Commit c022eadc authored Apr 01, 2025 by Pirama Arumuga Nainar

FTL: Provide definition of BaseFuture where third template parameter is ftl::Future

Bug: 405867217

After https://github.com/llvm/llvm-project/pull/100692, clang is
stricter about template deductions.  This causes the following error in
future_test.cpp:

...s/native/include/ftl/future.h:34:29: error: implicit instantiation of
undefined template
'android::ftl::details::BaseFuture<android::ftl::Future<int,
android::ftl::Future>, int, android::ftl::Future>'
   34 | class Future final : public details::BaseFuture<Future<T, FutureImpl>, T, FutureImpl> {
      |                             ^
frameworks/native/libs/ftl/future_test.cpp:47:31: note: in
instantiation of template class 'android::ftl::Future<int,
android::ftl::Future>' requested here
   47 |     ftl::Future<char> chain = ftl::Future(std::move(future))
      |                          ^
frameworks/native/include/ftl/details/future.h:52:7: note: template is declared here
   52 | class BaseFuture;
      |       ^

This is because ftl/details/future.h only provides
an instantiation where the third template parameter is either a
std::future or a std::shared_future.  This change extends the
instantiation to support any FutureImpl.

Test: Build future_test.cpp with new clang and old clang, in addition to
      presubmit.
Flag: EXEMPT fix error during compiler update
Change-Id: I1795f1f1237f5209fd8138a20c4de2a921c7395b

parent a83d862d

include/ftl/details/future.h

+5 −9

Original line number	Diff line number	Diff line
		@@ -48,12 +48,8 @@ using future_result_t = typename future_result<T>::type;

		struct ValueTag {};

		template <typename, typename T, template <typename> class>
		class BaseFuture;

		template <typename Self, typename T>
		class BaseFuture<Self, T, std::future> {
		using Impl = std::future<T>;
		template <typename Self, typename T, template <typename> class FutureImpl = std::future>
		class BaseFuture {

		public:
		Future<T, std::shared_future> share() {
		@@ -61,7 +57,7 @@ class BaseFuture<Self, T, std::future> {
		return {ValueTag{}, std::move(*value)};
		}

		return std::get<Impl>(self()).share();
		return std::get<FutureImpl<T>>(self()).share();
		}

		protected:
		@@ -70,7 +66,7 @@ class BaseFuture<Self, T, std::future> {
		return std::move(*value);
		}

		return std::get<Impl>(self()).get();
		return std::get<FutureImpl<T>>(self()).get();
		}

		template <class Rep, class Period>
		@@ -79,7 +75,7 @@ class BaseFuture<Self, T, std::future> {
		return std::future_status::ready;
		}

		return std::get<Impl>(self()).wait_for(timeout_duration);
		return std::get<FutureImpl<T>>(self()).wait_for(timeout_duration);
		}

		private: