Generic struct type whose fields are all unmanaged types is unmanaged #692
Description
Generic struct type whose fields are all unmanaged types is unmanaged
A non-generic struct type whose fields are all unmanaged types is unmanaged.
into
A generic struct type whose fields are all unmanaged types is unmanaged.
as
The unmanaged constraint on generic type T enforces the type to be an 'unmanaged' struct that does not recursively contain reference type fields.
as for cases
type Cell<'T when 'T: unmanaged> =
struct
val element: 'T
val next: nativeptr<Cell<'T>>
end
type UnmanagedCell<'T when 'T: unmanaged> =
struct
end
[<EntryPoint>]
let main argv =
let fine = UnmanagedCell<int>()
let FS0001 = UnmanagedCell<UnmanagedCell<int>>()
0
The existing way of approaching this problem in F# is prevent compilation with error
error FS0001: A generic construct requires that the type 'X' is an unmanaged type
I have asked the question on SO and found that it is F# limitation, not CLR.
Pros and Cons
See Related suggestions
Extra information
Related suggestions:
dotnet/csharplang#1504
dotnet/csharplang#1649
Affidavit (please submit!)
Please tick this by placing a cross in the box:
- [x ] 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