[support.runtime] - C++14 → C++17

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@@ -1,120 +1,208 @@
 ## Other runtime support <a id="support.runtime">[[support.runtime]]</a>
 Headers `<csetjmp>` (nonlocal jumps), `<csignal>` (signal handling),
-`<cstdalign> (alignment),` `<cstdarg>` (variable arguments),
-`<cstdbool>` (`\xname{bool_true_false_are_defined}`). `<cstdlib>`
-(runtime environment `getenv(), system()`), and `<ctime>` (system clock
-`clock(), time()`) provide further compatibility with C code.
-The contents of these headers are the same as the Standard C library
-headers `<setjmp.h>`, `<signal.h>`, `<stdalign.h>`, `<stdarg.h>`,
-`<stdbool.h>`, `<stdlib.h>`, and `<time.h>`, respectively, with the
-following changes:
-The restrictions that ISO C places on the second parameter to the
-`va_start()` macro in header `<stdarg.h>` are different in this
-International Standard. The parameter `parmN` is the identifier of the
-rightmost parameter in the variable parameter list of the function
-definition (the one just before the `...`).[^34] If the parameter
-`parmN` is of a reference type, or of a type that is not compatible with
-the type that results when passing an argument for which there is no
-parameter, the behavior is undefined.
-ISO C 4.8.1.1.
 The function signature `longjmp(jmp_buf jbuf, int val)` has more
 restricted behavior in this International Standard. A `setjmp`/`longjmp`
 call pair has undefined behavior if replacing the `setjmp` and `longjmp`
 by `catch` and `throw` would invoke any non-trivial destructors for any
 automatic objects.
-ISO C 7.10.4, 7.8, 7.6, 7.12.
-Calls to the function `getenv` shall not introduce a data race (
-[[res.on.data.races]]) provided that nothing modifies the environment.
-Calls to the POSIX functions `setenv` and `putenv` modify the
-environment.
-A call to the `setlocale` function may introduce a data race with other
-calls to the `setlocale` function or with calls to functions that are
-affected by the current C locale. The implementation shall behave as if
-no library function other than `locale::global()` calls the `setlocale`
-function.
-The header `<cstdalign>` and the header `<stdalign.h>` shall not define
-a macro named `alignas`.
-The header `<cstdbool>` and the header `<stdbool.h>` shall not define
-macros named `bool`, `true`, or `false`.
 A call to the function `signal` synchronizes with any resulting
 invocation of the signal handler so installed.
-The common subset of the C and C++languages consists of all
-declarations, definitions, and expressions that may appear in a well
-formed C++program and also in a conforming C program. A POF (“plain old
-function”) is a function that uses only features from this common
-subset, and that does not directly or indirectly use any function that
-is not a POF, except that it may use plain lock-free atomic operations.
-A *plain lock-free atomic operation* is an invocation of a function *f*
-from Clause  [[atomics]], such that *f* is not a member function, and
-either *f* is the function `atomic_is_lock_free`, or for every atomic
-argument `A` passed to *f*, `atomic_is_lock_free(A)` yields `true`. All
-signal handlers shall have C linkage. The behavior of any function other
-than a POF used as a signal handler in a C++program is
-*implementation-defined*.[^35]
 <!-- Link reference definitions -->
 [alloc.errors]: #alloc.errors
 [atomics]: atomics.md#atomics
 [bad.alloc]: #bad.alloc
 [bad.cast]: #bad.cast
 [bad.exception]: #bad.exception
 [bad.typeid]: #bad.typeid
 [basic.align]: basic.md#basic.align
 [basic.fundamental]: basic.md#basic.fundamental
 [basic.start]: basic.md#basic.start
 [basic.start.term]: basic.md#basic.start.term
 [basic.stc.dynamic]: basic.md#basic.stc.dynamic
 [basic.stc.dynamic.allocation]: basic.md#basic.stc.dynamic.allocation
 [basic.stc.dynamic.deallocation]: basic.md#basic.stc.dynamic.deallocation
 [basic.stc.dynamic.safety]: basic.md#basic.stc.dynamic.safety
-[c.limits]: #c.limits
 [class]: class.md#class
 [class.free]: special.md#class.free
 [complex]: numerics.md#complex
 [constraints]: library.md#constraints
 [conv.ptr]: conv.md#conv.ptr
 [conv.rank]: conv.md#conv.rank
 [cstdint]: #cstdint
 [cstdint.syn]: #cstdint.syn
 [dcl.init.list]: dcl.md#dcl.init.list
 [denorm.style]: #denorm.style
-[except.ctor]: except.md#except.ctor
 [except.handle]: except.md#except.handle
 [except.nested]: #except.nested
 [except.special]: except.md#except.special
 [except.terminate]: except.md#except.terminate
-[except.throw]: except.md#except.throw
-[except.unexpected]: except.md#except.unexpected
 [exception]: #exception
 [exception.terminate]: #exception.terminate
 [expr.add]: expr.md#expr.add
 [expr.delete]: expr.md#expr.delete
 [expr.dynamic.cast]: expr.md#expr.dynamic.cast
 [expr.new]: expr.md#expr.new
 [expr.sizeof]: expr.md#expr.sizeof
 [expr.typeid]: expr.md#expr.typeid
 [get.new.handler]: #get.new.handler
 [get.terminate]: #get.terminate
-[intro.execution]: intro.md#intro.execution
 [intro.memory]: intro.md#intro.memory
 [intro.multithread]: intro.md#intro.multithread
 [language.support]: #language.support
-[limits]: #limits
-[limits.numeric]: #limits.numeric
 [limits.syn]: #limits.syn
 [locale.codecvt]: localization.md#locale.codecvt
 [memory]: utilities.md#memory
 [multibyte.strings]: library.md#multibyte.strings
 [new.badlength]: #new.badlength
@@ -122,19 +210,22 @@ than a POF used as a signal handler in a C++program is
 [new.delete.array]: #new.delete.array
 [new.delete.dataraces]: #new.delete.dataraces
 [new.delete.placement]: #new.delete.placement
 [new.delete.single]: #new.delete.single
 [new.handler]: #new.handler
 [nullablepointer.requirements]: library.md#nullablepointer.requirements
 [numeric.limits]: #numeric.limits
 [numeric.limits.members]: #numeric.limits.members
 [numeric.special]: #numeric.special
 [propagation]: #propagation
 [res.on.data.races]: library.md#res.on.data.races
 [round.style]: #round.style
 [set.new.handler]: #set.new.handler
 [set.terminate]: #set.terminate
 [string.classes]: strings.md#string.classes
 [support.dynamic]: #support.dynamic
 [support.exception]: #support.exception
 [support.general]: #support.general
 [support.initlist]: #support.initlist
@@ -143,23 +234,25 @@ than a POF used as a signal handler in a C++program is
 [support.initlist.range]: #support.initlist.range
 [support.limits]: #support.limits
 [support.limits.general]: #support.limits.general
 [support.rtti]: #support.rtti
 [support.runtime]: #support.runtime
 [support.start.term]: #support.start.term
 [support.types]: #support.types
 [tab:lang.sup.lib.summary]: #tab:lang.sup.lib.summary
-[tab:support.hdr.cfloat]: #tab:support.hdr.cfloat
-[tab:support.hdr.climits]: #tab:support.hdr.climits
-[tab:support.hdr.cstddef]: #tab:support.hdr.cstddef
-[tab:support.hdr.cstdlib]: #tab:support.hdr.cstdlib
 [temp.dep.constexpr]: temp.md#temp.dep.constexpr
 [temp.dep.expr]: temp.md#temp.dep.expr
 [terminate]: #terminate
 [terminate.handler]: #terminate.handler
 [type.info]: #type.info
-[uncaught]: #uncaught
 [^1]: Possible definitions include `0` and `0L`, but not `(void*)0`.
 [^2]: Note that `offsetof` is required to work as specified even if
     unary `operator&` is overloaded for any of the types involved.
@@ -180,13 +273,12 @@ than a POF used as a signal handler in a C++program is
 [^9]: Distinguishes types with bases other than 2 (e.g. BCD).
 [^10]: Equivalent to `FLT_EPSILON`, `DBL_EPSILON`, `LDBL_EPSILON`.
-[^11]: Rounding error is described in ISO/IEC 10967-1 Language
- independent arithmetic - Part 1 Section 5.2.8 and Annex A Rationale
-    Section A.5.2.8 - Rounding constants.
 [^12]: Equivalent to `FLT_MIN_EXP`, `DBL_MIN_EXP`, `LDBL_MIN_EXP`.
 [^13]: Equivalent to `FLT_MIN_10_EXP`, `DBL_MIN_10_EXP`,
     `LDBL_MIN_10_EXP`.
@@ -200,55 +292,50 @@ than a POF used as a signal handler in a C++program is
 [^17]: Required by LIA-1.
 [^18]: Required by LIA-1.
-[^19]: See IEC 559.
 [^20]: Required by LIA-1.
 [^21]: Required by LIA-1.
 [^22]: Required by LIA-1.
 [^23]: Required by LIA-1.
-[^24]: International Electrotechnical Commission standard 559 is the
-    same as IEEE 754.
 [^25]: Required by LIA-1.
 [^26]: Required by LIA-1.
 [^27]: Required by LIA-1.
-[^28]: Refer to IEC 559. Required by LIA-1.
 [^29]: Equivalent to `FLT_ROUNDS`. Required by LIA-1.
 [^30]: A function is called for every time it is registered.
 [^31]: Objects with automatic storage duration are all destroyed in a
-    program whose function `main()` contains no automatic objects and
-    executes the call to `exit()`. Control can be transferred directly
-    to such a `main()` by throwing an exception that is caught in
-    `main()`.
 [^32]: The macros `EXIT_FAILURE` and `EXIT_SUCCESS` are defined in
     `<cstdlib>`.
-[^33]: It is not the direct responsibility of
-    `operator new[](std::size_t)` or `operator delete[](void*)` to note
-    the repetition count or element size of the array. Those operations
- are performed elsewhere in the array `new` and `delete` expressions.
- The array `new` expression, may, however, increase the `size`
- argument to `operator new[](std::size_t)` to obtain space to store
-    supplemental information.
 [^34]: Note that `va_start` is required to work as specified even if
     unary `operator&` is overloaded for the type of `parmN`.
-[^35]: In particular, a signal handler using exception handling is very
- likely to have problems. Also, invoking `std::exit` may cause
-    destruction of objects, including those of the standard library
-    implementation, which, in general, yields undefined behavior in a
-    signal handler (see  [[intro.execution]]).

 ## Other runtime support <a id="support.runtime">[[support.runtime]]</a>
 Headers `<csetjmp>` (nonlocal jumps), `<csignal>` (signal handling),
+`<cstdarg>` (variable arguments), and `<cstdlib>` (runtime environment
+`getenv, system`), provide further compatibility with C code.
+Calls to the function `getenv` ([[cstdlib.syn]]) shall not introduce a
+data race ([[res.on.data.races]]) provided that nothing modifies the
+environment.
+[*Note 1*: Calls to the POSIX functions `setenv` and `putenv` modify
+the environment. — *end note*]
+A call to the `setlocale` function ([[c.locales]]) may introduce a data
+race with other calls to the `setlocale` function or with calls to
+functions that are affected by the current C locale. The implementation
+shall behave as if no library function other than `locale::global` calls
+the `setlocale` function.
+### Header `<cstdarg>` synopsis <a id="cstdarg.syn">[[cstdarg.syn]]</a>
+``` cpp
+namespace std {
+  using va_list = see below;
+}
+#define va_arg(V, P) see below
+#define va_copy(VDST, VSRC) see below
+#define va_end(V) see below
+#define va_start(V, P) see below
+```
+The contents of the header `<cstdarg>` are the same as the C standard
+library header `<stdarg.h>`, with the following changes: The
+restrictions that ISO C places on the second parameter to the `va_start`
+macro in header `<stdarg.h>` are different in this International
+Standard. The parameter `parmN` is the rightmost parameter in the
+variable parameter list of the function definition (the one just before
+the `...`).[^34] If the parameter `parmN` is a pack expansion (
+[[temp.variadic]]) or an entity resulting from a lambda capture (
+[[expr.prim.lambda]]), the program is ill-formed, no diagnostic
+required. If the parameter `parmN` is of a reference type, or of a type
+that is not compatible with the type that results when passing an
+argument for which there is no parameter, the behavior is undefined.
+ISO C 7.16.1.1.
+### Header `<csetjmp>` synopsis <a id="csetjmp.syn">[[csetjmp.syn]]</a>
+``` cpp
+namespace std {
+  using jmp_buf = see below;
+  [[noreturn]] void longjmp(jmp_buf env, int val);
+}
+#define setjmp(env) see below
+```
+The contents of the header `<csetjmp>` are the same as the C standard
+library header `<setjmp.h>`.
 The function signature `longjmp(jmp_buf jbuf, int val)` has more
 restricted behavior in this International Standard. A `setjmp`/`longjmp`
 call pair has undefined behavior if replacing the `setjmp` and `longjmp`
 by `catch` and `throw` would invoke any non-trivial destructors for any
 automatic objects.
+ISO C 7.13.
+### Header `<csignal>` synopsis <a id="csignal.syn">[[csignal.syn]]</a>
+``` cpp
+namespace std {
+  using sig_atomic_t = see below;
+  // [support.signal], signal handlers
+  extern "C" using signal-handler = void(int);  // exposition only
+  signal-handler* signal(int sig, signal-handler* func);
+  int raise(int sig);
+}
+#define SIG_DFL see below
+#define SIG_ERR see below
+#define SIG_IGN see below
+#define SIGABRT see below
+#define SIGFPE see below
+#define SIGILL see below
+#define SIGINT see below
+#define SIGSEGV see below
+#define SIGTERM see below
+```
+The contents of the header `<csignal>` are the same as the C standard
+library header `<signal.h>`.
+### Signal handlers <a id="support.signal">[[support.signal]]</a>
 A call to the function `signal` synchronizes with any resulting
 invocation of the signal handler so installed.
+A *plain lock-free atomic operation* is an invocation of a function `f`
+from Clause  [[atomics]], such that:
+- `f` is the function `atomic_is_lock_free()`, or
+- `f` is the member function `is_lock_free()`, or
+- `f` is a non-static member function invoked on an object `A`, such
+  that `A.is_lock_free()` yields `true`, or
+- `f` is a non-member function, and for every pointer-to-atomic argument
+  `A` passed to `f`, `atomic_is_lock_free(A)` yields `true`.
+An evaluation is *signal-safe* unless it includes one of the following:
+- a call to any standard library function, except for plain lock-free
+  atomic operations and functions explicitly identified as signal-safe.
+  \[*Note 1*: This implicitly excludes the use of `new` and `delete`
+  expressions that rely on a library-provided memory
+  allocator. — *end note*]
+- an access to an object with thread storage duration;
+- a `dynamic_cast` expression;
+- throwing of an exception;
+- control entering a *try-block* or *function-try-block*;
+- initialization of a variable with static storage duration requiring
+  dynamic initialization ([[basic.start.dynamic]], [[stmt.dcl]]) [^35];
+  or
+- waiting for the completion of the initialization of a variable with
+  static storage duration ([[stmt.dcl]]).
+A signal handler invocation has undefined behavior if it includes an
+evaluation that is not signal-safe.
+The function `signal` is signal-safe if it is invoked with the first
+argument equal to the signal number corresponding to the signal that
+caused the invocation of the handler.
+ISO C 7.14.
 <!-- Link reference definitions -->
+[alg.c.library]: algorithms.md#alg.c.library
 [alloc.errors]: #alloc.errors
 [atomics]: atomics.md#atomics
 [bad.alloc]: #bad.alloc
 [bad.cast]: #bad.cast
 [bad.exception]: #bad.exception
 [bad.typeid]: #bad.typeid
 [basic.align]: basic.md#basic.align
+[basic.def.odr]: basic.md#basic.def.odr
 [basic.fundamental]: basic.md#basic.fundamental
+[basic.life]: basic.md#basic.life
 [basic.start]: basic.md#basic.start
+[basic.start.dynamic]: basic.md#basic.start.dynamic
 [basic.start.term]: basic.md#basic.start.term
 [basic.stc.dynamic]: basic.md#basic.stc.dynamic
 [basic.stc.dynamic.allocation]: basic.md#basic.stc.dynamic.allocation
 [basic.stc.dynamic.deallocation]: basic.md#basic.stc.dynamic.deallocation
 [basic.stc.dynamic.safety]: basic.md#basic.stc.dynamic.safety
+[c.locales]: localization.md#c.locales
+[c.malloc]: utilities.md#c.malloc
+[c.math.abs]: numerics.md#c.math.abs
+[c.math.rand]: numerics.md#c.math.rand
+[c.mb.wcs]: strings.md#c.mb.wcs
+[cfloat.syn]: #cfloat.syn
 [class]: class.md#class
 [class.free]: special.md#class.free
+[climits.syn]: #climits.syn
 [complex]: numerics.md#complex
 [constraints]: library.md#constraints
 [conv.ptr]: conv.md#conv.ptr
+[conv.qual]: conv.md#conv.qual
 [conv.rank]: conv.md#conv.rank
+[csetjmp.syn]: #csetjmp.syn
+[csignal.syn]: #csignal.syn
+[cstdarg.syn]: #cstdarg.syn
+[cstddef.syn]: #cstddef.syn
 [cstdint]: #cstdint
 [cstdint.syn]: #cstdint.syn
+[cstdlib.syn]: #cstdlib.syn
 [dcl.init.list]: dcl.md#dcl.init.list
 [denorm.style]: #denorm.style
 [except.handle]: except.md#except.handle
 [except.nested]: #except.nested
 [except.special]: except.md#except.special
 [except.terminate]: except.md#except.terminate
+[except.uncaught]: except.md#except.uncaught
 [exception]: #exception
+[exception.syn]: #exception.syn
 [exception.terminate]: #exception.terminate
 [expr.add]: expr.md#expr.add
 [expr.delete]: expr.md#expr.delete
 [expr.dynamic.cast]: expr.md#expr.dynamic.cast
 [expr.new]: expr.md#expr.new
+[expr.prim.lambda]: expr.md#expr.prim.lambda
 [expr.sizeof]: expr.md#expr.sizeof
 [expr.typeid]: expr.md#expr.typeid
+[fp.style]: #fp.style
 [get.new.handler]: #get.new.handler
 [get.terminate]: #get.terminate
+[hardware.interference]: #hardware.interference
+[initializer_list.syn]: #initializer_list.syn
 [intro.memory]: intro.md#intro.memory
 [intro.multithread]: intro.md#intro.multithread
 [language.support]: #language.support
+[library.c]: library.md#library.c
 [limits.syn]: #limits.syn
 [locale.codecvt]: localization.md#locale.codecvt
 [memory]: utilities.md#memory
 [multibyte.strings]: library.md#multibyte.strings
 [new.badlength]: #new.badlength
 [new.delete.array]: #new.delete.array
 [new.delete.dataraces]: #new.delete.dataraces
 [new.delete.placement]: #new.delete.placement
 [new.delete.single]: #new.delete.single
 [new.handler]: #new.handler
+[new.syn]: #new.syn
 [nullablepointer.requirements]: library.md#nullablepointer.requirements
 [numeric.limits]: #numeric.limits
 [numeric.limits.members]: #numeric.limits.members
 [numeric.special]: #numeric.special
 [propagation]: #propagation
+[ptr.launder]: #ptr.launder
 [res.on.data.races]: library.md#res.on.data.races
 [round.style]: #round.style
 [set.new.handler]: #set.new.handler
 [set.terminate]: #set.terminate
+[stmt.dcl]: stmt.md#stmt.dcl
 [string.classes]: strings.md#string.classes
 [support.dynamic]: #support.dynamic
 [support.exception]: #support.exception
 [support.general]: #support.general
 [support.initlist]: #support.initlist
 [support.initlist.range]: #support.initlist.range
 [support.limits]: #support.limits
 [support.limits.general]: #support.limits.general
 [support.rtti]: #support.rtti
 [support.runtime]: #support.runtime
+[support.signal]: #support.signal
 [support.start.term]: #support.start.term
 [support.types]: #support.types
+[support.types.byteops]: #support.types.byteops
+[support.types.layout]: #support.types.layout
+[support.types.nullptr]: #support.types.nullptr
 [tab:lang.sup.lib.summary]: #tab:lang.sup.lib.summary
 [temp.dep.constexpr]: temp.md#temp.dep.constexpr
 [temp.dep.expr]: temp.md#temp.dep.expr
+[temp.variadic]: temp.md#temp.variadic
 [terminate]: #terminate
 [terminate.handler]: #terminate.handler
 [type.info]: #type.info
+[typeinfo.syn]: #typeinfo.syn
+[uncaught.exceptions]: #uncaught.exceptions
 [^1]: Possible definitions include `0` and `0L`, but not `(void*)0`.
 [^2]: Note that `offsetof` is required to work as specified even if
     unary `operator&` is overloaded for any of the types involved.
 [^9]: Distinguishes types with bases other than 2 (e.g. BCD).
 [^10]: Equivalent to `FLT_EPSILON`, `DBL_EPSILON`, `LDBL_EPSILON`.
+[^11]: Rounding error is described in LIA-1 Section 5.2.4 and Annex C
+ Rationale Section C.5.2.4 — Rounding and rounding constants.
 [^12]: Equivalent to `FLT_MIN_EXP`, `DBL_MIN_EXP`, `LDBL_MIN_EXP`.
 [^13]: Equivalent to `FLT_MIN_10_EXP`, `DBL_MIN_10_EXP`,
     `LDBL_MIN_10_EXP`.
 [^17]: Required by LIA-1.
 [^18]: Required by LIA-1.
+[^19]: See ISO/IEC/IEEE 60559.
 [^20]: Required by LIA-1.
 [^21]: Required by LIA-1.
 [^22]: Required by LIA-1.
 [^23]: Required by LIA-1.
+[^24]: ISO/IEC/IEEE 60559:2011 is the same as IEEE 754-2008.
 [^25]: Required by LIA-1.
 [^26]: Required by LIA-1.
 [^27]: Required by LIA-1.
+[^28]: Refer to ISO/IEC/IEEE 60559. Required by LIA-1.
 [^29]: Equivalent to `FLT_ROUNDS`. Required by LIA-1.
 [^30]: A function is called for every time it is registered.
 [^31]: Objects with automatic storage duration are all destroyed in a
+    program whose `main` function ([[basic.start.main]]) contains no
+ automatic objects and executes the call to `exit()`. Control can be
+ transferred directly to such a `main` function by throwing an
+ exception that is caught in `main`.
 [^32]: The macros `EXIT_FAILURE` and `EXIT_SUCCESS` are defined in
     `<cstdlib>`.
+[^33]: It is not the direct responsibility of `operator new[]` or
+    `operator delete[]` to note the repetition count or element size of
+    the array. Those operations are performed elsewhere in the array
+    `new` and `delete` expressions. The array `new` expression, may,
+    however, increase the `size` argument to `operator new[]` to obtain
+    space to store supplemental information.
 [^34]: Note that `va_start` is required to work as specified even if
     unary `operator&` is overloaded for the type of `parmN`.
+[^35]: Such initialization might occur because it is the first odr-use (
+ [[basic.def.odr]]) of that variable.

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