Infer an array literal to be a slice when an array of different length is assigned

[jfecher]

Problem

The compiler currently disallows the code:

let mut slice = [];
slice = [1, 2, 3];

When it could be perfectly valid if we assume slice: [Field] rather than slice: [Field; 0] as the compiler currently infers.

Happy Case

Allow Type::Array(T, MaybeConstant(N)) to unify with Type::Array(T, MaybeConstant(M)) if N != M to Type::Array(T, NotConstant) ie. a slice type.

Alternatives Considered

No response

Additional Context

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Would you like to submit a PR for this Issue?

No

Support Needs

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