Fix HRMP message source location

[akru]

Question

Are HRMP messages should be tagged as routed from the relay chain for the XCM executor, didn't they?

[shawntabrizi]

@akru as far as I understand, horizontal messages are directly from Parachain to Parachain, so this change does not make sense to me.

[pepyakin]

Right

[akru]

@shawntabrizi probably, you didn’t write XCM executor. With your position is difficult to explain this naming https://github.com/paritytech/polkadot/blob/master/xcm/xcm-builder/src/location_conversion.rs#L92

So, let’s make it clear. HRMP message routing is parachain-to-parachain, as you said, right? Routing information about location should be removed, but in fact hrmp routes message, it’s not direct way, right?

[shawntabrizi]

@akru my apologies, I believe you were totally correct here.

An important note that I got from Gav was that the multilocation is completely unaffected by the messaging/delivery system. This was a fundamental misunderstanding that I had.

As such, when you have Parachain A and Parachain B connected to a Parent Relay Chain, the multi location in the eyes of Parachain B will always be Location(Parent, Parachain A).