vim-patch:9.0.0272: BufReadCmd not triggered when loading a "nofile" buffer

Problem:    BufReadCmd not triggered when loading a "nofile" buffer. (Maxim
            Kim)
Solution:   Call readfile() but bail out before reading a file.
            (closes vim/vim#10983)
b1d2c8116c

src/nvim/buffer.c

@@ -165,11 +165,12 @@ static int read_buffer(int read_stdin, exarg_T *eap, int flags)
 ///
 /// @param read_stdin  read file from stdin
 /// @param eap  for forced 'ff' and 'fenc' or NULL
-/// @param flags  extra flags for readfile()
+/// @param flags_arg  extra flags for readfile()
 ///
 /// @return  FAIL for failure, OK otherwise.
-int open_buffer(int read_stdin, exarg_T *eap, int flags)
+int open_buffer(int read_stdin, exarg_T *eap, int flags_arg)
 {
+  int flags = flags_arg;
   int retval = OK;
   bufref_T old_curbuf;
   long old_tw = curbuf->b_p_tw;
@@ -224,8 +225,14 @@ int open_buffer(int read_stdin, exarg_T *eap, int flags)
   // mark cursor position as being invalid
   curwin->w_valid = 0;
 
+  // A buffer without an actual file should not use the buffer name to read a
+  // file.
+  if (bt_quickfix(curbuf) || bt_nofilename(curbuf)) {
+    flags |= READ_NOFILE;
+  }
+
   // Read the file if there is one.
-  if (curbuf->b_ffname != NULL && !bt_quickfix(curbuf) && !bt_nofilename(curbuf)) {
+  if (curbuf->b_ffname != NULL) {
 #ifdef UNIX
     int save_bin = curbuf->b_p_bin;
     int perm;

src/nvim/fileio.c

@@ -167,6 +167,7 @@ void filemess(buf_T *buf, char_u *name, char_u *s, int attr)
 /// READ_STDIN   read from stdin instead of a file
 /// READ_BUFFER  read from curbuf instead of a file (converting after reading
 ///              stdin)
+/// READ_NOFILE  do not read a file, only trigger BufReadCmd
 /// READ_DUMMY   read into a dummy buffer (to check if file contents changed)
 /// READ_KEEP_UNDO  don't clear undo info or read it from a file
 /// READ_FIFO    read from fifo/socket instead of a file
@@ -334,6 +335,10 @@ int readfile(char *fname, char *sfname, linenr_T from, linenr_T lines_to_skip,
     }
 
     curbuf->b_op_start = orig_start;
+
+    if (flags & READ_NOFILE) {
+      return FAIL;
+    }
   }
 
   if ((shortmess(SHM_OVER) || curbuf->b_help) && p_verbose == 0) {

src/nvim/fileio.h

@@ -15,6 +15,7 @@
 #define READ_KEEP_UNDO  0x20    // keep undo info
 #define READ_FIFO       0x40    // read from fifo or socket
 #define READ_NOWINENTER 0x80    // do not trigger BufWinEnter
+#define READ_NOFILE     0x100   // do not read a file, do trigger BufReadCmd
 
 #define READ_STRING(x, y) (char_u *)read_string((x), (size_t)(y))
 

src/nvim/testdir/test_autocmd.vim

@@ -493,6 +493,18 @@ func Test_BufReadCmdHelpJump()
   au! BufReadCmd
 endfunc
 
+" BufReadCmd is triggered for a "nofile" buffer
+func Test_BufReadCmdNofile()
+  new somefile
+  set buftype=nofile
+  au BufReadCmd somefile call setline(1, 'triggered')
+  edit
+  call assert_equal('triggered', getline(1))
+
+  au! BufReadCmd
+  bwipe!
+endfunc
+
 func Test_augroup_deleted()
   " This caused a crash before E936 was introduced
   augroup x