$ swift --version swift-driver version: 1.26.21 Apple Swift version 5.5.2 (swiftlang-1300.0.47.5 clang-1300.0.29.30) Target: arm64-apple-macosx12.0

Issue Description:

Reporting this after asking on forums.swift.org, where user @xwu suggested to report this as a bug:

In this simple piece of code, the integer literal -1 is used where a value of type T is expected. T conforms to FixedWidthInteger so it's unknown at compile time whether the literal can be converted to the actual type T. If T is set to an unsigned integer type, the -1 simply becomes a 0:

func f<T: FixedWidthInteger>(_: T.Type) -> T { -1 as T }
f(UInt.self) // 0 (no error!)

I would have expected a runtime error, or at least a warning at compile time, when comparing this to how integer literals are checked agains concrete types as compile time and how explicit casts using an integer type's initializer result in a runtime error in such a case.