Getting "no matching function for call to 'to_int'" when trying to build with Emscripten

[Umenokin]

Hi everyone,

I am trying to make a build with Emscripten. Without flecs everything works fine but with flecs getting 20 errors looking like those:
/flecs/include/flecs/private/../addons/cpp/utils/enum.hpp:240:53: error: no matching function for call to 'to_int'

I have my own library which includes flecs and test application that consumes it:

My lib

cmake_minimum_required(VERSION 3.13)
project(my_lib VERSION 0.0.1 LANGUAGES CXX)
set(CMAKE_CXX_STANDARD 20)

file(GLOB_RECURSE SOURCES "src/*.cpp")
# file(GLOB SOURCES "src/*.cpp", "src/*/*.cpp")
add_library(${PROJECT_NAME} ${SOURCES})

# add_library(${PROJECT_NAME} src/engine.cpp src/modules/window.cpp)

target_include_directories(${PROJECT_NAME}
    PUBLIC
        $<INSTALL_INTERFACE:include>
        $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>

    PRIVATE
)

add_subdirectory("external/flecs" EXCLUDE_FROM_ALL)

target_link_libraries(${PROJECT_NAME} PUBLIC flecs::flecs_static)

if(EMSCRIPTEN)
    # set_target_properties(app PROPERTIES SUFFIX ".html")
    # target_link_options(app PRIVATE "-sUSE_WEBGPU=1" "-sUSE_GLFW=3")
else()
    set(DAWN_FETCH_DEPENDENCIES ON)
    add_subdirectory("external/dawn" EXCLUDE_FROM_ALL)

    target_link_libraries(${PROJECT_NAME}
    PUBLIC

    PRIVATE
        dawn::webgpu_dawn
        glfw
        webgpu_glfw
    )
endif()

And example application

cmake_minimum_required(VERSION 3.13)
project(sandbox VERSION 0.0.1 LANGUAGES CXX)
set(CMAKE_CXX_STANDARD 20)

add_executable(${PROJECT_NAME} src/main.cpp)

target_link_libraries(${PROJECT_NAME} my_lib)
target_include_directories(${PROJECT_NAME} PRIVATE my_lib)

if(EMSCRIPTEN)
    set_target_properties(${PROJECT_NAME} PROPERTIES SUFFIX ".html")
    target_link_options(${PROJECT_NAME}
    PRIVATE
        "-sUSE_WEBGPU=1"
        "-sUSE_GLFW=3"
        "-sALLOW_MEMORY_GROWTH=1"
        "-sSTACK_SIZE=1mb"
        "-sEXPORTED_RUNTIME_METHODS=cwrap"
        "-sMODULARIZE=1"
        "-sEXPORT_NAME=\"sandbox\""
    )
endif()

Errors cut:

/Users/slava/dev/tpr/my_lib/external/flecs/include/flecs/private/../addons/cpp/mixins/component/impl.hpp:12:12: note: in instantiation of member function 'flecs::component<ecs_primitive_kind_t>::component' requested here
   12 |     return flecs::component<T>(world_, FLECS_FWD(args)...);
      |            ^
/Users/slava/dev/tpr/my_lib/external/flecs/include/flecs/private/../addons/cpp/mixins/meta/impl.hpp:45:11: note: in instantiation of function template specialization 'flecs::world::component<ecs_primitive_kind_t, const char (&)[28]>' requested here
   45 |     world.component<primitive_kind_t>("flecs::meta::primitive_kind");
      |           ^
/Users/slava/dev/tpr/my_lib/external/flecs/include/flecs/private/../addons/cpp/utils/enum.hpp:183:43: note: candidate template ignored: invalid explicitly-specified argument for template parameter 'Value'
  183 |     static constexpr underlying_type_t<E> to_int() {
      |                                           ^
/Users/slava/dev/tpr/my_lib/external/flecs/include/flecs/private/../addons/cpp/utils/enum.hpp:240:53: error: no matching function for call to 'to_int'
  240 |         return (to_int<Low>() & to_int<High>()) || (to_int<High>() <= to_int<Low>() && to_int<High>() != high_bit)
      |                                                     ^~~~~~~~~~~~
/Users/slava/dev/tpr/my_lib/external/flecs/include/flecs/private/../addons/cpp/utils/enum.hpp:183:43: note: candidate template ignored: invalid explicitly-specified argument for template parameter 'Value'
  183 |     static constexpr underlying_type_t<E> to_int() {
      |                                           ^
/Users/slava/dev/tpr/my_lib/external/flecs/include/flecs/private/../addons/cpp/utils/enum.hpp:240:88: error: no matching function for call to 'to_int'
  240 |         return (to_int<Low>() & to_int<High>()) || (to_int<High>() <= to_int<Low>() && to_int<High>() != high_bit)
      |                                                                                        ^~~~~~~~~~~~
/Users/slava/dev/tpr/my_lib/external/flecs/include/flecs/private/../addons/cpp/utils/enum.hpp:183:43: note: candidate template ignored: invalid explicitly-specified argument for template parameter 'Value'
  183 |     static constexpr underlying_type_t<E> to_int() {
      |                                           ^
fatal error: too many errors emitted, stopping now [-ferror-limit=]

[SanderMertens]

Possibly related to #1311

[SanderMertens]

This should have been fixed!

[Umenokin]

@SanderMertens, it seems the compilation is almost successful with the message:
em++: error: customizing EXPORT_NAME requires that the HTML be customized to use that name (see https://github.com/emscripten-core/emscripten/issues/10086)

While it seems it assumes that I should use a proper HTML template and not strictly related to flecs. However, since flecs is the only dependency that prevents compilation without setting EXPORT_NAME, it may be worth having instructions in docs?