Swift version 4.1 (swift-4.1-RELEASE) (edited)<unknown>:0: error: fatal error encountered during compilation; please file a bug report with your project and the crash log <unknown>:0: note: Program used external function 'sel_registerName' which could not be resolved! /usr/bin/swift[0x3f24d54] /usr/bin/swift[0x3f25096] /lib/x86_64-linux-gnu/libpthread.so.0(+0x11390)[0x7f12ac409390] /lib/x86_64-linux-gnu/libc.so.6(gsignal+0x38)[0x7f12aab48428] /lib/x86_64-linux-gnu/libc.so.6(abort+0x16a)[0x7f12aab4a02a] /usr/bin/swift[0x4c3f75] /usr/bin/swift[0x3eb851f] /usr/bin/swift[0xffeddb] /usr/bin/swift[0xffd626] /usr/bin/swift[0xfead79] /usr/bin/swift[0x4d8e48] /usr/bin/swift[0x4c35d3] /usr/bin/swift[0x4beecc] /usr/bin/swift[0x4778c4] /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf0)[0x7f12aab33830] /usr/bin/swift[0x475179] Stack dump: 0. Program arguments: /usr/bin/swift -frontend -interpret /usercode/main.swift -disable-objc-interop -I /usr/lib/swift/clang/include/ -I /vendor/SwiftyMath/.build/release/ -I /vendor/swift-package-libbsd/ -module-name main -ldSwiftyMath Aborted (core dumped) (edited)swift-DEVELOPMENT-SNAPSHOT-2018-04-18-a Swift version 4.2-dev (LLVM d14a2b25f2, Clang da1edea3f7, Swift ac061632b2)/usercode/main.swift:7:22: error: 'Int' is not convertible to 'AnyObject'; did you mean to use 'as!' to force downcast? var x: AnyObject = 1 as AnyObject ~~^~~~~~~~~~~~ as!