What does memory leak free mean? It has a semantic meaning.

If I have a queue with elements and I won’t be accessing some of it in the next part of the program, is it a leak? Also, remember that certain GCd languages intern strings, is it a memory leak since it will not necessarily use it anymore?

Well, you would need a way to "tell" the compiler more about your intentions and maybe even explicitly declare rules for what you consider a memory leak in certain scenarios.

To provide an example for a different case: programs written in Gallina have the weak normalization property, implying that they always terminate.