Merge 2021-06 LWG Motion 16

P2216R3 std::format improvements

Author: tkoeppe

source/compatibility.tex

@@ -40,6 +40,27 @@
 \end{codeblock}
 \end{example}
 
+\rSec2[diff.cpp20.utilities]{\ref{utilities}: general utilities library}
+
+\diffref{format}
+\change
+Signature changes: \tcode{format}, \tcode{format_to}, \tcode{vformat_to},
+\tcode{format_to_n}, \tcode{formatted_size}.
+Removal of \tcode{format_args_t}.
+\rationale
+Improve safety via compile-time format string checks,
+avoid unnecessary template instantiations.
+\effect
+Valid \CppXX{} code that
+contained errors in format strings or
+relied on previous format string signatures or
+\tcode{format_args_t} may become ill-formed.
+For example:
+\begin{codeblock}
+auto s = std::format("{:d}", "I am not a number");      // ill-formed,
+                                                        // previously threw \tcode{format_error}
+\end{codeblock}
+
 \rSec1[diff.cpp17]{\Cpp{} and ISO \CppXVII{}}
 
 \rSec2[diff.cpp17.general]{General}

source/support.tex

@@ -609,7 +609,7 @@
 #define @\defnlibxname{cpp_lib_exchange_function}@                 201304L // also in \libheader{utility}
 #define @\defnlibxname{cpp_lib_execution}@                         201902L // also in \libheader{execution}
 #define @\defnlibxname{cpp_lib_filesystem}@                        201703L // also in \libheader{filesystem}
-#define @\defnlibxname{cpp_lib_format}@                            201907L // also in \libheader{format}
+#define @\defnlibxname{cpp_lib_format}@                            202106L // also in \libheader{format}
 #define @\defnlibxname{cpp_lib_gcd_lcm}@                           201606L // also in \libheader{numeric}
 #define @\defnlibxname{cpp_lib_generic_associative_lookup}@        201304L // also in \libheader{map}, \libheader{set}
 #define @\defnlibxname{cpp_lib_generic_unordered_lookup}@          201811L