https://github.com/apple/swift-clang/commit/1ac71826854a809f67ae15ddacaaa9a6eb8189e8 これっぽい

[driver][darwin] Take the OS version specified in "-target" as the ta… · apple/swift-clang@1ac7182

…rget OS instead of inferring it from SDK / environment The OS version is specified in -target should be used instead of the one in an environment variable / SDK name. rdar://35813850 Different...