Обсуждение: Using isatty() on WIN32 platform

Hi,

While following suggestions from Arthur Zakirov on a patch for
pg_basebackup I found that we are using isatty() in multiple places, but
we don't distinguish the WIN32 code which should use _isatty() as per [1].

It's true that isatty() is still supported by Visual C (else we'd fail
to compile) but per the documentation it could get removed at any moment.

Instead of just using #ifdef in my patch, I thought we could have a
cleaner patch which would cover all calls for isatty().

Attached is a patch for src/include/ports/win32.h

[1]: https://msdn.microsoft.com/en-us/library/ms235388.aspx

P.D.: Which would be the correct usage, per-standards: with or without
the _ prefix?

-- 
Martín Marqués                http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services

Martín Marqués <martin@2ndquadrant.com> writes:
> While following suggestions from Arthur Zakirov on a patch for
> pg_basebackup I found that we are using isatty() in multiple places, but
> we don't distinguish the WIN32 code which should use _isatty() as per [1].

I dunno, [1] looks like pure pedantry to me.  Unless they intend to stop
conforming to POSIX at all, they aren't going to be able to remove the
isatty() spelling.

Moreover, I don't think that isatty() is the only function name at issue.
I found this at:
https://docs.microsoft.com/en-us/cpp/c-runtime-library/compatibility
   The C++ standard reserves names that begin with an underscore in the   global namespace to the implementation.
Becausethe POSIX functions   are in the global namespace, but are not part of the standard C   runtime library, the
Microsoft-specificimplementations of these   functions have a leading underscore. For portability, the UCRT also
supportsthe default names, but the Visual C++ compiler issues a   deprecation warning when code that uses them is
compiled.Only the   default POSIX names are deprecated, not the functions. To suppress the   warning, define
_CRT_NONSTDC_NO_WARNINGSbefore including any headers   in code that uses the original POSIX names.
 

If you're seeing warnings from use of isatty(), I'd be inclined to think
about dealing with it by adding #define _CRT_NONSTDC_NO_WARNINGS,
rather than trying to individually #define every affected function.

> Attached is a patch for src/include/ports/win32.h

FWIW, if we do adopt that, I think it should now go into win32_port.h.
In either case, though, seems like it might be problematic to have
such a #define before including whatever file Microsoft's definition
lives in.
        regards, tom lane