fix undef var in conversion in rounding modes in MPFR

[KristofferC]

No description provided.

[martinholters]

Worth a test?

[simonbyrne]

(the change was only in 1.1, so doesn't need to be backported before that)

[simonbyrne]

I'm also not sure how one could test this. I guess use reinterpret to create an enum with an invalid value?

[martinholters]

Yes, something like this:

bad_rounding_mode = reinterpret(Base.MPFR.MPFRRoundingMode, Int32(42))
@test_throws ArgumentError convert(RoundingMode,  bad_rounding_mode)

Doing the reinterpret outside @test_throws has the advantage that the test doesn't pass accidentally in case the reinterpret throws an ArgumentError.

[KristofferC]

It seems really weird to have to do something like reinterpreting to an invalid enum to test something. In fact, it can be determined deterministically that the error path cannot happen. So I can change it to just error("this should not happen") if you want to.

[martinholters]

Yes, I was wondering the same. It's more an assertion then an ArgumentError.

[KristofferC]

Since this is unreachable code but more correct unreachable code, I'll just merge it.