@swiftbot
infix operator %+ struct E : Error {} func %+(a: UInt32, b: UInt32) throws -> UInt32 { let c = a.addingReportingOverflow(b) if c.overflow { throw E() } return c.partialValue } try UInt32(0x80_00_00_00) %+ UInt32(0x80_00_00_00)