more bug fixes and work around gcc<13 bugs

include/exec/sequence.hpp

@@ -186,15 +186,15 @@ namespace exec {
         stdexec::__minvoke<stdexec::__mfold_left<void, stdexec::__q2<_fold_fn>>, Sndrs...>;
     };
 
-    template <class... Sndrs>
-    struct _sndr {
+    template <class Sndr0, class... Sndrs>
+    struct _sndr<Sndr0, Sndrs...> {
       using sender_concept = stdexec::sender_t;
 
       template <class... Env>
-      using _completions_t = stdexec::__minvoke<_completions<Env...>, Sndrs...>;
+      using _completions_t = stdexec::__minvoke<_completions<Env...>, Sndr0, Sndrs...>;
 
       template <class Self, class... Env>
-        requires(stdexec::__decay_copyable<stdexec::__copy_cvref_t<Self, Sndrs>> && ...)
+        requires stdexec::__decay_copyable<Self>
       STDEXEC_ATTRIBUTE(host, device)
       STDEXEC_EXPLICIT_THIS_BEGIN(auto get_completion_signatures)(this Self&&, Env&&...)
         -> _completions_t<Env...> {
@@ -203,17 +203,17 @@ namespace exec {
       STDEXEC_EXPLICIT_THIS_END(get_completion_signatures)
 
       template <class Self, class Rcvr>
-        requires(stdexec::__decay_copyable<stdexec::__copy_cvref_t<Self, Sndrs>> && ...)
+        requires stdexec::__decay_copyable<Self>
       STDEXEC_ATTRIBUTE(host, device)
       STDEXEC_EXPLICIT_THIS_BEGIN(auto connect)(this Self&& self, Rcvr rcvr) {
-        return _opstate<Rcvr, Sndrs...>{
+        return _opstate<Rcvr, stdexec::__copy_cvref_t<Self, Sndr0>, Sndrs...>{
           static_cast<Rcvr&&>(rcvr), static_cast<Self&&>(self)._sndrs};
       }
       STDEXEC_EXPLICIT_THIS_END(connect)
 
       STDEXEC_ATTRIBUTE(no_unique_address, maybe_unused) sequence_t _tag;
       STDEXEC_ATTRIBUTE(no_unique_address, maybe_unused) stdexec::__ignore _ignore;
-      stdexec::__tuple<Sndrs...> _sndrs;
+      stdexec::__tuple<Sndr0, Sndrs...> _sndrs;
     };
 
     template <class Sndr>

include/nvexec/stream/continues_on.cuh

@@ -161,19 +161,19 @@ namespace nvexec::_strm {
         : sndr_(schedule_from(static_cast<Sender&&>(sndr))) {
       }
 
-      template <__decays_to<source_sender_t> Self, receiver Receiver>
+      template <__decay_copyable Self, receiver Receiver>
       STDEXEC_EXPLICIT_THIS_BEGIN(auto connect)(this Self&& self, Receiver rcvr)
         -> connect_result_t<__copy_cvref_t<Self, schedule_from_sender_t>, Receiver> {
         return stdexec::connect(static_cast<Self&&>(self).sndr_, static_cast<Receiver&&>(rcvr));
       }
       STDEXEC_EXPLICIT_THIS_END(connect)
 
-      template <__decays_to<source_sender_t> _Self, class... _Env>
+      template <__decay_copyable _Self, class... _Env>
       STDEXEC_EXPLICIT_THIS_BEGIN(auto get_completion_signatures)(this _Self&&, _Env&&...)
         -> __completion_signatures_of_t<__copy_cvref_t<_Self, Sender>, _Env...> {
         return {};
       }
-        STDEXEC_EXPLICIT_THIS_END(get_completion_signatures)
+      STDEXEC_EXPLICIT_THIS_END(get_completion_signatures)
 
       [[nodiscard]]
       auto get_env() const noexcept -> env_of_t<const Sender&> {

include/stdexec/__detail/__let.hpp

@@ -551,7 +551,7 @@ namespace stdexec {
         static_assert(sender_expr_for<_Sender, __let_t<_SetTag>>);
         using _Fun = __decay_t<__data_of<_Sender>>;
         using _Child = __child_of<_Sender>;
-        using _Env2 = __env2_t<_SetTag, env_of_t<const _Child&>, env_of_t<const _Receiver&>>;
+        using _Env2 = __env2_t<_SetTag, env_of_t<_Child>, env_of_t<_Receiver>>;
         using __mk_let_state = __mbind_front_q<__let_state, _Receiver, _Fun, _SetTag, _Env2>;
 
         using __let_state_t = __gather_completions_of<

include/stdexec/__detail/__meta.hpp

@@ -830,15 +830,12 @@ namespace stdexec {
     using __demangle_fn = decltype(__demangle_v<_Ty>);
 
     template <class _Ty>
-    extern __mcompose<__cplr, __demangle_fn<_Ty>> __demangle_v<_Ty &>;
-
-    template <class _Ty>
-    extern __mcompose<__cpclr, __demangle_fn<_Ty>> __demangle_v<_Ty const &>;
+    using __demangle_t = __minvoke<__demangle_fn<_Ty>, _Ty>;
   } // namespace __detail
 
   // A utility for pretty-printing type names in diagnostics
   template <class _Ty>
-  using __demangle_t = __minvoke<__detail::__demangle_fn<_Ty>, _Ty>;
+  using __demangle_t = __copy_cvref_t<_Ty, __detail::__demangle_t<std::remove_cvref_t<_Ty>>>;
 
   namespace __detail {
     //////////////////////////////////////////////////////////////////////////////////////////

include/stdexec/__detail/__shared.hpp

@@ -433,9 +433,10 @@ namespace stdexec::__shared {
   struct __shared_impl : __sexpr_defaults {
     static constexpr auto get_state =
       []<class _CvrefSender, class _Receiver>(_CvrefSender&& __sndr, _Receiver&) noexcept
-      -> __local_state<_CvrefSender, _Receiver> {
+      -> __local_state<_CvrefSender, _Receiver>
+      requires __decay_copyable<__data_of<_CvrefSender>>
+    {
       static_assert(sender_expr_for<_CvrefSender, _Tag>);
-      static_assert(__decay_copyable<_CvrefSender>);
       return __local_state<_CvrefSender, _Receiver>{static_cast<_CvrefSender&&>(__sndr)};
     };