Using std::move(object) and object.method() in the same assignment expression.

Question

Is the result of the following expression well-defined? What is it?

hash_map[object.key()] = std::move(object);

I'm not sure whether the effects of std::move part would occur before or after the object.key() part, hence my question.

Answer 1

It is well defined because it doesn't matter what comes first in this code: You can rewrite it to the following equivalent

hash_map[object.key()] = static_cast<objecttype&&>(object);

What can we say about the code:

1. object.key() should be executed before assignment to the map
2. std::move(object) should be executed before assignment to the map

Then there will be the assignment to the map which will accept xvalued object with whatever changes key function did.