Re: Remove _BSD_SOURCE and _SVID_SOURCE

["Joseph S. Myers" <joseph at codesourcery dot com>]

On Mon, 16 Dec 2013, Roland McGrath wrote:

> I think the suggestion of a feature-test macro that enables all the
> extension symbols but does not change any standard-specified symbols has
> merit.  It is probably wise to add this first, and then stage the
> removal of the old feature-test macros.  A long-term intermediate state
> that probably makes sense is to have _BSD_SOURCE and _SVID_SOURCE
> (without _GNU_SOURCE) trigger this new mode but with a #warning advising
> to use the cleaner new feature-test macro name.

This is a minimal patch, relative to a tree with
<https://sourceware.org/ml/libc-alpha/2013-12/msg00646.html> applied,
to remove _BSD_SOURCE and _SVID_SOURCE from the documented user API,
making them into aliases for _DEFAULT_SOURCE with a #warning given,
but keeping most of the features.h logic using those macros and all
the exising __USE_* conditionals, on the basis that all the consequent
cleanups will go in followup patches.

Tested x86_64.

2013-12-17  Joseph Myers  <joseph@codesourcery.com>

	* include/features.h: Update comment documenting feature test
	macros.
	[_BSD_SOURCE || _SVID_SOURCE]: Give #warning.  Define
	_DEFAULT_SOURCE.
	* manual/creature.texi (_BSD_SOURCE): Remove documentation.
	(_SVID_SOURCE): Likewise.
	(_DEFAULT_SOURCE): Update description of default features.
	(Feature Test Macros): Don't mention _SVID_SOURCE in conjunction
	with _GNU_SOURCE.
	* manual/filesys.texi (__ftw_func_t): Do not refer to _BSD_SOURCE.
	(S_ISVTX): Likewise.
	* manual/math.texi (Mathematical Constants): Likewise.
	* manual/signal.texi (Interrupted Primitives): Likewise.
	* manual/startup.texi (putenv): Do not refer to _SVID_SOURCE.
	* math/test-matherr.c (_SVID_SOURCE): Do not define.
	* sysvipc/sys/ipc.h [__USE_SVID && !__USE_XOPEN && __GNUC__ >= 2]:
	Don't refer to _SVID_SOURCE in warning text.

diff --git a/NEWS b/NEWS
index 61e40cb..23510d3 100644
--- a/NEWS
+++ b/NEWS
@@ -106,9 +106,14 @@ Version 2.19
   feature test macros or compiler options such as -std=c99 would otherwise
   disable some of those declarations.
 
-* The _BSD_SOURCE feature test macro no longer enables BSD interfaces that
-  conflict with POSIX.  The libbsd-compat library (which was a dummy library
-  that did nothing) has also been removed.
+* The _BSD_SOURCE and _SVID_SOURCE feature test macros are no longer
+  supported; they now act the same as _DEFAULT_SOURCE (but generate a
+  warning).  Except for cases where _BSD_SOURCE enabled BSD interfaces that
+  conflicted with POSIX, the interfaces those macros enabled remain
+  available when compiling with _GNU_SOURCE defined, with _DEFAULT_SOURCE
+  defined, or without any feature test macros defined.  The libbsd-compat
+  library (which was a dummy library that did nothing) has also been
+  removed.
 
 Version 2.18
 
diff --git a/include/features.h b/include/features.h
index 6acd5c8..d91c8f5 100644
--- a/include/features.h
+++ b/include/features.h
@@ -37,8 +37,6 @@
    _LARGEFILE_SOURCE	Some more functions for correct standard I/O.
    _LARGEFILE64_SOURCE	Additional functionality from LFS for large files.
    _FILE_OFFSET_BITS=N	Select default filesystem interface.
-   _BSD_SOURCE		ISO C, POSIX, and 4.3BSD things.
-   _SVID_SOURCE		ISO C, POSIX, and SVID things.
    _ATFILE_SOURCE	Additional *at interfaces.
    _GNU_SOURCE		All of the above, plus GNU extensions.
    _DEFAULT_SOURCE	The default set of features (taking precedence over
@@ -51,11 +49,11 @@
    The `-ansi' switch to the GNU C compiler, and standards conformance
    options such as `-std=c99', define __STRICT_ANSI__.  If none of
    these are defined, or if _DEFAULT_SOURCE is defined, the default is
-   to have _SVID_SOURCE, _BSD_SOURCE, and _POSIX_SOURCE set to one and
-   _POSIX_C_SOURCE set to 200809L.  If more than one of these are
-   defined, they accumulate.  For example __STRICT_ANSI__,
-   _POSIX_SOURCE and _POSIX_C_SOURCE together give you ISO C, 1003.1,
-   and 1003.2, but nothing else.
+   to have _POSIX_SOURCE set to one and _POSIX_C_SOURCE set to
+   200809L, as well as enabling miscellaneous functions from BSD and
+   SVID.  If more than one of these are defined, they accumulate.  For
+   example __STRICT_ANSI__, _POSIX_SOURCE and _POSIX_C_SOURCE together
+   give you ISO C, 1003.1, and 1003.2, but nothing else.
 
    These are defined by this file and are used by the
    header files to decide what to declare or define:
@@ -145,6 +143,13 @@
 # define __GNUC_PREREQ(maj, min) 0
 #endif
 
+/* _BSD_SOURCE and _SVID_SOURCE are deprecated aliases for
+   _DEFAULT_SOURCE.  */
+#if defined _BSD_SOURCE || defined _SVID_SOURCE
+# warning "_BSD_SOURCE and _SVID_SOURCE are deprecated, use _DEFAULT_SOURCE"
+# undef  _DEFAULT_SOURCE
+# define _DEFAULT_SOURCE	1
+#endif
 
 /* If _GNU_SOURCE was defined by the user, turn on all the other features.  */
 #ifdef _GNU_SOURCE
diff --git a/manual/creature.texi b/manual/creature.texi
index bbf16b7..3c68616 100644
--- a/manual/creature.texi
+++ b/manual/creature.texi
@@ -73,20 +73,6 @@ edition is made available.
 @end defvr
 
 @comment (none)
-@comment GNU
-@defvr Macro _BSD_SOURCE
-If you define this macro, functionality derived from 4.3 BSD Unix is
-included as well as the @w{ISO C}, POSIX.1, and POSIX.2 material.
-@end defvr
-
-@comment (none)
-@comment GNU
-@defvr Macro _SVID_SOURCE
-If you define this macro, functionality derived from SVID is
-included as well as the @w{ISO C}, POSIX.1, POSIX.2, and X/Open material.
-@end defvr
-
-@comment (none)
 @comment X/Open
 @defvr Macro _XOPEN_SOURCE
 @comment (none)
@@ -192,9 +178,9 @@ precedence.
 @comment GNU
 @defvr Macro _DEFAULT_SOURCE
 If you define this macro, most features are included apart from
-X/Open, LFS and GNU extensions; the effect is similar to defining
-@code{_POSIX_C_SOURCE} to @code{200809L} and @code{_POSIX_SOURCE},
-@code{_SVID_SOURCE}, and @code{_BSD_SOURCE} to 1.  Defining this
+X/Open, LFS and GNU extensions: the effect is to enable features from
+the 2008 edition of POSIX, as well as certain BSD and SVID features
+without a separate feature test macro to control them.  Defining this
 macro, on its own and without using compiler options such as
 @option{-ansi} or @option{-std=c99}, has the same effect as not
 defining any feature test macros; defining it together with other
@@ -229,4 +215,4 @@ it is harmless to define in addition a feature test macro for a subset of
 those features.  For example, if you define @code{_POSIX_C_SOURCE}, then
 defining @code{_POSIX_SOURCE} as well has no effect.  Likewise, if you
 define @code{_GNU_SOURCE}, then defining either @code{_POSIX_SOURCE} or
-@code{_POSIX_C_SOURCE} or @code{_SVID_SOURCE} as well has no effect.
+@code{_POSIX_C_SOURCE} as well has no effect.
diff --git a/manual/filesys.texi b/manual/filesys.texi
index 1cac453..7ebaeb0 100644
--- a/manual/filesys.texi
+++ b/manual/filesys.texi
@@ -812,7 +812,7 @@ seeing this value in a @code{ftw} callback function means the referenced
 file does not exist.  The situation for @code{nftw} is different.
 
 This value is only available if the program is compiled with
-@code{_BSD_SOURCE} or @code{_XOPEN_EXTENDED} defined before including
+@code{_XOPEN_EXTENDED} defined before including
 the first header.  The original SVID systems do not have symbolic links.
 @end vtable
 
@@ -2415,8 +2415,9 @@ the file's modification time onto disk reliably (the idea being that
 no-one cares for a swap file).
 
 This bit is only available on BSD systems (and those derived from
-them).  Therefore one has to use the @code{_BSD_SOURCE} feature select
-macro to get the definition (@pxref{Feature Test Macros}).
+them).  Therefore one has to use the @code{_GNU_SOURCE} feature select
+macro, or not define any feature test macros, to get the definition
+(@pxref{Feature Test Macros}).
 @end table
 
 The actual bit values of the symbols are listed in the table above
diff --git a/manual/math.texi b/manual/math.texi
index 5e7c90e..35662cd 100644
--- a/manual/math.texi
+++ b/manual/math.texi
@@ -106,7 +106,7 @@ The reciprocal of the square root of two (also the square root of 1/2).
 @end vtable
 
 These constants come from the Unix98 standard and were also available in
-4.4BSD; therefore they are only defined if @code{_BSD_SOURCE} or
+4.4BSD; therefore they are only defined if
 @code{_XOPEN_SOURCE=500}, or a more general feature select macro, is
 defined.  The default set of features includes these constants.
 @xref{Feature Test Macros}.
diff --git a/manual/signal.texi b/manual/signal.texi
index adcda37..facdfb5 100644
--- a/manual/signal.texi
+++ b/manual/signal.texi
@@ -2108,16 +2108,9 @@ that handler will cause @code{EINTR}.  @xref{Flags for Sigaction}.
 Another way to specify the choice is with the @code{siginterrupt}
 function.  @xref{BSD Handler}.
 
-@c !!! not true now about _BSD_SOURCE
 When you don't specify with @code{sigaction} or @code{siginterrupt} what
 a particular handler should do, it uses a default choice.  The default
-choice in @theglibc{} depends on the feature test macros you have
-defined.  If you define @code{_BSD_SOURCE} or @code{_GNU_SOURCE} before
-calling @code{signal}, the default is to resume primitives; otherwise,
-the default is to make them fail with @code{EINTR}.  (The library
-contains alternate versions of the @code{signal} function, and the
-feature test macros determine which one you really call.)  @xref{Feature
-Test Macros}.
+choice in @theglibc{} is to make primitives fail with @code{EINTR}.
 @cindex EINTR, and restarting interrupted primitives
 @cindex restarting interrupted primitives
 @cindex interrupting primitives
diff --git a/manual/startup.texi b/manual/startup.texi
index a277714..f7f5836 100644
--- a/manual/startup.texi
+++ b/manual/startup.texi
@@ -363,9 +363,8 @@ reflect in automatically in the environment.  This also requires that
 variable is removed from the environment.  The same applies of course to
 dynamically allocated variables which are freed later.
 
-This function is part of the extended Unix interface.  Since it was also
-available in old SVID libraries you should define either
-@var{_XOPEN_SOURCE} or @var{_SVID_SOURCE} before including any header.
+This function is part of the extended Unix interface.  You should define
+@var{_XOPEN_SOURCE} before including any header.
 @end deftypefun
 
 
diff --git a/math/test-matherr.c b/math/test-matherr.c
index 91657a8..cd09a39 100644
--- a/math/test-matherr.c
+++ b/math/test-matherr.c
@@ -1,5 +1,3 @@
-#undef _SVID_SOURCE
-#define _SVID_SOURCE
 #include <math.h>
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/sysvipc/sys/ipc.h b/sysvipc/sys/ipc.h
index 0a87aff..9516824 100644
--- a/sysvipc/sys/ipc.h
+++ b/sysvipc/sys/ipc.h
@@ -21,7 +21,7 @@
 #include <features.h>
 
 #if !defined __USE_SVID && !defined __USE_XOPEN && __GNUC__ >= 2
-# warning "Files using this header must be compiled with _SVID_SOURCE or _XOPEN_SOURCE"
+# warning "Files using this header must be compiled with _DEFAULT_SOURCE or _XOPEN_SOURCE"
 #endif
 
 /* Get system dependent definition of `struct ipc_perm' and more.  */

-- 
Joseph S. Myers
joseph@codesourcery.com