patch 8.0.1053: setline() does not work on startup

Problem:    setline() does not work on startup. (Manuel Ortega)
Solution:   Do not check for ml_mfp to be set for the current buffer.
            (Christian Brabandt)

src/evalfunc.c

@@ -9885,7 +9885,10 @@ set_buffer_lines(buf_T *buf, linenr_T lnum, typval_T *lines, typval_T *rettv)
     buf_T	*curbuf_save;
     int		is_curbuf = buf == curbuf;
 
-    if (buf == NULL || buf->b_ml.ml_mfp == NULL || lnum < 1)
+    /* When using the current buffer ml_mfp will be set if needed.  Useful when
+     * setline() is used on startup.  For other buffers the buffer must be
+     * loaded. */
+    if (buf == NULL || (!is_curbuf && buf->b_ml.ml_mfp == NULL) || lnum < 1)
     {
 	rettv->vval.v_number = 1;	/* FAIL */
 	return;

src/testdir/shared.vim

@@ -166,15 +166,21 @@ func s:feedkeys(timer)
 endfunc
 
 " Get the command to run Vim, with -u NONE and --not-a-term arguments.
+" If there is an argument use it instead of "NONE".
 " Returns an empty string on error.
-func GetVimCommand()
+func GetVimCommand(...)
   if !filereadable('vimcmd')
     return ''
   endif
+  if a:0 == 0
+    let name = 'NONE'
+  else
+    let name = a:1
+  endif
   let cmd = readfile('vimcmd')[0]
-  let cmd = substitute(cmd, '-u \f\+', '-u NONE', '')
-  if cmd !~ '-u NONE'
-    let cmd = cmd . ' -u NONE'
+  let cmd = substitute(cmd, '-u \f\+', '-u ' . name, '')
+  if cmd !~ '-u '. name
+    let cmd = cmd . ' -u ' . name
   endif
   let cmd .= ' --not-a-term'
   let cmd = substitute(cmd, 'VIMRUNTIME=.*VIMRUNTIME;', '', '')

src/testdir/test_alot.vim

@@ -1,6 +1,8 @@
 " A series of tests that can run in one Vim invocation.
 " This makes testing go faster, since Vim doesn't need to restart.
 
+source shared.vim
+
 set belloff=all
 source test_assign.vim
 source test_bufline.vim

src/testdir/test_bufline.vim

@@ -24,3 +24,16 @@ func Test_setbufline_getbufline()
   call assert_equal([], getbufline(b, 6))
   exe "bwipe! " . b
 endfunc
+
+func Test_setline_startup()
+  let cmd = GetVimCommand('Xscript')
+  if cmd == ''
+    return
+  endif
+  call writefile(['call setline(1, "Hello")', 'w Xtest', 'q!'], 'Xscript')
+  call system(cmd)
+  call assert_equal(['Hello'], readfile('Xtest'))
+
+  call delete('Xscript')
+  call delete('Xtest')
+endfunc

src/testdir/test_timers.vim

@@ -1,7 +1,5 @@
 " Test for timers
 
-source shared.vim
-
 if !has('timers')
   finish
 endif

src/version.c

@@ -769,6 +769,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1053,
 /**/
     1052,
 /**/