[PATCH, v3] std::thread ctor passes function pointer by reference to _M_make_shared_data.

[Chris Fairles <chris dot fairles at gmail dot com>]

I noticed that there were no tests for std::thread's first ctor taking
just a _Callable so I tried the following:

void f() {}

int main() {
  std::thread t(f);
  t.join();
}

but it failed. Segmentation fault in _M_run().

Turns out, the std::thread(_Callable) ctor is called with _Callable =
void(*)() (i.e. pointer by value), however when passed to
_M_make_shared_data(_Callable&&), _Callable there becomes void(*&)()
so _Impl ends up holding a reference to the local temporary pointer
from the ctor. This blows up when _M_run tries to execute _M_func().

By explicitly specifying the template argument to the
_M_make_shared_data call, pointers are passed by value and
rvalue/lvalue-refs are still forwarded correctly.

Tested x86_64, ok for trunk?

Chris

Attachment: thread_patch.txt
Description: Text document