patch 8.2.2542: highlight of char beyond line end is not correct

Problem:    Highlight of char beyond line end is not correct. (Chuan Wei Foo)
Solution:   Fix counting NUL as one cell.  Draw one more character if the EOL
            is part of the match. (closes #7883)

src/match.c

@@ -792,7 +792,15 @@ update_search_hl(
 			// highlight empty match, try again after
 			// it
 			if (has_mbyte)
-			    shl->endcol += (*mb_ptr2len)(*line + shl->endcol);
+			{
+			    char_u *p = *line + shl->endcol;
+
+			    if (*p == NUL)
+				// consistent with non-mbyte
+				++shl->endcol;
+			    else
+				shl->endcol += (*mb_ptr2len)(p);
+			}
 			else
 			    ++shl->endcol;
 		    }
@@ -842,18 +850,31 @@ get_prevcol_hl_flag(win_T *wp, match_T *search_hl, long curcol)
     int		prevcol_hl_flag = FALSE;
     matchitem_T *cur;			// points to the match list
 
+#if defined(FEAT_PROP_POPUP)
+    // don't do this in a popup window
+    if (popup_is_popup(wp))
+	return FALSE;
+#endif
+
     // we're not really at that column when skipping some text
     if ((long)(wp->w_p_wrap ? wp->w_skipcol : wp->w_leftcol) > prevcol)
 	++prevcol;
 
-    if (!search_hl->is_addpos && prevcol == (long)search_hl->startcol)
+    // Highlight a character after the end of the line if the match started
+    // at the end of the line or when the match continues in the next line
+    // (match includes the line break).
+    if (!search_hl->is_addpos && (prevcol == (long)search_hl->startcol
+		|| (prevcol > (long)search_hl->startcol
+					      && search_hl->endcol == MAXCOL)))
 	prevcol_hl_flag = TRUE;
     else
     {
 	cur = wp->w_match_head;
 	while (cur != NULL)
 	{
-	    if (!cur->hl.is_addpos && prevcol == (long)cur->hl.startcol)
+	    if (!cur->hl.is_addpos && (prevcol == (long)cur->hl.startcol
+			|| (prevcol > (long)cur->hl.startcol
+						 && cur->hl.endcol == MAXCOL)))
 	    {
 		prevcol_hl_flag = TRUE;
 		break;

src/testdir/dumps/Test_hlsearch_1.dump

@@ -0,0 +1,6 @@
+|x+0&#ffff4012@2| | +0&#ffffff0@45
+>x+8&#ffff4012@2| | +8&#ffffff0@45
+|x+0&#ffff4012@2| | +0&#ffffff0@45
+|~+0#4040ff13&| @48
+|~| @48
+| +0#0000000&@31|2|,|1| @10|A|l@1| 

src/testdir/dumps/Test_hlsearch_2.dump

@@ -0,0 +1,6 @@
+|x+0&#ffff4012@2| | +0&#ffffff0@45
+|x+0&#ffff4012@2| | +0&#ffffff0@45
+>x+8&#ffff4012@2| | +8&#ffffff0@45
+|~+0#4040ff13&| @48
+|~| @48
+|/+0#0000000&|\|_|.|*| @26|3|,|1| @10|A|l@1| 

src/testdir/test_search.vim

@@ -944,6 +944,26 @@ func Test_incsearch_search_dump()
   call delete('Xis_search_script')
 endfunc
 
+func Test_hlsearch_dump()
+  CheckOption hlsearch
+  CheckScreendump
+
+  call writefile([
+	\ 'set hlsearch cursorline',
+        \ 'call setline(1, ["xxx", "xxx", "xxx"])',
+	\ '/.*',
+	\ '2',
+	\ ], 'Xhlsearch_script')
+  let buf = RunVimInTerminal('-S Xhlsearch_script', {'rows': 6, 'cols': 50})
+  call VerifyScreenDump(buf, 'Test_hlsearch_1', {})
+
+  call term_sendkeys(buf, "/\\_.*\<CR>")
+  call VerifyScreenDump(buf, 'Test_hlsearch_2', {})
+
+  call StopVimInTerminal(buf)
+  call delete('Xhlsearch_script')
+endfunc
+
 func Test_incsearch_substitute()
   CheckOption incsearch
 

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2542,
 /**/
     2541,
 /**/