try_compile COPY_FILE fails when building for iOS with Makefiles / Ninja

Minimum project code:

cmake_minimum_required(VERSION 3.14.0)
set(CMAKE_OSX_ARCHITECTURES "arm64" CACHE STRING "")
project(app LANGUAGES CXX)

try_compile(
        result
        "${CMAKE_CURRENT_BINARY_DIR}"
        "${CMAKE_CURRENT_SOURCE_DIR}/test.cpp"
        COPY_FILE "${CMAKE_CURRENT_BINARY_DIR}/test_app"
        OUTPUT_VARIABLE out
        COPY_FILE_ERROR file_error
        )

message("result ${result}")
message("output ${out}")
message("file error ${file_error}")

test.cpp content

int main(int argc, char* argv[]) {
    return 0;
}

CMake invocation:

cmake .. -DCMAKE_SYSTEM_NAME=iOS -GNinja --debug-trycompile for Ninja

cmake .. -DCMAKE_SYSTEM_NAME=iOS --debug-trycompile for Unix makefiles

With Xcode generator it fails due to a different bug (see #18993)

Output:

result TRUE
output Change Dir: /Volumes/T3/Dev/projects/ios/cmake_ios_try_compile/build/CMakeFiles/CMakeTmp

Run Build Command(s):/usr/bin/make cmTC_e7132/fast && /Applications/Xcode.app/Contents/Developer/usr/bin/make -f CMakeFiles/cmTC_e7132.dir/build.make CMakeFiles/cmTC_e7132.dir/build
Building CXX object CMakeFiles/cmTC_e7132.dir/test.cpp.o
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++    -arch arm64 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS12.1.sdk   -o CMakeFiles/cmTC_e7132.dir/test.cpp.o -c /Volumes/T3/Dev/projects/ios/cmake_ios_try_compile/test.cpp
Linking CXX executable cmTC_e7132.app/cmTC_e7132
/Users/alex/Dev/cmake/build/bin/cmake -E cmake_link_script CMakeFiles/cmTC_e7132.dir/link.txt --verbose=1
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++    -arch arm64 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS12.1.sdk -Wl,-headerpad_max_install_names   CMakeFiles/cmTC_e7132.dir/test.cpp.o  -o cmTC_e7132.app/cmTC_e7132


file error Cannot copy output executable
  ''
to destination specified by COPY_FILE:
  '/Volumes/T3/Dev/projects/ios/cmake_ios_try_compile/build/test_app'
Unable to find the executable at any of:
  /Volumes/T3/Dev/projects/ios/cmake_ios_try_compile/build/CMakeFiles/CMakeTmp/cmTC_e7132
  /Volumes/T3/Dev/projects/ios/cmake_ios_try_compile/build/CMakeFiles/CMakeTmp/Debug/cmTC_e7132
  /Volumes/T3/Dev/projects/ios/cmake_ios_try_compile/build/CMakeFiles/CMakeTmp/Debug/cmTC_e7132.app/cmTC_e7132
  /Volumes/T3/Dev/projects/ios/cmake_ios_try_compile/build/CMakeFiles/CMakeTmp/Development/cmTC_e7132

-- Configuring done
-- Generating done
-- Build files have been written to: /Volumes/T3/Dev/projects/ios/cmake_ios_try_compile/build

List of files in CMakeTmp:

$ ls
CMakeCache.txt      CMakeFiles          CMakeLists.txt      Makefile            cmTC_5522d.app      cmake_install.cmake

Note that CMake is looking for the "cmTC_e7132.app" bundle in a Debug subfolder, which is not present when using a single-config generator like Ninja/Makefiles, thus the copying fails.

Also note that it is not possible to override CMAKE_MACOSX_BUNDLE variable to disable the bundle creation, via the source file variant of try_compile. Even if -DCMAKE_MACOSX_BUNDLE:BOOL=OFF is passed via CMAKE_FLAGS, the default iOS toolchain overrides the value to ON. So the only workaround would be to use the project variant of try_compile.