[PATCH] libstdc++/77795 Only declare ::gets for C++98 and C++11

[Jonathan Wakely]

On 30/09/16 12:08 +0100, Jonathan Wakely wrote:
>As noted in Bugzilla (and pointed out in LLVM's bugzilla by Richard
>Smith) we check for a ::gets() declaration with the default
>-std=gnu++14 mode, so for glibc we don't find it, and then we declare
>it ourselves in <cstdio> even though it's not meant to exist in C++14.
>
>This adjusts the check to use C++11, and doesn't declare it for C++14
>and later. I think this fixes the regression, without introducing any
>new problems.
>
>Please take a look and double-check I haven't missed something.
>
>	PR libstdc++/77795
>	* acinclude.m4 (GLIBCXX_CHECK_STDIO_PROTO): Use -std=gnu++11 to check
>	for gets.
>	* config.h.in: Regenerate.
>	* configure: Regenerate.
>	* include/c_global/cstdio [!_GLIBCXX_HAVE_GETS] (gets): Only declare
>	for C++98 and C++11.
>	* include/c_std/cstdio [!_GLIBCXX_HAVE_GETS] (gets): Likewise.
>	* testsuite/27_io/headers/cstdio/functions_neg.cc: New test.


Committed to trunk and gcc-6-branch.

>I think we could also get rid of the hack in
>config/os/gnu-linux/os_defines.h because it doesn't do anything:
>
>// Provide a declaration for the possibly deprecated gets function, as
>// glibc 2.15 and later does not declare gets for ISO C11 when
>// __GNU_SOURCE is defined.
>#if __GLIBC_PREREQ(2,15) && defined(_GNU_SOURCE)
># undef _GLIBCXX_HAVE_GETS
>#endif

Any reason to keep this part?