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Re: SIZEOF_LONG undefined when cross-compiling for iOS

From: Jonas Vautherin via curl-library <>
Date: Wed, 22 May 2019 12:17:36 +0200

Thanks a lot for the answer, that was helpful!

It turns out that the toolchain is actually setting multiple OSX
architectures, and CMake is behaving as per the doc [1], i.e.:

> The variable “${VARIABLE}” may be “0” when CMAKE_OSX_ARCHITECTURES has
multiple architectures for building OS X universal binaries. This indicates
that the type size varies across architectures.

So ${SIZEOF_LONG} gets set to "0", and therefore `#cmakedefine SIZEOF_LONG
${SIZEOF_LONG}` becomes "/* #undef SIZEOF_LONG */" [3].

One solution for me would be to build curl separately for 32-bits and
64-bits, and then merge them using the `lipo` tool. But I am thinking that
maybe, there could be a way to add support for multiple
CMAKE_OSX_ARCHITECTURES in curl: when ${SIZEOF_LONG} is "0", CMake also
defines other values [1], including ${SIZEOF_LONG_CODE}, which gives, e.g.
for CMAKE_OSX_ARCHITECTURES=armv7;armv7s;arm64:

    #if defined(__ARM_ARCH_7A__)
    # define SIZEOF_LONG 4
    #elif defined(__ARM_ARCH_7S__)
    # define SIZEOF_LONG 4
    #elif defined(__aarch64__)
    # define SIZEOF_LONG 8
    # error SIZEOF_LONG unknown

I think that if that could replace `#define SIZEOF_LONG <...>` in the
resulting `curl_config.h`, then that would be fine.

What do you think? And does somebody see a way to deal with this in
`curl_config.h.cmake`? I am not sure if it is possible to add some logic
there =/.


On Fri, May 17, 2019 at 10:21 AM Daniel Stenberg <> wrote:

> On Fri, 17 May 2019, Jonas Vautherin via curl-library wrote:
> > I have been trying to cross-compile curl for iOS, using leetal's
> toolchain
> > [1] (and another, similar one that has the same issue).
> >
> > When building for the "Xcode" cmake generator (cmake -G Xcode <...>),
> curl
> > build successfully. But when building for the "Unix Makefiles"
> generator, I
> > get an error saying that SIZEOF_LONG is undefined.
> Seems lame. The curl cmake file has always checked that size since the
> first
> day we had one. Although I don't know how good cmake is at doing that for
> cross-compiles...
> > I see that SIZEOF_LONG is defined in curl_config.h.cmake [2], but I don't
> > really get where it comes from.
> In cmake builds, here:
> (and obviouly similarly by configure, but that's not the topic here)
> > Should I set it somewhere manually?
> You should at least set it somewhere. Exactly what the best way is for you
> to
> set it, I leave to you.
> > And if yes, it is always right to say that it should be "8" on 64-bits
> > archs, and "4" on 32-bits archs (as described here [3])?
> All 64 bit iOS targets will have it at 8 as far as I know, yes.
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Received on 2019-05-22