gen: impl as cast

vlib/v/ast/ast.v

@@ -433,8 +433,10 @@ mut:
 
 pub struct AsCast {
 pub:
-	expr Expr
-	typ  table.Type
+	expr      Expr
+	typ       table.Type
+mut:
+	expr_type table.Type
 }
 
 // e.g. `[unsafe_fn]`

vlib/v/checker/checker.v

@@ -567,8 +567,7 @@ fn (c mut Checker) stmt(node ast.Stmt) {
 							sym.map_info().key_type
 						}
 						else {
-							table.int_type
-						}
+							table.int_type}
 	}
 					scope.override_var(ast.Var{
 						name: it.key_var
@@ -618,6 +617,7 @@ pub fn (c mut Checker) expr(node ast.Expr) table.Type {
 			return c.array_init(mut it)
 		}
 		ast.AsCast {
+			it.expr_type = c.expr(it.expr)
 			return it.typ
 		}
 		ast.AssignExpr {

vlib/v/gen/cgen.v

@@ -562,7 +562,17 @@ fn (g mut Gen) expr(node ast.Expr) {
 			else {}
 		}
 		ast.AsCast {
-			g.write('/* as */')
+			styp := g.typ(it.typ)
+			expr_type_sym := g.table.get_type_symbol(it.expr_type)
+			if expr_type_sym.kind == .sum_type {
+				g.write('/* as */ *($styp*)')
+				g.expr(it.expr)
+				g.write('.obj')
+			}
+			else {
+				g.write('/* as */ ($styp)')
+				g.expr(it.expr)
+			}
 		}
 		ast.AssignExpr {
 			if ast.expr_is_blank_ident(it.left) {