[2025-06-lwg-24] P3557R3 High-Quality Sender Diagnostics with Constexpr Exceptions #8035
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write_env is added here: #7973 |
So rebasing on motions-2025-06-lwg-5 will give me [exec.write.env] from P3284R4 (so I can apply changes to [exec.write.env]), but change to [exec.snd.expos]p39 is still a problem, because the wording it changes assumes P3164R4 was applied. |
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Edits should all be in now. |
* [exec.util.cmplsig] Subclause (now without siblings) promoted to \rSec1 (replacing [exec.util]) and renamed to [exec.cmplsig] "Completion signatures". Also fixes LWG4203.
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source/exec.tex
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| \begin{itemdescr} | ||
| \pnum | ||
| \exposid{write-env} is an exposition-only sender adaptor that, | ||
| when connected with a receiver \tcode{rcvr}, | ||
| connects the adapted sender with a receiver | ||
| whose execution environment is the result of | ||
| joining the \exposconcept{queryable} argument \tcode{env} | ||
| to the result of \tcode{get_env(rcvr)}. | ||
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| \pnum | ||
| Let \exposid{write-env-t} be an exposition-only empty class type. | ||
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| \pnum | ||
| \returns | ||
| \begin{codeblock} | ||
| @\exposid{make-sender}@(@\exposid{write-env-t}@(), std::forward<Env>(env), std::forward<Sndr>(sndr)) | ||
| \end{codeblock} | ||
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| \pnum | ||
| \remarks | ||
| The exposition-only class template \exposid{impls-for}\iref{exec.snd.general} | ||
| is specialized for \exposid{write-env-t} as follows: | ||
| \begin{codeblock} | ||
| template<> | ||
| struct @\exposid{impls-for}@<@\exposid{write-env-t}@> : @\exposid{default-impls}@ { | ||
| static constexpr auto @\exposid{get-env}@ = | ||
| [](auto, const auto& state, const auto& rcvr) noexcept { | ||
| return @\seebelow@; | ||
| }; | ||
| }; | ||
| \end{codeblock} | ||
| Invocation of | ||
| \tcode{\exposid{impls-for}<\exposid{write-env-t}>::\exposid{get-env}} | ||
| returns an object \tcode{e} such that | ||
| \begin{itemize} | ||
| \item | ||
| \tcode{decltype(e)} models \exposconcept{queryable} and | ||
| \item | ||
| given a query object \tcode{q}, | ||
| the expression \tcode{e.query(q)} is expression-equivalent | ||
| to \tcode{state.query(q)} if that expression is valid, | ||
| otherwise, \tcode{e.query(q)} is expression-equivalent | ||
| to \tcode{get_env(rcvr).que\-ry(q)}. | ||
| \end{itemize} | ||
| \end{itemdescr} |
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This is old wording for what used to be the write-env exposition-only function. P3284 removed this wording and added the execution::write_env sender adaptor.
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Is there anything I need to do here?
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yes. this whole section needs to be struck. it was removed in #7973. this bit of specification was turned into [exec.write.env] and moved into the sender adaptors section by P3284.
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I see, thanks! Please check to see that it is correct now.
Also, the additions to the end of [exec.snd.expos] seem out of place since they follow itemdecl-itemdescr pairs and appear to pop out of nowhere with no introduction. Are they correct? Also note my FIXMEs asking if they were supposed to be in a namespace.
| otherwise, \exposid{none-such}, | ||
| where \exposid{none-such} is an unspecified empty class type. | ||
| otherwise, \tcode{\placeholder{none-such}}, | ||
| where \tcode{\placeholder{none-such}} is an unspecified empty class type. |
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just curious, why did these change from \exposid to \placeholder? i don't know what the difference it.
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My understanding is that \exposid is used for declarations marked \expos (or otherwise introduced as exposition entities). Here, we're introducing a local thingy to help describe/define something else, so \placeholder, math font, or even plain \tcode should be used. That said, I didn't realize I was "fixing" existing text when I was checking to make sure my additions were using the correct format, hopefully that was ok.
Also fixes LWG4203.
Fixes #7961.