Ad-hoc fix for ref readonly parameters

[vzarytovskii]

Fixes dotnet/runtime#94317

Note that this is an ad-hoc fix which will just treat ref readonly as inref during parameters import, for long-term fix, please refer to #16222

ref readonly is encoded as [in]&T with RequiresLocationAttribute, we import inref<_> only from [in]&T with IsReadOnlyAttribute, this PR adds a second check.

[vzarytovskii]

That's ready @dotnet/fsharp-team-msft

@baronfel what should we do to backport it to 8.0.1xx which will follow the release? We probably don't want to wait until 8.0.2xx.

If 17.8 maps to 8.0.1xx now in darc, should we just make a back port after release?

[baronfel]

Yeah - backport to the branch you have that maps to release/8.0.1xx in the SDK, then get Tactics approval before you merge that PR. Codeflow via darc will take care of the rest and you'll be automatically included in the first servicing release (in December).

[tannergooding]

ref readonly is encoded as [in]&T with RequiresLocationAttribute, we import inref<_> only from [in]&T with IsReadOnlyAttribute, this PR adds a second check.

@vzarytovskii, it's worth noting that it while Roslyn currently encodes it as [in]&T, it is not required to have the [in] and only actually looks for &T + RequiresLocation or [IsReadOnly].

It looks like F# isn't actually checking for [in] itself, but wanted to make the callout on what's part of the requirement vs not.

[vzarytovskii]

ref readonly is encoded as [in]&T with RequiresLocationAttribute, we import inref<_> only from [in]&T with IsReadOnlyAttribute, this PR adds a second check.

@vzarytovskii, it's worth noting that it while Roslyn currently encodes it as [in]&T, it is not required to have the [in] and only actually looks for &T + RequiresLocation or [IsReadOnly].

It looks like F# isn't actually checking for [in] itself, but wanted to make the callout on what's part of the requirement vs not.

Yeah, I think we only emit it, not read. As you said, we pretty much only check attributes for refs

[vzarytovskii]

/backport to release/dev17.8

[github-actions]

Started backporting to release/dev17.8: https://github.com/dotnet/fsharp/actions/runs/6826852984