Replace __ANDROID__ with __BIONIC__.

[danalbert]

Summary

None of these checks are specific to Android devices. If libc++ was
used with Bionic on a normal Linux system these checks would still be
needed.

[compnerd]

So, the only thing that Im confused about is where does __BIONIC__ get defined?

include/__config

766 ↗

(On Diff #71714)

Not your fault, but _WIN32 and __unix__? Im not sure if MinGW or cygwin define both.

[EricWF]

include/__config

340 ↗

(On Diff #71714)

What happened to this include? I believe it's needed to get __GLIBC_PREREQ.

[danalbert]

In D24690#545523, @compnerd wrote:

So, the only thing that Im confused about is where does __BIONIC__ get defined?

It's in Bionic's <sys/cdefs.h>, which gets pulled in via <features.h>.

include/__config

340 ↗

(On Diff #71714)

Included much earlier now (L90). We always needed this for Linux, and having it at the top of the file means we won't accidentally forget to include it for an earlier check.

766 ↗

(On Diff #71714)

That is odd. I would assume that _WIN32 implies !__unix__.

[EricWF]

LGTM after addressing the MUSL libc comment.

include/__config

90 ↗

(On Diff #71714)

Does MUSL libc have a features.h? This include was previously guarded by if !defined(_LIBCPP_HAS_MUSL_LIBC).

[danalbert]

include/__config

90 ↗

(On Diff #71714)

Yep: https://github.com/wermut/musl/blob/master/include/features.h

libcxx/trunk/include/__config

 #define __has_feature(__x) 0
 #endif
 // '__is_identifier' returns '0' if '__x' is a reserved identifier provided by
 // the compiler and '1' otherwise.
 #ifndef __is_identifier
 #define __is_identifier(__x) 1
 #endif
 
+// Need to detect which libc we're using if we're on Linux.
+#if defined(__linux__)
+#include <features.h>
+#if !defined(__GLIBC_PREREQ)
+#define __GLIBC_PREREQ(a, b) 0
+#endif // !defined(__GLIBC_PREREQ)
+#endif // defined(__linux__)
 
 #ifdef __LITTLE_ENDIAN__
 #if __LITTLE_ENDIAN__
 #define _LIBCPP_LITTLE_ENDIAN 1
 #define _LIBCPP_BIG_ENDIAN    0
 #endif  // __LITTLE_ENDIAN__
 #endif  // __LITTLE_ENDIAN__
 

 #if !(__has_feature(cxx_variable_templates))
 #define _LIBCPP_HAS_NO_VARIABLE_TEMPLATES
 #endif
 
 #if __ISO_C_VISIBLE >= 2011 || __cplusplus >= 201103L
 #if defined(__FreeBSD__)
 #define _LIBCPP_HAS_QUICK_EXIT
 #define _LIBCPP_HAS_C11_FEATURES
-#elif defined(__ANDROID__)
-#define _LIBCPP_HAS_QUICK_EXIT
 #elif defined(__linux__)
 #if !defined(_LIBCPP_HAS_MUSL_LIBC)
-# include <features.h>
-#if __GLIBC_PREREQ(2, 15)
+#if __GLIBC_PREREQ(2, 15) || defined(__BIONIC__)
 #define _LIBCPP_HAS_QUICK_EXIT
 #endif
 #if __GLIBC_PREREQ(2, 17)
 #define _LIBCPP_HAS_C11_FEATURES
 #endif
 #else // defined(_LIBCPP_HAS_MUSL_LIBC)
 #define _LIBCPP_HAS_QUICK_EXIT
 #define _LIBCPP_HAS_C11_FEATURES

 
 #if defined(__APPLE__) || defined(__FreeBSD__) || defined(_WIN32) || \
     defined(__sun__) || defined(__NetBSD__) || defined(__CloudABI__)
 #define _LIBCPP_LOCALE__L_EXTENSIONS 1
 #endif
 
 #if defined(__unix__) || (defined(__APPLE__) && defined(__MACH__))
 // Most unix variants have catopen.  These are the specific ones that don't.
-#if !defined(_WIN32) && !defined(__ANDROID__) && !defined(_NEWLIB_VERSION)
+#if !defined(_WIN32) && !defined(__BIONIC__) && !defined(_NEWLIB_VERSION)
 #define _LIBCPP_HAS_CATOPEN 1
 #endif
 #endif
 
 #ifdef __FreeBSD__
 #define _DECLARE_C99_LDBL_MATH 1
 #endif
 

 
 // CloudABI is intended for running networked services. Processes do not
 // have standard input and output channels.
 #ifdef __CloudABI__
 #define _LIBCPP_HAS_NO_STDIN
 #define _LIBCPP_HAS_NO_STDOUT
 #endif
 
-#if defined(__ANDROID__) || defined(__CloudABI__) || defined(_LIBCPP_HAS_MUSL_LIBC)
+#if defined(__BIONIC__) || defined(__CloudABI__) ||                            \
+    defined(_LIBCPP_HAS_MUSL_LIBC)
 #define _LIBCPP_PROVIDES_DEFAULT_RUNE_TABLE
 #endif
 
 // Thread-unsafe functions such as strtok(), mbtowc() and localtime()
 // are not available.
 #ifdef __CloudABI__
 #define _LIBCPP_HAS_NO_THREAD_UNSAFE_C_FUNCTIONS
 #endif

libcxx/trunk/include/support/android/locale_bionic.h

 // -*- C++ -*-
 //===------------------- support/android/locale_bionic.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_SUPPORT_ANDROID_LOCALE_BIONIC_H
 #define _LIBCPP_SUPPORT_ANDROID_LOCALE_BIONIC_H
 
-#if defined(__ANDROID__)
+#if defined(__BIONIC__)
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
 #include <stdlib.h>
 #include <xlocale.h>
 
 #ifdef __cplusplus
 }
 #endif
 
 #include <support/xlocale/__posix_l_fallback.h>
 #include <support/xlocale/__strtonum_fallback.h>
 
-#endif // defined(__ANDROID__)
+#endif // defined(__BIONIC__)
 #endif // _LIBCPP_SUPPORT_ANDROID_LOCALE_BIONIC_H

libcxx/trunk/src/locale.cpp

 #  include "type_traits"
 #endif
 #include "clocale"
 #include "cstring"
 #include "cwctype"
 #include "__sso_allocator"
 #if defined(_LIBCPP_MSVCRT) || defined(__MINGW32__)
 #include "support/win32/locale_win32.h"
-#elif !defined(__ANDROID__)
+#elif !defined(__BIONIC__)
 #include <langinfo.h>
 #endif
 #include <stdlib.h>
 #include <stdio.h>
 
 // On Linux, wint_t and wchar_t have different signed-ness, and this causes
 // lots of noise in the build log, but no bugs that I know of. 
 #if defined(__clang__)