Merge 2023-02 LWG Motion 3

P2790R0 C++ Standard Library Immediate Issues to be moved in Issaquah, Feb. 2023; excluding issue 3441

Author: tkoeppe

source/algorithms.tex

@@ -10781,7 +10781,7 @@
 \begin{codeblock}
 template<class T>
   constexpr void* @\placeholdernc{voidify}@(T& obj) noexcept {
-    return const_cast<void*>(static_cast<const volatile void*>(addressof(obj)));
+    return addressof(obj);
   }
 \end{codeblock}
 

source/compatibility.tex

@@ -249,6 +249,19 @@
                                     // implementation-defined number of \tcode{'*'} characters
 \end{codeblock}
 
+\diffref{format.formatter.spec}
+\change
+Removed the \tcode{formatter} specialization:
+\begin{codeblock}
+template<size_t N> struct formatter<const charT[N], charT>;
+\end{codeblock}
+\rationale
+The specialization is inconsistent with the design of \tcode{formatter},
+which is intended to be instantiated only with cv-unqualified object types.
+\effect
+Valid \CppXX{} code that instantiated the removed specialization
+can become ill-formed.
+
 \rSec2[diff.cpp20.strings]{\ref{strings}: strings library}
 
 \diffref{string.classes}

source/containers.tex

@@ -538,7 +538,6 @@
 \indexlibraryglobal{ENETUNREACH}%
 \indexlibraryglobal{ENFILE}%
 \indexlibraryglobal{ENOBUFS}%
-\indexlibraryglobal{ENODATA}%
 \indexlibraryglobal{ENODEV}%
 \indexlibraryglobal{ENOENT}%
 \indexlibraryglobal{ENOEXEC}%
@@ -548,8 +547,6 @@
 \indexlibraryglobal{ENOMSG}%
 \indexlibraryglobal{ENOPROTOOPT}%
 \indexlibraryglobal{ENOSPC}%
-\indexlibraryglobal{ENOSR}%
-\indexlibraryglobal{ENOSTR}%
 \indexlibraryglobal{ENOSYS}%
 \indexlibraryglobal{ENOTCONN}%
 \indexlibraryglobal{ENOTDIR}%
@@ -571,7 +568,6 @@
 \indexlibraryglobal{EROFS}%
 \indexlibraryglobal{ESPIPE}%
 \indexlibraryglobal{ESRCH}%
-\indexlibraryglobal{ETIME}%
 \indexlibraryglobal{ETIMEDOUT}%
 \indexlibraryglobal{ETXTBSY}%
 \indexlibraryglobal{EWOULDBLOCK}%
@@ -619,7 +615,6 @@
 #define ENETUNREACH @\seebelow@
 #define ENFILE @\seebelow@
 #define ENOBUFS @\seebelow@
-#define ENODATA @\seebelow@
 #define ENODEV @\seebelow@
 #define ENOENT @\seebelow@
 #define ENOEXEC @\seebelow@
@@ -629,8 +624,6 @@
 #define ENOMSG @\seebelow@
 #define ENOPROTOOPT @\seebelow@
 #define ENOSPC @\seebelow@
-#define ENOSR @\seebelow@
-#define ENOSTR @\seebelow@
 #define ENOSYS @\seebelow@
 #define ENOTCONN @\seebelow@
 #define ENOTDIR @\seebelow@
@@ -652,7 +645,6 @@
 #define EROFS @\seebelow@
 #define ESPIPE @\seebelow@
 #define ESRCH @\seebelow@
-#define ETIME @\seebelow@
 #define ETIMEDOUT @\seebelow@
 #define ETXTBSY @\seebelow@
 #define EWOULDBLOCK @\seebelow@
@@ -750,18 +742,15 @@
     no_child_process,                   // \tcode{ECHILD}
     no_link,                            // \tcode{ENOLINK}
     no_lock_available,                  // \tcode{ENOLCK}
-    no_message_available,               // \tcode{ENODATA}
     no_message,                         // \tcode{ENOMSG}
     no_protocol_option,                 // \tcode{ENOPROTOOPT}
     no_space_on_device,                 // \tcode{ENOSPC}
-    no_stream_resources,                // \tcode{ENOSR}
     no_such_device_or_address,          // \tcode{ENXIO}
     no_such_device,                     // \tcode{ENODEV}
     no_such_file_or_directory,          // \tcode{ENOENT}
     no_such_process,                    // \tcode{ESRCH}
     not_a_directory,                    // \tcode{ENOTDIR}
     not_a_socket,                       // \tcode{ENOTSOCK}
-    not_a_stream,                       // \tcode{ENOSTR}
     not_connected,                      // \tcode{ENOTCONN}
     not_enough_memory,                  // \tcode{ENOMEM}
     not_supported,                      // \tcode{ENOTSUP}
@@ -779,7 +768,6 @@
     resource_unavailable_try_again,     // \tcode{EAGAIN}
     result_out_of_range,                // \tcode{ERANGE}
     state_not_recoverable,              // \tcode{ENOTRECOVERABLE}
-    stream_timeout,                     // \tcode{ETIME}
     text_file_busy,                     // \tcode{ETXTBSY}
     timed_out,                          // \tcode{ETIMEDOUT}
     too_many_files_open_in_system,      // \tcode{ENFILE}

source/diagnostics.tex

@@ -218,6 +218,25 @@
 unless the function's \throws element
 specifies throwing an exception when the precondition is violated.
 
+\rSec1[depr.c.macros]{Deprecated C macros}
+
+\pnum
+The header \libheader{stdalign.h} has the following macro:
+\indexheader{stdalign.h}%
+\indexlibraryglobal{__alignas_is_defined}%
+\begin{codeblock}
+#define @\xname{alignas_is_defined}@ 1
+\end{codeblock}
+
+\pnum
+The header \libheader{stdbool.h} has the following macro:
+\indexheader{stdbool.h}%
+\indexhdr{stdbool.h}%
+\indexlibraryglobal{__bool_true_false_are_defined}%
+\begin{codeblock}
+#define @\xname{bool_true_false_are_defined}@ 1
+\end{codeblock}
+
 \rSec1[depr.relops]{Relational operators}%
 \indexlibraryglobal{rel_ops}%
 
@@ -1322,6 +1341,42 @@
 \tcode{rdbuf()->pcount()}.
 \end{itemdescr}
 
+\rSec1[depr.cerrno]{Deprecated error numbers}
+
+\pnum
+The following macros are defined in addition to those
+specified in \ref{cerrno.syn}:
+
+\indexlibraryglobal{ENODATA}%
+\indexlibraryglobal{ENOSR}%
+\indexlibraryglobal{ENOSTR}%
+\indexlibraryglobal{ETIME}%
+\begin{codeblock}
+#define ENODATA @\seebelow@
+#define ENOSR @\seebelow@
+#define ENOSTR @\seebelow@
+#define ETIME @\seebelow@
+\end{codeblock}
+
+\pnum
+The meaning of these macros is defined by the POSIX standard.
+
+\pnum
+The following \tcode{enum errc} enumerators are defined
+in addition to those specified in \ref{system.error.syn}:
+
+\begin{codeblock}
+no_message_available,               // \tcode{ENODATA}
+no_stream_resources,                // \tcode{ENOSR}
+not_a_stream,                       // \tcode{ENOSTR}
+stream_timeout,                     // \tcode{ETIME}
+\end{codeblock}
+
+\pnum
+The value of each \tcode{enum errc} enumerator above
+is the same as the value of the \libheader{cerrno} macro
+shown in the above synopsis.
+
 \rSec1[depr.default.allocator]{The default allocator}
 
 \pnum

source/future.tex

@@ -506,6 +506,17 @@
 The results of including \libheader{iostream} in a translation unit shall be as if
 \libheader{iostream} defined an instance of \tcode{ios_base::Init} with static
 storage duration.
+Each \Cpp{} library module\iref{std.modules} in a hosted implementation
+shall behave as if it contains an interface unit that
+defines an unexported \tcode{ios_base::Init} variable with
+ordered initialization\iref{basic.start.dynamic}.
+
+\begin{note}
+As a result, the definition of that variable is appearance-ordered before
+any declaration following the point of importation of a \Cpp{} library module.
+Whether such a definition exists is unobservable by a program that
+does not reference any of the standard iostream objects.
+\end{note}
 
 \pnum
 Mixing operations on corresponding wide- and narrow-character streams
@@ -18592,6 +18603,10 @@
 The header \libheader{cinttypes} includes the header \libheaderref{cstdint} instead
 of \libheader{stdint.h}, and
 \item
+\tcode{intmax_t} and \tcode{uintmax_t} are not required
+to be able to represent all values of extended integer types
+wider than \tcode{long long} and \tcode{unsigned long long}, respectively, and
+\item
 if and only if the type \tcode{intmax_t} designates an extended integer
 type\iref{basic.fundamental}, the following function signatures are added:
 \begin{codeblock}

source/iostreams.tex

@@ -350,14 +350,17 @@
     class basic_const_iterator;                                                     // freestanding
 
   template<class T, @\libconcept{common_with}@<T> U>
+    requires @\libconcept{input_iterator}@<common_type_t<T, U>>
   struct common_type<basic_const_iterator<T>, U> {                                  // freestanding
     using type = basic_const_iterator<common_type_t<T, U>>;
   };
   template<class T, @\libconcept{common_with}@<T> U>
+    requires @\libconcept{input_iterator}@<common_type_t<T, U>>
   struct common_type<U, basic_const_iterator<T>> {                                  // freestanding
     using type = basic_const_iterator<common_type_t<T, U>>;
   };
   template<class T, @\libconcept{common_with}@<T> U>
+    requires @\libconcept{input_iterator}@<common_type_t<T, U>>
   struct common_type<basic_const_iterator<T>, basic_const_iterator<U>> {            // freestanding
     using type = basic_const_iterator<common_type_t<T, U>>;
   };
@@ -4213,10 +4216,16 @@
   template<class I>
     concept @\exposconcept{not-a-const-iterator}@ = @\seebelow@;                   // \expos
 
+  template<@\libconcept{indirectly_readable}@ I>
+    using @\exposidnc{iter-const-rvalue-reference-t}@ =                       // \expos
+      common_reference_t<const iter_value_t<I>&&, iter_rvalue_reference_t<I>>;
+
   template<@\libconcept{input_iterator}@ Iterator>
   class @\libglobal{basic_const_iterator}@ {
     Iterator @\exposidnc{current_}@ = Iterator();                             // \expos
     using @\exposidnc{reference}@ = iter_const_reference_t<Iterator>;         // \expos
+    using @\exposidnc{rvalue-reference}@ =                                    // \expos
+      @\exposid{iter-const-rvalue-reference-t}@<Iterator>;
 
   public:
     using iterator_concept = @\seebelow@;
@@ -4312,6 +4321,11 @@
     template<@\exposconcept{not-a-const-iterator}@ S>
       requires @\libconcept{sized_sentinel_for}@<S, Iterator>
       friend constexpr difference_type operator-(const S& x, const basic_const_iterator& y);
+    friend constexpr @\exposid{rvalue-reference}@ iter_move(const basic_const_iterator& i)
+      noexcept(noexcept(static_cast<@\exposid{rvalue-reference}@>(ranges::iter_move(i.@\exposid{current_}@))))
+      {
+        return static_cast<@\exposid{rvalue-reference}@>(ranges::iter_move(i.@\exposid{current_}@));
+      }
   };
 }
 \end{codeblock}

source/iterators.tex

@@ -1471,15 +1471,6 @@
 the freestanding items\iref{freestanding.item} declared in the header.
 \indextext{implementation!freestanding|)}%
 
-\pnum
-\begin{note}
-Throwing a standard library provided exception
-is not observably different from \tcode{terminate()}
-if the implementation does not
-unwind the stack during exception handling\iref{except.handle} and
-the user's program contains no catch blocks.
-\end{note}
-
 \rSec2[using]{Using the library}
 
 \rSec3[using.overview]{Overview}

source/lib-intro.tex

@@ -4993,6 +4993,24 @@
 Initializes \tcode{s} with \tcode{smart},
 \tcode{a} with \tcode{std::forward<Args>(args)...}, and
 value-initializes \tcode{p}.
+Then, equivalent to:
+\begin{itemize}
+\item
+\begin{codeblock}
+s.reset();
+\end{codeblock}
+if the expression \tcode{s.reset()} is well-formed;
+
+\item
+otherwise,
+\begin{codeblock}
+s = Smart();
+\end{codeblock}
+if \tcode{is_constructible_v<Smart>} is \tcode{true};
+
+\item
+otherwise, the program is ill-formed.
+\end{itemize}
 
 \pnum
 \begin{note}