scanner: fix string interpolation for '$a.b().c' (#5612)

vlib/v/scanner/scanner.v

@@ -745,13 +745,15 @@ fn (mut s Scanner) text_scan() token.Token {
 	}
 	// Handle `'$fn()'`
 	if c == `)` && s.is_inter_start {
-		s.is_inter_end = true
-		s.is_inter_start = false
 		next_char := s.look_ahead(1)
-		if next_char == s.quote {
-			s.is_inside_string = false
+		if next_char != `.` {
+			s.is_inter_end = true
+			s.is_inter_start = false
+			if next_char == s.quote {
+				s.is_inside_string = false
+			}
+			return s.new_token(.rpar, '', 1)
 		}
-		return s.new_token(.rpar, '', 1)
 	}
 	// all other tokens
 	match c {

vlib/v/tests/string_interpolation_test.v

@@ -160,3 +160,25 @@ fn test_string_interpolation_with_negative_format_width_should_compile_and_run_w
 	eprintln('---------------------------------------------------------------------------------------------')
 	assert true
 }
+
+struct Aa {
+	a int
+}
+
+struct Bb {
+	b Aa
+}
+
+fn (x Bb) f() Aa {
+	return x.b
+}
+
+fn test_method_interpolation() {
+	y := Bb{
+		b: Aa{
+			a: 2
+		}
+	}
+	assert '>${y.f().a}<' == '>2<'
+	assert '>$y.f().a<' == '>2<'
+}