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Use 'never' type for empty array literals - #8907
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Anders Hejlsberg (ahejlsberg) wants to merge 2 commits into
Closed
Use 'never' type for empty array literals#8907Anders Hejlsberg (ahejlsberg) wants to merge 2 commits into
Anders Hejlsberg (ahejlsberg) wants to merge 2 commits into
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Mohamed Hegazy (mhegazy)
commented
Jun 1, 2016
Contributor
👍 |
| const emptyArrayElementType = createIntrinsicType(TypeFlags.Undefined | TypeFlags.ContainsUndefinedOrNull, "undefined"); | ||
| const unknownType = createIntrinsicType(TypeFlags.Any, "unknown"); | ||
| const neverType = createIntrinsicType(TypeFlags.Never, "never"); | ||
| const wideningNeverType = createIntrinsicType(TypeFlags.Never | TypeFlags.ContainsWideningType, "never"); |
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Leave a comment on what a wideningnever implies over an unwidened never and why you need it.
Anders Hejlsberg (ahejlsberg)
commented
Jun 3, 2016
MemberAuthor
Superceded by #8944. |
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This PR introduces a widening form of the
nevertype that we use for empty array literals in--strictNullChecksmode. This fixes the following issue reported in #8878:Before this fix the inferred type above was
(string | undefined)[]because we were using typeundefined[]for empty array literals, andundefinedisn't a bottom type in strict null checking mode.