Merge 2024-06 LWG Motion 8

P3235R3 std::print more types faster with less memory

Author: tkoeppe

source/iostreams.tex

@@ -7746,14 +7746,14 @@
 If the ordinary literal encoding\iref{lex.charset} is UTF-8, equivalent to:
 \begin{codeblock}
 locksafe
-  ? vprint_unicode_locking(stream, fmt.str, make_format_args(args...))
-  : vprint_unicode(stream, fmt.str, make_format_args(args...));
+  ? vprint_unicode(stream, fmt.str, make_format_args(args...))
+  : vprint_unicode_buffered(stream, fmt.str, make_format_args(args...));
 \end{codeblock}
 Otherwise, equivalent to:
 \begin{codeblock}
 locksafe
-  ? vprint_nonunicode_locking(stream, fmt.str, make_format_args(args...))
-  : vprint_nonunicode(stream, fmt.str, make_format_args(args...));
+  ? vprint_nonunicode(stream, fmt.str, make_format_args(args...))
+  : vprint_nonunicode_buffered(stream, fmt.str, make_format_args(args...));
 \end{codeblock}
 \end{itemdescr}
 
@@ -7829,9 +7829,9 @@
 \end{codeblock}
 \end{itemdescr}
 
-\indexlibraryglobal{vprint_unicode}%
+\indexlibraryglobal{vprint_unicode_buffered}%
 \begin{itemdecl}
-void vprint_unicode(FILE* stream, string_view fmt, format_args args);
+void vprint_unicode_buffered(FILE* stream, string_view fmt, format_args args);
 \end{itemdecl}
 
 \begin{itemdescr}
@@ -7840,13 +7840,13 @@
 Equivalent to:
 \begin{codeblock}
 string out = vformat(fmt, args);
-vprint_unicode_locking(stream, "{}", make_format_args(out));
+vprint_unicode(stream, "{}", make_format_args(out));
 \end{codeblock}
 \end{itemdescr}
 
-\indexlibraryglobal{vprint_unicode_locking}%
+\indexlibraryglobal{vprint_unicode}%
 \begin{itemdecl}
-void vprint_unicode_locking(FILE* stream, string_view fmt, format_args args);
+void vprint_unicode(FILE* stream, string_view fmt, format_args args);
 \end{itemdecl}
 
 \begin{itemdescr}
@@ -7912,9 +7912,9 @@
 \end{codeblock}
 \end{itemdescr}
 
-\indexlibraryglobal{vprint_nonunicode}%
+\indexlibraryglobal{vprint_nonunicode_buffered}%
 \begin{itemdecl}
-void vprint_nonunicode(FILE* stream, string_view fmt, format_args args);
+void vprint_nonunicode_buffered(FILE* stream, string_view fmt, format_args args);
 \end{itemdecl}
 
 \begin{itemdescr}
@@ -7923,13 +7923,13 @@
 Equivalent to:
 \begin{codeblock}
 string out = vformat(fmt, args);
-vprint_nonunicode_locking("{}", make_format_args(out));
+vprint_nonunicode("{}", make_format_args(out));
 \end{codeblock}
 \end{itemdescr}
 
-\indexlibraryglobal{vprint_nonunicode_locking}%
+\indexlibraryglobal{vprint_nonunicode}%
 \begin{itemdecl}
-void vprint_nonunicode_locking(FILE* stream, string_view fmt, format_args args);
+void vprint_nonunicode(FILE* stream, string_view fmt, format_args args);
 \end{itemdecl}
 
 \begin{itemdescr}

source/support.tex

@@ -732,7 +732,7 @@
 #define @\defnlibxname{cpp_lib_out_ptr}@                           202311L // freestanding, also in \libheader{memory}
 #define @\defnlibxname{cpp_lib_parallel_algorithm}@                201603L // also in \libheader{algorithm}, \libheader{numeric}
 #define @\defnlibxname{cpp_lib_polymorphic_allocator}@             201902L // also in \libheader{memory_resource}
-#define @\defnlibxname{cpp_lib_print}@                             202403L // also in \libheader{print}, \libheader{ostream}
+#define @\defnlibxname{cpp_lib_print}@                             202406L // also in \libheader{print}, \libheader{ostream}
 #define @\defnlibxname{cpp_lib_quoted_string_io}@                  201304L // also in \libheader{iomanip}
 #define @\defnlibxname{cpp_lib_ranges}@                            202406L
   // also in \libheader{algorithm}, \libheader{functional}, \libheader{iterator}, \libheader{memory}, \libheader{ranges}

source/time.tex

@@ -10828,6 +10828,27 @@
 \end{codeblock}
 \end{example}
 
+\pnum
+For \tcode{chrono::duration}
+the library only provides the following specialization
+of \tcode{enable_nonlocking_formatter_optimization}:
+\begin{codeblock}
+template<class Rep, class Period>
+  inline constexpr bool enable_nonlocking_formatter_optimization<
+    chrono::duration<Rep, Period>> =
+      enable_nonlocking_formatter_optimization<Rep>;
+\end{codeblock}
+
+\pnum
+For \tcode{chrono::zoned_time}
+the library only provides the following specialization of
+\tcode{enable_nonlocking_formatter_optimization}:
+\begin{codeblock}
+template<class Duration>
+  inline constexpr bool enable_nonlocking_formatter_optimization<
+    chrono::zoned_time<Duration, const std::chrono::time_zone*>> = true;
+\end{codeblock}
+
 \indexlibrary{\idxcode{formatter}!specializations!\idxcode{chrono::sys_time}}%
 \begin{itemdecl}
 template<class Duration, class charT>

source/utilities.tex

@@ -15897,6 +15897,10 @@
              @\libconcept{formattable}@<ranges::range_reference_t<R>, charT>
   struct formatter<R, charT> : @\exposid{range-default-formatter}@<format_kind<R>, R, charT> { };
 
+  template<ranges::input_range R>
+      requires (format_kind<R> != range_format::disabled)
+    inline constexpr bool enable_nonlocking_formatter_optimization<R> = false;
+
   // \ref{format.arguments}, arguments
   // \ref{format.arg}, class template \tcode{basic_format_arg}
   template<class Context> class basic_format_arg;
@@ -17214,9 +17218,10 @@
 interpret the format specification
 as a \fmtgrammarterm{std-format-spec}
 as described in \ref{format.string.std}.
-In addition,
-for each type \tcode{T} for which
-a \tcode{formatter} specialization is provided above,
+
+\pnum
+Unless specified otherwise, for each type \tcode{T} for which
+a \tcode{formatter} specialization is provided by the library,
 each of the headers provides the following specialization:
 \begin{codeblock}
 template<> inline constexpr bool enable_nonlocking_formatter_optimization<T> = true;
@@ -18795,6 +18800,10 @@
       typename FormatContext::iterator
         format(@\seebelow@& elems, FormatContext& ctx) const;
   };
+
+  template<class... Ts>
+    inline constexpr bool enable_nonlocking_formatter_optimization<@\placeholder{pair-or-tuple}@<Ts...>> =
+      (enable_nonlocking_formatter_optimization<Ts> && ...);
 }
 \end{codeblock}