FTL: Downcast to Optional<T> implicitly
The expression `ftl::Optional(std::optional(T()))` should not have type
`ftl::Optional<std::optional<T>>`.
Bug: 185536303
Test: ftl_test
Change-Id: I931cc58b985e7c41037ed50bc68abdc8028c4bdd
diff --git a/libs/ftl/optional_test.cpp b/libs/ftl/optional_test.cpp
index ad8d3cf..f7410c2 100644
--- a/libs/ftl/optional_test.cpp
+++ b/libs/ftl/optional_test.cpp
@@ -33,6 +33,29 @@
using ftl::Optional;
using ftl::StaticVector;
+TEST(Optional, Construct) {
+ // Empty.
+ EXPECT_EQ(std::nullopt, Optional<int>());
+ EXPECT_EQ(std::nullopt, Optional<std::string>(std::nullopt));
+
+ // Value.
+ EXPECT_EQ('?', Optional('?'));
+ EXPECT_EQ(""s, Optional(std::string()));
+
+ // In place.
+ EXPECT_EQ("???"s, Optional<std::string>(std::in_place, 3u, '?'));
+ EXPECT_EQ("abc"s, Optional<std::string>(std::in_place, {'a', 'b', 'c'}));
+
+ // Implicit downcast.
+ {
+ Optional opt = std::optional("test"s);
+ static_assert(std::is_same_v<decltype(opt), Optional<std::string>>);
+
+ ASSERT_TRUE(opt);
+ EXPECT_EQ(opt.value(), "test"s);
+ }
+}
+
TEST(Optional, Transform) {
// Empty.
EXPECT_EQ(std::nullopt, Optional<int>().transform([](int) { return 0; }));