Feature test macros overhaul: sys/features.h

This is the complete rework of the feature tests macros for better
compatibility with GNU libc, primarily based on the Linux man pages
documentation:

http://man7.org/linux/man-pages/man7/feature_test_macros.7.html

The previous implementation was flawed in its approach that macros were
often used to hide symbols if defined (e.g. !defined __STRICT_ANSI__ or
!defined _POSIX_SOURCE), whereas the approach of glibc is that these macros
make symbols available when defined (e.g. defined _BSD_SOURCE, or as used
internally, #if __BSD_VISIBLE).  As much open-source software is written
with glibc in mind, this necessitated patching numerous packages just to
compile.

In particular, __STRICT_ANSI__ (which is defined by gcc -ansi or -std=c*)
was given too much importance.  This implementation limits the influence
of __STRICT_ANSI__ to controlling the default when no other feature test
macros are defined, and to the inclusion of <alloca.h> in <stdlib.h> as
documented.  These are the only places where __STRICT_ANSI__ should be
tested.

The following macros are now accepted: _ATFILE_SOURCE, _BSD_SOURCE,
_DEFAULT_SOURCE, _ISOC99_SOURCE, _ISOC11_SOURCE, _LARGEFILE_SOURCE,
_SVID_SOURCE, _XOPEN_SOURCE_EXTENDED.

The existing __*_VISIBLE internal macros have been kept mostly
compatible with the original BSD implementation, with some changes to
the criteria which controls them.  Several more macros in this style
have been added where needed for concision or accuracy.

Enabling C++11 or newer in the compiler also enables C99 and C11
functions.  Doing so should help move away from the need to define
_GNU_SOURCE in g++ for _GLIBCXX_USE_C99 support as on Linux:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=51749

Signed-off-by: Yaakov Selkowitz <yselkowi@redhat.com>

1 files changed, 0 insertions, 126 deletions

diff --git a/newlib/libc/include/sys/cdefs.h b/newlib/libc/include/sys/cdefs.h
index 773ac25d6..2a55a92e9 100644
--- a/newlib/libc/include/sys/cdefs.h
+++ b/newlib/libc/include/sys/cdefs.h
@@ -624,132 +624,6 @@
 #define	__DEQUALIFY(type, var)	((type)(__uintptr_t)(const volatile void *)(var))
 #endif
 
-/*-
- * The following definitions are an extension of the behavior originally
- * implemented in <sys/_posix.h>, but with a different level of granularity.
- * POSIX.1 requires that the macros we test be defined before any standard
- * header file is included.
- *
- * Here's a quick run-down of the versions:
- *  defined(_POSIX_SOURCE)		1003.1-1988
- *  _POSIX_C_SOURCE == 1		1003.1-1990
- *  _POSIX_C_SOURCE == 2		1003.2-1992 C Language Binding Option
- *  _POSIX_C_SOURCE == 199309		1003.1b-1993
- *  _POSIX_C_SOURCE == 199506		1003.1c-1995, 1003.1i-1995,
- *					and the omnibus ISO/IEC 9945-1: 1996
- *  _POSIX_C_SOURCE == 200112		1003.1-2001
- *  _POSIX_C_SOURCE == 200809		1003.1-2008
- *
- * In addition, the X/Open Portability Guide, which is now the Single UNIX
- * Specification, defines a feature-test macro which indicates the version of
- * that specification, and which subsumes _POSIX_C_SOURCE.
- *
- * Our macros begin with two underscores to avoid namespace screwage.
- */
-
-/* Deal with _GNU_SOURCE, which implies everything and the kitchen sink */
-#ifdef _GNU_SOURCE
-#undef _XOPEN_SOURCE
-#define	_XOPEN_SOURCE		700
-#define	__BSD_VISIBLE		1
-#define	__GNU_VISIBLE		1
-#endif
-
-/* Deal with IEEE Std. 1003.1-1990, in which _POSIX_C_SOURCE == 1. */
-#if defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE == 1
-#undef _POSIX_C_SOURCE		/* Probably illegal, but beyond caring now. */
-#define	_POSIX_C_SOURCE		199009
-#endif
-
-/* Deal with IEEE Std. 1003.2-1992, in which _POSIX_C_SOURCE == 2. */
-#if defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE == 2
-#undef _POSIX_C_SOURCE
-#define	_POSIX_C_SOURCE		199209
-#endif
-
-/* Deal with various X/Open Portability Guides and Single UNIX Spec. */
-#ifdef _XOPEN_SOURCE
-#if _XOPEN_SOURCE - 0 >= 700
-#define	__XSI_VISIBLE		700
-#undef _POSIX_C_SOURCE
-#define	_POSIX_C_SOURCE		200809
-#elif _XOPEN_SOURCE - 0 >= 600
-#define	__XSI_VISIBLE		600
-#undef _POSIX_C_SOURCE
-#define	_POSIX_C_SOURCE		200112
-#elif _XOPEN_SOURCE - 0 >= 500
-#define	__XSI_VISIBLE		500
-#undef _POSIX_C_SOURCE
-#define	_POSIX_C_SOURCE		199506
-#endif
-#endif
-
-/*
- * Deal with all versions of POSIX.  The ordering relative to the tests above is
- * important.
- */
-#if defined(_POSIX_SOURCE) && !defined(_POSIX_C_SOURCE)
-#define	_POSIX_C_SOURCE		198808
-#endif
-#ifdef _POSIX_C_SOURCE
-#if _POSIX_C_SOURCE >= 200809
-#define	__POSIX_VISIBLE		200809
-#define	__ISO_C_VISIBLE		1999
-#elif _POSIX_C_SOURCE >= 200112
-#define	__POSIX_VISIBLE		200112
-#define	__ISO_C_VISIBLE		1999
-#elif _POSIX_C_SOURCE >= 199506
-#define	__POSIX_VISIBLE		199506
-#define	__ISO_C_VISIBLE		1990
-#elif _POSIX_C_SOURCE >= 199309
-#define	__POSIX_VISIBLE		199309
-#define	__ISO_C_VISIBLE		1990
-#elif _POSIX_C_SOURCE >= 199209
-#define	__POSIX_VISIBLE		199209
-#define	__ISO_C_VISIBLE		1990
-#elif _POSIX_C_SOURCE >= 199009
-#define	__POSIX_VISIBLE		199009
-#define	__ISO_C_VISIBLE		1990
-#else
-#define	__POSIX_VISIBLE		198808
-#define	__ISO_C_VISIBLE		0
-#endif /* _POSIX_C_SOURCE */
-#else
-/*-
- * Deal with _ANSI_SOURCE:
- * If it is defined, and no other compilation environment is explicitly
- * requested, then define our internal feature-test macros to zero.  This
- * makes no difference to the preprocessor (undefined symbols in preprocessing
- * expressions are defined to have value zero), but makes it more convenient for
- * a test program to print out the values.
- *
- * If a program mistakenly defines _ANSI_SOURCE and some other macro such as
- * _POSIX_C_SOURCE, we will assume that it wants the broader compilation
- * environment (and in fact we will never get here).
- */
-#if defined(_ANSI_SOURCE)	/* Hide almost everything. */
-#define	__POSIX_VISIBLE		0
-#define	__XSI_VISIBLE		0
-#define	__BSD_VISIBLE		0
-#define	__ISO_C_VISIBLE		1990
-#elif defined(_C99_SOURCE)	/* Localism to specify strict C99 env. */
-#define	__POSIX_VISIBLE		0
-#define	__XSI_VISIBLE		0
-#define	__BSD_VISIBLE		0
-#define	__ISO_C_VISIBLE		1999
-#elif defined(_C11_SOURCE)	/* Localism to specify strict C11 env. */
-#define	__POSIX_VISIBLE		0
-#define	__XSI_VISIBLE		0
-#define	__BSD_VISIBLE		0
-#define	__ISO_C_VISIBLE		2011
-#else				/* Default: everything except __GNU_VISIBLE. */
-#define	__POSIX_VISIBLE		200809
-#define	__XSI_VISIBLE		700
-#define	__BSD_VISIBLE		1
-#define	__ISO_C_VISIBLE		2011
-#endif
-#endif
-
 /*
  * Type Safety Checking
  *