[cmake] Add macro to create defaulted settings

Adding a macro to tie non-boolean variables into the defaulting
mechanism.

Author: etcwilde

Runtimes/Core/CMakeLists.txt

@@ -66,12 +66,12 @@ defaulted_option(SwiftCore_ENABLE_COMMANDLINE_SUPPORT "Enable command line argum
 defaulted_option(SwiftCore_ENABLE_RUNTIME_FUNCTION_COUNTERS "Enable runtime function counter support")
 
 defaulted_option(SwiftCore_ENABLE_BACKTRACING "Enable backtracing runtime support")
-set(SwiftCore_BACKTRACER_PATH ${SwiftCore_BACKTRACER_PATH_default} CACHE STRING "Set a fixed path to the Swift backtracer")
+defaulted_set(SwiftCore_BACKTRACER_PATH STRING "Set a fixed path to the Swift backtracer")
 
 option(SwiftCore_ENABLE_CLOBBER_FREED_OBJECTS "" OFF)
 option(SwiftCore_ENABLE_RUNTIME_LEAK_CHECKER "" OFF)
 
-set(SwiftCore_OBJECT_FORMAT "${SwiftCore_OBJECT_FORMAT_default}" CACHE STRING "Object format")
+defaulted_set(SwiftCore_OBJECT_FORMAT STRING "Object format: ELF COFF")
 
 add_compile_definitions(
   $<$<BOOL:${SwiftCore_ENABLE_OBJC_INTEROP}>:-DSWIFT_OBJC_INTEROP>
@@ -82,7 +82,7 @@ add_compile_definitions(
   $<$<COMPILE_LANGUAGE:C,CXX>:-DSWIFT_RUNTIME_ENABLE_LEAK_CHECKER=$<BOOL:${SwiftCore_ENABLE_RUNTIME_LEAK_CHECKER}>>
   $<$<COMPILE_LANGUAGE:C,CXX>:-DSWIFT_RUNTIME_CLOBBER_FREED_OBJECTS=$<BOOL:${SwiftCore_ENABLE_CLOBBER_FREED_OBJECTS}>>)
 
-add_compile_options( $<$<AND:$<COMPILE_LANGUAGE:Swift>,$<BOOL:${SwiftCore_ENABLE_LIBRARY_EVOLUTION}>>:-enable-library-evolution>)
+add_compile_options($<$<AND:$<COMPILE_LANGUAGE:Swift>,$<BOOL:${SwiftCore_ENABLE_LIBRARY_EVOLUTION}>>:-enable-library-evolution>)
 
 include_directories(include)
 

Runtimes/Core/cmake/modules/DefaultSettings.cmake

@@ -17,6 +17,12 @@ macro(defaulted_option variable helptext)
   option(${variable} ${helptext} ${${variable}_default})
 endmacro()
 
+macro(defaulted_set variable type helptext)
+  if(DEFINED ${variable}_default)
+    set(${variable} ${variable}_default CACHE ${type} ${helptext})
+  endif()
+endmacro()
+
 if(APPLE)
   set(SwiftCore_ENABLE_LIBRARY_EVOLUTION_default ON)
   set(SwiftCore_ENABLE_CRASH_REPORTER_CLIENT_default ON)