P2319R5 Prevent path presentation problems

Fixes #7967
Fixes cplusplus/papers#1987

Author: AlisdairM

source/future.tex

@@ -841,6 +841,45 @@
 \end{note}
 \end{itemdescr}
 
+\rSec1[depr.fs.path.obs]{Deprecated filesystem path format observers}
+
+\indexlibraryglobal{path}%
+\pnum
+The following members are declared in addition to those members specified in
+\iref{fs.path.member}:
+
+\begin{codeblock}
+namespace std::filesystem {
+  class path {
+  public:
+    std::string string() const;
+    std::string generic_string() const;
+  };
+}
+\end{codeblock}
+
+\indexlibrarymember{string}{path}%
+\begin{itemdecl}
+std::string string() const;
+\end{itemdecl}
+
+\begin{itemdescr}
+\pnum
+\returns
+\tcode{system_encoded_string()}.
+\end{itemdescr}
+
+\indexlibrarymember{generic_string}{path}%
+\begin{itemdecl}
+std::string generic_string() const;
+\end{itemdecl}
+
+\begin{itemdescr}
+\pnum
+\returns
+\tcode{generic_system_encoded_string()}.
+\end{itemdescr}
+
 \rSec1[depr.atomics]{Deprecated atomic operations}
 
 \rSec2[depr.atomics.general]{General}

source/iostreams.tex

@@ -13707,7 +13707,8 @@
              class Allocator = allocator<EcharT>>
       basic_string<EcharT, traits, Allocator>
         string(const Allocator& a = Allocator()) const;
-    std::string    string() const;
+    std::string    display_string() const;
+    std::string    system_encoded_string() const;
     std::wstring   wstring() const;
     std::u8string  u8string() const;
     std::u16string u16string() const;
@@ -13718,7 +13719,8 @@
              class Allocator = allocator<EcharT>>
       basic_string<EcharT, traits, Allocator>
         generic_string(const Allocator& a = Allocator()) const;
-    std::string    generic_string() const;
+    std::string    generic_display_string() const;
+    std::string    generic_system_encoded_string() const;
     std::wstring   generic_wstring() const;
     std::u8string  generic_u8string() const;
     std::u16string generic_u16string() const;
@@ -14689,13 +14691,13 @@
 \ref{fs.path.cvt}.
 \end{itemdescr}
 
-\indexlibrarymember{string}{path}%
+\indexlibrarymember{system_encoded_string}{path}%
 \indexlibrarymember{wstring}{path}%
 \indexlibrarymember{u8string}{path}%
 \indexlibrarymember{u16string}{path}%
 \indexlibrarymember{u32string}{path}%
 \begin{itemdecl}
-std::string string() const;
+std::string system_encoded_string() const;
 std::wstring wstring() const;
 std::u8string u8string() const;
 std::u16string u16string() const;
@@ -14713,6 +14715,20 @@
 by \ref{fs.path.cvt}.
 \end{itemdescr}
 
+\indexlibrarymember{display_string}{path}%
+\begin{itemdecl}
+std::string display_string() const;
+\end{itemdecl}
+
+\begin{itemdescr}
+\pnum
+\returns
+\tcode{format("{}", *this)}.
+\begin{note}
+The returned string is suitable for use with formatting \iref{format.functions}
+and print functions \iref{print.fun}.
+\end{note}
+\end{itemdescr}
 
 \rSec4[fs.path.generic.obs]{Generic format observers}
 
@@ -14752,13 +14768,13 @@
 \ref{fs.path.cvt}.
 \end{itemdescr}
 
-\indexlibrarymember{generic_string}{path}%
+\indexlibrarymember{generic_system_encoded_string}{path}%
 \indexlibrarymember{generic_wstring}{path}%
 \indexlibrarymember{generic_u8string}{path}%
 \indexlibrarymember{generic_u16string}{path}%
 \indexlibrarymember{generic_u32string}{path}%
 \begin{itemdecl}
-std::string generic_string() const;
+std::string generic_system_encoded_string() const;
 std::wstring generic_wstring() const;
 std::u8string generic_u8string() const;
 std::u16string generic_u16string() const;
@@ -14775,6 +14791,21 @@
 Conversion, if any, is specified by~\ref{fs.path.cvt}.
 \end{itemdescr}
 
+\indexlibrarymember{generic_display_string}{path}%
+\begin{itemdecl}
+std::string generic_display_string() const;
+\end{itemdecl}
+
+\begin{itemdescr}
+\pnum
+\returns
+\tcode{format("{:g}", *this)}.
+\begin{note}
+The returned string is suitable for use with formatting \iref{format.functions}
+and print functions \iref{print.fun}.
+\end{note}
+\end{itemdescr}
+
 \rSec4[fs.path.compare]{Compare}
 
 \indexlibrarymember{compare}{path}%

source/support.tex

@@ -660,7 +660,7 @@
 #define @\defnlibxname{cpp_lib_flat_set}@                          202207L // also in \libheader{flat_set}
 #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_format_path}@                       202403L // also in \libheader{filesystem}
+#define @\defnlibxname{cpp_lib_format_path}@                       202506L // also in \libheader{filesystem}
 #define @\defnlibxname{cpp_lib_format_uchar}@                      202311L // 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}