voidptr should be considered as an unmanaged type

[Happypig375]

dotnet/fsharp#11424
Currently F# does not treat voidptr as an unmanaged type. Therefore types like nativeptr<voidptr>, etc. cause compiler errors.

However on IL level this works and C# libraries (e.g. Silk.NET.OpenGL) expose methods expecting this kind of argument (which currently can't be created in F# due the above)

The existing way of approaching this problem in F# is to make use of C# to wrap around problematic methods.

Pros and Cons

The advantages of making this adjustment to F# are

1. Consistency with C#
2. Convenience
3. Less surprises

The disadvantages of making this adjustment to F# are that native interop is not an area F# focuses on. However, it's still beneficial to unblock scenarios where we must make use of C#.

Extra information

Estimated cost (XS, S, M, L, XL, XXL): XS to S

Related suggestions: dotnet/fsharp#11424

Affidavit (please submit!)

Please tick this by placing a cross in the box:

• This is not a question (e.g. like one you might ask on stackoverflow) and I have searched stackoverflow for discussions of this issue
• I have searched both open and closed suggestions on this site and believe this is not a duplicate
• This is not something which has obviously "already been decided" in previous versions of F#. If you're questioning a fundamental design decision that has obviously already been taken (e.g. "Make F# untyped") then please don't submit it.

Please tick all that apply:

• This is not a breaking change to the F# language design
• I or my company would be willing to help implement and/or test this

For Readers

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[reijerh]

Agree, in practice I currently often just fall back to nativeint to work around type juggling headaches that arise because of this.

[cartermp]

Agreed, this feels like something that's just the right thing to do. I have approved this in principle. While I cannot speak for the priority of the team to implement, I think this would also make a fine contribution to F# vNext.

[realvictorprm]

@cartermp I believe this can be closed now that dotnet/fsharp#15725 is merged