Fix typing of SeqLiterals #1166
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The field keeps track of the element type. This is necessary because JavaSeqLiteral is nonvariant and the elements might be empty, so we cannot always compute the type from the element types.
The test contained an error that was unvovered by the "Nothing is not Nullable" fix.
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@odersky, as current scheme fails only for empty seq literals, instead of going for the old scalac scheme, would you consider this: case class SeqLiteral[-T >: Untyped] private[ast] (elems: List[Tree[T]])
class EmptySeqLiteral[-T >: Untyped] private[ast] (elems: List[Tree[T]], elemtpt: Tree[T]) extends SeqLiteral(elems)Only empty SeqLiterals would need to retain the elem type and only TypeAssigner would needs to know of their existance. |
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@DarkDimius It turns out this does not help much, since the element type has to be propagated everywhere in any case. |
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@odersky, as empty sequences are only created by Typer, couldn't EmptySeqLiteral simply remember the prototype that they were created with? |
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@DarkDimius Adding the second parameter is precisely for remembering the prototype. |
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Now it's more like what scalac is doing - unfortunately the previous, far simpler scheme fails in the presence of empty non-variant Java seq literals, as #1136 illustrates.
Fixes #1136.