patch 9.0.0673: first line wong with 'smoothscroll' and 'scrolloff' zero

Problem:    First line not scrolled properly with 'smoothscroll' and
            'scrolloff' zero and using "k".
Solution:   Make sure the cursor position is visible.

src/move.c

@@ -266,7 +266,7 @@ update_topline(void)
      */
     else
     {
-	if (curwin->w_topline > 1)
+	if (curwin->w_topline > 1 || curwin->w_skipcol > 0)
 	{
 	    // If the cursor is above topline, scrolling is always needed.
 	    // If the cursor is far below topline and there is no folding,
@@ -275,6 +275,16 @@ update_topline(void)
 		check_topline = TRUE;
 	    else if (check_top_offset())
 		check_topline = TRUE;
+	    else if (curwin->w_cursor.lnum == curwin->w_topline)
+	    {
+		colnr_T vcol;
+
+		// check the cursor position is visible.  Add 3 for the ">>>"
+		// displayed in the top-left.
+		getvvcol(curwin, &curwin->w_cursor, &vcol, NULL, NULL);
+		if (curwin->w_skipcol + 3 >= vcol)
+		    check_topline = TRUE;
+	    }
 	}
 #ifdef FEAT_DIFF
 	    // Check if there are more filler lines than allowed.
@@ -2007,6 +2017,7 @@ scroll_cursor_top(int min_scroll, int always)
     linenr_T	top;		// just above displayed lines
     linenr_T	bot;		// just below displayed lines
     linenr_T	old_topline = curwin->w_topline;
+    int		old_skipcol = curwin->w_skipcol;
 #ifdef FEAT_DIFF
     linenr_T	old_topfill = curwin->w_topfill;
 #endif
@@ -2118,7 +2129,14 @@ scroll_cursor_top(int min_scroll, int always)
 	}
 	check_topfill(curwin, FALSE);
 #endif
+	// TODO: if the line doesn't fit may optimize w_skipcol
+	if (curwin->w_topline == curwin->w_cursor.lnum)
+	{
+	    curwin->w_skipcol = 0;
+	    redraw_later(UPD_NOT_VALID);
+	}
 	if (curwin->w_topline != old_topline
+		|| curwin->w_skipcol != old_skipcol
 #ifdef FEAT_DIFF
 		|| curwin->w_topfill != old_topfill
 #endif

src/testdir/dumps/Test_smooth_wrap_5.dump

@@ -0,0 +1,8 @@
+>L+0&#ffffff0|i|n|e| |w|i|t|h| |s|o|m|e| |t|e|x|t| |w|i|t|h| |s|o|m|e| |t|e|x|t| |w|i|t|h| 
+|s|o|m|e| |t|e|x|t| |w|i|t|h| |s|o|m|e| |t|e|x|t| |w|i|t|h| |s|o|m|e| |t|e|x|t| 
+|w|i|t|h| |s|o|m|e| |t|e|x|t| |w|i|t|h| |s|o|m|e| |t|e|x|t| @10
+|L|i|n|e| |w|i|t|h| |s|o|m|e| |t|e|x|t| |w|i|t|h| |s|o|m|e| |t|e|x|t| |w|i|t|h| 
+|s|o|m|e| |t|e|x|t| |w|i|t|h| |s|o|m|e| |t|e|x|t| |w|i|t|h| |s|o|m|e| |t|e|x|t| 
+|w|i|t|h| |s|o|m|e| |t|e|x|t| |w|i|t|h| |s|o|m|e| |t|e|x|t| @10
+|@+0#4040ff13&@2| @36
+| +0#0000000&@21|5|,|1| @10|8|0|%| 

src/testdir/test_scroll_opt.vim

@@ -181,6 +181,7 @@ func Test_smoothscroll_wrap_scrolloff_zero()
 
   call VerifyScreenDump(buf, 'Test_smooth_wrap_1', {})
 
+  " moving cursor down - whole bottom line shows
   call term_sendkeys(buf, "j")
   call VerifyScreenDump(buf, 'Test_smooth_wrap_2', {})
 
@@ -190,6 +191,10 @@ func Test_smoothscroll_wrap_scrolloff_zero()
   call term_sendkeys(buf, "G")
   call VerifyScreenDump(buf, 'Test_smooth_wrap_4', {})
 
+  " moving cursor up - whole top line shows
+  call term_sendkeys(buf, "2k")
+  call VerifyScreenDump(buf, 'Test_smooth_wrap_5', {})
+
   call StopVimInTerminal(buf)
 endfunc
 

src/version.c

@@ -699,6 +699,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    673,
 /**/
     672,
 /**/