[PATCH 1/4] favor _Thread_local under C11

[Eric Wong <mwrap-perl@80x24.org>]

__thread is a gcc-ism which clang supports, but _Thread_local is
part of C11 and more likely to be supported by future compilers.
---
 Mwrap.xs | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/Mwrap.xs b/Mwrap.xs
index bb51930..e888a1c 100644
--- a/Mwrap.xs
+++ b/Mwrap.xs
@@ -26,6 +26,14 @@
 #include <urcu/rculist.h>
 #include "jhash.h"
 
+#if __STDC_VERSION__ >= 201112
+#	define MWRAP_TSD _Thread_local
+#elif defined(__GNUC__)
+#	define MWRAP_TSD __thread
+#else
+#	error _Thread_local nor __thread supported
+#endif
+
 /*
  * Perl doesn't have a GC the same way (C) Ruby does, so no GC count.
  * Instead, the relative age of an object is the number of total bytes
@@ -62,7 +70,7 @@ static int resolving_malloc;
 	} \
 } while (0)
 
-static __thread size_t locating;
+static MWRAP_TSD size_t locating;
 #ifndef PERL_IMPLICIT_CONTEXT
 static size_t *root_locating; /* determines if PL_curcop is our thread */
 #endif
@@ -237,7 +245,7 @@ struct alloc_hdr {
 	size_t size;
 };
 
-static __thread char kbuf[
+static MWRAP_TSD char kbuf[
 	PATH_MAX + INT2STR_MAX + sizeof(struct alloc_hdr) + 2
 ];