ObjC: Add try_compile support

Fixes: #19920

Tests/RunCMake/CMakeLists.txt

@@ -313,6 +313,8 @@ function(add_RunCMake_test_try_compile)
       CMAKE_CXX_COMPILER_VERSION
       CMAKE_CXX_STANDARD_DEFAULT
       CMake_TEST_CUDA
+      CMAKE_OBJC_STANDARD_DEFAULT
+      CMAKE_OBJCXX_STANDARD_DEFAULT
       )
     if(DEFINED ${var})
       list(APPEND try_compile_ARGS -D${var}=${${var}})

Tests/RunCMake/try_compile/ObjCStandard-result.txt

+1

Tests/RunCMake/try_compile/ObjCStandard-stderr.txt

+^CMake Error at .*/Tests/RunCMake/try_compile/ObjCStandard-build/CMakeFiles/CMakeTmp/CMakeLists.txt:[0-9]+ \(add_executable\):
+  OBJC_STANDARD is set to invalid value '3'
++
+CMake Error at ObjCStandard.cmake:[0-9]+ \(try_compile\):
+  Failed to generate test project build system.
+Call Stack \(most recent call first\):
+  CMakeLists.txt:[0-9]+ \(include\)$

Tests/RunCMake/try_compile/ObjCStandard.cmake

+enable_language(OBJC)
+try_compile(result ${CMAKE_CURRENT_BINARY_DIR}
+  SOURCES ${CMAKE_CURRENT_SOURCE_DIR}/src.m
+  OBJC_STANDARD 3
+  OUTPUT_VARIABLE out
+  )
+message("try_compile output:\n${out}")

Tests/RunCMake/try_compile/ObjCxxStandard-result.txt

+1

Tests/RunCMake/try_compile/ObjCxxStandard-stderr.txt

+^CMake Error at .*/Tests/RunCMake/try_compile/ObjCxxStandard-build/CMakeFiles/CMakeTmp/CMakeLists.txt:[0-9]+ \(add_executable\):
+  OBJCXX_STANDARD is set to invalid value '3'
++
+CMake Error at ObjCxxStandard.cmake:[0-9]+ \(try_compile\):
+  Failed to generate test project build system.
+Call Stack \(most recent call first\):
+  CMakeLists.txt:[0-9]+ \(include\)$

Tests/RunCMake/try_compile/ObjCxxStandard.cmake

+enable_language(OBJCXX)
+try_compile(result ${CMAKE_CURRENT_BINARY_DIR}
+  SOURCES ${CMAKE_CURRENT_SOURCE_DIR}/src.mm
+  OBJCXX_STANDARD 3
+  OUTPUT_VARIABLE out
+  )
+message("try_compile output:\n${out}")

Tests/RunCMake/try_compile/RunCMakeTest.cmake

@@ -37,11 +37,17 @@ if(CMAKE_C_STANDARD_DEFAULT)
 elseif(DEFINED CMAKE_C_STANDARD_DEFAULT)
   run_cmake(CStandardNoDefault)
 endif()
+if(CMAKE_OBJC_STANDARD_DEFAULT)
+  run_cmake(ObjCStandard)
+endif()
 if(CMAKE_CXX_STANDARD_DEFAULT)
   run_cmake(CxxStandard)
 elseif(DEFINED CMAKE_CXX_STANDARD_DEFAULT)
   run_cmake(CxxStandardNoDefault)
 endif()
+if(CMAKE_OBJCXX_STANDARD_DEFAULT)
+  run_cmake(ObjCxxStandard)
+endif()
 if(CMake_TEST_CUDA)
   if(CMAKE_HOST_WIN32)
     run_cmake(CudaStandardNoDefault)

Tests/RunCMake/try_compile/src.m

+int main()
+{
+  return 0;
+}

Tests/RunCMake/try_compile/src.mm

+int main()
+{
+  return 0;
+}

Tests/TryCompile/CMakeLists.txt

@@ -365,6 +365,25 @@ if (APPLE)
     TEST_ASSERT(SIMPLE_OBJCXX_RUN_SHOULD_WORK "CHECK_OBJCXX_SOURCE_RUNS() failed, but should have succeeded")
     TEST_FAIL(OBJCXX_RUN_SHOULD_FAIL "CHECK_OBJCXX_SOURCE_RUNS() succeeds, but should have failed")
     TEST_ASSERT(OBJCXX_RUN_SHOULD_WORK "CHECK_OBJCXX_SOURCE_RUNS() failed, but should have succeeded")
+
+    # try to compile a file that should compile
+    try_compile(SHOULD_PASS
+      ${TryCompile_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeTmp
+      ${TryCompile_SOURCE_DIR}/pass.m
+      OUTPUT_VARIABLE TRY_OUT)
+    if(NOT SHOULD_PASS)
+      message(SEND_ERROR "should pass failed ${TRY_OUT}")
+    endif()
+
+    # try to compile a file that should not compile
+    try_compile(SHOULD_FAIL
+      ${TryCompile_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeTmp
+      ${TryCompile_SOURCE_DIR}/fail.m
+      OUTPUT_VARIABLE TRY_OUT)
+    if(SHOULD_FAIL)
+      message(SEND_ERROR "Should fail passed ${TRY_OUT}")
+    endif()
+
 endif()
 
 #######################################################################

Tests/TryCompile/fail.m

+asdflkjasdlj

Tests/TryCompile/pass.m

+int main()
+{
+  return 0;
+}