parser: fix type detection in `match` (#5679)

vlib/v/parser/if.v

@@ -115,10 +115,9 @@ fn (mut p Parser) match_expr() ast.MatchExpr {
 		if p.tok.kind == .key_else {
 			is_else = true
 			p.next()
-		} else if p.tok.kind == .name && !(p.tok.lit == 'C' &&
+		} else if p.tok.kind == .name && !(p.tok.lit == 'C' && p.peek_tok.kind == .dot) &&
-			p.peek_tok.kind == .dot) && (p.tok.lit in table.builtin_type_names ||
+				(p.tok.lit in table.builtin_type_names || p.tok.lit[0].is_capital() ||
-			(p.tok.lit[0].is_capital() && !p.tok.lit.is_upper()) ||
+				(p.peek_tok.kind == .dot && p.peek_tok2.lit[0].is_capital())) {
-			(p.peek_tok.kind == .dot && p.peek_tok2.lit[0].is_capital())) {
 			if var_name.len == 0 {
 				match cond {
 					ast.Ident {

vlib/v/tests/match_test.v

@@ -82,3 +82,29 @@ fn test_match_enums() {
 	}
 	assert b == .blue
 }
+
+type Sum = A1 | B1
+
+struct A1 {
+	pos int
+}
+struct B1 {
+	val string
+}
+
+fn f(s Sum) string {
+    match s {
+        A1 {
+            return typeof(s)
+        }
+        B1 {
+			return ''
+		}
+    }
+	return ''
+}
+
+fn test_sum_type_name() {
+	a := A1{pos: 22}
+	assert f(a) == 'A1'
+}