[Bug libstdc++/54005] Use __atomic_always_lock_free in libstdc++ is_lock_free instead of __atomic_is_lock_free

[hp at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54005

--- Comment #10 from Hans-Peter Nilsson <hp at gcc dot gnu.org> 2012-08-16 22:23:32 UTC ---
(In reply to comment #9)
> Actually, that's the way __atomic_is_lock_free()  has always been implemented
> (even in 4.7).  

There's miscommunication here.  The point of this PR is, the code for
is_lock_free must be per-type, agreed?  It used __atomic_is_lock_free() with a
non-null pointer, hence it was per-object, a bug, agreed?  (Mr. Crowl asserts
on IRC what can be understood from the referenced URL; that the function
started as per-object but semantics later changed to be per-type.)

The committed changes were to make it use __atomic_always_lock_free() so
per-type.
IIUC you mean it should instead use __atomic_is_lock_free() with the object
pointer changed to NULL.  That might be: whether that is preferred to r190216 I
can't say, in particular with a pending rewrite.