Re-Structure cmake solution to be closer to the scons solution.

This is just a single step, re-arranging the code without actually changing its functionality.

new docs/cmake.md
moved the block of comments from the start of the CMakeLists.txt into the cmake.md file and converted content to markdown.

new cmake/godotcpp.cmake
Moved all exposed options into a new function godotcpp_options()
Moved configuration and generation code into godotcpp_generate()

To get all the options into the godotcpp_options() I changed the logic of GODOT_USE_HOT_RELOAD which I believe is a closer match to scons, that if the options is not set, and the build type is not release, then it defaults to ON.

I msvc builds require the default flags to be modified or it will throw errors. I have added the links to articles in the commit, but its about removing the runtime error checks /RTC1 from the CMAKE_CXX_FLAGS_DEBUG variable. This needs to happen before the files are included.
https://stackoverflow.com/questions/74426638/how-to-remove-rtc1-from-specific-target-or-file-in-cmake
https://discourse.cmake.org/t/how-do-i-remove-compile-options-from-target/5965

Renamed GodotCompilerWarnings.cmake to common_compiler_flags.cmake to match scons

Included files explicitly by path, as we dont need to append to the CMAKE_MODULES_PATH which effects the whole build tree.

This prevents consumers of the library from clobbering the names of the cmake include files and breaking the build.

Author: enetheru

CMakeLists.txt

@@ -1,248 +1,24 @@
-# cmake arguments
-# CMAKE_BUILD_TYPE:         Compilation target (Debug or Release defaults to Debug)
-#
-# godot-cpp cmake arguments
-# GODOT_GDEXTENSION_DIR:    Path to the directory containing GDExtension interface header and API JSON file
-# GODOT_SYSTEM_HEADERS:     Mark the header files as SYSTEM. This may be useful to suppress warnings in projects including this one.
-# GODOT_WARNING_AS_ERROR:   Treat any warnings as errors
-# GODOT_USE_HOT_RELOAD:     Build with hot reload support. Defaults to YES for Debug-builds and NO for Release-builds.
-# GODOT_CUSTOM_API_FILE:    Path to a custom GDExtension API JSON file (takes precedence over `gdextension_dir`)
-# GODOT_PRECISION:          Floating-point precision level ("single", "double")
-#
-# Android cmake arguments
-# CMAKE_TOOLCHAIN_FILE:     The path to the android cmake toolchain ($ANDROID_NDK/build/cmake/android.toolchain.cmake)
-# ANDROID_NDK:              The path to the android ndk root folder
-# ANDROID_TOOLCHAIN_NAME:   The android toolchain (arm-linux-androideabi-4.9 or aarch64-linux-android-4.9 or x86-4.9 or x86_64-4.9)
-# ANDROID_PLATFORM:         The android platform version (android-23)
-# More info here: https://godot.readthedocs.io/en/latest/development/compiling/compiling_for_android.html
-#
-# Examples
-#
-# Builds a debug version:
-# cmake .
-# cmake --build .
-#
-# Builds a release version with clang
-# CC=/usr/bin/clang CXX=/usr/bin/clang++ cmake -DCMAKE_BUILD_TYPE=Release -G "Unix Makefiles" .
-# cmake --build .
-#
-# Builds an android armeabi-v7a debug version:
-# cmake -DCMAKE_TOOLCHAIN_FILE=$ANDROID_NDK/build/cmake/android.toolchain.cmake -DANDROID_NDK=$ANDROID_NDK \
-#		-DANDROID_TOOLCHAIN_NAME=arm-linux-androideabi-4.9 -DANDROID_PLATFORM=android-23 -DCMAKE_BUILD_TYPE=Debug .
-# cmake --build .
-#
-# Protip
-# Generate the buildfiles in a sub directory to not clutter the root directory with build files:
-# mkdir build && cd build && cmake -G "Unix Makefiles" .. && cmake --build .
-#
-# Ensure that you avoid exposing godot-cpp symbols - this might lead to hard to debug errors if you ever load multiple
-# plugins using difference godot-cpp versions. Use visibility hidden whenever possible:
-# set_target_properties(<all-my-plugin-related-targets> PROPERTIES CXX_VISIBILITY_PRESET hidden)
-#
-# Todo
-# Test build for Windows, Mac and mingw.
-
 cmake_minimum_required(VERSION 3.13)
 project(godot-cpp LANGUAGES CXX)
 
-option(GODOT_GENERATE_TEMPLATE_GET_NODE "Generate a template version of the Node class's get_node. (ON|OFF)" ON)
-option(GODOT_SYSTEM_HEADERS "Expose headers as SYSTEM." ON)
-option(GODOT_WARNING_AS_ERROR "Treat warnings as errors" OFF)
-
-set( GODOT_SYMBOL_VISIBILITY "hidden" CACHE STRING "Symbols visibility on GNU platforms. Use 'auto' to apply the default value. (auto|visible|hidden)")
-set_property( CACHE GODOT_SYMBOL_VISIBILITY PROPERTY STRINGS "auto;visible;hidden" )
-
-# CXX_VISIBILITY_PRESET supported values are: default, hidden, protected, and internal
-# which is inline with the gcc -fvisibility=
-# https://gcc.gnu.org/onlinedocs/gcc/Code-Gen-Options.html
-# To match the scons options we need to change the text to match the -fvisibility flag
-# it is probably worth another PR which changes both to use the flag options
-if( ${GODOT_SYMBOL_VISIBILITY} STREQUAL "auto" OR ${GODOT_SYMBOL_VISIBILITY} STREQUAL "visible" )
-    set( GODOT_SYMBOL_VISIBILITY "default" )
+# Configure CMake
+# https://discourse.cmake.org/t/how-do-i-remove-compile-options-from-target/5965
+# https://stackoverflow.com/questions/74426638/how-to-remove-rtc1-from-specific-target-or-file-in-cmake
+if(${CMAKE_CXX_COMPILER_ID} STREQUAL MSVC)
+    if(NOT CMAKE_BUILD_TYPE MATCHES Debug)
+        STRING(REGEX REPLACE "/RTC(su|[1su])" "" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
+        string(REPLACE "/RTC1" "" CMAKE_CXX_FLAGS_DEBUG ${CMAKE_CXX_FLAGS_DEBUG})
+    endif ()
 endif ()
 
-# Add path to modules
-list( APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake/" )
-
-# Set some helper variables for readability
-set( compiler_is_clang "$<OR:$<CXX_COMPILER_ID:AppleClang>,$<CXX_COMPILER_ID:Clang>>" )
-set( compiler_is_gnu "$<CXX_COMPILER_ID:GNU>" )
-set( compiler_is_msvc "$<CXX_COMPILER_ID:MSVC>" )
-
-# Default build type is Debug in the SConstruct
-if("${CMAKE_BUILD_TYPE}" STREQUAL "")
-	set(CMAKE_BUILD_TYPE Debug)
-endif()
-
-# Hot reload is enabled by default in Debug-builds
-if("${CMAKE_BUILD_TYPE}" STREQUAL "Debug")
-    option(GODOT_USE_HOT_RELOAD "Enable the extra accounting required to support hot reload. (ON|OFF)" ON)
-else()
-    option(GODOT_USE_HOT_RELOAD "Enable the extra accounting required to support hot reload. (ON|OFF)" OFF)
-endif()
-
-if(NOT DEFINED BITS)
-	set(BITS 32)
-	if(CMAKE_SIZEOF_VOID_P EQUAL 8)
-		set(BITS 64)
-	endif(CMAKE_SIZEOF_VOID_P EQUAL 8)
-endif()
-
-# Input from user for GDExtension interface header and the API JSON file
-set(GODOT_GDEXTENSION_DIR "gdextension" CACHE PATH
-        "Path to a custom directory containing GDExtension interface header and API JSON file ( /path/to/gdextension_dir )" )
-set(GODOT_CUSTOM_API_FILE "" CACHE FILEPATH
-        "Path to a custom GDExtension API JSON file (takes precedence over `gdextension_dir`) ( /path/to/custom_api_file )")
-
-set(GODOT_GDEXTENSION_API_FILE "${GODOT_GDEXTENSION_DIR}/extension_api.json")
-if (NOT "${GODOT_CUSTOM_API_FILE}" STREQUAL "")  # User-defined override.
-	set(GODOT_GDEXTENSION_API_FILE "${GODOT_CUSTOM_API_FILE}")
-endif()
-
-set(GODOT_PRECISION "single" CACHE STRING "Set the floating-point precision level (single|double)")
-if ("${GODOT_PRECISION}" STREQUAL "double")
-	add_definitions(-DREAL_T_IS_DOUBLE)
-endif()
-
-set( GODOT_COMPILE_FLAGS )
-
-if ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "MSVC")
-	# using Visual Studio C++
-	set(GODOT_COMPILE_FLAGS "/utf-8") # /GF /MP
-
-	if(CMAKE_BUILD_TYPE MATCHES Debug)
-		set(GODOT_COMPILE_FLAGS "${GODOT_COMPILE_FLAGS} /MDd") # /Od /RTC1 /Zi
-	else()
-		set(GODOT_COMPILE_FLAGS "${GODOT_COMPILE_FLAGS} /MD /O2") # /Oy /GL /Gy
-		STRING(REGEX REPLACE "/RTC(su|[1su])" "" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
-		string(REPLACE "/RTC1" "" CMAKE_CXX_FLAGS_DEBUG ${CMAKE_CXX_FLAGS_DEBUG})
-	endif(CMAKE_BUILD_TYPE MATCHES Debug)
-
-	add_definitions(-DNOMINMAX)
-else()  # GCC/Clang
-	if(CMAKE_BUILD_TYPE MATCHES Debug)
-		set(GODOT_COMPILE_FLAGS "${GODOT_COMPILE_FLAGS} -fno-omit-frame-pointer -O0 -g")
-	else()
-		set(GODOT_COMPILE_FLAGS "${GODOT_COMPILE_FLAGS} -O3")
-	endif(CMAKE_BUILD_TYPE MATCHES Debug)
-endif()
-
-# Disable exception handling. Godot doesn't use exceptions anywhere, and this
-# saves around 20% of binary size and very significant build time (GH-80513).
-option(GODOT_DISABLE_EXCEPTIONS "Force disabling exception handling code (ON|OFF)" ON )
-if (GODOT_DISABLE_EXCEPTIONS)
-	if ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "MSVC")
-		set(GODOT_COMPILE_FLAGS "${GODOT_COMPILE_FLAGS} -D_HAS_EXCEPTIONS=0")
-	else()
-		set(GODOT_COMPILE_FLAGS "${GODOT_COMPILE_FLAGS} -fno-exceptions")
-	endif()
-else()
-	if ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "MSVC")
-		set(GODOT_COMPILE_FLAGS "${GODOT_COMPILE_FLAGS} /EHsc")
-	endif()
-endif()
-
-# Generate source from the bindings file
-find_package(Python3 3.4 REQUIRED) # pathlib should be present
-if(GODOT_GENERATE_TEMPLATE_GET_NODE)
-	set(GENERATE_BINDING_PARAMETERS "True")
-else()
-	set(GENERATE_BINDING_PARAMETERS "False")
-endif()
-
-execute_process(COMMAND "${Python3_EXECUTABLE}" "-c" "import binding_generator; binding_generator.print_file_list(\"${GODOT_GDEXTENSION_API_FILE}\", \"${CMAKE_CURRENT_BINARY_DIR}\", headers=True, sources=True)"
-	WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
-	OUTPUT_VARIABLE GENERATED_FILES_LIST
-	OUTPUT_STRIP_TRAILING_WHITESPACE
-)
-
-add_custom_command(OUTPUT ${GENERATED_FILES_LIST}
-		COMMAND "${Python3_EXECUTABLE}" "-c" "import binding_generator; binding_generator.generate_bindings(\"${GODOT_GDEXTENSION_API_FILE}\", \"${GENERATE_BINDING_PARAMETERS}\", \"${BITS}\", \"${GODOT_PRECISION}\", \"${CMAKE_CURRENT_BINARY_DIR}\")"
-		VERBATIM
-		WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
-		MAIN_DEPENDENCY ${GODOT_GDEXTENSION_API_FILE}
-		DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/binding_generator.py
-		COMMENT "Generating bindings"
-)
-
-# Get Sources
-file(GLOB_RECURSE SOURCES CONFIGURE_DEPENDS src/*.c**)
-file(GLOB_RECURSE HEADERS CONFIGURE_DEPENDS include/*.h**)
-
-# Define our godot-cpp library
-add_library(${PROJECT_NAME} STATIC
-		${SOURCES}
-		${HEADERS}
-		${GENERATED_FILES_LIST}
-)
-add_library(godot::cpp ALIAS ${PROJECT_NAME})
-
-include(GodotCompilerWarnings)
-
-target_compile_features(${PROJECT_NAME}
-	PRIVATE
-		cxx_std_17
-)
-
-if(GODOT_USE_HOT_RELOAD)
-	target_compile_definitions(${PROJECT_NAME} PUBLIC HOT_RELOAD_ENABLED)
-	target_compile_options(${PROJECT_NAME} PUBLIC $<${compiler_is_gnu}:-fno-gnu-unique>)
-endif()
-
-target_compile_definitions(${PROJECT_NAME} PUBLIC
-	$<$<CONFIG:Debug>:
-		DEBUG_ENABLED
-		DEBUG_METHODS_ENABLED
-	>
-	$<${compiler_is_msvc}:
-		TYPED_METHOD_BIND
-	>
-)
-
-target_link_options(${PROJECT_NAME} PRIVATE
-	$<$<NOT:${compiler_is_msvc}>:
-		-static-libgcc
-		-static-libstdc++
-		-Wl,-R,'$$ORIGIN'
-	>
-)
-
-# Optionally mark headers as SYSTEM
-set(GODOT_SYSTEM_HEADERS_ATTRIBUTE "")
-if (GODOT_SYSTEM_HEADERS)
-	set(GODOT_SYSTEM_HEADERS_ATTRIBUTE SYSTEM)
-endif ()
-
-target_include_directories(${PROJECT_NAME} ${GODOT_SYSTEM_HEADERS_ATTRIBUTE} PUBLIC
-	include
-	${CMAKE_CURRENT_BINARY_DIR}/gen/include
-	${GODOT_GDEXTENSION_DIR}
-)
-
-# Add the compile flags
-set_property(TARGET ${PROJECT_NAME} APPEND_STRING PROPERTY COMPILE_FLAGS ${GODOT_COMPILE_FLAGS})
+include( ${PROJECT_SOURCE_DIR}/cmake/godotcpp.cmake )
 
-# Create the correct name (godot.os.build_type.system_bits)
-string(TOLOWER "${CMAKE_SYSTEM_NAME}" SYSTEM_NAME)
-string(TOLOWER "${CMAKE_BUILD_TYPE}" BUILD_TYPE)
+# I know this doesn't look like a typical CMakeLists.txt, but as we are
+# attempting mostly feature parity with SCons, and easy maintenance, the closer
+# the two build systems look the easier they will be to keep in lockstep.
 
-if(ANDROID)
-	# Added the android abi after system name
-	set(SYSTEM_NAME ${SYSTEM_NAME}.${ANDROID_ABI})
+# The typical target definitions are in ${PROJECT_SOURCE_DIR}/cmake/godotcpp.cmake
 
-	# Android does not have the bits at the end if you look at the main godot repo build
-	set(OUTPUT_NAME "godot-cpp.${SYSTEM_NAME}.${BUILD_TYPE}")
-else()
-	set(OUTPUT_NAME "godot-cpp.${SYSTEM_NAME}.${BUILD_TYPE}.${BITS}")
-endif()
+godotcpp_options()
 
-set_target_properties(${PROJECT_NAME}
-	PROPERTIES
-		CXX_EXTENSIONS OFF
-		POSITION_INDEPENDENT_CODE ON
-		CXX_VISIBILITY_PRESET ${GODOT_SYMBOL_VISIBILITY}
-		ARCHIVE_OUTPUT_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/bin"
-		LIBRARY_OUTPUT_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/bin"
-		RUNTIME_OUTPUT_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/bin"
-		OUTPUT_NAME "${OUTPUT_NAME}"
-)
+godotcpp_generate()