gint64 array length parameters cause invalid cast error

[adamreeve]

Since #1067 was merged, I now get errors building bindings for methods where the array length has type gint64. I've pushed a change to the GirTest library to reproduce the error here: adamreeve@f93b90f

The generated method looks like:

public static int GetDataWithGint64Size(Span<int> data)
{
    var resultGetDataWithGint64Size = GirTest.Internal.IntegerArrayTester.GetDataWithGint64Size(ref MemoryMarshal.GetReference(data), (long) data.Length);
    return resultGetDataWithGint64Size;
}

The expected type of the length parameter to the internal method is CLong rather than long, which causes errors when building the generated code like:

error CS1503: Argument 2: cannot convert from 'long' to 'System.Runtime.InteropServices.CLong'

This appears to be due to the PrimitiveValueTypeArray implementation of ToNativeParameterConverter here:

gir.core/src/Generation/Generator/Renderer/Public/ParameterToNativeExpression/Converter/PrimitiveValueTypeArray.cs

Line 56 in 7c1b5a8

lengthParameter.SetCallName(() => $"({type}) {parameterName}.Length");

But I haven't yet figured out how best to fix this. I guess we want to reuse the Long instance of ToNativeParameterConverter rather than hard code the cast here?

[badcel]

Hey, thanks for the report. I did not yet take a detailed look at this bug but it can be that there is no easy fix for it and needs updating the typehandling of the generator.

Gint64 is guaranteed to be 64 bits on all platforms.

The GirLoader maps Gint64 to long.

The GirModel.Long is currently mapped to CLong in the internal APIs as the C long is only 32bit on windows and 64Bit on other platforms.

This is obviously wrong for GInt64 as it has 64Bit on all platforms. So either there must be a new Type like Long64 or a property must be added to Long detailing whether it is always 64 bit or not.

I need to take a more detailed look here.

[adamreeve]

Ah good point, yeah gint64 should definitely end up mapped to .NET long without going via CLong and being truncated to 32 bits on Windows.

[badcel]

@adamreeve This should be fixed again. Thanks for reporting. I added your test scenario to the tests, too.

[adamreeve]

👍 thanks for fixing this!