extern C-like parameters are not supported

[auduchinok]

Issue created from fantomas-online

Code

extern int M1(int)

extern int M2(int i)

extern int M3([<A>] int i)

extern int M4(int[] i)

extern int M5(int* i)

extern int M5(int& i)

extern int M5(void* i)

extern int M6(void* i1, void* i2)

Error

Fantomas was able to format the code but the result appears to be invalid F# code.
Please open an issue.

Formatted result:

let M1 _: int: int =
    failwith "extern was not given a DllImport attribute"

let M2 i: int: int =
    failwith "extern was not given a DllImport attribute"

let M3 [<A>] i: int: int =
    failwith "extern was not given a DllImport attribute"

let M4 i: int ``[]``: int =
    failwith "extern was not given a DllImport attribute"

let M5 i: int nativeptr: int =
    failwith "extern was not given a DllImport attribute"

let M5 i: int byref: int =
    failwith "extern was not given a DllImport attribute"

let M5 i: nativeint: int =
    failwith "extern was not given a DllImport attribute"

let M6 i1: nativeint, i2: nativeint: int =
    failwith "extern was not given a DllImport attribute"

Related parser rules:
https://github.com/dotnet/fsharp/blob/05b0569a7d6acefd21ad31bce49f780d961db651/src/fsharp/pars.fsy#L2654

[nojaf]

This is available in the 5.1 series.