vecToTuple not needed anymore

[leonschoorl]

foo :: Vec 2 Bool -> Bool
foo xs = x && y
 where
   x :> y :> _ = xs

Starting with GHC 9.2 this produces warnings with -Wall enabled:

Blaat.hs:6:4: warning: [-Wincomplete-uni-patterns]
    Pattern match(es) are non-exhaustive
    In a pattern binding:
        Patterns of type ‘Vec 2 Bool’ not matched:
            Cons _ _
            :> _ (Cons _ _)
  |
6 |    x :> y :> _ = xs
  |    ^^^^^^^^^^^^^^^^

To workaround that we added vecToTuple in #2682:

foo :: Vec 2 Bool -> Bool
foo xs = x && y
 where
   (x, y) = vecToTuple xs

But I just discovered that since the addition of the COMPLETE pragma in #2716 the original code now compiles warning free.

And while vecToTuple was backported to the 1.8 branch, it hasn't made it into a released version yet.

I think we should revert the introduction of vecToTuple. (and backport #2716 to 1.8)

[DigitalBrains1]

Is there a compelling reason to backport?

I'm inclined to say it's okay to backport, but I have this nagging feeling that since we ran into issues with Vec, its constructors and patterns before, that we might be overlooking some intricate aspect somewhere.

[leonschoorl]

In my mind the combination of reverting the addition of vecToTuple and the addition of the COMPLETE pragma went together, to keep the 1.8 functionally on par with its current state.

Not backporting the COMPLETE pragma would keep it on par with the current released 1.8 version.

But I don't have a strong preference either way.

[DigitalBrains1]

I hadn't realised we backported vecToTuple. I must have accidentally skipped the part where you actually mention that above.

I'm fine with backporting the COMPLETE pragma.