swift234

fix <rdar://problem/20918869> Confusing diagnostic for @convention(c) throws

for: func blah(x: @convention(c) Int throws -> Int) { }

we'd previously complain:
error: @convention(c) type is not representable in Objective-C

now we produce:
error: 'Int throws -> Int' is not representable in Objective-C, so it cannot be used with '@convention(c)'



Swift SVN r32007