1*4882a593SmuzhiyunFrom e915ab84fd0c02d37504f3eb1e1f3be93ea6dc37 Mon Sep 17 00:00:00 2001 2*4882a593SmuzhiyunFrom: Michael Jeanson <mjeanson@efficios.com> 3*4882a593SmuzhiyunDate: Thu, 9 Sep 2021 12:11:16 -0400 4*4882a593SmuzhiyunSubject: [PATCH] fix: don't use C++ thread_local on MacOs 5*4882a593Smuzhiyun 6*4882a593SmuzhiyunRecent versions of Apple's clang++ do support 'thread_local' but the 7*4882a593Smuzhiyunimplementation generates additional helper symbols. This is a problem 8*4882a593Smuzhiyunwhen accessing an extern TLS variable in a C++ compile unit that is 9*4882a593Smuzhiyunprovided by a C library that doesn't have those extra symbols. 10*4882a593Smuzhiyun 11*4882a593SmuzhiyunFallback to using '__thread' on MacOs. 12*4882a593Smuzhiyun 13*4882a593SmuzhiyunChange-Id: I87cb5b3c9293f7bf66f7115f453b546dd793a449 14*4882a593SmuzhiyunSigned-off-by: Michael Jeanson <mjeanson@efficios.com> 15*4882a593SmuzhiyunSigned-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> 16*4882a593Smuzhiyun 17*4882a593Smuzhiyun[Retrieved from: 18*4882a593Smuzhiyunhttps://github.com/urcu/userspace-rcu/commit/e915ab84fd0c02d37504f3eb1e1f3be93ea6dc37] 19*4882a593SmuzhiyunSigned-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com> 20*4882a593Smuzhiyun--- 21*4882a593Smuzhiyun include/urcu/tls-compat.h | 7 ++++++- 22*4882a593Smuzhiyun 1 file changed, 6 insertions(+), 1 deletion(-) 23*4882a593Smuzhiyun 24*4882a593Smuzhiyundiff --git a/include/urcu/tls-compat.h b/include/urcu/tls-compat.h 25*4882a593Smuzhiyunindex 24ef1b9a..25cf375a 100644 26*4882a593Smuzhiyun--- a/include/urcu/tls-compat.h 27*4882a593Smuzhiyun+++ b/include/urcu/tls-compat.h 28*4882a593Smuzhiyun@@ -34,7 +34,12 @@ extern "C" { 29*4882a593Smuzhiyun 30*4882a593Smuzhiyun #ifdef CONFIG_RCU_TLS 31*4882a593Smuzhiyun 32*4882a593Smuzhiyun-#if defined (__cplusplus) && (__cplusplus >= 201103L) 33*4882a593Smuzhiyun+/* 34*4882a593Smuzhiyun+ * Don't use C++ 'thread_local' on MacOs, the implementation is incompatible 35*4882a593Smuzhiyun+ * with C and will result in a link error when accessing an extern variable 36*4882a593Smuzhiyun+ * provided by the C library from C++ code. 37*4882a593Smuzhiyun+ */ 38*4882a593Smuzhiyun+#if defined (__cplusplus) && (__cplusplus >= 201103L) && !defined(__APPLE__) 39*4882a593Smuzhiyun # define URCU_TLS_STORAGE_CLASS thread_local 40*4882a593Smuzhiyun #elif defined (__STDC_VERSION__) && (__STDC_VERSION__ >= 201112L) 41*4882a593Smuzhiyun # define URCU_TLS_STORAGE_CLASS _Thread_local 42