[swift-evolution] #if os(Windows) and MSVC/Cygwin Compatibility

[hitstergtd+swiftevo at gmail.com]

Dear Joe, Chris, Swift Community,

Here is my quick fire view.

What about adding a builtin directive called environ(...) for holding
OS-specific environmental differences. So in the case of Windows, we would
potentially have environ(msvc), environ(cygwin), environ(mingw),
environ(nano) etc. Thus, having environment as a separate builtin directive
allows Swift and its users to cleanly handle significant divergence on a
single operating system by way of combinations.

Similarly, an environ(posix) could also be added in the same spirit, in the
future, if required, if a POSIX specific environment is required.

The good thing about the above is that it can be intuitively used to build
combinations such as the following and has good readability:

#if os(Windows)
// ... common stuff to Windows in general
#if environ(Cygwin) and arch(x86_64)
// ... specific stuff of Cygwin on 64-bit arch
#elseif environ(msvc)
// ... stuff specific to MSVC generally
#endif

#else
// ... Non Windows stuff.
#endif

Chris, for your reference, the following is how D does it:
https://dlang.org/spec/version.html#predefined-versions. TL;DR - precursory
look indicates that they cobble everything into version() with predefined
identifiers.

I have specifically left out any comments on OS versions such as Vista,
Windows 7 etc., as I am not sure on how it should be handled, either
presently or as a proposal. As for Cygwin and MinGW, I am not sure if it
should be called cygwin32 and mingw32 with their 64-bit analogues,
respectively, but AFAICS, not suffixing with 32 and 64 seems much cleaner.

Thanks.

On Wed, 4 May 2016 at 05:41, Chris Lattner via swift-evolution <
swift-evolution at swift.org> wrote:

>
> > On May 3, 2016, at 9:39 PM, Joe Groff <jgroff at apple.com> wrote:
> >
> >
> >> On May 3, 2016, at 9:27 PM, Chris Lattner via swift-evolution <
> swift-evolution at swift.org> wrote:
> >>
> >> MSVC and MinGW (again, AFAIK) use the same C ABI, and thus could be
> treated as the same target.
> >>
> > Part of the problem is that MSVC and Mingw *don't* share a C ABI or
> runtime. Only 'stdcall' and COM stuff from the Win32 system APIs is
> portable between them at the binary level.
>
> I thought that MinGW worked with the system libc?
>
> -Chris
> _______________________________________________
> swift-evolution mailing list
> swift-evolution at swift.org
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>
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