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+[support.coroutine]
+
+# 17 Language support library [[support]](./#support)
+
+## 17.13 Coroutines [support.coroutine]
+
+### [17.13.1](#general) General [[support.coroutine.general]](support.coroutine.general)
+
+[1](#general-1)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L5749)
+
+The header <coroutine> defines several types providing
+compile and run-time support for
+coroutines in a C++ program[.](#general-1.sentence-1)
+
+### [17.13.2](#coroutine.syn) Header <coroutine> synopsis [[coroutine.syn]](coroutine.syn)
+
+[ð](#header:%3ccoroutine%3e_)
+
+// all freestanding#include <compare> // see [[compare.syn]](compare.syn "17.12.1 Header <compare> synopsis")namespace std {// [[coroutine.traits]](#coroutine.traits "17.13.3 Coroutine traits"), coroutine traitstemplate<class R, class... ArgTypes>struct coroutine_traits; // [[coroutine.handle]](#coroutine.handle "17.13.4 Class template coroutine_handle"), coroutine handletemplate<class Promise = void>struct coroutine_handle; // [[coroutine.handle.compare]](#coroutine.handle.compare "17.13.4.8 Comparison operators"), comparison operatorsconstexpr bool operator==(coroutine_handle<> x, coroutine_handle<> y) noexcept; constexpr strong_ordering operator<=>(coroutine_handle<> x, coroutine_handle<> y) noexcept; // [[coroutine.handle.hash]](#coroutine.handle.hash "17.13.4.9 Hash support"), hash supporttemplate<class T> struct hash; template<class P> struct hash<coroutine_handle<P>>; // [[coroutine.noop]](#coroutine.noop "17.13.5 No-op coroutines"), no-op coroutinesstruct noop_coroutine_promise; template<> struct coroutine_handle<noop_coroutine_promise>; using noop_coroutine_handle = coroutine_handle<noop_coroutine_promise>;
+
+ noop_coroutine_handle noop_coroutine() noexcept; // [[coroutine.trivial.awaitables]](#coroutine.trivial.awaitables "17.13.6 Trivial awaitables"), trivial awaitablesstruct suspend_never; struct suspend_always;}
+
+### [17.13.3](#coroutine.traits) Coroutine traits [[coroutine.traits]](coroutine.traits)
+
+#### [17.13.3.1](#coroutine.traits.general) General [[coroutine.traits.general]](coroutine.traits.general)
+
+[1](#coroutine.traits.general-1)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L5798)
+
+Subclause [[coroutine.traits]](#coroutine.traits "17.13.3 Coroutine traits") defines requirements on classes representing[*coroutine traits*](#def:coroutine_traits),
+and defines the class templatecoroutine_traits that meets those requirements[.](#coroutine.traits.general-1.sentence-1)
+
+#### [17.13.3.2](#coroutine.traits.primary) Class template coroutine_traits [[coroutine.traits.primary]](coroutine.traits.primary)
+
+[1](#coroutine.traits.primary-1)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L5808)
+
+The header [<coroutine>](#header:%3ccoroutine%3e "17.13.2 Header <coroutine> synopsis [coroutine.syn]") defines the primary templatecoroutine_traits such that
+if ArgTypes is a parameter pack of types and
+if the [*qualified-id*](expr.prim.id.qual#nt:qualified-id "7.5.5.3 Qualified names [expr.prim.id.qual]") R::promise_type is valid and
+denotes a type ([[temp.deduct]](temp.deduct "13.10.3 Template argument deduction")),
+then coroutine_traits<R, ArgTypes...> has the following publicly
+accessible member:using promise_type = typename R::promise_type;
+
+Otherwise, coroutine_traits<R, ArgTypes...> has no members[.](#coroutine.traits.primary-1.sentence-2)
+
+[2](#coroutine.traits.primary-2)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L5822)
+
+Program-defined specializations of this template shall define a publicly
+accessible nested type named promise_type[.](#coroutine.traits.primary-2.sentence-1)
+
+### [17.13.4](#coroutine.handle) Class template coroutine_handle [[coroutine.handle]](coroutine.handle)
+
+#### [17.13.4.1](#coroutine.handle.general) General [[coroutine.handle.general]](coroutine.handle.general)
+
+[ð](#lib:coroutine_handle)
+
+namespace std {template<>struct coroutine_handle<void>{// [[coroutine.handle.con]](#coroutine.handle.con "17.13.4.2 Construct/reset"), construct/resetconstexpr coroutine_handle() noexcept; constexpr coroutine_handle(nullptr_t) noexcept;
+ coroutine_handle& operator=(nullptr_t) noexcept; // [[coroutine.handle.export.import]](#coroutine.handle.export.import "17.13.4.4 Export/import"), export/importconstexpr void* address() const noexcept; static constexpr coroutine_handle from_address(void* addr); // [[coroutine.handle.observers]](#coroutine.handle.observers "17.13.4.5 Observers"), observersconstexpr explicit operator bool() const noexcept; bool done() const; // [[coroutine.handle.resumption]](#coroutine.handle.resumption "17.13.4.6 Resumption"), resumptionvoid operator()() const; void resume() const; void destroy() const; private:void* ptr; // *exposition only*}; template<class Promise>struct coroutine_handle {// [[coroutine.handle.con]](#coroutine.handle.con "17.13.4.2 Construct/reset"), construct/resetconstexpr coroutine_handle() noexcept; constexpr coroutine_handle(nullptr_t) noexcept; static coroutine_handle from_promise(Promise&);
+ coroutine_handle& operator=(nullptr_t) noexcept; // [[coroutine.handle.export.import]](#coroutine.handle.export.import "17.13.4.4 Export/import"), export/importconstexpr void* address() const noexcept; static constexpr coroutine_handle from_address(void* addr); // [[coroutine.handle.conv]](#coroutine.handle.conv "17.13.4.3 Conversion"), conversionconstexpr operator coroutine_handle<>() const noexcept; // [[coroutine.handle.observers]](#coroutine.handle.observers "17.13.4.5 Observers"), observersconstexpr explicit operator bool() const noexcept; bool done() const; // [[coroutine.handle.resumption]](#coroutine.handle.resumption "17.13.4.6 Resumption"), resumptionvoid operator()() const; void resume() const; void destroy() const; // [[coroutine.handle.promise]](#coroutine.handle.promise "17.13.4.7 Promise access"), promise access Promise& promise() const; private:void* ptr; // *exposition only*};}
+
+[1](#coroutine.handle.general-1)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L5892)
+
+An object of typecoroutine_handle<T> is called a [*coroutine handle*](#def:coroutine_handle) and can be used to refer to a suspended or executing coroutine[.](#coroutine.handle.general-1.sentence-1)
+
+A coroutine_handle object whose
+member address() returns a null pointer value
+does not refer to any
+coroutine[.](#coroutine.handle.general-1.sentence-2)
+
+Two coroutine_handle objects refer to the same coroutine
+if and only if their member address() returns the same non-null value[.](#coroutine.handle.general-1.sentence-3)
+
+[2](#coroutine.handle.general-2)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L5903)
+
+If a program declares an explicit or partial specialization ofcoroutine_handle, the behavior is undefined[.](#coroutine.handle.general-2.sentence-1)
+
+#### [17.13.4.2](#coroutine.handle.con) Construct/reset [[coroutine.handle.con]](coroutine.handle.con)
+
+[ð](#lib:coroutine_handle,constructor)
+
+`constexpr coroutine_handle() noexcept;
+constexpr coroutine_handle(nullptr_t) noexcept;
+`
+
+[1](#coroutine.handle.con-1)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L5916)
+
+*Postconditions*: address() == nullptr[.](#coroutine.handle.con-1.sentence-1)
+
+[ð](#lib:from_promise,coroutine_handle)
+
+`static coroutine_handle from_promise(Promise& p);
+`
+
+[2](#coroutine.handle.con-2)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L5927)
+
+*Preconditions*: p is a reference to a promise object of a coroutine[.](#coroutine.handle.con-2.sentence-1)
+
+[3](#coroutine.handle.con-3)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L5931)
+
+*Postconditions*: addressof(h.promise()) == addressof(p)[.](#coroutine.handle.con-3.sentence-1)
+
+[4](#coroutine.handle.con-4)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L5935)
+
+*Returns*: A coroutine handle h referring to the coroutine[.](#coroutine.handle.con-4.sentence-1)
+
+[ð](#lib:operator=,coroutine_handle)
+
+`coroutine_handle& operator=(nullptr_t) noexcept;
+`
+
+[5](#coroutine.handle.con-5)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L5946)
+
+*Postconditions*: address() == nullptr[.](#coroutine.handle.con-5.sentence-1)
+
+[6](#coroutine.handle.con-6)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L5950)
+
+*Returns*: *this[.](#coroutine.handle.con-6.sentence-1)
+
+#### [17.13.4.3](#coroutine.handle.conv) Conversion [[coroutine.handle.conv]](coroutine.handle.conv)
+
+[ð](#lib:operator_coroutine_handle%3c%3e,coroutine_handle)
+
+`constexpr operator coroutine_handle<>() const noexcept;
+`
+
+[1](#coroutine.handle.conv-1)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L5963)
+
+*Effects*: Equivalent to: return coroutine_handle<>::from_address(address());
+
+#### [17.13.4.4](#coroutine.handle.export.import) Export/import [[coroutine.handle.export.import]](coroutine.handle.export.import)
+
+[ð](#lib:address,coroutine_handle)
+
+`constexpr void* address() const noexcept;
+`
+
+[1](#coroutine.handle.export.import-1)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L5976)
+
+*Returns*: ptr[.](#coroutine.handle.export.import-1.sentence-1)
+
+[ð](#lib:from_address,coroutine_handle)
+
+`static constexpr coroutine_handle<> coroutine_handle<>::from_address(void* addr);
+`
+
+[2](#coroutine.handle.export.import-2)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L5987)
+
+*Preconditions*: addr was obtained via a prior call to address on an object whose type is a specialization of coroutine_handle[.](#coroutine.handle.export.import-2.sentence-1)
+
+[3](#coroutine.handle.export.import-3)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L5992)
+
+*Postconditions*: from_address(address()) == *this[.](#coroutine.handle.export.import-3.sentence-1)
+
+[ð](#lib:from_address,coroutine_handle_)
+
+`static constexpr coroutine_handle<Promise> coroutine_handle<Promise>::from_address(void* addr);
+`
+
+[4](#coroutine.handle.export.import-4)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L6003)
+
+*Preconditions*: addr was obtained via a prior call to address on an object of type cv coroutine_handle<Promise>[.](#coroutine.handle.export.import-4.sentence-1)
+
+[5](#coroutine.handle.export.import-5)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L6008)
+
+*Postconditions*: from_address(address()) == *this[.](#coroutine.handle.export.import-5.sentence-1)
+
+#### [17.13.4.5](#coroutine.handle.observers) Observers [[coroutine.handle.observers]](coroutine.handle.observers)
+
+[ð](#lib:operator_bool,coroutine_handle)
+
+`constexpr explicit operator bool() const noexcept;
+`
+
+[1](#coroutine.handle.observers-1)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L6021)
+
+*Returns*: address() != nullptr[.](#coroutine.handle.observers-1.sentence-1)
+
+[ð](#lib:done,coroutine_handle)
+
+`bool done() const;
+`
+
+[2](#coroutine.handle.observers-2)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L6032)
+
+*Preconditions*: *this refers to a suspended coroutine[.](#coroutine.handle.observers-2.sentence-1)
+
+[3](#coroutine.handle.observers-3)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L6036)
+
+*Returns*: true if the coroutine is suspended at its
+final suspend point, otherwise false[.](#coroutine.handle.observers-3.sentence-1)
+
+#### [17.13.4.6](#coroutine.handle.resumption) Resumption [[coroutine.handle.resumption]](coroutine.handle.resumption)
+
+[1](#coroutine.handle.resumption-1)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L6044)
+
+Resuming a coroutine via resume, operator(), or destroy on an execution agent other than the one on which it was suspended
+has implementation-defined behavior
+unless
+each execution agent either is
+an instance of std::thread or std::jthread,
+or is the thread that executes main[.](#coroutine.handle.resumption-1.sentence-1)
+
+[*Note [1](#coroutine.handle.resumption-note-1)*:
+
+A coroutine that is resumed on a different execution agent should
+avoid relying on consistent thread identity throughout, such as holding
+a mutex object across a suspend point[.](#coroutine.handle.resumption-1.sentence-2)
+
+â *end note*]
+
+[*Note [2](#coroutine.handle.resumption-note-2)*:
+
+A concurrent resumption of the coroutine can result in a data race[.](#coroutine.handle.resumption-1.sentence-3)
+
+â *end note*]
+
+[ð](#lib:operator(),coroutine_handle)
+
+`void operator()() const;
+void resume() const;
+`
+
+[2](#coroutine.handle.resumption-2)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L6069)
+
+*Preconditions*: *this refers to a suspended coroutine[.](#coroutine.handle.resumption-2.sentence-1)
+
+The coroutine is not suspended at its final suspend point[.](#coroutine.handle.resumption-2.sentence-2)
+
+[3](#coroutine.handle.resumption-3)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L6074)
+
+*Effects*: Resumes the execution of the coroutine[.](#coroutine.handle.resumption-3.sentence-1)
+
+[ð](#lib:destroy,coroutine_handle)
+
+`void destroy() const;
+`
+
+[4](#coroutine.handle.resumption-4)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L6085)
+
+*Preconditions*: *this refers to a suspended coroutine[.](#coroutine.handle.resumption-4.sentence-1)
+
+[5](#coroutine.handle.resumption-5)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L6089)
+
+*Effects*: Destroys the coroutine ([[dcl.fct.def.coroutine]](dcl.fct.def.coroutine "9.6.4 Coroutine definitions"))[.](#coroutine.handle.resumption-5.sentence-1)
+
+#### [17.13.4.7](#coroutine.handle.promise) Promise access [[coroutine.handle.promise]](coroutine.handle.promise)
+
+[ð](#lib:promise,coroutine_handle)
+
+`Promise& promise() const;
+`
+
+[1](#coroutine.handle.promise-1)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L6102)
+
+*Preconditions*: *this refers to a coroutine[.](#coroutine.handle.promise-1.sentence-1)
+
+[2](#coroutine.handle.promise-2)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L6106)
+
+*Returns*: A reference to the promise of the coroutine[.](#coroutine.handle.promise-2.sentence-1)
+
+#### [17.13.4.8](#coroutine.handle.compare) Comparison operators [[coroutine.handle.compare]](coroutine.handle.compare)
+
+[ð](#lib:operator==,coroutine_handle)
+
+`constexpr bool operator==(coroutine_handle<> x, coroutine_handle<> y) noexcept;
+`
+
+[1](#coroutine.handle.compare-1)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L6120)
+
+*Returns*: x.address() == y.address()[.](#coroutine.handle.compare-1.sentence-1)
+
+[ð](#lib:operator%3c=%3e,coroutine_handle)
+
+`constexpr strong_ordering operator<=>(coroutine_handle<> x, coroutine_handle<> y) noexcept;
+`
+
+[2](#coroutine.handle.compare-2)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L6131)
+
+*Returns*: compare_three_way()(x.address(), y.address())[.](#coroutine.handle.compare-2.sentence-1)
+
+#### [17.13.4.9](#coroutine.handle.hash) Hash support [[coroutine.handle.hash]](coroutine.handle.hash)
+
+[ð](#lib:hash,coroutine_handle)
+
+`template<class P> struct hash<coroutine_handle<P>>;
+`
+
+[1](#coroutine.handle.hash-1)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L6144)
+
+The specialization is enabled ([[unord.hash]](unord.hash "22.10.19 Class template hash"))[.](#coroutine.handle.hash-1.sentence-1)
+
+### [17.13.5](#coroutine.noop) No-op coroutines [[coroutine.noop]](coroutine.noop)
+
+#### [17.13.5.1](#coroutine.promise.noop) Class noop_coroutine_promise [[coroutine.promise.noop]](coroutine.promise.noop)
+
+[ð](#lib:noop_coroutine_promise)
+
+`struct noop_coroutine_promise {};
+`
+
+[1](#coroutine.promise.noop-1)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L6158)
+
+The class noop_coroutine_promise defines the promise type for
+the coroutine referred to
+by noop_coroutine_handle ([[coroutine.syn]](#coroutine.syn "17.13.2 Header <coroutine> synopsis"))[.](#coroutine.promise.noop-1.sentence-1)
+
+#### [17.13.5.2](#coroutine.handle.noop) Class coroutine_handle<noop_coroutine_promise> [[coroutine.handle.noop]](coroutine.handle.noop)
+
+#### [17.13.5.2.1](#coroutine.handle.noop.general) General [[coroutine.handle.noop.general]](coroutine.handle.noop.general)
+
+[ð](#lib:coroutine_handle%3cnoop_coroutine_promise%3e)
+
+namespace std {template<>struct coroutine_handle<noop_coroutine_promise>{// [[coroutine.handle.noop.conv]](#coroutine.handle.noop.conv "17.13.5.2.2 Conversion"), conversionconstexpr operator coroutine_handle<>() const noexcept; // [[coroutine.handle.noop.observers]](#coroutine.handle.noop.observers "17.13.5.2.3 Observers"), observersconstexpr explicit operator bool() const noexcept; constexpr bool done() const noexcept; // [[coroutine.handle.noop.resumption]](#coroutine.handle.noop.resumption "17.13.5.2.4 Resumption"), resumptionconstexpr void operator()() const noexcept; constexpr void resume() const noexcept; constexpr void destroy() const noexcept; // [[coroutine.handle.noop.promise]](#coroutine.handle.noop.promise "17.13.5.2.5 Promise access"), promise access noop_coroutine_promise& promise() const noexcept; // [[coroutine.handle.noop.address]](#coroutine.handle.noop.address "17.13.5.2.6 Address"), addressconstexpr void* address() const noexcept; private: coroutine_handle(*unspecified*); void* ptr; // *exposition only*};}
+
+#### [17.13.5.2.2](#coroutine.handle.noop.conv) Conversion [[coroutine.handle.noop.conv]](coroutine.handle.noop.conv)
+
+[ð](#lib:operator_coroutine_handle%3c%3e,coroutine_handle%3cnoop_coroutine_promise%3e)
+
+`constexpr operator coroutine_handle<>() const noexcept;
+`
+
+[1](#coroutine.handle.noop.conv-1)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L6206)
+
+*Effects*: Equivalent to: return coroutine_handle<>::from_address(address());
+
+#### [17.13.5.2.3](#coroutine.handle.noop.observers) Observers [[coroutine.handle.noop.observers]](coroutine.handle.noop.observers)
+
+[ð](#lib:operator_bool,coroutine_handle%3cnoop_coroutine_promise%3e)
+
+`constexpr explicit operator bool() const noexcept;
+`
+
+[1](#coroutine.handle.noop.observers-1)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L6219)
+
+*Returns*: true[.](#coroutine.handle.noop.observers-1.sentence-1)
+
+[ð](#lib:done,coroutine_handle%3cnoop_coroutine_promise%3e)
+
+`constexpr bool done() const noexcept;
+`
+
+[2](#coroutine.handle.noop.observers-2)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L6230)
+
+*Returns*: false[.](#coroutine.handle.noop.observers-2.sentence-1)
+
+#### [17.13.5.2.4](#coroutine.handle.noop.resumption) Resumption [[coroutine.handle.noop.resumption]](coroutine.handle.noop.resumption)
+
+[ð](#lib:operator(),coroutine_handle%3cnoop_coroutine_promise%3e)
+
+`constexpr void operator()() const noexcept;
+constexpr void resume() const noexcept;
+constexpr void destroy() const noexcept;
+`
+
+[1](#coroutine.handle.noop.resumption-1)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L6247)
+
+*Effects*: None[.](#coroutine.handle.noop.resumption-1.sentence-1)
+
+[2](#coroutine.handle.noop.resumption-2)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L6251)
+
+*Remarks*: If noop_coroutine_handle is converted to coroutine_handle<>,
+calls to operator(), resume and destroy on that handle
+will also have no observable effects[.](#coroutine.handle.noop.resumption-2.sentence-1)
+
+#### [17.13.5.2.5](#coroutine.handle.noop.promise) Promise access [[coroutine.handle.noop.promise]](coroutine.handle.noop.promise)
+
+[ð](#lib:promise,coroutine_handle%3cnoop_coroutine_promise%3e)
+
+`noop_coroutine_promise& promise() const noexcept;
+`
+
+[1](#coroutine.handle.noop.promise-1)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L6266)
+
+*Returns*: A reference to the promise object associated with this
+coroutine handle[.](#coroutine.handle.noop.promise-1.sentence-1)
+
+#### [17.13.5.2.6](#coroutine.handle.noop.address) Address [[coroutine.handle.noop.address]](coroutine.handle.noop.address)
+
+[ð](#lib:address,coroutine_handle%3cnoop_coroutine_promise%3e)
+
+`constexpr void* address() const noexcept;
+`
+
+[1](#coroutine.handle.noop.address-1)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L6280)
+
+*Returns*: ptr[.](#coroutine.handle.noop.address-1.sentence-1)
+
+[2](#coroutine.handle.noop.address-2)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L6284)
+
+*Remarks*: A noop_coroutine_handle's ptr is always a
+non-null pointer value[.](#coroutine.handle.noop.address-2.sentence-1)
+
+#### [17.13.5.3](#coroutine.noop.coroutine) Function noop_coroutine [[coroutine.noop.coroutine]](coroutine.noop.coroutine)
+
+[ð](#lib:noop_coroutine)
+
+`noop_coroutine_handle noop_coroutine() noexcept;
+`
+
+[1](#coroutine.noop.coroutine-1)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L6298)
+
+*Returns*: A handle to a coroutine that has no observable effects
+when resumed or destroyed[.](#coroutine.noop.coroutine-1.sentence-1)
+
+[2](#coroutine.noop.coroutine-2)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L6303)
+
+*Remarks*: A handle returned from noop_coroutine may or may not
+compare equal to a handle returned from another invocation
+of noop_coroutine[.](#coroutine.noop.coroutine-2.sentence-1)
+
+### [17.13.6](#coroutine.trivial.awaitables) Trivial awaitables [[coroutine.trivial.awaitables]](coroutine.trivial.awaitables)
+
+[ð](#lib:suspend_never)
+
+namespace std {struct suspend_never {constexpr bool await_ready() const noexcept { return true; }constexpr void await_suspend(coroutine_handle<>) const noexcept {}constexpr void await_resume() const noexcept {}}; struct suspend_always {constexpr bool await_ready() const noexcept { return false; }constexpr void await_suspend(coroutine_handle<>) const noexcept {}constexpr void await_resume() const noexcept {}};}
+
+[1](#coroutine.trivial.awaitables-1)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L6335)
+
+[*Note [1](#coroutine.trivial.awaitables-note-1)*:
+
+The types suspend_never and suspend_always can be used
+to indicate that an [*await-expression*](expr.await#nt:await-expression "7.6.2.4 Await [expr.await]") either never
+suspends or always suspends, and in either case does not produce a value[.](#coroutine.trivial.awaitables-1.sentence-1)
+
+â *end note*]