patch 9.0.2095: statusline may look different than expected

Problem:  statusline may look different than expected
Solution: do not check for highlighting of stl and stlnc characters

statusline fillchar may be different than expected

If the highlighting group for the statusline for the current window
|hl-StatusLine| or the non-current window |hl-StatusLineNC| are cleared
(or do not differ from each other), than Vim will use the hard-coded
fallback values '^' (for the non-current windows) or '=' (for the
current window).  I believe this was done, to make sure the statusline
will always be visible and be distinguishable from the rest of the
window.

However, this may be unexpected, if a user explicitly defined those
fillchar characters just to notice that those values are then not used
by Vim.

So, let's assume users know what they are doing and just always return
the configured stl and stlnc values.  And if they want the statusline to
be non-distinguishable from the rest of the window space, so be it.  It
is their responsibility and Vim shall not know better what to use.

fixes: #13366
closes: #13488

Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/doc/options.txt

@@ -1,4 +1,4 @@
-*options.txt*	For Vim version 9.0.  Last change: 2023 Oct 23
+*options.txt*	For Vim version 9.0.  Last change: 2023 Nov 06
 
 
 		  VIM REFERENCE MANUAL	  by Bram Moolenaar
@@ -3494,8 +3494,8 @@ A jump table for the options with a short description can be found at |Q_op|.
 	and the value of that item:
 
 	  item name	default		Used for ~
-	  stl		' ' or '^'	statusline of the current window
-	  stlnc		' ' or '='	statusline of the non-current windows
+	  stl		' '		statusline of the current window
+	  stlnc		' '		statusline of the non-current windows
 	  vert		'|'		vertical separators |:vsplit|
 	  fold		'-'		filling 'foldtext'
 	  foldopen	'-'		mark the beginning of a fold
@@ -3505,15 +3505,11 @@ A jump table for the options with a short description can be found at |Q_op|.
 	  eob		'~'		empty lines below the end of a buffer
 	  lastline	'@'		'display' contains lastline/truncate
 
-	Any one that is omitted will fall back to the default.  For "stl" and
-	"stlnc" the space will be used when there is highlighting, '^' or '='
-	otherwise.
+	Any one that is omitted will fall back to the default.
 
 	Example: >
-	    :set fillchars=stl:^,stlnc:=,vert:\|,fold:-,diff:-
-<	This is similar to the default, except that these characters will also
-	be used when there is highlighting.
-
+	    :set fillchars=stl:\ ,stlnc:\ ,vert:\|,fold:-,diff:-
+<
 	For the "stl", "stlnc", "foldopen", "foldclose" and "foldsep" items
 	single-byte and multibyte characters are supported.  But double-width
 	characters are not supported.

src/screen.c

@@ -4462,16 +4462,7 @@ fillchar_status(int *attr, win_T *wp)
 	*attr = HL_ATTR(HLF_SNC);
 	fill = wp->w_fill_chars.stlnc;
     }
-    // Use fill when there is highlighting, and highlighting of current
-    // window differs, or the fillchars differ, or this is not the
-    // current window
-    if (*attr != 0 && ((HL_ATTR(HLF_S) != HL_ATTR(HLF_SNC)
-			|| wp != curwin || ONE_WINDOW)
-		    || (wp->w_fill_chars.stl != wp->w_fill_chars.stlnc)))
-	return fill;
-    if (wp == curwin)
-	return '^';
-    return '=';
+    return fill;
 }
 
 /*

src/testdir/dumps/Test_statusline_stl_1.dump

@@ -0,0 +1,20 @@
+> +0&#ffffff0@74
+|~+0#4040ff13&| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|[+0#0000000&|N|o| |N|a|m|e|]| @47|0|,|0|-|1| @9|A|l@1
+| @74
+|~+0#4040ff13&| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|[+0#0000000&|N|o| |N|a|m|e|]| @47|0|,|0|-|1| @9|A|l@1
+| @74

src/testdir/test_statusline.vim

@@ -610,4 +610,25 @@ func Test_statusline_showcmd()
   call StopVimInTerminal(buf)
 endfunc
 
+func Test_statusline_highlight_group_cleared()
+  CheckScreendump
+
+  " the laststatus option is there to prevent
+  " the code-style test from complaining about
+  " trailing whitespace
+  let lines =<< trim END
+    set fillchars=stl:\ ,stlnc:\  laststatus=2
+    split
+    hi clear StatusLine
+    hi clear StatusLineNC
+  END
+  call writefile(lines, 'XTest_statusline_stl', 'D')
+
+  let buf = RunVimInTerminal('-S XTest_statusline_stl', {})
+
+  call VerifyScreenDump(buf, 'Test_statusline_stl_1', {})
+
+  call StopVimInTerminal(buf)
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab

src/version.c

@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2095,
 /**/
     2094,
 /**/