[cxx-interop] Add tests for the available operations of std::iterator

[cabmeurer]

Adding tests for the current supported operations to be used with std::iterator, which is currently just advance

@zoecarver @hyp

[cabmeurer]

Was adding a test for std::distance however there seems to be an issue with the method import.

Test:

StdIteratorTestSuite.test("distance") {
    var vector = Vector()
    var _1: CInt = 1, _2: CInt = 2, _3: CInt = 3
    vector.push_back(&_1)
    vector.push_back(&_2)
    vector.push_back(&_3)
    let v = vector.beginMutating()
    let e = vector.endMutating()
    let d = std.__1.distance(v, e)
    expectEqual(d, 3)
}

std.__1.distance doesnt return a value, module dump output for the method:
static func distance<_InputIter>(_ __first: _InputIter, _ __last: _InputIter)

am i missing something?

[cabmeurer]

Was adding a test for std::distance however there seems to be an issue with the method import.

Test:

StdIteratorTestSuite.test("distance") {
    var vector = Vector()
    var _1: CInt = 1, _2: CInt = 2, _3: CInt = 3
    vector.push_back(&_1)
    vector.push_back(&_2)
    vector.push_back(&_3)
    let v = vector.beginMutating()
    let e = vector.endMutating()
    let d = std.__1.distance(v, e)
    expectEqual(d, 3)
}

std.__1.distance doesnt return a value, module dump output for the method: static func distance<_InputIter>(_ __first: _InputIter, _ __last: _InputIter)

am i missing something?

Looks like a bug related to dependent return types, will investigate further after merging #42411

[cabmeurer]

@zoecarver I spoke with @hyp about this during the office hours and added comments describing the issue with push_back.

[zoecarver]

Looks like a bug related to dependent return types, will investigate further after merging #42411

Sounds good, thanks.

[zoecarver]

@swift-ci please test