Redo The Notes For "Uninhabited" Parameter Types #39477
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For those that care, here's Harper's paper https://www.cs.cmu.edu/~rwh/papers/intensional/popl95.pdf |
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The use of the term 'uninhabited' does not make sense outside of formal type theoretic contexts. In Swift, we also do not use this term in a standard way - hence the term "structurally uninhabited" since we only consider products and sums eligible for the check. (Aside: We do not do exponentials because... well, Swift's type system implements Harper's "typerec" operator and as a consequence parametricity is just _not a thing_). I digress... So, improve upon the old diagnostic in two ways: 1) Do away with 'uninhabited' - instead, mention that it's either an enum or a tuple with an enum in it that 'has no cases' 2) Since the SIL parameter convention flattens all tuples, point directly at the offending uninhabited element type rdar://83600669
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@swift-ci smoke test |
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The use of the term 'uninhabited' does not make sense outside of formal type theoretic contexts. In Swift, we also do not use this term in a standard way - hence the term "structurally uninhabited" since we only consider products and sums eligible for the check. (Aside: We do not do exponentials because... well, Swift's type system implements Harper's "typerec" operator and as a consequence parametricity is just not a thing). I digress...
So, improve upon the old diagnostic in two ways:
rdar://83600669