Merge pull request #36 from beman-project/fix-read_env-signatures

fixed completion signatures for read_env and noexcept for get_env

Author: dietmarkuehl

include/beman/execution26/detail/get_env.hpp

@@ -20,7 +20,7 @@ namespace beman::execution26
                 not requires(Object&& object) { ::std::as_const(object).get_env(); }
                 || ::beman::execution26::detail::queryable<std::remove_cvref_t<decltype(::std::declval<::std::remove_cvref_t<Object> const&>().get_env())>>
             )
-        auto operator()(Object&& object) const -> decltype(auto)
+        auto operator()(Object&& object) const noexcept -> decltype(auto)
         {
             if constexpr (requires{ ::std::as_const(object).get_env(); })
             {

include/beman/execution26/detail/read_env.hpp

@@ -64,12 +64,22 @@ namespace beman::execution26::detail
         Env
         >
     {
-        using type = ::beman::execution26::completion_signatures<
-            ::beman::execution26::set_value_t(
+        using set_value_type = ::beman::execution26::set_value_t(
                 decltype(::std::declval<Query>()(::std::as_const(::std::declval<Env>())))
-            ),
-            ::beman::execution26::set_error_t(::std::exception_ptr)
-            >;
+            );
+        using set_error_type = ::beman::execution26::set_error_t(
+                ::std::exception_ptr
+            );
+        using type = ::std::conditional_t<
+            noexcept(::std::declval<Query>()(::std::declval<Env const&>())),
+            ::beman::execution26::completion_signatures<
+                set_value_type
+            >,
+            ::beman::execution26::completion_signatures<
+                set_value_type,
+                set_error_type
+            >
+        >;
     };
 }
 

include/test/execution.hpp

@@ -5,6 +5,7 @@
 #define INCLUDED_TEST_EXECUTION
 
 #include <beman/execution26/stop_token.hpp>
+#include <concepts>
 #include <cassert>
 #include <cstddef>
 
@@ -16,6 +17,11 @@ namespace test_detail = ::beman::execution26::detail;
 namespace test
 {
     template <typename> auto type_exists() {}
+    template <typename T0, typename T1>
+    auto check_type(T1&&)
+    {
+        static_assert(std::same_as<T0, T1>);
+    }
 
     auto use(auto&&...) noexcept -> void {}
 }

src/beman/execution26/tests/exec-read-env.pass.cpp

@@ -2,12 +2,14 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
 #include <beman/execution26/detail/read_env.hpp>
+#include <beman/execution26/detail/common.hpp>
 #include <beman/execution26/detail/get_domain.hpp>
 #include <beman/execution26/detail/sender.hpp>
 #include <beman/execution26/detail/sender_in.hpp>
 #include <beman/execution26/detail/receiver.hpp>
 #include <beman/execution26/detail/connect.hpp>
 #include <beman/execution26/detail/start.hpp>
+#include <beman/execution26/detail/get_stop_token.hpp>
 #include <test/execution.hpp>
 #include <concepts>
 
@@ -59,8 +61,8 @@ namespace
         static_assert(test_std::sender_in<decltype(sender), env>);
         static_assert(std::same_as<
             test_std::completion_signatures<
-                test_std::set_value_t(domain),
-                test_std::set_error_t(std::exception_ptr)
+                test_std::set_value_t(domain)
+                //-dk:TODO verify , test_std::set_error_t(std::exception_ptr)
             >,
             decltype(test_std::get_completion_signatures(sender, env{}))
             >);
@@ -75,10 +77,22 @@ namespace
         test_std::start(op);
         assert(called);
     }
+
+    auto test_read_env_completions() -> void
+    {
+        auto r{test_std::read_env(test_std::get_stop_token)};
+        test::check_type<
+            test_std::completion_signatures<
+                test_std::set_value_t(test_std::never_stop_token)
+            >
+        >(test_std::get_completion_signatures(r, test_std::empty_env{}));
+        test_std::detail::use(r);
+    }
 }
 
 auto main() -> int
 {
     static_assert(std::same_as<test_std::read_env_t const, decltype(test_std::read_env)>);
     test_read_env();
+    test_read_env_completions();
 }