patch 8.0.0649: when opening a help file the filetype is set several timesv8.0.0649

Problem:    When opening a help file the filetype is set several times.
Solution:   When setting the filetype to the same value from a modeline, don't
            trigger FileType autocommands.  Don't set the filetype to "help"
            when it's already set correctly.

4 files changed, 22 insertions, 6 deletions

diff --git a/runtime/filetype.vim b/runtime/filetype.vim
index 635e1c3ce..d676329bd 100644
--- a/runtime/filetype.vim
+++ b/runtime/filetype.vim
@@ -1,7 +1,7 @@
 " Vim support file to detect file types
 "
 " Maintainer:	Bram Moolenaar <Bram@vim.org>
-" Last Change:	2017 Jun 12
+" Last Change:	2017 Jun 20
 
 " Listen very carefully, I will say this only once
 if exists("did_load_filetypes")
@@ -48,6 +48,9 @@ func! s:StarSetf(ft)
   endif
 endfunc
 
+" Vim help file
+au BufNewFile,BufRead $VIMRUNTIME/doc/*.txt	setf help
+
 " Abaqus or Trasys
 au BufNewFile,BufRead *.inp			call s:Check_inp()
 
diff --git a/src/ex_cmds.c b/src/ex_cmds.c
index 59531bea0..adf1e3bd2 100644
--- a/src/ex_cmds.c
+++ b/src/ex_cmds.c
@@ -6832,8 +6832,9 @@ fix_help_buffer(void)
     char_u	*rt;
     int		mustfree;
 
-    /* set filetype to "help". */
-    set_option_value((char_u *)"ft", 0L, (char_u *)"help", OPT_LOCAL);
+    /* Set filetype to "help" if still needed. */
+    if (STRCMP(curbuf->b_p_ft, "help") != 0)
+	set_option_value((char_u *)"ft", 0L, (char_u *)"help", OPT_LOCAL);
 
 #ifdef FEAT_SYN_HL
     if (!syntax_present(curwin))
diff --git a/src/option.c b/src/option.c
index 2a92bc5ae..154c28b5a 100644
--- a/src/option.c
+++ b/src/option.c
@@ -6009,6 +6009,9 @@ did_set_string_option(
     /* set when changing an option that only requires a redraw in the GUI */
     int		redraw_gui_only = FALSE;
 #endif
+#ifdef FEAT_AUTOCMD
+    int		ft_changed = FALSE;
+#endif
 
     /* Get the global option to compare with, otherwise we would have to check
      * two values for all local options. */
@@ -7418,6 +7421,8 @@ did_set_string_option(
     {
 	if (!valid_filetype(*varp))
 	    errmsg = e_invarg;
+	else
+	    ft_changed = STRCMP(oldval, *varp) != 0;
     }
 #endif
 
@@ -7531,10 +7536,15 @@ did_set_string_option(
 # endif
 	else if (varp == &(curbuf->b_p_ft))
 	{
-	    /* 'filetype' is set, trigger the FileType autocommand */
-	    did_filetype = TRUE;
-	    apply_autocmds(EVENT_FILETYPE, curbuf->b_p_ft,
+	    /* 'filetype' is set, trigger the FileType autocommand.
+	     * Skip this when called from a modeline and the filetype was
+	     * already set to this value. */
+	    if (!(opt_flags & OPT_MODELINE) || ft_changed)
+	    {
+		did_filetype = TRUE;
+		apply_autocmds(EVENT_FILETYPE, curbuf->b_p_ft,
 					       curbuf->b_fname, TRUE, curbuf);
+	    }
 	}
 #endif
 #ifdef FEAT_SPELL
diff --git a/src/version.c b/src/version.c
index b221ce259..47e1da5ec 100644
--- a/src/version.c
+++ b/src/version.c
@@ -765,6 +765,8 @@ static char *(features[]) =
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    649,
+/**/
     648,
 /**/
     647,