what happen if i emplace same component multi times in same entity？

[armorhu]

eg.
reg->emplace(entity);
reg->emplace(entity);
reg->emplace(entity);
reg->emplace(entity);

reg->view([](CompA& value)
{
// how many times call?
// call once. value = first comp A？
// call once ，value = last comp a？
// call forth
}
)

[skypjack]

It triggers an assert the second time you try to emplace the same component. That's it.

[armorhu]

I actually do this success without any assert.

[skypjack]

Tests explicitly verify this and it's pretty easy to reproduce actually. See here for an example.
Remember that ENTT_ASSERT forwards the request to assert by default, therefore it doesn't work in release mode. Is this the case?