patch 8.1.0116: display problem with 'vartabstop' and 'linebreak'

Problem:    Display problem with 'vartabstop' and 'linebreak'. (Chauca
            Fuentes)
Solution:   Call tabstop_padding(). (Christian Brabandt, closes #3076)

Author: brammool

src/screen.c

@@ -4753,8 +4753,13 @@ win_line(
 		    n_extra = win_lbr_chartabsize(wp, line, p, (colnr_T)vcol,
 								    NULL) - 1;
 		    if (c == TAB && n_extra + col > wp->w_width)
+#ifdef FEAT_VARTABS
+			n_extra = tabstop_padding(vcol, wp->w_buffer->b_p_ts,
+					wp->w_buffer->b_p_vts_array) - 1;
+#else
 			n_extra = (int)wp->w_buffer->b_p_ts
 				       - vcol % (int)wp->w_buffer->b_p_ts - 1;
+ #endif
 
 # ifdef FEAT_MBYTE
 		    c_extra = mb_off > 0 ? MB_FILLER_CHAR : ' ';

src/testdir/test_vartabs.vim

@@ -4,6 +4,11 @@ if !has("vartabs")
   finish
 endif
 
+source view_util.vim
+function! s:compare_lines(expect, actual)
+  call assert_equal(join(a:expect, "\n"), join(a:actual, "\n"))
+endfunction
+
 func! Test_vartabs()
   new
   %d
@@ -255,3 +260,23 @@ func! Test_vartabs_breakindent()
 
   bwipeout!
 endfunc
+
+func! Test_vartabs_linebreak()
+  if winwidth(0) < 80
+    return
+  endif
+  new
+  70vnew
+  %d
+  setl linebreak vartabstop=10,15,20,40
+  call setline(1, "\tx\tx\tx\tx")
+
+  let lines = ScreenLines([1, 2], winwidth(0))
+  let expect = ['          x              x                   x                        ',
+        \       '               x                                                      ']
+  call s:compare_lines(expect, lines)
+
+  " cleanup
+  bw!
+  bw!
+endfunc

src/version.c

@@ -789,6 +789,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    116,
 /**/
     115,
 /**/