[gcc(refs/users/iains/heads/d-for-darwin)] D, Darwin : Do not allow moving fibres between pthreads.

[Iain D Sandoe <iains@gcc.gnu.org>]

https://gcc.gnu.org/g:f590fa6dc8f96c4d54eb0d7953e602744a141946

commit f590fa6dc8f96c4d54eb0d7953e602744a141946
Author: Iain Sandoe <iain@sandoe.co.uk>
Date:   Thu Dec 10 14:06:07 2020 +0000

    D, Darwin : Do not allow moving fibres between pthreads.
    
    Emulated TLS targets (and, indeed some native TLS ones too)
    on GCC should not allow fibres to be moved between threads
    since the ME keeps pointers to TLS vars cached as an internal
    detail and cannot see that a function call could return on a
    different thread.

Diff:
---
 libphobos/libdruntime/core/thread.d | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/libphobos/libdruntime/core/thread.d b/libphobos/libdruntime/core/thread.d
index 5381cda103b..843125831aa 100644
--- a/libphobos/libdruntime/core/thread.d
+++ b/libphobos/libdruntime/core/thread.d
@@ -5311,6 +5311,11 @@ unittest
 // Multiple threads running shared fibers
 version (PPC)   version = UnsafeFiberMigration;
 version (PPC64) version = UnsafeFiberMigration;
+version (Darwin)
+{
+  version (X86)   version = UnsafeFiberMigration;
+  version (X86_64) version = UnsafeFiberMigration;
+}
 
 version (UnsafeFiberMigration)
 {