Use of undeclared 'connect' with clang-11 (single include)

[jonpas]

Using entt/single_include v3.16.0 with Clang 11 results in the following error when simply including the single include header file:

/builds/acre/acre-core/lib/entt/single_include/entt/entt.hpp:25855:41: error: use of undeclared 'connect'
            sink{construction}.template connect<&underlying_type::element_type::on_construct>();
                                        ^

/builds/acre/acre-core/lib/entt/single_include/entt/entt.hpp:25859:35: error: use of undeclared 'connect'
            sink{update}.template connect<&underlying_type::element_type::on_update>();
                                  ^

/builds/acre/acre-core/lib/entt/single_include/entt/entt.hpp:25863:40: error: use of undeclared 'connect'
            sink{destruction}.template connect<&underlying_type::element_type::on_destroy>();
                                       ^

Those are all in basic_sigh_mixin constructor.

Clang 12 and newer work fine.

EnTT v3.15.0 has the same issue.
EnTT v3.14.0 works fine with Clang 11 and newer.

[skypjack]

Do you have the same problem if you include the right files from the entt directory?
I don't see why the compiler should complain here to be honest. I'm cursious to know if it's a single-include only thing or what.

[jonpas]

I will give it a try, we have only used single-include so far, although as I understand that is not the recommended way to use EnTT. We don't directly use those functions, so I think direct includes won't ever reach this part of code to begin with?

[jonpas]

Using src/entt/entt.hpp instead produces the exact same error:

In file included from /builds/acre/acre-core/src/ecs/include/simulation.hpp:12:
In file included from /builds/acre/acre-core/lib/entt/src/entt/entt.hpp:32:
/builds/acre/acre-core/lib/entt/src/entt/entity/mixin.hpp:153:41: error: use of undeclared 'connect'
            sink{construction}.template connect<&underlying_type::element_type::on_construct>();
                                        ^
/builds/acre/acre-core/lib/entt/src/entt/entity/mixin.hpp:157:35: error: use of undeclared 'connect'
            sink{update}.template connect<&underlying_type::element_type::on_update>();
                                  ^
/builds/acre/acre-core/lib/entt/src/entt/entity/mixin.hpp:161:40: error: use of undeclared 'connect'
            sink{destruction}.template connect<&underlying_type::element_type::on_destroy>();
                                       ^

Using only src/entt/entity/{registry.hpp,entity.hpp} (all we actually use in the project) produces a similar error (in some places only construction sink, some other sinks):

In file included from /builds/acre/acre-core/src/ecs/include/simulation.hpp:12:
In file included from /builds/acre/acre-core/lib/entt/src/entt/entity/registry.hpp:27:
/builds/acre/acre-core/lib/entt/src/entt/entity/mixin.hpp:153:41: error: use of undeclared 'connect'
            sink{construction}.template connect<&underlying_type::element_type::on_construct>();
                                        ^