[PATCH 3/5] Clean up conditionals for declaration of gets().

[Zack Weinberg]

On 11/28/2016 11:00 AM, Zack Weinberg wrote:
> gets() has the dubious honor of being the only C89 library feature
> that has been completely removed from the current C and C++ standards.
> glibc follows suit by not declaring it in _GNU_SOURCE mode either, but
> it remains present in older compatibility modes.  Internally, two test
> cases need to see stdio.h make the declaration, but all our internal
> code is of course compiled under _GNU_SOURCE.  This is currently
> kludged by duplicating the gets declaration, fortify wrapper and all,
> in include/stdio.h.  Also, the conditional in the public headers for
> deciding when to declare gets is complicated, contains a non-obvious
> dependence on short-circuit evaluation, and is repeated in two places.
> 
> This patch adds a new macro to features.h that encapsulates the
> complicated rule for when to declare gets.  stdio.h and bits/stdio2.h
> can simply test __GLIBC_USE (DEPRECATED_GETS).  Then, instead of
> having a duplicate gets declaration in include/stdio.h,
> debug/tst-chk1.c and stdio-common/tst-gets.c force that flag on.

Ping.