Alternative approach for supporting Android in CMake (#751)

Added a new CMake setting OVERRIDE_CXX_FLAGS that prevents Jolt's CMakeLists.txt to override CMAKE_CXX_FLAGS_DEBUG/CMAKE_CXX_FLAGS_RELEASE which is important for Android as it uses a lot of extra flags. This allows us to merge the Android and Linux branches which means Android gets the correct floating point settings.

Build/CMakeLists.txt

@@ -8,6 +8,9 @@ option(DOUBLE_PRECISION "Use double precision math" OFF)
 # When turning this option on, the library will be compiled with debug symbols
 option(GENERATE_DEBUG_SYMBOLS "Generate debug symbols" ON)
 
+# When turning this option on, the library will override the default CMAKE_CXX_FLAGS_DEBUG/RELEASE values, otherwise they will use the platform defaults
+option(OVERRIDE_CXX_FLAGS "Override CMAKE_CXX_FLAGS_DEBUG/RELEASE" ON)
+
 # When turning this option on, the library will be compiled in such a way to attempt to keep the simulation deterministic across platforms
 option(CROSS_PLATFORM_DETERMINISTIC "Cross platform deterministic" OFF)
 
@@ -125,10 +128,7 @@ if (("${CMAKE_SYSTEM_NAME}" STREQUAL "Windows" OR "${CMAKE_SYSTEM_NAME}" STREQUA
 		set(CMAKE_EXE_LINKER_FLAGS_RELEASEUBSAN "${CMAKE_EXE_LINKER_FLAGS_RELEASE} /LIBPATH:${CLANG_LIB_PATH}")
 		set(CMAKE_EXE_LINKER_FLAGS_RELEASECOVERAGE "${CMAKE_EXE_LINKER_FLAGS_RELEASE} /LIBPATH:${CLANG_LIB_PATH}")
 	endif()
-elseif ("${CMAKE_SYSTEM_NAME}" STREQUAL "Linux" OR "${CMAKE_SYSTEM_NAME}" STREQUAL "Darwin" OR "${CMAKE_SYSTEM_NAME}" STREQUAL "iOS" OR MINGW OR EMSCRIPTEN)
-	# Set general compiler flags
-	set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -I.")
-
+elseif ("${CMAKE_SYSTEM_NAME}" STREQUAL "Linux" OR "${CMAKE_SYSTEM_NAME}" STREQUAL "Darwin" OR "${CMAKE_SYSTEM_NAME}" STREQUAL "iOS" OR MINGW OR EMSCRIPTEN OR ANDROID)
 	# Enable warnings
 	if (ENABLE_ALL_WARNINGS)
 		set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Werror")
@@ -160,17 +160,17 @@ elseif ("${CMAKE_SYSTEM_NAME}" STREQUAL "Linux" OR "${CMAKE_SYSTEM_NAME}" STREQU
 	endif()
 
 	# Set compiler flags for various configurations
-	set(CMAKE_CXX_FLAGS_DEBUG "")
-	set(CMAKE_CXX_FLAGS_RELEASE "-O3")
-	set(CMAKE_CXX_FLAGS_DISTRIBUTION "-O3")
+	if (OVERRIDE_CXX_FLAGS)
+		set(CMAKE_CXX_FLAGS_DEBUG "")
+		set(CMAKE_CXX_FLAGS_RELEASE "-O3")
+	endif()
+	set(CMAKE_CXX_FLAGS_DISTRIBUTION "${CMAKE_CXX_FLAGS_RELEASE}")
 	set(CMAKE_CXX_FLAGS_RELEASEASAN "-fsanitize=address")
 	set(CMAKE_CXX_FLAGS_RELEASEUBSAN "-fsanitize=undefined,implicit-conversion,float-divide-by-zero,local-bounds -fno-sanitize-recover=all")
 	set(CMAKE_CXX_FLAGS_RELEASECOVERAGE "-O0 -DJPH_NO_FORCE_INLINE -fprofile-instr-generate -fcoverage-mapping")
 
 	# Set linker flags
 	set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -pthread")
-elseif("${CMAKE_SYSTEM_NAME}" STREQUAL "Android")
-	set(CMAKE_CXX_FLAGS_DISTRIBUTION "${CMAKE_CXX_FLAGS_RELEASE}")
 endif()
 
 # Set linker flags