fixup: add 34.9.4 and 34.9.5

Author: jensmaurer

source/exec.tex

@@ -2072,7 +2072,135 @@
 its members need not be defined.
 \end{note}
 
+\rSec2[exec.domain.default]{\tcode{execution::default_domain}}
 
+\pnum
+\begin{codeblock}
+namespace std::execution {
+  struct default_domain {
+    template<@\libconcept{sender}@ Sndr, @\exposconcept{queryable}@... Env>
+        requires (sizeof...(Env) <= 1)
+      static constexpr @\libconcept{sender}@ decltype(auto) transform_sender(Sndr&& sndr, const Env&... env)
+        noexcept(@\seebelow@);
+
+    template<@\libconcept{sender}@ Sndr, @\exposconcept{queryable}@ Env>
+      static constexpr @\exposconcept{queryable}@ decltype(auto) transform_env(Sndr&& sndr, Env&& env) noexcept;
+
+    template<class Tag, @\libconcept{sender}@ Sndr, class... Args>
+      static constexpr decltype(auto) apply_sender(Tag, Sndr&& sndr, Args&&... args)
+        noexcept(@\seebelow@);
+  };
+}
+\end{codeblock}
+
+\begin{itemdecl}
+template<@\libconcept{sender}@ Sndr, @\exposconcept{queryable}@... Env>
+  requires (sizeof...(Env) <= 1)
+constexpr @\libconcept{sender}@ decltype(auto) transform_sender(Sndr&& sndr, const Env&... env)
+  noexcept(@\seebelow@);
+\end{itemdecl}
+
+\begin{itemdescr}
+\pnum
+Let \tcode{e} be the expression
+\begin{codeblock}
+tag_of_t<Sndr>().transform_sender(std::forward<Sndr>(sndr), env...)
+\end{codeblock}
+if that expression is well-formed;
+otherwise, \tcode{std::forward<Sndr>(sndr)}.
+
+\pnum
+\returns
+\tcode{e}
+
+\remarks
+The exception specification is equivalent to \tcode{noexcept(e)}.
+\end{itemdescr}
+
+\begin{itemdecl}
+template<@\libconcept{sender}@ Sndr, @\exposconcept{queryable}@ Env>
+  constexpr @\exposconcept{queryable}@ decltype(auto) transform_env(Sndr&& sndr, Env&& env) noexcept;
+\end{itemdecl}
+
+\begin{itemdescr}
+\pnum
+Let \tcode{e} be the expression
+\begin{codeblock}
+tag_of_t<Sndr>().transform_env(std::forward<Sndr>(sndr), std::forward<Env>(env))
+\end{codeblock}
+if that expression is well-formed;
+otherwise, \tcode{static_cast<Env>(std::forward<Env>(env))}.
+
+\pnum
+\mandates \tcode{noexcept(e)} is \tcode{true}.
+
+\pnum
+\returns
+\tcode{e}
+\end{itemdescr}
+
+\begin{itemdecl}
+template<class Tag, @\libconcept{sender}@ Sndr, class... Args>
+constexpr decltype(auto) apply_sender(Tag, Sndr&& sndr, Args&&... args)
+  noexcept(@\seebelow@);
+\end{itemdecl}
+
+\begin{itemdescr}
+\pnum
+Let \tcode{e} be the expression
+\begin{codeblock}
+  Tag().apply_sender(std::forward<Sndr>(sndr), std::forward<Args>(args)...)
+\end{codeblock}
+
+\pnum
+\constraints
+\tcode{e} is a well-formed expression.
+
+\pnum
+\returns
+\tcode{e}
+
+\pnum
+\remarks
+The exception specification is equivalent to \tcode{noexcept(e)}.
+\end{itemdescr}
+
+\rSec2[exec.snd.transform]{\tcode{execution::transform_sender}}
+
+\begin{itemdecl}
+namespace std::execution {
+  template<class Domain, @\libconcept{sender}@ Sndr, @\exposconcept{queryable}@... Env>
+      requires (sizeof...(Env) <= 1)
+    constexpr @\libconcept{sender}@ decltype(auto) transform_sender(Domain dom, Sndr&& sndr, const Env&... env)
+      noexcept(@\seebelow@);
+}
+\end{itemdecl}
+
+\begin{itemdescr}
+\pnum
+Let \exposid{transformed-sndr} be the expression
+\begin{codeblock}
+dom.transform_sender(std::forward<Sndr>(sndr), env...)
+\end{codeblock}
+if that expression is well-formed; otherwise,
+\begin{codeblock}
+default_domain().transform_sender(std::forward<Sndr>(sndr), env...)
+\end{codeblock}
+Let \exposid{final-sndr} be the expression \exposid{transformed-sndr}
+if \exposid{transformed-sndr} and \exposid{sndr}
+have the same type ignoring cv-qualifiers;
+otherwise, it is
+the expression \tcode{transform_sender(dom, transformed-sndr, env...)}.
+
+\pnum
+\returns
+\exposid{final-sndr}
+
+\pnum
+\remarks
+The exception specification is equivalent to
+\tcode{noexcept(\exposid{final-sndr})}.
+\end{itemdescr}
 
 \rSec1[exec.util]{Sender/receiver utilities}