P3391R2 constexpr std::format

Fixes NB FR-028-271, US 167-270 (C++26 CD).

Author: eisenwave

source/strings.tex

@@ -1927,15 +1927,15 @@
   float stof(const string& str, size_t* idx = nullptr);
   double stod(const string& str, size_t* idx = nullptr);
   long double stold(const string& str, size_t* idx = nullptr);
-  string to_string(int val);
-  string to_string(unsigned val);
-  string to_string(long val);
-  string to_string(unsigned long val);
-  string to_string(long long val);
-  string to_string(unsigned long long val);
-  string to_string(float val);
-  string to_string(double val);
-  string to_string(long double val);
+  constexpr string to_string(int val);
+  constexpr string to_string(unsigned val);
+  constexpr string to_string(long val);
+  constexpr string to_string(unsigned long val);
+  constexpr string to_string(long long val);
+  constexpr string to_string(unsigned long long val);
+  constexpr string to_string(float val);
+  constexpr string to_string(double val);
+  constexpr string to_string(long double val);
 
   int stoi(const wstring& str, size_t* idx = nullptr, int base = 10);
   long stol(const wstring& str, size_t* idx = nullptr, int base = 10);
@@ -1945,15 +1945,15 @@
   float stof(const wstring& str, size_t* idx = nullptr);
   double stod(const wstring& str, size_t* idx = nullptr);
   long double stold(const wstring& str, size_t* idx = nullptr);
-  wstring to_wstring(int val);
-  wstring to_wstring(unsigned val);
-  wstring to_wstring(long val);
-  wstring to_wstring(unsigned long val);
-  wstring to_wstring(long long val);
-  wstring to_wstring(unsigned long long val);
-  wstring to_wstring(float val);
-  wstring to_wstring(double val);
-  wstring to_wstring(long double val);
+  constexpr wstring to_wstring(int val);
+  constexpr wstring to_wstring(unsigned val);
+  constexpr wstring to_wstring(long val);
+  constexpr wstring to_wstring(unsigned long val);
+  constexpr wstring to_wstring(long long val);
+  constexpr wstring to_wstring(unsigned long long val);
+  constexpr wstring to_wstring(float val);
+  constexpr wstring to_wstring(double val);
+  constexpr wstring to_wstring(long double val);
 
   namespace pmr {
     template<class charT, class traits = char_traits<charT>>
@@ -5273,15 +5273,15 @@
 
 \indexlibraryglobal{to_string}%
 \begin{itemdecl}
-string to_string(int val);
-string to_string(unsigned val);
-string to_string(long val);
-string to_string(unsigned long val);
-string to_string(long long val);
-string to_string(unsigned long long val);
-string to_string(float val);
-string to_string(double val);
-string to_string(long double val);
+constexpr string to_string(int val);
+constexpr string to_string(unsigned val);
+constexpr string to_string(long val);
+constexpr string to_string(unsigned long val);
+constexpr string to_string(long long val);
+constexpr string to_string(unsigned long long val);
+constexpr string to_string(float val);
+constexpr string to_string(double val);
+constexpr string to_string(long double val);
 \end{itemdecl}
 
 \begin{itemdescr}
@@ -5360,15 +5360,15 @@
 
 \indexlibraryglobal{to_wstring}%
 \begin{itemdecl}
-wstring to_wstring(int val);
-wstring to_wstring(unsigned val);
-wstring to_wstring(long val);
-wstring to_wstring(unsigned long val);
-wstring to_wstring(long long val);
-wstring to_wstring(unsigned long long val);
-wstring to_wstring(float val);
-wstring to_wstring(double val);
-wstring to_wstring(long double val);
+constexpr wstring to_wstring(int val);
+constexpr wstring to_wstring(unsigned val);
+constexpr wstring to_wstring(long val);
+constexpr wstring to_wstring(unsigned long val);
+constexpr wstring to_wstring(long long val);
+constexpr wstring to_wstring(unsigned long long val);
+constexpr wstring to_wstring(float val);
+constexpr wstring to_wstring(double val);
+constexpr wstring to_wstring(long double val);
 \end{itemdecl}
 
 \begin{itemdescr}

source/support.tex

@@ -631,6 +631,7 @@
   // also in \libheader{exception}, \libheader{stdexcept}, \libheader{expected}, \libheader{optional}, \libheader{variant}, and \libheader{format}
 #define @\defnlibxname{cpp_lib_constexpr_flat_map}@                202502L // also in \libheader{flat_map}
 #define @\defnlibxname{cpp_lib_constexpr_flat_set}@                202502L // also in \libheader{flat_set}
+#define @\defnlibxname{cpp_lib_constexpr_format}@                  202511L // also in \libheader{format}
 #define @\defnlibxname{cpp_lib_constexpr_forward_list}@            202502L // also in \libheader{forward_list}
 #define @\defnlibxname{cpp_lib_constexpr_functional}@              201907L // freestanding, also in \libheader{functional}
 #define @\defnlibxname{cpp_lib_constexpr_inplace_vector}@          202502L // also in \libheader{inplace_vector}