[libc++] Undeprecate POSIX STREAM macros. (#88296)

LWG3869 Deprecate std::errc constants related to UNIX STREAMS

deprecates the POSIX macros ENODATA, ENOSR, ENOSTR, and ETIME. These
were deprecated in libc++ in
#80542. Based on the post
commit feedback the macro are no longer deprecated. Instead libc++
leaves the deprecation to the provider of errno.h.

---------

Co-authored-by: Hristo Hristov <[email protected]>
Co-authored-by: Louis Dionne <[email protected]>

Author: 3 people

libcxx/include/__system_error/errc.h

@@ -112,6 +112,11 @@ enum class errc
 // macros. So GCC does not need the pushing and popping.
 //
 // TODO Remove this when the deprecated constants are removed.
+//
+// Note based on the post-review comments in
+// https://github.com/llvm/llvm-project/pull/80542 libc++ no longer deprecates
+// the macros. Since C libraries may start to deprecate these POSIX macros the
+// deprecation warning avoidance is kept.
 #if defined(_LIBCPP_COMPILER_CLANG_BASED)
 #  define _LIBCPP_SUPPRESS_DEPRECATED_ERRC_PUSH _LIBCPP_SUPPRESS_DEPRECATED_PUSH
 #  define _LIBCPP_SUPPRESS_DEPRECATED_ERRC_POP _LIBCPP_SUPPRESS_DEPRECATED_POP

libcxx/include/cerrno

@@ -38,17 +38,11 @@ Macros:
 #  pragma GCC system_header
 #endif
 
-#ifdef ENODATA
-#  pragma clang deprecated(ENODATA, "ENODATA is deprecated in ISO C++")
-#endif
-#ifdef ENOSR
-#  pragma clang deprecated(ENOSR, "ENOSR is deprecated in ISO C++")
-#endif
-#ifdef ENOSTR
-#  pragma clang deprecated(ENOSTR, "ENOSTR is deprecated in ISO C++")
-#endif
-#ifdef ETIME
-#  pragma clang deprecated(ETIME, "ETIME is deprecated in ISO C++")
-#endif
+// LWG3869 Deprecate std::errc constants related to UNIX STREAMS
+//
+// This LWG issue deprecates the POSIX macros ENODATA, ENOSR, ENOSTR, and ETIME. These were
+// deprecated in libc++ in https://github.com/llvm/llvm-project/pull/80542.
+// Based on the post commit feedback the macro are no longer deprecated.
+// Instead libc++ leaves the deprecation to the provider of errno.h.
 
 #endif // _LIBCPP_CERRNO