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-rw-r--r--misc/sys/cdefs.h16
1 files changed, 16 insertions, 0 deletions
diff --git a/misc/sys/cdefs.h b/misc/sys/cdefs.h
index 74f9a49b05..06523bfe9c 100644
--- a/misc/sys/cdefs.h
+++ b/misc/sys/cdefs.h
@@ -464,4 +464,20 @@
# define __glibc_macro_warning(msg)
#endif
+/* Support for generic selection (ISO C11) is available in GCC since
+ version 4.9. Previous versions do not provide generic selection,
+ even though they might set __STDC_VERSION__ to 201112L, when in
+ -std=c11 mode. Thus, we must check for !defined __GNUC__ when
+ testing __STDC_VERSION__ for generic selection support.
+ On the other hand, Clang also defines __GNUC__, so a clang-specific
+ check is required to enable the use of generic selection. */
+#if __GNUC_PREREQ (4, 9) \
+ || __glibc_clang_has_extension (c_generic_selections) \
+ || (!defined __GNUC__ && defined __STDC_VERSION__ \
+ && __STDC_VERSION__ >= 201112L)
+# define __HAVE_GENERIC_SELECTION 1
+#else
+# define __HAVE_GENERIC_SELECTION 0
+#endif
+
#endif /* sys/cdefs.h */