ci: build tetris with -autofree

.github/workflows/ci.yml

@@ -169,6 +169,9 @@ jobs:
       run: VJOBS=1 ./v -silent test-fixed
     - name: Build examples
       run: ./v -silent build-examples
+    - name: Build examples with -autofree
+      run: |
+        ./v -autofree -experimental -o tetris examples/tetris/tetris.v && ./tetris
     - name: v doctor
       run: |
         ./v doctor
@@ -228,6 +231,9 @@ jobs:
       run: ./v -o vprod -prod cmd/v && ./vprod -silent test-fixed
     - name: Build examples
       run: ./v -silent build-examples
+    - name: Build examples with -autofree
+      run: |
+        ./v -autofree -experimental -o tetris examples/tetris/tetris.v && ./tetris
     - name: Build modules
       run: |
         ./v build-module vlib/os

examples/tetris/tetris.v

@@ -177,7 +177,7 @@ fn (mut g Game) init_game() {
 		mut row := [0].repeat(field_width + 2)
 		row[0] = -1
 		row[field_width + 1] = -1
-		g.field << row
+		g.field << row.clone()
 	}
 	for j in 0 .. field_width + 2 {
 		g.field[0][j] = -1
@@ -264,8 +264,7 @@ fn (mut g Game) move_right(dx int) bool {
 		tetro := g.tetro[i]
 		y := tetro.y + g.pos_y
 		x := tetro.x + g.pos_x + dx
-		row := g.field[y]
-		if row[x] != 0 {
+		if g.field[y][x] != 0 {
 			// Do not move
 			return false
 		}