursor;
   check_cursor(curwin);
   update_topline(curwin);
-  keep_filetype = false;
+  curbuf->b_keep_filetype = false;
 
   // Update folds unless they are defined manually.
   FOR_ALL_TAB_WINDOWS(tp, wp) {
diff --git a/src/nvim/globals.h b/src/nvim/globals.h
index bb9aca38b7..83fef1fe75 100644
--- a/src/nvim/globals.h
+++ b/src/nvim/globals.h
@@ -341,8 +341,6 @@ EXTERN bool did_check_timestamps INIT( = false);   // did check timestamps
                                                    // recently
 EXTERN int no_check_timestamps INIT( = 0);         // Don't check timestamps
 
-EXTERN int modified_was_set;                     // did ":set modified"
-
 // Mouse coordinates, set by handle_mouse_event()
 EXTERN int mouse_grid;
 EXTERN int mouse_row;
diff --git a/src/nvim/option.c b/src/nvim/option.c
index 2c7922908c..799513e018 100644
--- a/src/nvim/option.c
+++ b/src/nvim/option.c
@@ -2244,7 +2244,7 @@ static const char *did_set_modified(optset_T *args)
     save_file_ff(buf);  // Buffer is unchanged
   }
   redraw_titles();
-  modified_was_set = (int)args->os_newval.boolean;
+  buf->b_modified_was_set = (int)args->os_newval.boolean;
   return NULL;
 }
 
diff --git a/src/nvim/quickfix.c b/src/nvim/quickfix.c
index 9f431556e8..94e176bd94 100644
--- a/src/nvim/quickfix.c
+++ b/src/nvim/quickfix.c
@@ -4274,10 +4274,10 @@ static void qf_fill_buffer(qf_list_T *qfl, buf_T *buf, qfline_T *old_last, int q
     set_option_value_give_err(kOptFiletype, STATIC_CSTR_AS_OPTVAL("qf"), OPT_LOCAL);
     curbuf->b_p_ma = false;
 
-    keep_filetype = true;                 // don't detect 'filetype'
+    curbuf->b_keep_filetype = true;  // don't detect 'filetype'
     apply_autocmds(EVENT_BUFREADPOST, "quickfix", NULL, false, curbuf);
     apply_autocmds(EVENT_BUFWINENTER, "quickfix", NULL, false, curbuf);
-    keep_filetype = false;
+    curbuf->b_keep_filetype = false;
     curbuf->b_ro_locked--;
 
     // make sure it will be redrawn
diff --git a/test/old/testdir/test_autocmd.vim b/test/old/testdir/test_autocmd.vim
index 9dbd4ac521..61de6775fb 100644
--- a/test/old/testdir/test_autocmd.vim
+++ b/test/old/testdir/test_autocmd.vim
@@ -3977,4 +3977,81 @@ func Test_Changed_ChangedI_2()
   call delete('XTextChangedI3')
 endfunc
 
+" Test that filetype detection still works when SwapExists autocommand sets
+" filetype in another buffer.
+func Test_SwapExists_set_other_buf_filetype()
+  let lines =<< trim END
+    set nocompatible directory=.
+    filetype on
+
+    let g:buf = bufnr()
+    new
+
+    func SwapExists()
+      let v:swapchoice = 'o'
+      call setbufvar(g:buf, '&filetype', 'text')
+    endfunc
+
+    func SafeState()
+      edit <script>
+      redir! > XftSwapExists.out
+        set readonly? filetype?
+      redir END
+      qall!
+    endfunc
+
+    autocmd SwapExists * ++nested call SwapExists()
+    autocmd SafeState * ++nested ++once call SafeState()
+  END
+  call writefile(lines, 'XftSwapExists.vim', 'D')
+
+  new XftSwapExists.vim
+  if RunVim('', '', ' -S XftSwapExists.vim')
+    call assert_equal(
+          \ ['', '  readonly', '  filetype=vim'],
+          \ readfile('XftSwapExists.out'))
+    call delete('XftSwapExists.out')
+  endif
+
+  bwipe!
+endfunc
+
+" Test that file is not marked as modified when SwapExists autocommand sets
+" 'modified' in another buffer.
+func Test_SwapExists_set_other_buf_modified()
+  let lines =<< trim END
+    set nocompatible directory=.
+
+    let g:buf = bufnr()
+    new
+
+    func SwapExists()
+      let v:swapchoice = 'o'
+      call setbufvar(g:buf, '&modified', 1)
+    endfunc
+
+    func SafeState()
+      edit <script>
+      redir! > XmodSwapExists.out
+        set readonly? modified?
+      redir END
+      qall!
+    endfunc
+
+    autocmd SwapExists * ++nested call SwapExists()
+    autocmd SafeState * ++nested ++once call SafeState()
+  END
+  call writefile(lines, 'XmodSwapExists.vim', 'D')
+
+  new XmodSwapExists.vim
+  if RunVim('', '', ' -S XmodSwapExists.vim')
+    call assert_equal(
+          \ ['', '  readonly', 'nomodified'],
+          \ readfile('XmodSwapExists.out'))
+    call delete('XmodSwapExists.out')
+  endif
+
+  bwipe!
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab