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Better diagnostics for nullness inference related errors #17433
Description
I think it would be good to be more explicit about nullness inference happening behind the scenes.
For the code
let xs = [| ""; ""; null |]
we'll get
Nullness warning: The type 'string' does not support 'null'
It would be helpful to have something like
"xs was inferred to have the type
string[]but got null among its values. Either explicitly specify null in the return type ((string | null)[]), or remove null from the collection - or suppress the warning but no please don't."
Originally posted by @psfinaki in #15181 (comment)
Activity
vzarytovskii commentedon Jul 23, 2024
We don't differentiate between collections and other types.
stringandstring arrayare no different for us. This would probably be better solved in analyzers, rather than typechecker.T-Gro commentedon Jul 31, 2024
Related to: #17409
T-Gro commentedon Jul 31, 2024
Option: Specialize type unification for list/array/sequence builders.
T-Gro commentedon Jul 31, 2024
Diagnostics can offer: Explicit annotation or "be first" rule.