[RFC PATCH] Deprecate _REENTRANT and _THREAD_SAFE.

[Joseph Myers]

On Tue, 6 Dec 2016, Zack Weinberg wrote:

> -D_REENTRANT all by itself also won't, because _DEFAULT_SOURCE implies
> _POSIX_C_SOURCE > 199506.  I could be persuaded to make that final
> case also warn.

Given that GCC specs include %{pthread:-D_REENTRANT} (in many 
architecture-specific specs), and that -pthread is (approximately) an 
OS-independent way of saying to add whatever compiler and linker options 
are needed for threads, I'd discourage warning in that case.

-- 
Joseph S. Myers
joseph@codesourcery.com