[2025-06 LWG Motion 34] P3552R3 Add a Coroutine Task #8032

dietmarkuehl · 2025-06-29T16:15:06Z

I have applied the changes for P3552r3 (Add a Coroutine Task Type). Compared to the actual text of P3552r3
I made some [I think editorial] changes:

added with_error and change_coroutine_scheduler declarations to the synopsis before task; they are in the detailed description but not in the synopsis (possibly they should only be in the synopsis) as there is no further description)
inconsistent default template arguments for the ctor in the class declaration (allocator and the later description (allocator); the wording consistently uses allocator
added "of the" to a sentence about the type of a completion datum: "... defines the type of the value completion datum"
the use of the template parameter of the nested type state is Rcvr which has two problems: 1. the ctor also uses the name Rcvr for its template parameter 2. the class stores an object of type R which is the receiver named rcvr the most logic fix is to use Rcvr consistently for the state and change the name for the ctor's parameter:
1. change the ctor template parameter type to use R
2. change the member to use Rcvr
3. change the type R used for the own-env-t to be "...get_env(declval())..."

Fixes #7971
Fixes cplusplus/papers#2200

I have applied some [I think editorial] changes compared to P3552r3: - added with_error and change_coroutine_scheduler declarations to the synopsis before task; they are in the detailed description but not in the synopsis (possibly they should only be in the synopsis) as there is no further description) - inconsistent default template arguments for the ctor in the class declaration (allocator<byte> and the later description (allocator<void>); the wording consistently uses allocator<void> - added "of the" to a sentence about the type of a completion datum: "... defines the type *of the* value completion datum" - the use of the template parameter of the nested type state is Rcvr which has two problems: 1. the ctor also uses the name Rcvr for its template parameter 2. the class stores an object of type R which is the receiver named rcvr the most logic fix is to use Rcvr consistently for the state and change the name for the ctor's parameter: 1. change the ctor template parameter type to use R 2. change the member to use Rcvr 3. change the type R used for the own-env-t to be "...get_env(declval<Rcvr>())..."

The CI objected to use of \exposid{sender} => renamed sender to ts-sender. This change should be editorial but is more invovled

Eisenwave

Thanks for drafting this up.

Lots of work required before this is ready to go.

Also note that fixing up CI builds is not a fixup commit; it should just go into the main commit. The point of fixups is just to distinguish between turning the paper into TeX, and fixing typos and other minor issues afterwards.

Massaging whitespace or paragraph justification is not a separate commit.

Eisenwave · 2025-07-11T18:18:56Z

source/exceptions.tex

+whose promise type has an \tcode{unhandled_stopped} member function, or
+
+\item%
+when an exception is thrown from a coroutine \tcode{std::execution::task}\iref{exec.task} which doesn't support a \tcode{std::execution::set_error_t(std::execption_ptr)} completion.


Suggested change

when an exception is thrown from a coroutine \tcode{std::execution::task}\iref{exec.task} which doesn't support a \tcode{std::execution::set_error_t(std::execption_ptr)} completion.

when an exception is thrown from a coroutine \tcode{std::execution::task}\iref{exec.task}

which doesn't support a \tcode{std::execution::set_error_t(std::exception_ptr)} completion.

This line is overly long, the paper has a typo that needs to be fixed up, and added \irefs should typically go into a separate fixup commit. I do like the extra \iref though.

Eisenwave · 2025-07-11T18:21:12Z

source/exec.tex

+  class @\libglobal{task_scheduler}@;
+
+  // \ref{exec.task}
+  template<class E>


New declarations like these should be in a separate commit.

What? The incoming paper is missing a declaration? That's at least worth a proper non-fixup "[blah.syn] Add missing declarations" commit.

As dietmar explained above, those definitions exist, but are missing declarations in the synopsis.

Ah, ok. And those declarations seem to have no add-on info, so they probably should exist in the synopsis only.

Eisenwave · 2025-07-11T18:23:02Z

source/exec.tex

+\tcode{affine_on} adapts a sender into one that completes on
+the specified scheduler. If the algorithm determines that the adapted
+sender already completes on the correct scheduler it can avoid any
+scheduling operation.


This repository uses semantic line breaks (https://sembr.org/). I don't want to bother you too much, but please put new sentences on a separate line at least. That is, newline after ..

Note that the TeX still renders the same whether you put a space or a newline into the source.

Eisenwave · 2025-07-11T18:24:30Z

source/exec.tex

+except that \tcode{sndr} is evalutated only once.
+
+\pnum
+The exposition-only class template \exposid{impls-for}\iref{exec.snd.general}


New \irefs should be in a separate commit.

Eisenwave · 2025-07-11T18:26:15Z

source/exec.tex

+\begin{codeblock}
+namespace std::execution {
+  template<>
+  struct @\exposid{impls-for}@<affine_on_t>: @\exposid{default-impls}@ {


Suggested change

struct @\exposid{impls-for}@<affine_on_t>: @\exposid{default-impls}@ {

struct @\exposid{impls-for}@<affine_on_t> : @\exposid{default-impls}@ {

Eisenwave · 2025-07-11T19:15:49Z

source/exec.tex

+\tcode{as_awaitable(affine_on(\linebreak std::forward<Sender>(sndr), % avoid Overfull
+SCHED(*this)), *this)}.


Suggested change

\tcode{as_awaitable(affine_on(\linebreak std::forward<Sender>(sndr), % avoid Overfull

SCHED(*this)), *this)}.

\tcode{as_awaitable(affine_on(\brk{}std::forward<Sender>(sndr), \exposid{SCHED}(*this)), *this)}.

Eisenwave · 2025-07-11T19:17:28Z

source/exec.tex

+Equivalent to: \tcode{returns await_transform(just(exchange(SCHED(*this),
+\linebreak scheduler_type(sch.scheduler))), *this);} % avoid Overfull


Suggested change

Equivalent to: \tcode{returns await_transform(just(exchange(SCHED(*this),

\linebreak scheduler_type(sch.scheduler))), *this);} % avoid Overfull

Equivalent to:

\begin{codeblock}

return await_transform(just(exchange(SCHED(*this), scheduler_type(sch.scheduler))), *this);

\end{codeblock}

Note the typo in returns (paper has this), but I think this doesn't really need a separate commit.

Eisenwave · 2025-07-11T19:18:06Z

source/exec.tex

+\pnum
+\effects
+If the signature \tcode{set_error_t(exception_ptr)} is not an element
+of \tcode{error_types}, calls \tcode{terminate()} \iref{except.terminate}.


Suggested change

of \tcode{error_types}, calls \tcode{terminate()} \iref{except.terminate}.

of \tcode{error_types}, calls \tcode{terminate()}\iref{except.terminate}.

Eisenwave · 2025-07-11T19:19:49Z

source/exec.tex

+\tcode{PAlloc} is \tcode{allocator_traits<Allocator>::template
+rebind_alloc\linebreak<U>} where \tcode{U} is an unspecified type % avoid Overfull


Suggested change

\tcode{PAlloc} is \tcode{allocator_traits<Allocator>::template

rebind_alloc\linebreak<U>} where \tcode{U} is an unspecified type % avoid Overfull

\tcode{PAlloc} is \tcode{allocator_traits<Allocator>::template

re\-bind_alloc\brk{}<U>} where \tcode{U} is an unspecified type

Eisenwave · 2025-07-11T19:20:36Z

source/exec.tex

+coroutine state of size \tcode{size}, and unspecified additional
+state necessary to ensure that \tcode{operator delete} can later
+deallocate this memory block with an allocator equal to \tcode{palloc}.
+\pnum


Suggested change

\pnum

\pnum

Yes, pnum needs an empty line in front (or a \begin{itemdescr}, otherwise it's not functioning properly.

jensmaurer · 2025-07-11T20:45:08Z

@Eisenwave and @dietmarkuehl , let me recap the general rules for paper pull requests, and their rationale.

We generally do not want force-pushes during paper application, because that might impede in-flight review. (We're fine with / encourage force-pushes for non-paper pull requests.)
Any commit prefixed by "fixup" in the title will be squashed when @tkoeppe merges the pull request. These are the kind of commits that should appear when you've forgotten to apply a change in the incoming paper. Obviously, we don't want to keep this for posterity. Having a separate commit also helps with "look, I've really fixed that". Since this will be squashed, the commit description doesn't matter a lot (of course, it should be readable).
For example, "fixup: add indexing" is a perfectly fine commit title here (provided the contents is related to the title). Or "fixup: avoid overfull hboxes".
Punctuation fixes (Oxford comma, after bullets, after subordinate clauses etc.) should be done silently in the original commit, or as a "fixup" later (if you notice punctuation issues after creating the pull request).
More involved, but still "obviously editorial" fixes should be mentioned in the original commit description, e.g. "dissolved lone subclause X" or "marked exposition-only identifiers"
Anything beyond that warrants a separate, proper editorial commit in the usual format "[sub.clause.label] What is changed".

Adding cross-references to definitions of terms is probably in the "obviously editorial" area, but requires a check whether the xref is pointing to the right place (and thus is putting additional burden on the reviewers). Having a separate, proper editorial commit "[sub.clause.label] Add cross-references to term definitions" would be a bit more transparent, and clearly differentiates paper content from add-on editorial fixes. Occasionally, cross-references are normative (we mean exactly those situations), and changing / amending them would not be editorial.

Hope that helps.

dietmarkuehl added 6 commits June 29, 2025 18:03

Fixup: actioned CI feedback

de6b8e0

Fixup: address more issues reported by the CI

1587aa4

Fixup: addressed more CI feedback

308523f

Fixup: address more CI feedback

123ff25

The CI objected to use of \exposid{sender} => renamed sender to ts-sender. This change should be editorial but is more invovled

Fixup: addressed more CI feedback (on referencing Cpp17Allocator)

af0f16f

dietmarkuehl mentioned this pull request Jun 29, 2025

[2025-06 LWG Motion 34] P3552R3 Add a Coroutine Task Type #7971

Open

jensmaurer changed the title ~~FIXES: 7971 [2025-06 LWG Motion 34] P3552R3 Add a Coroutine Task~~ [2025-06 LWG Motion 34] P3552R3 Add a Coroutine Task Jun 30, 2025

Eisenwave requested changes Jul 11, 2025

View reviewed changes

	when an exception is thrown from a coroutine \tcode{std::execution::task}\iref{exec.task} which doesn't support a \tcode{std::execution::set_error_t(std::execption_ptr)} completion.
	when an exception is thrown from a coroutine \tcode{std::execution::task}\iref{exec.task}
	which doesn't support a \tcode{std::execution::set_error_t(std::exception_ptr)} completion.

	struct @\exposid{impls-for}@<affine_on_t>: @\exposid{default-impls}@ {
	struct @\exposid{impls-for}@<affine_on_t> : @\exposid{default-impls}@ {

		\tcode{as_awaitable(affine_on(\linebreak std::forward<Sender>(sndr), % avoid Overfull
		SCHED(this)), this)}.

	\tcode{as_awaitable(affine_on(\linebreak std::forward<Sender>(sndr), % avoid Overfull
	SCHED(this)), this)}.
	\tcode{as_awaitable(affine_on(\brk{}std::forward<Sender>(sndr), \exposid{SCHED}(this)), this)}.

		Equivalent to: \tcode{returns await_transform(just(exchange(SCHED(*this),
		\linebreak scheduler_type(sch.scheduler))), *this);} % avoid Overfull

	of \tcode{error_types}, calls \tcode{terminate()} \iref{except.terminate}.
	of \tcode{error_types}, calls \tcode{terminate()}\iref{except.terminate}.

		\tcode{PAlloc} is \tcode{allocator_traits<Allocator>::template
		rebind_alloc\linebreak<U>} where \tcode{U} is an unspecified type % avoid Overfull

[2025-06 LWG Motion 34] P3552R3 Add a Coroutine Task #8032

Are you sure you want to change the base?

[2025-06 LWG Motion 34] P3552R3 Add a Coroutine Task #8032

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jensmaurer commented Jul 11, 2025

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dietmarkuehl commented Jun 29, 2025 •

edited by jensmaurer

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Eisenwave left a comment •

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