MantisBT - CMake
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IDProjectCategoryView StatusDate SubmittedLast Update
0016084CMakeCMakepublic2016-04-27 06:412016-06-10 14:31
Reporterranjak 
Assigned ToKitware Robot 
PrioritynormalSeveritymajorReproducibilityalways
StatusclosedResolutionmoved 
PlatformiPhoneOSiOSOS Versionany
Product VersionCMake 3.5.2 
Target VersionFixed in Version 
Summary0016084: try_compile incorrect behavior for iOS universal build (device + simulator) with CMAKE_IOS_INSTALL_COMBINED
DescriptionWhen configuring an iOS Xcode project using CMAKE_IOS_INSTALL_COMBINED (introduced in CMake 3.5) to produce universal binaries that contain code for both iPhone (ARM) and simulator (x86) code, I would like try_compile to compile for both the device and the simulator. However, currently, try_compile only compiles for the device.

This causes projects that rely on try_compile to be possibly misconfigured for the simulator build (which can obviously lead to build failures and/or incorrect/non-existent values for architecture-dependent parameters set at configuration time).

This problem also arises without CMAKE_IOS_INSTALL_COMBINED, if you want to use Xcode to build for both device(s) and simulator(s) without re-running CMake every time you switch between the two.

Try_compile should instead call xcodebuild twice, one time with -sdk iphoneos and the other with -sdk iphonesimulator.
Steps To ReproduceConfigure a project with IOS_INSTALL_COMBINED set to TRUE, and use try_compile in this project.
Additional Information
TagsNo tags attached.
Relationships
Attached Files? TryCompileIOS.cmake (6,108) 2016-04-29 05:47
https://public.kitware.com/Bug/file/5685/TryCompileIOS.cmake
Issue History
Date ModifiedUsernameFieldChange
2016-04-27 06:41ranjakNew Issue
2016-04-27 16:55Gregor JasnyNote Added: 0040943
2016-04-27 17:06Brad KingNote Added: 0040944
2016-04-28 04:16ranjakNote Added: 0040945
2016-04-29 05:47ranjakFile Added: TryCompileIOS.cmake
2016-04-29 05:54ranjakNote Added: 0040946
2016-05-04 08:02Ruslan BaratovNote Added: 0041022
2016-05-09 08:10ranjakNote Added: 0041036
2016-05-11 03:20Gregor JasnyNote Added: 0041045
2016-06-10 14:29Kitware RobotNote Added: 0042990
2016-06-10 14:29Kitware RobotStatusnew => resolved
2016-06-10 14:29Kitware RobotResolutionopen => moved
2016-06-10 14:29Kitware RobotAssigned To => Kitware Robot
2016-06-10 14:31Kitware RobotStatusresolved => closed

Notes
(0040943)
Gregor Jasny   
2016-04-27 16:55   
More of less the same problem arises when building fat binaries. There for example check_symbol_exists does not work reliable for symbols like __i386__ or __x86_64__.

The only way I see to handle those problems is to provide some special try_compile command where one can select SDK and ARCH.
(0040944)
Brad King   
2016-04-27 17:06   
There is an undocumented CMAKE_TRY_COMPILE_OSX_ARCHITECTURES variable that tells try_compile what CMAKE_OSX_ARCHITECTURES to pass to its test project. One can set this to choose the architecture to use for try_compile checks. There is currently no such option for SDK selection.

This all comes from a fundamental design limitation of CMake in that it is really only meant to target one architecture/platform at a time. Universal binary support works only because the native tools (compiler, linker, etc.) support multiple architectures in single files with single command lines. The only safe way to get per-architecture information in the case of universal binaries is to do preprocessor checks and not try_compile.
(0040945)
ranjak   
2016-04-28 04:16   
I have started working on a wrapper for try_compile that issues two calls to the actual try_compile with setting CMAKE_OSX_SYSROOT to iphoneos and iphonesimulator. I don't know if it's a very clean approach, but I'll share it if I manage to get it to work.
(0040946)
ranjak   
2016-04-29 05:54   
I've uploaded my wrapper. It's a try_compile "overload" that issues two try_compile calls (one for device and another for simulator) and should handle every use case. That fixes the problem for me, I hope it can for others as well.
(0041022)
Ruslan Baratov   
2016-05-04 08:02   
Just for the record behaviour not related to CMAKE_IOS_INSTALL_COMBINED at all. Either *_COMBINED=TRUE or *_COMBINED=FALSE you can choose sdk by '-sdk iphoneos'/'-sdk iphonesimulator'. Actually already said: "This problem also arises without CMAKE_IOS_INSTALL_COMBINED" so I'm just clarifying this fact.
(0041036)
ranjak   
2016-05-09 08:10   
You are correct, sorry for not being clearer about that.
(0041045)
Gregor Jasny   
2016-05-11 03:20   
Just selecting any ios SDK will break with xcode containing multiple ios sdks. Please have a look at the CMakeIOSInstallCombined.cmake/_ios_install_combined_detect_sdks.

What about CMAKE_SYSTEM_FRAMEWORK_PATH (set in Platform/Darwin.cmake). It contains paths relative to the selected SYSROOT.
(0042990)
Kitware Robot   
2016-06-10 14:29   
Resolving issue as `moved`.

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