cgen: allow unwrapping of foo.bar as string, where foo.bar is ?string (fix #22960) (#22973)

Author: Delta456

vlib/v/gen/c/cgen.v

@@ -7797,10 +7797,18 @@ fn (mut g Gen) as_cast(node ast.AsCast) {
 	} else {
 		mut is_optional_ident_var := false
 		if node.expr is ast.Ident {
-			if node.expr.info is ast.IdentVar && node.expr.info.is_option {
+			if node.expr.info is ast.IdentVar && node.expr.info.is_option
+				&& !unwrapped_node_typ.has_flag(.option) {
 				g.unwrap_option_type(unwrapped_node_typ, node.expr.name, node.expr.is_auto_heap())
 				is_optional_ident_var = true
 			}
+		} else if node.expr is ast.SelectorExpr {
+			if node.expr.expr is ast.Ident && node.expr.typ.has_flag(.option)
+				&& !unwrapped_node_typ.has_flag(.option) {
+				g.unwrap_option_type(node.expr.typ, '${node.expr.expr.name}.${node.expr.field_name}',
+					node.expr.expr.is_auto_heap())
+				is_optional_ident_var = true
+			}
 		}
 		if !is_optional_ident_var {
 			g.expr(node.expr)

vlib/v/tests/option_unwrap_as_cast_test.v renamed to vlib/v/tests/options/option_unwrap_as_cast_test.v

@@ -0,0 +1,20 @@
+struct Foo {
+	foo string
+	bar ?string
+}
+
+fn (f Foo) str() string {
+	mut ret := f.foo
+	bar_value := f.bar as string
+	if bar_value == '' {
+		return ret
+	}
+	return ret + '%' + bar_value
+}
+
+fn test_selector_expr_as_cast() {
+	ff := Foo{
+		foo: 'Fooooo'
+	}
+	assert '${ff}' == 'Fooooo'
+}