Update list-patterns.md #5364
Update list-patterns.md #5364
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proposals/list-patterns.md
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| The following assumptions are made on the members being used: | ||
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| - `Length` or `Count` properties are assumed to always return a non-negative value, if and only if the type is *indexable*. For instance, the pattern `{ Length: -1 }` can never match an array. | ||
| - The `Slice` method or the range indexer is assumed to be well-behaved, that is, the return value is never null and that it is a proper subslice of the containing list. |
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Note that this only affects the codegen and nullability exhaustiveness.
We never produce an error if an unannotated type is matched with null.
Additionally, if the type is annotated (which is not what we'd expect), a slice variable remains annotated.
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Thanks for the follow-through (remembering to document the assumptions) :-) |
Almost. |
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Oops. I may have merged too soon. |
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Notes say: "If a Slice method is annotated, we will treat it as potentially returning null for the purposes of subsumption and exhaustiveness." |
No, that's not what's been discussed in LDM. |
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Details to discuss: #5364 (comment) |
Relates to the PR dotnet/roslyn#57457