@rintaro +0 系のコミットってこれが最初ですかね？タグがブレててよくわからない・・・ https://github.com/apple/swift/commit/503db5fc653c92c350d302ac8a771ee9d38bf65e

[all-+0] Add the ability to toggle the "normal parameter convention" … · apple/swift@503db5f

…of DefaultConventions to guaranteed. This is implemented by introducing an enum called NormalParameterConvention, enum class NormalParameterConvention { Owned, Guaranteed }; When one construc...

3:35 AM

https://github.com/apple/swift/pull/13024

Normal Guaranteed Argument Support by gottesmm · Pull Request #13024 · apple/swift

This PR contains support for enabling via the frontend option enable-guaranteed-normal-arguments for normal parameters to be emitted at +0 instead of +1. rdar://34222540

3:36 AM

このPRからっぽいかな・・・