Add feature test macro _ISOC2Y_SOURCE

This patch starts preparation for C2Y support in glibc headers by
adding a feature test macro _ISOC2Y_SOURCE and corresponding
__GLIBC_USE (ISOC2Y). (I mostly copied the work of Joseph Myers
for C2X). As with other such macros, C2Y features are also
enabled by compiling for a standard newer than C23, or by using
_GNU_SOURCE.

This patch does not itself enable anything new in the headers for C2Y;
that is to be done in followup patches. (For example an implementation
of WG14 N3349.)

Once C2Y becomes an actual standard we'll presumably move to using the
actual year in the feature test macro and __GLIBC_USE, with some
period when both macro spellings are accepted, as was done with
_ISOC2X_SOURCE.

Tested for x86_64.

Signed-off-by: Lenard Mollenkopf <glibc@lenardmollenkopf.de>

diff --git a/NEWS b/NEWS
index 2fe0396b2d18517dda6f35b5b9f0716cb077b35c..1d048de0e69a97abd10b0bf143297f996ff5df85 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -31,6 +31,13 @@ Major new features:
 * The iconv program now supports converting files in place.  The program
   automatically uses a temporary file if required.
 
+* The GNU C Library now supports a feature test macro _ISOC2Y_SOURCE to
+  enable features from the draft ISO C2Y standard.  Only some features from
+  this draft standard are supported by the GNU C Library, and as the draft
+  is under active development, the set of features enabled by this macro is
+  liable to change.  Features from C2Y are also enabled by _GNU_SOURCE, or
+  by compiling with "gcc -std=gnu2y".
+
 Deprecated and removed features, and other changes affecting compatibility:
 
 * The big-endian ARC port (arceb-linux-gnu) has been removed.

diff --git a/include/features.h b/include/features.h
index 093de6f44cd168fe1e8727851af1baf666ae57fc..0a8aa7c4f9b8c6e27215ec67829f6306a7e5dc06 100644 (file)
--- a/include/features.h
+++ b/include/features.h
@@ -26,6 +26,7 @@
    _ISOC11_SOURCE      Extensions to ISO C99 from ISO C11.
    _ISOC23_SOURCE      Extensions to ISO C99 from ISO C23.
    _ISOC2X_SOURCE      Old name for _ISOC23_SOURCE.
+   _ISOC2Y_SOURCE      Extensions to ISO C23 from ISO C2Y.
    __STDC_WANT_LIB_EXT2__
                        Extensions to ISO C99 from TR 27431-2:2010.
    __STDC_WANT_IEC_60559_BFP_EXT__
@@ -150,6 +151,7 @@
 #undef __USE_FORTIFY_LEVEL
 #undef __KERNEL_STRICT_NAMES
 #undef __GLIBC_USE_ISOC23
+#undef __GLIBC_USE_ISOC2Y
 #undef __GLIBC_USE_DEPRECATED_GETS
 #undef __GLIBC_USE_DEPRECATED_SCANF
 #undef __GLIBC_USE_C23_STRTOL
@@ -216,6 +218,8 @@
 # define _ISOC11_SOURCE        1
 # undef  _ISOC23_SOURCE
 # define _ISOC23_SOURCE        1
+# undef  _ISOC2Y_SOURCE
+# define _ISOC2Y_SOURCE        1
 # undef  _POSIX_SOURCE
 # define _POSIX_SOURCE 1
 # undef  _POSIX_C_SOURCE
@@ -239,15 +243,23 @@
 #if (defined _DEFAULT_SOURCE                                   \
      || (!defined __STRICT_ANSI__                              \
         && !defined _ISOC99_SOURCE && !defined _ISOC11_SOURCE  \
-        && !defined _ISOC23_SOURCE                             \
+        && !defined _ISOC23_SOURCE && !defined _ISOC2Y_SOURCE  \
         && !defined _POSIX_SOURCE && !defined _POSIX_C_SOURCE  \
         && !defined _XOPEN_SOURCE))
 # undef  _DEFAULT_SOURCE
 # define _DEFAULT_SOURCE       1
 #endif
 
+/* This is to enable the ISO C2Y extension.  */
+#if (defined _ISOC2Y_SOURCE \
+     || (defined __STDC_VERSION__ && __STDC_VERSION__ > 202311L))
+# define __GLIBC_USE_ISOC2Y    1
+#else
+# define __GLIBC_USE_ISOC2Y    0
+#endif
+
 /* This is to enable the ISO C23 extension.  */
-#if (defined _ISOC23_SOURCE \
+#if (defined _ISOC23_SOURCE || defined _ISOC2Y_SOURCE \
      || (defined __STDC_VERSION__ && __STDC_VERSION__ > 201710L))
 # define __GLIBC_USE_ISOC23    1
 #else
@@ -255,21 +267,22 @@
 #endif
 
 /* This is to enable the ISO C11 extension.  */
-#if (defined _ISOC11_SOURCE || defined _ISOC23_SOURCE \
+#if (defined _ISOC11_SOURCE || defined _ISOC23_SOURCE  \
+     || defined _ISOC2Y_SOURCE                         \
      || (defined __STDC_VERSION__ && __STDC_VERSION__ >= 201112L))
 # define __USE_ISOC11  1
 #endif
 
 /* This is to enable the ISO C99 extension.  */
 #if (defined _ISOC99_SOURCE || defined _ISOC11_SOURCE                  \
-     || defined _ISOC23_SOURCE                                         \
+     || defined _ISOC23_SOURCE || defined _ISOC2Y_SOURCE               \
      || (defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L))
 # define __USE_ISOC99  1
 #endif
 
 /* This is to enable the ISO C90 Amendment 1:1995 extension.  */
 #if (defined _ISOC99_SOURCE || defined _ISOC11_SOURCE                  \
-     || defined _ISOC23_SOURCE                                         \
+     || defined _ISOC23_SOURCE || defined _ISOC2Y_SOURCE               \
      || (defined __STDC_VERSION__ && __STDC_VERSION__ >= 199409L))
 # define __USE_ISOC95  1
 #endif

diff --git a/manual/creature.texi b/manual/creature.texi
index be0a5ac7e6814b29777aa8af2fd9269682e4c95e..09e1c9670f5c31ef9faa81185387910d2e920115 100644 (file)
--- a/manual/creature.texi
+++ b/manual/creature.texi
@@ -233,6 +233,13 @@ Only some features from this draft standard are supported by
 @theglibc{}.  The older name @code{_ISOC2X_SOURCE} is also supported.
 @end defvr
 
+@defvr Macro _ISOC2Y_SOURCE
+@standards{C2Y, (none)}
+If this macro is defined, ISO C2Y extensions to ISO C23 are included.
+Only some features from this draft standard are supported by
+@theglibc{}.
+@end defvr
+
 @defvr Macro __STDC_WANT_LIB_EXT2__
 @standards{ISO, (none)}
 If you define this macro to the value @code{1}, features from ISO/IEC