test/AutoDiff/downstream/compiler_crashers_fixed/Inputs/tf1202-eliminating-differentiability-witness-original-function.swift

@inlinable
@differentiable(where T: Differentiable)
public func identity<T>(_ x: T) -> T { x }

public func foo<T: Differentiable>(_ f: @differentiable (T) -> T = identity) -> T {
    fatalError()
}