ByRefLike structs can be declared in Anonymous Record types

[cartermp]

The following compiles:

open System

let f (r: {| S: Span<int> |})=  r.S.Length

f {| S=Span<int>.Empty |}

It should not compile, because r is reference type, thus violating the rules of ByRefLike structs.

Given that we cannot declare a ByRefLike struct anonymous record, ByReflike types such as Span should not be allowed inside of an anonymous record at all.

[thinkbeforecoding]

Or could it be auto promoted to byreflike in this case ?

[cartermp]

Not in this case, no. This isn't a struct anonymous record declaration.

[thinkbeforecoding]

True, but would it be promoted if it was:

let f (r: struct {| S: Span<int> |})= r.S.Length

??

[cartermp]

In this case it could be, yes.

[dsyme]

This has been fixed somewhere along the way