patch 8.2.3547: opening the quickfix window triggers BufWinEnter twice

Problem:    Opening the quickfix window triggers BufWinEnter twice. (Yorick
            Peterse)
Solution:   Only trigger BufWinEnter with "quickfix". (closes #9022)

src/buffer.c

@@ -360,11 +360,12 @@ open_buffer(
 	    do_modelines(0);
 	    curbuf->b_flags &= ~(BF_CHECK_RO | BF_NEVERLOADED);
 
+	    if ((flags & READ_NOWINENTER) == 0)
 #ifdef FEAT_EVAL
-	    apply_autocmds_retval(EVENT_BUFWINENTER, NULL, NULL, FALSE, curbuf,
-								      &retval);
+		apply_autocmds_retval(EVENT_BUFWINENTER, NULL, NULL, FALSE,
+							      curbuf, &retval);
 #else
-	    apply_autocmds(EVENT_BUFWINENTER, NULL, NULL, FALSE, curbuf);
+		apply_autocmds(EVENT_BUFWINENTER, NULL, NULL, FALSE, curbuf);
 #endif
 
 	    // restore curwin/curbuf and a few other things

src/ex_cmds.c

@@ -2473,6 +2473,7 @@ theend:
  *	ECMD_FORCEIT: ! used for Ex command
  *	 ECMD_ADDBUF: don't edit, just add to buffer list
  *	 ECMD_ALTBUF: like ECMD_ADDBUF and also set the alternate file
+ *   ECMD_NOWINENTER: Do not trigger BufWinEnter
  *   oldwin: Should be "curwin" when editing a new buffer in the current
  *	     window, NULL when splitting the window first.  When not NULL info
  *	     of the previous buffer for "oldwin" is stored.
@@ -3030,6 +3031,8 @@ do_ecmd(
 	    /*
 	     * Open the buffer and read the file.
 	     */
+	    if (flags & ECMD_NOWINENTER)
+		readfile_flags |= READ_NOWINENTER;
 #if defined(FEAT_EVAL)
 	    if (should_abort(open_buffer(FALSE, eap, readfile_flags)))
 		retval = FAIL;
@@ -3051,10 +3054,11 @@ do_ecmd(
 	    // changed by the user.
 	    do_modelines(OPT_WINONLY);
 
-	    apply_autocmds_retval(EVENT_BUFENTER, NULL, NULL, FALSE, curbuf,
-								    &retval);
-	    apply_autocmds_retval(EVENT_BUFWINENTER, NULL, NULL, FALSE, curbuf,
-								    &retval);
+	    apply_autocmds_retval(EVENT_BUFENTER, NULL, NULL, FALSE,
+							      curbuf, &retval);
+	    if ((flags & ECMD_NOWINENTER) == 0)
+		apply_autocmds_retval(EVENT_BUFWINENTER, NULL, NULL, FALSE,
+							      curbuf, &retval);
 	}
 	check_arg_idx(curwin);
 

src/quickfix.c

@@ -4199,13 +4199,14 @@ qf_open_new_cwindow(qf_info_T *qi, int height)
     {
 	// Use the existing quickfix buffer
 	if (do_ecmd(qf_buf->b_fnum, NULL, NULL, NULL, ECMD_ONE,
-				      ECMD_HIDE + ECMD_OLDBUF, oldwin) == FAIL)
+		    ECMD_HIDE + ECMD_OLDBUF + ECMD_NOWINENTER, oldwin) == FAIL)
 	    return FAIL;
     }
     else
     {
 	// Create a new quickfix buffer
-	if (do_ecmd(0, NULL, NULL, NULL, ECMD_ONE, ECMD_HIDE, oldwin) == FAIL)
+	if (do_ecmd(0, NULL, NULL, NULL, ECMD_ONE, ECMD_HIDE + ECMD_NOWINENTER,
+							       oldwin) == FAIL)
 	    return FAIL;
 
 	// save the number of the new buffer

src/testdir/test_quickfix.vim

@@ -786,6 +786,23 @@ func Test_vimgreptitle()
   augroup! QfBufWinEnter
 endfunc
 
+func Test_bufwinenter_once()
+  augroup QfBufWinEnter
+    au!
+    au BufWinEnter * let g:got_afile ..= 'got ' .. expand('<afile>')
+  augroup END
+  let g:got_afile = ''
+  copen
+  call assert_equal('got quickfix', g:got_afile)
+
+  cclose
+  unlet g:got_afile
+  augroup QfBufWinEnter
+    au!
+  augroup END
+  augroup! QfBufWinEnter
+endfunc
+
 func XqfTitleTests(cchar)
   call s:setup_commands(a:cchar)
 

src/version.c

@@ -757,6 +757,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    3547,
 /**/
     3546,
 /**/

src/vim.h

@@ -977,6 +977,7 @@ extern int (*dyn_libintl_wputenv)(const wchar_t *envstring);
 #define READ_DUMMY	0x10	// reading into a dummy buffer
 #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
 
 // Values for change_indent()
 #define INDENT_SET	1	// set indent
@@ -1043,6 +1044,7 @@ extern int (*dyn_libintl_wputenv)(const wchar_t *envstring);
 #define ECMD_FORCEIT	0x08	// ! used in Ex command
 #define ECMD_ADDBUF	0x10	// don't edit, just add to buffer list
 #define ECMD_ALTBUF	0x20	// like ECMD_ADDBUF and set the alternate file
+#define ECMD_NOWINENTER	0x40	// do not trigger BufWinEnter
 
 // for lnum argument in do_ecmd()
 #define ECMD_LASTL	(linenr_T)0	// use last position in loaded file