[libc++] Deprecates std::errc constants. (#80542)

Implements:
- LWG3869 Deprecate std::errc constants related to UNIX STREAMS

libcxx/docs/Status/Cxx23Issues.csv

@@ -295,7 +295,7 @@
 "`3847 <https://wg21.link/LWG3847>`__","``ranges::to`` can still return views","February 2023","|Complete|","17.0","|ranges|"
 "`3862 <https://wg21.link/LWG3862>`__","``basic_const_iterator``'s ``common_type`` specialization is underconstrained","February 2023","","",""
 "`3865 <https://wg21.link/LWG3865>`__","Sorting a range of ``pairs``","February 2023","|Complete|","17.0","|ranges|"
-"`3869 <https://wg21.link/LWG3869>`__","Deprecate ``std::errc`` constants related to UNIX STREAMS","February 2023","","",""
+"`3869 <https://wg21.link/LWG3869>`__","Deprecate ``std::errc`` constants related to UNIX STREAMS","February 2023","|Complete|","19.0",""
 "`3870 <https://wg21.link/LWG3870>`__","Remove ``voidify``","February 2023","","",""
 "`3871 <https://wg21.link/LWG3871>`__","Adjust note about ``terminate``","February 2023","","",""
 "`3872 <https://wg21.link/LWG3872>`__","``basic_const_iterator`` should have custom ``iter_move``","February 2023","","",""

libcxx/include/__system_error/errc.h

@@ -58,18 +58,18 @@ enum class errc
     no_child_process,                   // ECHILD
     no_link,                            // ENOLINK
     no_lock_available,                  // ENOLCK
-    no_message_available,               // ENODATA
+    no_message_available,               // ENODATA         // deprecated
     no_message,                         // ENOMSG
     no_protocol_option,                 // ENOPROTOOPT
     no_space_on_device,                 // ENOSPC
-    no_stream_resources,                // ENOSR
+    no_stream_resources,                // ENOSR           // deprecated
     no_such_device_or_address,          // ENXIO
     no_such_device,                     // ENODEV
     no_such_file_or_directory,          // ENOENT
     no_such_process,                    // ESRCH
     not_a_directory,                    // ENOTDIR
     not_a_socket,                       // ENOTSOCK
-    not_a_stream,                       // ENOSTR
+    not_a_stream,                       // ENOSTR          // deprecated
     not_connected,                      // ENOTCONN
     not_enough_memory,                  // ENOMEM
     not_supported,                      // ENOTSUP
@@ -87,7 +87,7 @@ enum class errc
     resource_unavailable_try_again,     // EAGAIN
     result_out_of_range,                // ERANGE
     state_not_recoverable,              // ENOTRECOVERABLE
-    stream_timeout,                     // ETIME
+    stream_timeout,                     // ETIME           // deprecated
     text_file_busy,                     // ETXTBSY
     timed_out,                          // ETIMEDOUT
     too_many_files_open_in_system,      // ENFILE
@@ -107,12 +107,34 @@ enum class errc
 #  pragma GCC system_header
 #endif
 
+// The method of pushing and popping the diagnostics fails for GCC.  GCC does
+// not recognize the pragma's used to generate deprecated diagnostics for
+// macros. So GCC does not need the pushing and popping.
+//
+// TODO Remove this when the deprecated constants are removed.
+#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
+#else
+#  define _LIBCPP_SUPPRESS_DEPRECATED_ERRC_PUSH
+#  define _LIBCPP_SUPPRESS_DEPRECATED_ERRC_POP
+#endif
+
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 // Some error codes are not present on all platforms, so we provide equivalents
 // for them:
 
 // enum class errc
+//
+// LWG3869 deprecates the UNIX STREAMS macros and enum values.
+// This makes the code clumbersome:
+// - the enum value is deprecated and should show a diagnostic,
+// - the macro is deprecated and should _not_ show a diagnostic in this
+//   context, and
+// - the macro is not always available.
+// This leads to the odd pushing and popping of the deprecated
+// diagnostic.
 _LIBCPP_DECLARE_STRONG_ENUM(errc){
     address_family_not_supported       = EAFNOSUPPORT,
     address_in_use                     = EADDRINUSE,
@@ -154,30 +176,48 @@ _LIBCPP_DECLARE_STRONG_ENUM(errc){
     no_child_process                   = ECHILD,
     no_link                            = ENOLINK,
     no_lock_available                  = ENOLCK,
+    // clang-format off
+    no_message_available _LIBCPP_DEPRECATED =
+    _LIBCPP_SUPPRESS_DEPRECATED_ERRC_PUSH
 #ifdef ENODATA
-    no_message_available = ENODATA,
+                                              ENODATA
 #else
-    no_message_available = ENOMSG,
+                                              ENOMSG
 #endif
+    _LIBCPP_SUPPRESS_DEPRECATED_ERRC_POP
+    ,
+    // clang-format on
     no_message         = ENOMSG,
     no_protocol_option = ENOPROTOOPT,
     no_space_on_device = ENOSPC,
+    // clang-format off
+    no_stream_resources _LIBCPP_DEPRECATED =
+    _LIBCPP_SUPPRESS_DEPRECATED_ERRC_PUSH
 #ifdef ENOSR
-    no_stream_resources = ENOSR,
+                                              ENOSR
 #else
-    no_stream_resources = ENOMEM,
+                                              ENOMEM
 #endif
+    _LIBCPP_SUPPRESS_DEPRECATED_ERRC_POP
+    ,
+    // clang-format on
     no_such_device_or_address = ENXIO,
     no_such_device            = ENODEV,
     no_such_file_or_directory = ENOENT,
     no_such_process           = ESRCH,
     not_a_directory           = ENOTDIR,
     not_a_socket              = ENOTSOCK,
+    // clang-format off
+    not_a_stream _LIBCPP_DEPRECATED =
+    _LIBCPP_SUPPRESS_DEPRECATED_ERRC_PUSH
 #ifdef ENOSTR
-    not_a_stream = ENOSTR,
+                                      ENOSTR
 #else
-    not_a_stream = EINVAL,
+                                      EINVAL
 #endif
+    _LIBCPP_SUPPRESS_DEPRECATED_ERRC_POP
+    ,
+    // clang-format on
     not_connected                  = ENOTCONN,
     not_enough_memory              = ENOMEM,
     not_supported                  = ENOTSUP,
@@ -195,11 +235,17 @@ _LIBCPP_DECLARE_STRONG_ENUM(errc){
     resource_unavailable_try_again = EAGAIN,
     result_out_of_range            = ERANGE,
     state_not_recoverable          = ENOTRECOVERABLE,
+    // clang-format off
+    stream_timeout _LIBCPP_DEPRECATED =
+    _LIBCPP_SUPPRESS_DEPRECATED_ERRC_PUSH
 #ifdef ETIME
-    stream_timeout = ETIME,
+                                        ETIME
 #else
-    stream_timeout = ETIMEDOUT,
+                                        ETIMEDOUT
 #endif
+    _LIBCPP_SUPPRESS_DEPRECATED_ERRC_POP
+    ,
+    // clang-format on
     text_file_busy                = ETXTBSY,
     timed_out                     = ETIMEDOUT,
     too_many_files_open_in_system = ENFILE,

libcxx/include/cerrno

@@ -38,4 +38,17 @@ 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
+
 #endif // _LIBCPP_CERRNO

libcxx/src/random.cpp

@@ -79,8 +79,10 @@ unsigned random_device::operator()() {
   char* p  = reinterpret_cast<char*>(&r);
   while (n > 0) {
     ssize_t s = read(__f_, p, n);
+    _LIBCPP_SUPPRESS_DEPRECATED_PUSH
     if (s == 0)
-      __throw_system_error(ENODATA, "random_device got EOF");
+      __throw_system_error(ENODATA, "random_device got EOF"); // TODO ENODATA -> ENOMSG
+    _LIBCPP_SUPPRESS_DEPRECATED_POP
     if (s == -1) {
       if (errno != EINTR)
         __throw_system_error(errno, "random_device got an unexpected error");

libcxx/test/std/depr.cerro/cerrno.syn.verify.cpp

@@ -0,0 +1,37 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: clang-modules-build
+// UNSUPPORTED: apple-clang && c++03
+
+// <cerrno>
+
+// tests LWG 3869 deprecated macros.
+//
+// Note the macros may not be defined. When they are not defined the
+// ifdef XXX does not trigger a deprecated message. So use them in the
+// ifdef and test for 2 deprecated messages.
+
+#include <cerrno>
+
+#ifdef ENODATA
+[[maybe_unused]] int nodata =
+    ENODATA; // expected-warning@cerrno.syn.verify.cpp:* 2 {{macro 'ENODATA' has been marked as deprecated}}
+#endif
+#ifdef ENOSR
+[[maybe_unused]] int nosr =
+    ENOSR; // expected-warning@cerrno.syn.verify.cpp:* 2 {{macro 'ENOSR' has been marked as deprecated}}
+#endif
+#ifdef ENOSTR
+[[maybe_unused]] int nostr =
+    ENOSTR; // expected-warning@cerrno.syn.verify.cpp:* 2 {{macro 'ENOSTR' has been marked as deprecated}}
+#endif
+#ifdef ETIME
+[[maybe_unused]] int timeout =
+    ETIME; // expected-warning@cerrno.syn.verify.cpp:* 2 {{macro 'ETIME' has been marked as deprecated}}
+#endif

libcxx/test/std/depr.cerro/system.error.syn.verify.cpp

@@ -0,0 +1,28 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// These macros do not seem to behave as expected on all Apple platforms.
+// Since the macros are not provided newer POSIX versions it is expected the
+// macros will be retroactively removed from C++. (The deprecation was
+// retroactively.)
+// UNSUPPORTED: apple-clang && (c++03 || clang-modules-build)
+
+// <system_error>
+
+// enum errc {...}
+
+// tests LWG 3869 deprecated enum members.
+
+#include <system_error>
+
+[[maybe_unused]] std::errc nodata =
+    std::errc::no_message_available; // expected-warning {{'no_message_available' is deprecated}}
+[[maybe_unused]] std::errc nosr =
+    std::errc::no_stream_resources; // expected-warning {{'no_stream_resources' is deprecated}}
+[[maybe_unused]] std::errc nostr   = std::errc::not_a_stream;   // expected-warning {{'not_a_stream' is deprecated}}
+[[maybe_unused]] std::errc timeout = std::errc::stream_timeout; // expected-warning {{'stream_timeout' is deprecated}}

libcxx/test/std/diagnostics/syserr/errc.pass.cpp

@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+// ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_DISABLE_DEPRECATION_WARNINGS
+
 // <system_error>
 
 // enum errc {...}