parser: check undefined variables in array inits (#10746)

vlib/v/checker/tests/assign_expr_undefined_err_i.out

@@ -0,0 +1,6 @@
+vlib/v/checker/tests/assign_expr_undefined_err_i.vv:2:23: error: undefined variable: `a`
+    1 | fn main() {
+    2 |     mut a := []int{init: a}
+      |                          ^
+    3 |     println(a)
+    4 | }

vlib/v/checker/tests/assign_expr_undefined_err_i.vv

@@ -0,0 +1,4 @@
+fn main() {
+	mut a := []int{init: a}
+	println(a)
+}

vlib/v/parser/assign.v

@@ -30,6 +30,17 @@ fn (mut p Parser) check_undefined_variables(exprs []ast.Expr, val ast.Expr) ? {
 				}
 			}
 		}
+		ast.ArrayInit {
+			if val.has_cap {
+				p.check_undefined_variables(exprs, val.cap_expr) ?
+			}
+			if val.has_len {
+				p.check_undefined_variables(exprs, val.len_expr) ?
+			}
+			if val.has_default {
+				p.check_undefined_variables(exprs, val.default_expr) ?
+			}
+		}
 		ast.CallExpr {
 			p.check_undefined_variables(exprs, val.left) ?
 			for arg in val.args {