[libcxx] Set _LIBCPP_ELAST for mingw.

[danalbert]

Normally wouldn't bother with a review for something so trivial, but I know close to nothing about mingw, so I'm hoping someone can tell me if this is right. AIUI, mingw should emulate Linux, so that's what I've done here.

[EricWF]

I have a mingw environment set up so I'll test this and look into it tomorrow.

[mclow.lists]

I, too, know pretty much nothing about mingw. but structurally, this looks fine to me.

[majnemer]

I don't think it makes sense to use 4095, that number comes from Linux's kernel-user space ABI. MinGW targets link against the MSVC runtime, we should use _sys_nerr.

[danalbert]

Use _sys_nerr at David's suggestion.

[danalbert]

Thanks, figured you might know yet forgot to add you as a reviewer...

[EricWF]

_sys_nerr seems to be the correct value but it is not available in <__config>. In my mingw setup the definition is located in <stdlib.h>, so an include needs to be added.

[mclow.lists]

I'm reluctant to add yet another include into <__config>.
It includes too much stuff already.

[jroelofs]

can it be forward declared?

[EricWF]

_LIBCPP_ELAST is sparsely used, and it already drags in <errno.h>. I think we should just find a new place for it to live.
It's only used in src/system_error.cpp and src/ios.cpp so it doesn't even have to live in the headers.

[danalbert]

Factor ELAST configuration out into src/config_elast.h.
Use _WIN32 instead of MINGW32 since this is true for MSVC as well.

[danalbert]

Fix file name in file header.

[mclow.lists]

Other than that - this looks good to me.

Has anyone tried this on FreeBSD?

src/system_error.cpp

13

Please always include <__config> first.

This is a convention, rather than a requirement, since the first thing that <system_error> does is include <__config>

[danalbert]

Move __config inclusion back to the top of the list.

[EricWF]

LGTM.

include/__config

 #endif
 
 #ifdef __GNUC__
 #define _GNUC_VER (__GNUC__ * 100 + __GNUC_MINOR__)
 #endif
 
 #if !_WIN32
 #include <unistd.h>
-#include <errno.h>  // for ELAST on FreeBSD
 #endif
 
 #define _LIBCPP_VERSION 1101
 
 #define _LIBCPP_ABI_VERSION 1
 
 #define _LIBCPP_CONCAT1(_LIBCPP_X,_LIBCPP_Y) _LIBCPP_X##_LIBCPP_Y
 #define _LIBCPP_CONCAT(_LIBCPP_X,_LIBCPP_Y) _LIBCPP_CONCAT1(_LIBCPP_X,_LIBCPP_Y)

 #if defined(__APPLE__) || defined(__FreeBSD__)
 #define _LIBCPP_HAS_DEFAULTRUNELOCALE
 #endif
 
 #if defined(__APPLE__) || defined(__FreeBSD__) || defined(__sun__)
 #define _LIBCPP_WCTYPE_IS_MASK
 #endif
 
-#if defined(ELAST)
-#define _LIBCPP_ELAST ELAST
-#elif defined(__linux__)
-#define _LIBCPP_ELAST 4095
-#elif defined(_NEWLIB_VERSION)
-#define _LIBCPP_ELAST __ELASTERROR
-#elif defined(__APPLE__)
-// Not _LIBCPP_ELAST needed on Apple
-#elif defined(__sun__)
-#define _LIBCPP_ELAST ESTALE
-#else
-// Warn here so that the person doing the libcxx port has an easier time:
-#warning This platform's ELAST hasn't been ported yet
-#endif
-
 #ifndef _LIBCPP_TRIVIAL_PAIR_COPY_CTOR
 #  define _LIBCPP_TRIVIAL_PAIR_COPY_CTOR 1
 #endif
 
 #ifndef _LIBCPP_STD_VER
 #  if  __cplusplus <= 201103L
 #    define _LIBCPP_STD_VER 11
 #  elif __cplusplus <= 201402L

src/config_elast.h

+//===----------------------- config_elast.h -------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP_CONFIG_ELAST
+#define _LIBCPP_CONFIG_ELAST
+
+#if defined(_WIN32)
+#include <stdlib.h>
+#else
+#include <errno.h>
+#endif
+
+#if defined(ELAST)
+#define _LIBCPP_ELAST ELAST
+#elif defined(_NEWLIB_VERSION)
+#define _LIBCPP_ELAST __ELASTERROR
+#elif defined(__linux__)
+#define _LIBCPP_ELAST 4095
+#elif defined(__APPLE__)
+// No _LIBCPP_ELAST needed on Apple
+#elif defined(__sun__)
+#define _LIBCPP_ELAST ESTALE
+#elif defined(_WIN32)
+#define _LIBCPP_ELAST _sys_nerr
+#else
+// Warn here so that the person doing the libcxx port has an easier time:
+#warning This platform's ELAST hasn't been ported yet
+#endif
+
+#endif // _LIBCPP_CONFIG_ELAST

src/ios.cpp

 //===-------------------------- ios.cpp -----------------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is dual licensed under the MIT and the University of Illinois Open
 // Source Licenses. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
 #include "__config"
+
 #include "ios"
-#include "streambuf"
-#include "istream"
-#include "string"
+
+#include <stdlib.h>
+
 #include "__locale"
 #include "algorithm"
+#include "config_elast.h"
+#include "istream"
+#include "limits"
 #include "memory"
 #include "new"
-#include "limits"
-#include <stdlib.h>
+#include "streambuf"
+#include "string"
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 template class basic_ios<char>;
 template class basic_ios<wchar_t>;
 
 template class basic_streambuf<char>;
 template class basic_streambuf<wchar_t>;

src/system_error.cpp

 //===---------------------- system_error.cpp ------------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is dual licensed under the MIT and the University of Illinois Open
 // Source Licenses. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
-#define _LIBCPP_BUILDING_SYSTEM_ERROR
 #include "__config"
+
+#define _LIBCPP_BUILDING_SYSTEM_ERROR
 #include "system_error"
-#include "string"
+
+#include "config_elast.h"
 #include "cstring"
+#include "string"
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 // class error_category
 
 error_category::error_category() _NOEXCEPT
 {
 }