Computation of CMAKE_OSX_SYSROOT

[CMake mailing list]

Hi,

The docs here:

        https://cmake.org/cmake/help/v3.12/variable/CMAKE_OSX_SYSROOT.html

state that CMAKE_OSX_SYSROOT is computed from CMAKE_OSX_DEPLOYMENT_TARGET if not explicitly set. Can anyone comment on how this works, because in my setup it seems to be failing. This showed up as -isysroot not being passed to the compiler, which then causes weird compile failures building on High Sierra with Xcode 10 and the 10.14 SDK.

If explicitly set SDKROOT or CMAKE_OSX_SYSROOT to the 10.14 SDK, everything compiles fine. (Without passing -isysroot, some header is /usr/include are used, and apparently these don’t work for building the 10.14 frameworks)

Deployment target is set to:

        set(CMAKE_OSX_DEPLOYMENT_TARGET "10.7”)

Note that I do this *after* calling project() because contrary to its docs, I find that when I call it before project(), it has no effect. (eg, passing -mmacosx-version-min=10.7 to the compiler).

Full CMakeList.txt is here:

        https://sourceforge.net/p/flightgear/flightgear/ci/next/tree/CMakeLists.txt

Any comments on what is going on, would be appreciated.

Kind regards,
James


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[Craig Scott-3]

On Mon, Oct 1, 2018 at 10:53 PM James Turner via CMake <[hidden email]> wrote:

Hi,

The docs here:

        https://cmake.org/cmake/help/v3.12/variable/CMAKE_OSX_SYSROOT.html

state that CMAKE_OSX_SYSROOT is computed from CMAKE_OSX_DEPLOYMENT_TARGET if not explicitly set. Can anyone comment on how this works, because in my setup it seems to be failing. This showed up as -isysroot not being passed to the compiler, which then causes weird compile failures building on High Sierra with Xcode 10 and the 10.14 SDK.

If explicitly set SDKROOT or CMAKE_OSX_SYSROOT to the 10.14 SDK, everything compiles fine. (Without passing -isysroot, some header is /usr/include are used, and apparently these don’t work for building the 10.14 frameworks)

Deployment target is set to:

        set(CMAKE_OSX_DEPLOYMENT_TARGET "10.7”)

Note that I do this *after* calling project() because contrary to its docs, I find that when I call it before project(), it has no effect. (eg, passing -mmacosx-version-min=10.7 to the compiler).

Full CMakeList.txt is here:

        https://sourceforge.net/p/flightgear/flightgear/ci/next/tree/CMakeLists.txt

Any comments on what is going on, would be appreciated.

You need to set CMAKE_OSX_DEPLOYMENT_TARGET as a cache variable before calling the project() command. If you set it as a normal (i.e. non-cache) variable, the compiler detection logic triggered by the project() call creates a cache variable if one doesn't exist, which would discard the non-cache variable. It's a bit unfortunate, but that's what happens when you set a cache variable for the first time. The relevant code related to your observations is in Modules/Platform/Darwin-Initialize.cmake.

 

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[CMake mailing list]

On 1 Oct 2018, at 14:25, Craig Scott <[hidden email]> wrote:

You need to set CMAKE_OSX_DEPLOYMENT_TARGET as a cache variable before calling the project() command. If you set it as a normal (i.e. non-cache) variable, the compiler detection logic triggered by the project() call creates a cache variable if one doesn't exist, which would discard the non-cache variable. It's a bit unfortunate, but that's what happens when you set a cache variable for the first time. The relevant code related to your observations is in Modules/Platform/Darwin-Initialize.cmake.

Thanks, that was indeed the solution.

I’d suggest the docs page for CMAKE_OSX_DEPLOYMENT_TARGET could use some wording to point this out, but I don’t know who . how a docs change gets done.

James

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[Robert Maynard]

Documentation changes can be done through the CMake project hosted on gitlab. You would want to modify the file: https://gitlab.kitware.com/cmake/cmake/blob/master/Help/variable/CMAKE_OSX_DEPLOYMENT_TARGET.rst

On Mon, Oct 1, 2018 at 11:13 AM James Turner via CMake <[hidden email]> wrote:

On 1 Oct 2018, at 14:25, Craig Scott <[hidden email]> wrote:

You need to set CMAKE_OSX_DEPLOYMENT_TARGET as a cache variable before calling the project() command. If you set it as a normal (i.e. non-cache) variable, the compiler detection logic triggered by the project() call creates a cache variable if one doesn't exist, which would discard the non-cache variable. It's a bit unfortunate, but that's what happens when you set a cache variable for the first time. The relevant code related to your observations is in Modules/Platform/Darwin-Initialize.cmake.

Thanks, that was indeed the solution.

I’d suggest the docs page for CMAKE_OSX_DEPLOYMENT_TARGET could use some wording to point this out, but I don’t know who . how a docs change gets done.

James

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