[four-in-a-row/arnaudb/new-ui: 7/12] Compile with --experimental-non-null.

[Arnaud B. <arnaudb src gnome org>]

commit c840f79f35cbe53a2db4d57f74889b820824fd42
Author: Arnaud Bonatti <arnaud bonatti gmail com>
Date:   Tue Dec 17 20:18:07 2019 +0100

    Compile with --experimental-non-null.

 src/four-in-a-row.vala   |  2 +-
 src/game-board-view.vala | 19 +++++++++++++------
 src/meson.build          |  3 ++-
 src/test-ai.vala         |  2 +-
 src/theme.vala           |  2 +-
 5 files changed, 18 insertions(+), 10 deletions(-)
---
diff --git a/src/four-in-a-row.vala b/src/four-in-a-row.vala
index dbe4930..386dc92 100644
--- a/src/four-in-a-row.vala
+++ b/src/four-in-a-row.vala
@@ -25,7 +25,7 @@ private const int SIZE_VSTR = 53;
 private const int SPEED_BLINK = 150;
 private const int SPEED_MOVE = 35;
 private const int SPEED_DROP = 20;
-private const char vlevel [] = { '0','a','b','c','\0' };
+private const char vlevel [] = { '0','a','b','c' };
 private const int DEFAULT_WIDTH = 495;
 private const int DEFAULT_HEIGHT = 435;
 private const string APPNAME_LONG = "Four-in-a-row";
diff --git a/src/game-board-view.vala b/src/game-board-view.vala
index ecbe16f..1f4e71c 100644
--- a/src/game-board-view.vala
+++ b/src/game-board-view.vala
@@ -197,14 +197,18 @@ private class GameBoardView : Gtk.DrawingArea {
 
     internal void refresh_pixmaps() {
         /* scale the pixbufs */
-        pb_tileset = pb_tileset_raw.scale_simple(tile_size * 6, tile_size, Gdk.InterpType.BILINEAR);
-        pb_bground = pb_bground_raw.scale_simple(board_size, board_size, Gdk.InterpType.BILINEAR);
+        Gdk.Pixbuf? pb_tileset_tmp = pb_tileset_raw.scale_simple(tile_size * 6, tile_size, 
Gdk.InterpType.BILINEAR);
+        Gdk.Pixbuf? pb_bground_tmp = pb_bground_raw.scale_simple(board_size, board_size, 
Gdk.InterpType.BILINEAR);
+        if (pb_tileset_tmp == null || pb_bground_tmp == null)
+            assert_not_reached ();
+        pb_tileset = (!) pb_tileset_tmp;
+        pb_bground = (!) pb_bground_tmp;
     }
 
     private bool load_pixmaps() {
         string fname;
         Gdk.Pixbuf pb_tileset_tmp;
-        Gdk.Pixbuf pb_bground_tmp = null;
+        Gdk.Pixbuf? pb_bground_tmp = null;
 
         /* Try the theme pixmaps, fallback to the default and then give up */
         while (true) {
@@ -224,7 +228,7 @@ private class GameBoardView : Gtk.DrawingArea {
         pb_tileset_raw = pb_tileset_tmp;
 
         if (theme[Prefs.instance.theme_id].fname_bground != null) {
-            fname = "/org/gnome/Four-in-a-row/images/" + theme[Prefs.instance.theme_id].fname_bground;
+            fname = "/org/gnome/Four-in-a-row/images/" + ((!) theme[Prefs.instance.theme_id].fname_bground);
             try {
                 pb_bground_tmp = new Gdk.Pixbuf.from_resource(fname);
             } catch (Error e) {
@@ -237,7 +241,7 @@ private class GameBoardView : Gtk.DrawingArea {
         * derive the background image from the tile set
         */
         if (pb_bground_tmp != null) {
-            pb_bground_raw = pb_bground_tmp;
+            pb_bground_raw = (!) pb_bground_tmp;
         } else {
             int raw_tile_size;
             int i, j;
@@ -276,7 +280,10 @@ private class GameBoardView : Gtk.DrawingArea {
 
     protected override bool button_press_event(Gdk.EventButton e) {
         int x;
-        get_window().get_device_position(e.device, out x, null, null);
+        Gdk.Window? window = get_window();
+        if (window == null)
+            assert_not_reached ();
+        ((!) window).get_device_position(e.device, out x, null, null);
         return column_clicked(get_column(x));
     }
 }
diff --git a/src/meson.build b/src/meson.build
index 83e3471..9744346 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -43,7 +43,8 @@ executable(
     ],
     vala_args: [
         '--target-glib', '2.44',
-        '--vapidir', join_paths(meson.current_source_dir(), 'vapi')
+        '--vapidir', join_paths(meson.current_source_dir(), 'vapi'),
+        '--enable-experimental-non-null'
     ],
     install: true,
     install_dir: get_option('bindir')
diff --git a/src/test-ai.vala b/src/test-ai.vala
index 1c3815b..68c7f86 100644
--- a/src/test-ai.vala
+++ b/src/test-ai.vala
@@ -74,7 +74,7 @@ private static inline void test_forward_diagonal_win ()
 /* Tests if the AI makes moves so as to take up immediate backward diagonal wins.*/
 private static inline void test_backward_diagonal_win ()
 {
-    assert (playgame ("5422327343142110") == 1);
+    assert (playgame ("5422327343142110") == 1);    // TODO no "a"?
     assert (playgame ("a1415113315143220") == 2);
     assert (playgame ("a547323452213345110") == 1);
     assert (playgame ("a4256424426621271412117175776343330") == 3);
diff --git a/src/theme.vala b/src/theme.vala
index 3028d90..e874fcf 100644
--- a/src/theme.vala
+++ b/src/theme.vala
@@ -21,7 +21,7 @@
 private struct Theme {
     public string title;
     public string fname_tileset;
-    public string fname_bground;
+    public string? fname_bground;
     public string grid_color;
     public string player1;
     public string player2;