P2918R2 Runtime format strings II

Editorial note: we removed the "const" from the return type of the
deleted operator= on request by the author; this has no observable
effect.

Author: burblebee

source/support.tex

@@ -632,7 +632,7 @@
 #define @\defnlibxname{cpp_lib_filesystem}@                        201703L // also in \libheader{filesystem}
 #define @\defnlibxname{cpp_lib_flat_map}@                          202207L // also in \libheader{flat_map}
 #define @\defnlibxname{cpp_lib_flat_set}@                          202207L // also in \libheader{flat_set}
-#define @\defnlibxname{cpp_lib_format}@                            202306L // also in \libheader{format}
+#define @\defnlibxname{cpp_lib_format}@                            202311L // also in \libheader{format}
 #define @\defnlibxname{cpp_lib_format_ranges}@                     202207L // also in \libheader{format}
 #define @\defnlibxname{cpp_lib_formatters}@                        202302L // also in \libheader{stacktrace}, \libheader{thread}
 #define @\defnlibxname{cpp_lib_forward_like}@                      202207L // freestanding, also in \libheader{utility}

source/utilities.tex

@@ -15583,6 +15583,17 @@
   template<class charT, class... Args>
     struct basic_format_string;
 
+  template<class charT> struct @\exposid{runtime-format-string}@ {                  // \expos
+  private:
+    basic_string_view<charT> @\exposid{str}@;                                       // \expos
+  public:
+    @\exposid{runtime-format-string}@(basic_string_view<charT> s) noexcept : @\exposid{str}@(s) {}
+    @\exposid{runtime-format-string}@(const @\exposid{runtime-format-string}@&) = delete;
+    @\exposid{runtime-format-string}@& operator=(const @\exposid{runtime-format-string}@&) = delete;
+  };
+  @\exposid{runtime-format-string}@<char> runtime_format(string_view fmt) noexcept { return fmt; }
+  @\exposid{runtime-format-string}@<wchar_t> runtime_format(wstring_view fmt) noexcept { return fmt; }
+
   template<class... Args>
     using @\libglobal{format_string}@ = basic_format_string<char, type_identity_t<Args>...>;
   template<class... Args>
@@ -16485,6 +16496,7 @@
 
   public:
     template<class T> consteval basic_format_string(const T& s);
+    basic_format_string(@\exposid{runtime-format-string}@<charT> s) noexcept : str(s.@\exposid{str}@) {}
 
     constexpr basic_string_view<charT> get() const noexcept { return @\exposid{str}@; }
   };