Re: Avoid gnulib redefinitions - MDA

[Bruno Haible]

Gavin Smith wrote:
> so it sounds like we are better off using #undef before
> including the Perl headers to avoid depending on undocumented
> functionalities.  Thanks.

Using #undef means to decline all corrections done by Gnulib.
These are documented in the manual. For example, for 'fdopen' [1]
we have documented

  Portability problems fixed by Gnulib:

    This function crashes when invoked with invalid arguments on
    some platforms: MSVC 14.
    On Windows platforms (excluding Cygwin), this function does not
    set errno upon failure. 

So, if you always use fdopen() with correct arguments and if, in
case of a NULL return of this function, the code does not look at
errno, then the '#undef fdopen' is OK. (On those platforms where
the Microsoft deprecated alias still work, or when it is overridden
by a redirect to some perl internal function.)

Bruno

[1] https://www.gnu.org/software/gnulib/manual/html_node/fdopen.html