https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110552
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> --- Created attachment 55470 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=55470&action=edit reduced but invalid code This is the reduced testcase I got but it became invalid code; maybe the original is invalid too. But clang's error message is: <source>:31:25: error: member reference base type '__tag_t' (aka 'void') is not a structure or union 31 | noexcept(__tag_t().get_env(__self))) {} | ~~~~~~~~~^~~~~~~~ <source>:30:15: note: in instantiation of exception specification for 'tag_invoke<stdexec::__env::get_env_t, stdexec::__basic_sender<stdexec::(lambda at <source>:33:25)>>' requested here 30 | friend auto tag_invoke(_Tag, const _Self &__self) noexcept( | ^ <source>:6:14: note: in instantiation of function template specialization 'stdexec::tag_invoke<stdexec::__env::get_env_t, stdexec::__basic_sender<stdexec::(lambda at <source>:33:25)>>' requested here 6 | decltype(tag_invoke(__declval<_Tag>(), __declval<_Args>()...)); | ^ <source>:13:10: note: in instantiation of template type alias 'tag_invoke_result_t' requested here 13 | -> tag_invoke_result_t<get_env_t, const _EnvProvider &> {} | ^ <source>:19:36: note: while substituting deduced template arguments into function template 'operator()' [with _EnvProvider = stdexec::__basic_sender<stdexec::(lambda at <source>:33:25)>] 19 | { get_env(__ep) }; | ^ <source>:19:36: note: in instantiation of requirement here 19 | { get_env(__ep) }; | ^~~~~~~~~~~~~ <source>:18:32: note: while substituting template arguments into constraint expression here 18 | concept environment_provider = requires(_EnvProvider &__ep) { | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 19 | { get_env(__ep) }; | ~~~~~~~~~~~~~~~~~~ 20 | }; | ~ <source>:35:15: note: while checking the satisfaction of concept 'environment_provider<stdexec::__basic_sender<stdexec::(lambda at <source>:33:25)>>' requested here 35 | static_assert(stdexec::environment_provider<S>); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
