gdb: Fix scrolling in TUI

Hannes Domani pointed out that my previous patch to fix the "list"
command in the TUI instead broke vertical scrolling.  While looking at
this, I found that do_scroll_vertical calls print_source_lines, which
seems like a very roundabout way to change the source window.  This
patch removes this oddity and fixes the bug at the same time.

I've added a new test case.  This is somewhat tricky, because the
obvious approach of sending a dummy command after the scroll did not
work -- due to how the TUI works, sennding a command causes the scroll
to take effect.

gdb/ChangeLog
2019-12-22  Tom Tromey  <tom@tromey.com>

	PR tui/18932:
	* tui/tui-source.c (tui_source_window::do_scroll_vertical): Call
	update_source_window, not print_source_lines.

gdb/testsuite/ChangeLog
2019-12-22  Tom Tromey  <tom@tromey.com>

	PR tui/18932:
	* lib/tuiterm.exp (Term::wait_for): Rename from _accept.  Return a
	meangingful value.
	(Term::command, Term::resize): Update.
	* gdb.tui/basic.exp: Add scrolling test.

Change-Id: I9636a7c8a8cade37431c6165ee996a9d556ef1c8

1 files changed, 13 insertions, 10 deletions

diff --git a/gdb/tui/tui-source.c b/gdb/tui/tui-source.c
index 1503cd4..13f2dc7 100644
--- a/gdb/tui/tui-source.c
+++ b/gdb/tui/tui-source.c
@@ -136,26 +136,29 @@ tui_source_window::do_scroll_vertical (int num_to_scroll)
 {
   if (!content.empty ())
     {
-      struct tui_line_or_address l;
       struct symtab *s;
       struct symtab_and_line cursal = get_current_source_symtab_and_line ();
+      struct gdbarch *arch = gdbarch;
 
       if (cursal.symtab == NULL)
-	s = find_pc_line_symtab (get_frame_pc (get_selected_frame (NULL)));
+	{
+	  struct frame_info *fi = get_selected_frame (NULL);
+	  s = find_pc_line_symtab (get_frame_pc (fi));
+	  arch = get_frame_arch (fi);
+	}
       else
 	s = cursal.symtab;
 
-      l.loa = LOA_LINE;
-      l.u.line_no = start_line_or_addr.u.line_no
-	+ num_to_scroll;
+      int line_no = start_line_or_addr.u.line_no + num_to_scroll;
       const std::vector<off_t> *offsets;
       if (g_source_cache.get_line_charpos (s, &offsets)
-	  && l.u.line_no > offsets->size ())
-	l.u.line_no = start_line_or_addr.u.line_no;
-      if (l.u.line_no <= 0)
-	l.u.line_no = 1;
+	  && line_no > offsets->size ())
+	line_no = start_line_or_addr.u.line_no;
+      if (line_no <= 0)
+	line_no = 1;
 
-      print_source_lines (s, l.u.line_no, l.u.line_no + 1, 0);
+      cursal.line = line_no;
+      update_source_window (arch, cursal);
     }
 }