Joe_Groff I have (belatedly) generated a new toolchain with the latest implementation of the feature, which also supports the ABI resilience aspects of the proposal, and uses the proposed some P syntax:

https://forums.swift.org/t/se-0244-opaque-result-types-reopened/22942/52

I have (belatedly) generated a new toolchain with the latest implementation of the feature, which also supports the ABI resilience aspects of the proposal, and uses the proposed some P syntax: