From e915ab84fd0c02d37504f3eb1e1f3be93ea6dc37 Mon Sep 17 00:00:00 2001 From: Michael Jeanson Date: Thu, 9 Sep 2021 12:11:16 -0400 Subject: [PATCH] fix: don't use C++ thread_local on MacOs Recent versions of Apple's clang++ do support 'thread_local' but the implementation generates additional helper symbols. This is a problem when accessing an extern TLS variable in a C++ compile unit that is provided by a C library that doesn't have those extra symbols. Fallback to using '__thread' on MacOs. Change-Id: I87cb5b3c9293f7bf66f7115f453b546dd793a449 Signed-off-by: Michael Jeanson Signed-off-by: Mathieu Desnoyers [Retrieved from: https://github.com/urcu/userspace-rcu/commit/e915ab84fd0c02d37504f3eb1e1f3be93ea6dc37] Signed-off-by: Fabrice Fontaine --- include/urcu/tls-compat.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/include/urcu/tls-compat.h b/include/urcu/tls-compat.h index 24ef1b9a..25cf375a 100644 --- a/include/urcu/tls-compat.h +++ b/include/urcu/tls-compat.h @@ -34,7 +34,12 @@ extern "C" { #ifdef CONFIG_RCU_TLS -#if defined (__cplusplus) && (__cplusplus >= 201103L) +/* + * Don't use C++ 'thread_local' on MacOs, the implementation is incompatible + * with C and will result in a link error when accessing an extern variable + * provided by the C library from C++ code. + */ +#if defined (__cplusplus) && (__cplusplus >= 201103L) && !defined(__APPLE__) # define URCU_TLS_STORAGE_CLASS thread_local #elif defined (__STDC_VERSION__) && (__STDC_VERSION__ >= 201112L) # define URCU_TLS_STORAGE_CLASS _Thread_local