Raise error when using active pattern in literal binding

[ErikSchierboom]

This PR aims to fix #10816, which noted that one can use an active pattern in a [<Literal>] binding.

Repro:

let (|A|) x = x + 1
let [<Literal>] (A x) = 1

Compiled to:

> let (|A|) x = x + 1;;
val ( |A| ) : x:int -> int

> let [<Literal>] (A x) = 1;;
val x : int = 1

With this PR, this now outputs:

test.fs(2,17): error FS3391: A [<Literal>] declaration cannot use an active pattern for its identifier

This is my very first F# compiler PR (excluding docs), so I'd welcome any feedback.

[ErikSchierboom]

I'm not sure whether HasFSharpAttribute cenv.g cenv.g.attrib_LiteralAttribute attrs reads well enough. I could add an usesLiteralAttribute binding before this is used, but that would come at the cost of executing that function each time, even when the above pattern matches.

[auduchinok]

I'm not sure whether HasFSharpAttribute cenv.g cenv.g.attrib_LiteralAttribute attrs reads well enough.

It looks similar to many of other checks in the compiler, I guess it should be fine.

[ErikSchierboom]

I've tried looking into re-using an existing error, and there were some candidates. In the end I think it made more sense to introduce a new error message that is very specific to this case.

[auduchinok]

Separate errors will definitely make it easier on the tooling side, thanks.

[ErikSchierboom]

I don't know if these translation files should be checked in too.

[cartermp]

These do need to be checked in, yes. It's a part of our localization system for VS.

[ErikSchierboom]

There is another InvalidNumericLiteralsTests.fs file, but this doesn't really belong there. I then had to decide between creating a test file for this specific case, or introducing a more general file that could contain other invalid literals. I've opted for the latter.

[cartermp]

Thanks!

[cartermp]

N.B. - not required to get this merged, but we do have a different approach that we're slowly moving tests over to use:

FSharp """
// the code
    """
    |> compile
    |> shouldFail
    |> withSingleDiagnostic (Error 123, Line 3, Col 17, Line 3, Col 22, "The message")
    |> ignore

[ErikSchierboom]

Ah, I didn't know. I just copied from another test. I'll update!

[ErikSchierboom]

I've updated to:

    FSharp """
let (|A|) x = x + 1
let [<Literal>] (A x) = 1
    """
    |> typecheck
    |> shouldFail
    |> withSingleDiagnostic (Error 3391, Line 3, Col 17, Line 3, Col 22, "A [<Literal>] declaration cannot use an active pattern for its identifier")

I've changed the compile call to typecheck, to be in line with what other tests were doing and due to it not making the tests pass due to the code missing a module/namespace. Is that okay?

I also noticed that the other test suites seem to omit the ignore call at the end. Do you want me to add it here? It does work without it.

[ErikSchierboom]

The new approach looks a lot nicer BTW 👍

[vzarytovskii]

I think it's fine without the explicit "ignore".