CMake source_group() not working correctly with hierarchical project setup

Question

After a change to make a CMake project have hierarchical folder management, source_group() no longer seems to be working correctly. CMake just dumps everything into the default filters.

I've tried various regexes to get the relative file path from the parent for every source file and even hard coding the source files in the parent CMakeLists.txt just to see if that was the issue. I've also tried regenerating the VS project a couple times after these changes.

Here's sample files for your viewing pleasure:

Parent CMakeLists.txt

cmake_minimum_required (VERSION 3.3)
set(SRCS)
add_subdirectory(PlatformDetection)
include_directories (.)
add_library(SystemAbstraction STATIC ${SRCS})
set_property(TARGET SystemAbstraction PROPERTY FOLDER "Engine")
set_target_properties(SystemAbstraction PROPERTIES LINKER_LANGUAGE CXX)
install (TARGETS SystemAbstraction
     ARCHIVE DESTINATION lib)

Child CMakeLists.txt:

cmake_minimum_required (VERSION 3.3)
add_subdirectory(Compilers)
set(SRCS ${SRCS} PARENT_SCOPE)

and

cmake_minimum_required (VERSION 3.3)      
set (COMPILER_DETECTION_HEADERS ${CMAKE_CURRENT_SOURCE_DIR}/CompilerDetection.h)
set (COMPILER_DETECTION_SRC ${CMAKE_CURRENT_SOURCE_DIR}/CompilerDetection.cpp)    
source_group("Header Files\\Platform Detection\\Compilers" FILES     ${COMPILER_DETECTION_HEADERS})
source_group("Source Files\\Platform Detection\\Compilers" FILES         ${COMPILER_DETECTION_SRC})  
set(SRCS ${SRCS} ${COMPILER_DETECTION_HEADERS} ${COMPILER_DETECTION_SRC} PARENT_SCOPE)

Answer 1

I fixed my problem by writing a foreach loop which iterates over the source files and groups them by their relative path and if they're header or source files. Then just run this as a macro in every place where you define a library/executable.

foreach(FILE ${SRCS}) 
    # Get the directory of the source file
    get_filename_component(PARENT_DIR "${FILE}" DIRECTORY)

    # Remove common directory prefix to make the group
    string(REPLACE "${CMAKE_CURRENT_SOURCE_DIR}" "" GROUP "${PARENT_DIR}")

    # Make sure we are using windows slashes
    string(REPLACE "/" "\\" GROUP "${GROUP}")

    # Group into "Source Files" and "Header Files"
    if ("${FILE}" MATCHES ".*\\.cpp")
       set(GROUP "Source Files${GROUP}")
    elseif("${FILE}" MATCHES ".*\\.h")
       set(GROUP "Header Files${GROUP}")
    endif()

    source_group("${GROUP}" FILES "${FILE}")
endforeach()