ast, parser, cgen: fix anon sumtype cast (fix #14967) (#14976)

vlib/v/gen/c/auto_str_methods.v

@@ -401,7 +401,7 @@ fn (mut g Gen) gen_str_for_union_sum_type(info ast.SumType, styp string, str_fn_
 	mut clean_sum_type_v_type_name := ''
 	if info.is_anon {
 		variant_names := info.variants.map(util.strip_main_name(g.table.sym(it).name))
-		clean_sum_type_v_type_name = '(${variant_names.join(' | ')})'
+		clean_sum_type_v_type_name = '${variant_names.join('|')}'
 	} else {
 		clean_sum_type_v_type_name = styp.replace('__', '.')
 		if styp.ends_with('*') {

vlib/v/parser/parser.v

@@ -2493,6 +2493,24 @@ pub fn (mut p Parser) name_expr() ast.Expr {
 				typ: typ
 				pos: type_pos
 			}
+		} else if !known_var && language == .v && (p.table.known_type(p.tok.lit) || lit0_is_capital)
+			&& p.peek_tok.kind == .pipe {
+			start_pos := p.tok.pos()
+			mut to_typ := p.parse_type()
+			p.check(.lpar)
+			expr := p.expr(0)
+			end_pos := p.tok.pos()
+			p.check(.rpar)
+			node = ast.CastExpr{
+				typ: to_typ
+				typname: p.table.sym(to_typ).name
+				expr: expr
+				arg: ast.empty_expr()
+				has_arg: false
+				pos: start_pos.extend(end_pos)
+			}
+			p.expr_mod = ''
+			return node
 		}
 
 		ident := p.parse_ident(language)

vlib/v/tests/cast_to_anon_sumtype_test.v

@@ -0,0 +1,7 @@
+module main
+
+fn test_cast_to_anon_sumtype() {
+	x := string|none(none)
+	println(x)
+	assert '$x' == 'string|none(none)'
+}