[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:73a03aaca5be37a6de554603dc7a046b6614fda2

commit 73a03aaca5be37a6de554603dc7a046b6614fda2
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)
 {