ast: add Expr to AsCast

vlib/v/ast/ast.v

@@ -411,6 +411,7 @@ pub:
 
 pub struct AsCast {
 pub:
+	expr Expr
 	typ table.Type
 }
 

vlib/v/fmt/fmt.v

@@ -308,6 +308,11 @@ fn (f mut Fmt) expr(node ast.Expr) {
 				f.write(']')
 			}
 		}
+		ast.AsCast {
+			type_str := f.table.type_to_str(it.typ)
+			f.expr(it.expr)
+			f.write(' as $type_str')
+		}
 		ast.AssignExpr {
 			f.expr(it.left)
 			f.write(' $it.op.str() ')

vlib/v/fmt/tests/simple_expected.vv

@@ -123,6 +123,10 @@ pub mut:
 	pub_mut_field string
 }
 
+struct Bar {
+	val int
+}
+
 const (
 	reserved_types = {
 		'i8': true
@@ -188,3 +192,13 @@ fn fn_with_match_expr() {
 fn fn_variadic(arg int, args ...string) {
 	println('Do nothing')
 }
+
+fn test_as() {
+	a := sum_expr() as Bar
+}
+
+fn sum_expr() FooBar {
+	return Bar{
+		val: 5
+	}
+}

vlib/v/fmt/tests/simple_input.vv

@@ -125,6 +125,12 @@ struct Foo {
 	pub_mut_field string
 }
 
+struct Bar {
+	val int
+}
+
+type FooBar = Foo | Bar
+
 const (
 reserved_types = {
          'i8': true
@@ -188,3 +194,11 @@ fn fn_with_match_expr() {
 fn fn_variadic(arg int, args... string) {
 	println('Do nothing')
 }
+
+fn test_as() {
+	a := sum_expr() as Bar
+}
+
+fn sum_expr() FooBar {
+	return Bar{ val: 5 }
+}

vlib/v/parser/parser.v

@@ -766,6 +766,7 @@ pub fn (p mut Parser) expr(precedence int) ast.Expr {
 			p.next()
 			typ = p.parse_type()
 			node = ast.AsCast{
+				expr: node
 				typ: typ
 			}
 		}