From 2a0d6c32ac5ea8ca2fcfa25816024c59de5fbb19 Mon Sep 17 00:00:00 2001
From: Maria Matejka <mq@ucw.cz>
Date: Wed, 22 Apr 2020 17:14:26 +0200
Subject: [PATCH] Fix thread local storage support in GCC older than 4.9.

Let's hope this will be history soon.
---
 aclocal.m4        | 11 ++++++++++-
 configure.ac      |  4 +++-
 filter/filter.c   |  4 ++--
 proto/bgp/attrs.c |  2 +-
 4 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/aclocal.m4 b/aclocal.m4
index 1613d680..00453e5f 100644
--- a/aclocal.m4
+++ b/aclocal.m4
@@ -15,8 +15,17 @@ AC_DEFUN([BIRD_CHECK_THREAD_LOCAL],
       )
     ],
     [bird_cv_thread_local=yes],
+    AC_COMPILE_IFELSE([
+      AC_LANG_PROGRAM(
+	[
+	  static __thread int x = 42;
+	],
+	[]
+      )
+    ],
+    [bird_cv_thread_local=__thread],
     [bird_cv_thread_local=no]
-    )
+    ))
   )
 ])
 
diff --git a/configure.ac b/configure.ac
index 7ef31fb4..31db7bd1 100644
--- a/configure.ac
+++ b/configure.ac
@@ -120,7 +120,9 @@ fi
 
 BIRD_CHECK_THREAD_LOCAL
 if test "$bird_cv_thread_local" = no ; then
-  AC_MSG_ERROR([Thread-local storage not available]) 
+  AC_MSG_ERROR([Thread-local storage not available])
+elif test "$bird_cv_thread_local" != yes ; then
+  CFLAGS="$CFLAGS -D_Thread_local=$bird_cv_thread_local"
 fi
 
 BIRD_CHECK_PTHREADS
diff --git a/filter/filter.c b/filter/filter.c
index ca2bfc14..ec727740 100644
--- a/filter/filter.c
+++ b/filter/filter.c
@@ -91,8 +91,8 @@ struct filter_state {
   struct buffer buf;
 };
 
-_Thread_local static struct filter_state filter_state;
-_Thread_local static struct filter_stack filter_stack;
+static _Thread_local struct filter_state filter_state;
+static _Thread_local struct filter_stack filter_stack;
 
 void (*bt_assert_hook)(int result, const struct f_line_item *assert);
 
diff --git a/proto/bgp/attrs.c b/proto/bgp/attrs.c
index 439de507..a7aa2805 100644
--- a/proto/bgp/attrs.c
+++ b/proto/bgp/attrs.c
@@ -2248,7 +2248,7 @@ bgp_rte_modify_stale(struct rte_storage *r, struct linpool *pool)
   if (ad && int_set_contains(ad, BGP_COMM_LLGR_STALE))
     return r->attrs;
 
-  _Thread_local static struct {
+  static _Thread_local struct {
     rta a;
     u32 labels[MPLS_MAX_LABEL_STACK];
   } aloc;