Prepare for radical source tree reorganization.zack/build-layout-experiment

All top-level files and directories are moved into a temporary storage
directory, REORG.TODO, except for files that will certainly still
exist in their current form at top level when we're done (COPYING,
COPYING.LIB, LICENSES, NEWS, README), all old ChangeLog files (which
are moved to the new directory OldChangeLogs, instead), and the
generated file INSTALL (which is just deleted; in the new order, there
will be no generated files checked into version control).

1 files changed, 249 insertions, 0 deletions

diff --git a/REORG.TODO/manual/creature.texi b/REORG.TODO/manual/creature.texi
new file mode 100644
index 0000000000..23218bbac3
--- /dev/null
+++ b/REORG.TODO/manual/creature.texi
@@ -0,0 +1,249 @@
+@node Feature Test Macros
+@subsection Feature Test Macros
+
+@cindex feature test macros
+The exact set of features available when you compile a source file
+is controlled by which @dfn{feature test macros} you define.
+
+If you compile your programs using @samp{gcc -ansi}, you get only the
+@w{ISO C} library features, unless you explicitly request additional
+features by defining one or more of the feature macros.
+@xref{Invoking GCC,, GNU CC Command Options, gcc.info, The GNU CC Manual},
+for more information about GCC options.@refill
+
+You should define these macros by using @samp{#define} preprocessor
+directives at the top of your source code files.  These directives
+@emph{must} come before any @code{#include} of a system header file.  It
+is best to make them the very first thing in the file, preceded only by
+comments.  You could also use the @samp{-D} option to GCC, but it's
+better if you make the source files indicate their own meaning in a
+self-contained way.
+
+This system exists to allow the library to conform to multiple standards.
+Although the different standards are often described as supersets of each
+other, they are usually incompatible because larger standards require
+functions with names that smaller ones reserve to the user program.  This
+is not mere pedantry --- it has been a problem in practice.  For instance,
+some non-GNU programs define functions named @code{getline} that have
+nothing to do with this library's @code{getline}.  They would not be
+compilable if all features were enabled indiscriminately.
+
+This should not be used to verify that a program conforms to a limited
+standard.  It is insufficient for this purpose, as it will not protect you
+from including header files outside the standard, or relying on semantics
+undefined within the standard.
+
+@comment (none)
+@comment POSIX.1
+@defvr Macro _POSIX_SOURCE
+If you define this macro, then the functionality from the POSIX.1
+standard (IEEE Standard 1003.1) is available, as well as all of the
+@w{ISO C} facilities.
+
+The state of @code{_POSIX_SOURCE} is irrelevant if you define the
+macro @code{_POSIX_C_SOURCE} to a positive integer.
+@end defvr
+
+@comment (none)
+@comment POSIX.2
+@defvr Macro _POSIX_C_SOURCE
+Define this macro to a positive integer to control which POSIX
+functionality is made available.  The greater the value of this macro,
+the more functionality is made available.
+
+If you define this macro to a value greater than or equal to @code{1},
+then the functionality from the 1990 edition of the POSIX.1 standard
+(IEEE Standard 1003.1-1990) is made available.
+
+If you define this macro to a value greater than or equal to @code{2},
+then the functionality from the 1992 edition of the POSIX.2 standard
+(IEEE Standard 1003.2-1992) is made available.
+
+If you define this macro to a value greater than or equal to @code{199309L},
+then the functionality from the 1993 edition of the POSIX.1b standard
+(IEEE Standard 1003.1b-1993) is made available.
+
+Greater values for @code{_POSIX_C_SOURCE} will enable future extensions.
+The POSIX standards process will define these values as necessary, and
+@theglibc{} should support them some time after they become standardized.
+The 1996 edition of POSIX.1 (ISO/IEC 9945-1: 1996) states that
+if you define @code{_POSIX_C_SOURCE} to a value greater than
+or equal to @code{199506L}, then the functionality from the 1996
+edition is made available.
+@end defvr
+
+@comment (none)
+@comment X/Open
+@defvr Macro _XOPEN_SOURCE
+@comment (none)
+@comment X/Open
+@defvrx Macro _XOPEN_SOURCE_EXTENDED
+If you define this macro, functionality described in the X/Open
+Portability Guide is included.  This is a superset of the POSIX.1 and
+POSIX.2 functionality and in fact @code{_POSIX_SOURCE} and
+@code{_POSIX_C_SOURCE} are automatically defined.
+
+As the unification of all Unices, functionality only available in
+BSD and SVID is also included.
+
+If the macro @code{_XOPEN_SOURCE_EXTENDED} is also defined, even more
+functionality is available.  The extra functions will make all functions
+available which are necessary for the X/Open Unix brand.
+
+If the macro @code{_XOPEN_SOURCE} has the value @math{500} this includes
+all functionality described so far plus some new definitions from the
+Single Unix Specification, @w{version 2}.
+@end defvr
+
+@comment (NONE)
+@comment X/Open
+@defvr Macro _LARGEFILE_SOURCE
+If this macro is defined some extra functions are available which
+rectify a few shortcomings in all previous standards.  Specifically,
+the functions @code{fseeko} and @code{ftello} are available.  Without
+these functions the difference between the @w{ISO C} interface
+(@code{fseek}, @code{ftell}) and the low-level POSIX interface
+(@code{lseek}) would lead to problems.
+
+This macro was introduced as part of the Large File Support extension (LFS).
+@end defvr
+
+@comment (NONE)
+@comment X/Open
+@defvr Macro _LARGEFILE64_SOURCE
+If you define this macro an additional set of functions is made available
+which enables @w{32 bit} systems to use files of sizes beyond
+the usual limit of 2GB.  This interface is not available if the system
+does not support files that large.  On systems where the natural file
+size limit is greater than 2GB (i.e., on @w{64 bit} systems) the new
+functions are identical to the replaced functions.
+
+The new functionality is made available by a new set of types and
+functions which replace the existing ones.  The names of these new objects
+contain @code{64} to indicate the intention, e.g., @code{off_t}
+vs. @code{off64_t} and @code{fseeko} vs. @code{fseeko64}.
+
+This macro was introduced as part of the Large File Support extension
+(LFS).  It is a transition interface for the period when @w{64 bit}
+offsets are not generally used (see @code{_FILE_OFFSET_BITS}).
+@end defvr
+
+@comment (NONE)
+@comment X/Open
+@defvr Macro _FILE_OFFSET_BITS
+This macro determines which file system interface shall be used, one
+replacing the other.  Whereas @code{_LARGEFILE64_SOURCE} makes the @w{64
+bit} interface available as an additional interface,
+@code{_FILE_OFFSET_BITS} allows the @w{64 bit} interface to
+replace the old interface.
+
+If @code{_FILE_OFFSET_BITS} is undefined, or if it is defined to the
+value @code{32}, nothing changes.  The @w{32 bit} interface is used and
+types like @code{off_t} have a size of @w{32 bits} on @w{32 bit}
+systems.
+
+If the macro is defined to the value @code{64}, the large file interface
+replaces the old interface.  I.e., the functions are not made available
+under different names (as they are with @code{_LARGEFILE64_SOURCE}).
+Instead the old function names now reference the new functions, e.g., a
+call to @code{fseeko} now indeed calls @code{fseeko64}.
+
+This macro should only be selected if the system provides mechanisms for
+handling large files.  On @w{64 bit} systems this macro has no effect
+since the @code{*64} functions are identical to the normal functions.
+
+This macro was introduced as part of the Large File Support extension
+(LFS).
+@end defvr
+
+@comment (none)
+@comment GNU
+@defvr Macro _ISOC99_SOURCE
+Until the revised @w{ISO C} standard is widely adopted the new features
+are not automatically enabled.  @Theglibc{} nevertheless has a complete
+implementation of the new standard and to enable the new features the
+macro @code{_ISOC99_SOURCE} should be defined.
+@end defvr
+
+@comment (none)
+@comment ISO
+@defvr Macro __STDC_WANT_LIB_EXT2__
+If you define this macro to the value @code{1}, features from ISO/IEC
+TR 24731-2:2010 (Dynamic Allocation Functions) are enabled.  Only some
+of the features from this TR are supported by @theglibc{}.
+@end defvr
+
+@comment (none)
+@comment ISO
+@defvr Macro __STDC_WANT_IEC_60559_BFP_EXT__
+If you define this macro, features from ISO/IEC TS 18661-1:2014
+(Floating-point extensions for C: Binary floating-point arithmetic)
+are enabled.  Only some of the features from this TS are supported by
+@theglibc{}.
+@end defvr
+
+@comment (none)
+@comment ISO
+@defvr Macro __STDC_WANT_IEC_60559_FUNCS_EXT__
+If you define this macro, features from ISO/IEC TS 18661-4:2015
+(Floating-point extensions for C: Supplementary functions) are
+enabled.  Only some of the features from this TS are supported by
+@theglibc{}.
+@end defvr
+
+@comment (none)
+@comment ISO
+@defvr Macro __STDC_WANT_IEC_60559_TYPES_EXT__
+If you define this macro, features from ISO/IEC TS 18661-3:2015
+(Floating-point extensions for C: Interchange and extended types) are
+enabled.  Only some of the features from this TS are supported by
+@theglibc{}.
+@end defvr
+
+@comment (none)
+@comment GNU
+@defvr Macro _GNU_SOURCE
+If you define this macro, everything is included: @w{ISO C89}, @w{ISO
+C99}, POSIX.1, POSIX.2, BSD, SVID, X/Open, LFS, and GNU extensions.  In
+the cases where POSIX.1 conflicts with BSD, the POSIX definitions take
+precedence.
+@end defvr
+
+@comment (none)
+@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 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
+feature test macros, or when options such as @option{-ansi} are used,
+enables those features even when the other options would otherwise
+cause them to be disabled.
+@end defvr
+
+@comment (none)
+@comment GNU
+@defvr Macro _REENTRANT
+@defvrx Macro _THREAD_SAFE
+These macros are obsolete.  They have the same effect as defining
+@code{_POSIX_C_SOURCE} with the value @code{199506L}.
+
+Some very old C libraries required one of these macros to be defined
+for basic functionality (e.g.@: @code{getchar}) to be thread-safe.
+@end defvr
+
+We recommend you use @code{_GNU_SOURCE} in new programs.  If you don't
+specify the @samp{-ansi} option to GCC, or other conformance options
+such as @option{-std=c99}, and don't define any of these macros
+explicitly, the effect is the same as defining @code{_DEFAULT_SOURCE}
+to 1.
+
+When you define a feature test macro to request a larger class of features,
+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} as well has no effect.