Improve type inference for destructuring of shaped array assignments#4873
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Improve type inference for destructuring of shaped array assignments#4873
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Previously, when analyzing an assignment like `[$a, $b] = expr`, if `expr` had at least one shaped array in its UnionType, we would mostly ignore whatever generic arrays it had in its UnionType (e.g. `Foo[]`) when inferring the type of `$a` and `$b`. That is, if `expr` had a UnionType like `Foo[]|array{0:null,1:null}`, we would only infer that `$a` and `$b` can be `null`.
The goal of this changeset is to instead infer that `$a` and `$b` are `Foo|null`.
…rayDestructuringAccess
…rayDestructuringAccess, take 2???
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I played around with this a bit on the v6 branch. The approach works for the specific destructuring issue but has unintended consequences for type precision across the codebase. |
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Previously, when analyzing an assignment like
[$a, $b] = expr, ifexprhad at least one shaped array in its UnionType, we would mostly ignore whatever generic arrays it had in its UnionType (e.g.Foo[]) when inferring the type of$aand$b. That is, ifexprhad a UnionType likeFoo[]|array{0:null,1:null}, we would only infer that$aand$bcan benull.The goal of this changeset is to instead infer that
$aand$bareFoo|null.