patch 8.0.1393: too much highlighting with 'hlsearch' and 'incsearch' set

Problem:    Too much highlighting with 'hlsearch' and 'incsearch' set.
Solution:   Do not highlight matches when the pattern matches everything.

Author: brammool

src/ex_getln.c

@@ -172,6 +172,22 @@ abandon_cmdline(void)
     redraw_cmdline = TRUE;
 }
 
+/*
+ * Guess that the pattern matches everything.  Only finds specific cases, such
+ * as a trailing \|, which can happen while typing a pattern.
+ */
+    static int
+empty_pattern(char_u *p)
+{
+    int n = STRLEN(p);
+
+    /* remove trailing \v and the like */
+    while (n >= 2 && p[n - 2] == '\\'
+			  && vim_strchr((char_u *)"mMvVcCZ", p[n - 1]) != NULL)
+	n -= 2;
+    return n == 0 || (n >= 2 && p[n - 2] == '\\' && p[n - 1] == '|');
+}
+
 /*
  * getcmdline() - accept a command line starting with firstc.
  *
@@ -2023,6 +2039,11 @@ getcmdline(
 	    else
 		end_pos = curwin->w_cursor; /* shutup gcc 4 */
 
+	    /* Disable 'hlsearch' highlighting if the pattern matches
+	     * everything. Avoids a flash when typing "foo\|". */
+	    if (empty_pattern(ccline.cmdbuff))
+		SET_NO_HLSEARCH(TRUE);
+
 	    validate_cursor();
 	    /* May redraw the status line to show the cursor position. */
 	    if (p_ru && curwin->w_status_height > 0)

src/version.c

@@ -771,6 +771,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1393,
 /**/
     1392,
 /**/