Problems with fortran an Xcode generator

Usage
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1

I don’t know if this a bug, principally not possible or if I’m doing something wrong.

I have a C,C++,Fortran cmake project which builds nicely with Apple clang and gfortran from brew on macOS.

Usually I use Eclipse with external make project but now I want to try Xcode.

I need to give the compilers and run
cmake -G Xcode -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang -DCMAKE_Fortran_COMPILER=gfortran ..
and get

-- Using CMake 3.26.3 with generator Xcode
-- The C compiler identification is AppleClang 15.0.0.15000309
-- The CXX compiler identification is AppleClang 15.0.0.15000309
-- The Fortran compiler identification is unknown
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Checking whether Fortran compiler has -isysroot
-- Checking whether Fortran compiler has -isysroot - yes
-- Checking whether Fortran compiler supports OSX deployment target flag
-- Checking whether Fortran compiler supports OSX deployment target flag - yes
-- Detecting Fortran compiler ABI info
-- Detecting Fortran compiler ABI info - failed
-- Check for working Fortran compiler: /opt/homebrew/bin/gfortran
-- Check for working Fortran compiler: /opt/homebrew/bin/gfortran - broken
CMake Error at /opt/homebrew/Cellar/cmake/3.26.3/share/cmake/Modules/CMakeTestFortranCompiler.cmake:59 (message):
  The Fortran compiler

    "/opt/homebrew/bin/gfortran"

  is not able to compile a simple test program.

  It fails with the following output:

    Change Dir: /Users/fwein/code/cfs/xcode/CMakeFiles/CMakeScratch/TryCompile-xSyBNY
    
    Run Build Command(s):/usr/bin/xcodebuild -project CMAKE_TRY_COMPILE.xcodeproj build -target cmTC_03712 -parallelizeTargets -configuration Debug -hideShellScriptEnvironment && Command line invocation:
        /Applications/Xcode.app/Contents/Developer/usr/bin/xcodebuild -project CMAKE_TRY_COMPILE.xcodeproj build -target cmTC_03712 -parallelizeTargets -configuration Debug -hideShellScriptEnvironment
    
    User defaults from command line:
        HideShellScriptEnvironment = YES
        IDEPackageSupportUseBuiltinSCM = YES
    
    ComputeTargetDependencyGraph
    note: Building targets in dependency order
    note: Target dependency graph (1 target)
        Target 'cmTC_03712' in project 'CMAKE_TRY_COMPILE' (no dependencies)
    
    GatherProvisioningInputs
    
    CreateBuildDescription
    
    ExecuteExternalTool /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang -v -E -dM -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.5.sdk -x c -c /dev/null
    
    Build description signature: 76ea46e32cab0d3dddb69af387d79758
    Build description path: /Users/fwein/code/cfs/xcode/CMakeFiles/CMakeScratch/TryCompile-xSyBNY/build/XCBuildData/76ea46e32cab0d3dddb69af387d79758.xcbuilddata
    CreateBuildDirectory /Users/fwein/code/cfs/xcode/CMakeFiles/CMakeScratch/TryCompile-xSyBNY/Debug
        cd /Users/fwein/code/cfs/xcode/CMakeFiles/CMakeScratch/TryCompile-xSyBNY/CMAKE_TRY_COMPILE.xcodeproj
        builtin-create-build-directory /Users/fwein/code/cfs/xcode/CMakeFiles/CMakeScratch/TryCompile-xSyBNY/Debug
    
    CreateBuildDirectory /Users/fwein/code/cfs/xcode/CMakeFiles/CMakeScratch/TryCompile-xSyBNY/build
        cd /Users/fwein/code/cfs/xcode/CMakeFiles/CMakeScratch/TryCompile-xSyBNY/CMAKE_TRY_COMPILE.xcodeproj
        builtin-create-build-directory /Users/fwein/code/cfs/xcode/CMakeFiles/CMakeScratch/TryCompile-xSyBNY/build
    
    ClangStatCache /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang-stat-cache /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.5.sdk /var/folders/q5/g9j2r7ps5tz94gkrhf85mqbr0000gn/C/com.apple.DeveloperTools/15.4-15F31d/Xcode/SDKStatCaches.noindex/macosx14.5-23F73-7e3fd6dc4171e65dbd154ba8db3956d2.sdkstatcache
        cd /Users/fwein/code/cfs/xcode/CMakeFiles/CMakeScratch/TryCompile-xSyBNY/CMAKE_TRY_COMPILE.xcodeproj
        /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang-stat-cache /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX14.5.sdk -o /var/folders/q5/g9j2r7ps5tz94gkrhf85mqbr0000gn/C/com.apple.DeveloperTools/15.4-15F31d/Xcode/SDKStatCaches.noindex/macosx14.5-23F73-7e3fd6dc4171e65dbd154ba8db3956d2.sdkstatcache
    
    CreateBuildDirectory /Users/fwein/code/cfs/xcode/CMakeFiles/CMakeScratch/TryCompile-xSyBNY/build/EagerLinkingTBDs/Debug
        cd /Users/fwein/code/cfs/xcode/CMakeFiles/CMakeScratch/TryCompile-xSyBNY/CMAKE_TRY_COMPILE.xcodeproj
        builtin-create-build-directory /Users/fwein/code/cfs/xcode/CMakeFiles/CMakeScratch/TryCompile-xSyBNY/build/EagerLinkingTBDs/Debug
    
    RegisterExecutionPolicyException /Users/fwein/code/cfs/xcode/CMakeFiles/CMakeScratch/TryCompile-xSyBNY/Debug/cmTC_03712 (in target 'cmTC_03712' from project 'CMAKE_TRY_COMPILE')
        cd /Users/fwein/code/cfs/xcode/CMakeFiles/CMakeScratch/TryCompile-xSyBNY
        builtin-RegisterExecutionPolicyException /Users/fwein/code/cfs/xcode/CMakeFiles/CMakeScratch/TryCompile-xSyBNY/Debug/cmTC_03712
    error: Build input file cannot be found: '/Users/fwein/code/cfs/xcode/CMakeFiles/CMakeScratch/TryCompile-xSyBNY/Debug/cmTC_03712'. Did you forget to declare this file as an output of a script phase or custom build rule which produces it? (in target 'cmTC_03712' from project 'CMAKE_TRY_COMPILE')
    
    warning: no rule to process file '/Users/fwein/code/cfs/xcode/CMakeFiles/CMakeScratch/TryCompile-xSyBNY/testFortranCompiler.f' of type 'sourcecode.fortran.f90' for architecture 'arm64' (in target 'cmTC_03712' from project 'CMAKE_TRY_COMPILE')
    ** BUILD FAILED **
    
    
    The following build commands failed:
    	RegisterExecutionPolicyException /Users/fwein/code/cfs/xcode/CMakeFiles/CMakeScratch/TryCompile-xSyBNY/Debug/cmTC_03712 (in target 'cmTC_03712' from project 'CMAKE_TRY_COMPILE')
    (1 failure)

  CMake will not be able to correctly generate this project.
Call Stack (most recent call first):
  CMakeLists.txt:59 (project)

-- Configuring incomplete, errors occurred!

I cannot reproduce, as /Users/fwein/code/cfs/xcode/CMakeFiles/CMakeScratch/ is empty.

/opt/homebrew/bin/gfortran is the correct compiler, I use for the default Unix Makefiles generator

2

For Unix Makefiles, the fortan compiler detection works

-- Detecting Fortran compiler ABI info - done
-- Check for working Fortran compiler: /opt/homebrew/bin/gfortran - skipped

Can I somehow enforce skipping the check?

3

I’m not really sure what level of support we have for Xcode and Fortran… It probably needs someone to make an Xcode project that works at all before we can dissect it and figure out how to make CMake generate such a project.

(Note: even if Fortran is/can be supported, modular Fortran is definitely not supported at the moment.)