Fix Value Type Out Parameters

[Saalvage]

Currently, using value types as out parameters generates incorrect code:

Given

union MyCoolUnion
{
    int a;
    float b;
};

int DLL_API DoCoolThing(CS_OUT MyCoolUnion* myCoolUnion);

the following code is generated:

public static void DoCoolThing(out global::Test.MyCoolUnion myCoolUnion)
{
    myCoolUnion = new global::Test.MyCoolUnion();
    var ____arg0 = new global::Test.MyCoolUnion.__Internal();
    var __arg0 = new __IntPtr(&____arg0);
    __Internal.DoCoolThing(__arg0);
}

This does not use the out parameter's internal value, but a newly created one, leaving the out parameter unchanged.

Following this PR the following code is generated:

public static void DoCoolThing(out global::Test.MyCoolUnion myCoolUnion)
{
    myCoolUnion = new global::Test.MyCoolUnion();
    fixed (global::Test.MyCoolUnion.__Internal* ____arg0 = &myCoolUnion.__Instance)
    {
    var __arg0 = new __IntPtr(____arg0);
    testerB = new global::Test.MyCoolUnion();
    __Internal.DoCoolThing(__arg0);
    }
}

Considerations:

• The indentation is broken, the insides of the fixed statements are not being indented. I hope this is either 1. negligible or 2. easily fixable with greater understanding of the library.
• Instead of using fixed a local could be used and the result later copied into the out parameter. I assume this would be more expensive, as it'd require an extra copy of a potentially very large structure. (If this is a big concern, it should probably be benchmarked)
• The line Context.Return.Write($"new {typePrinter.IntPtrType}(&{arg})"); is duplicated once, with only the & being omitted. I'm currently not seeing a clean solution, but there might be one.

[tritao]

Cool, thanks for the fix!

[Saalvage]

Thank you for the quick merge! Are there any estimates on when there'll be another nuget release? I would like to use this fix in a project of mine but would want to avoid having to deal with git submodule or nuget shenanigans.

[tritao]

Thank you for the quick merge! Are there any estimates on when there'll be another nuget release? I would like to use this fix in a project of mine but would want to avoid having to deal with git submodule or nuget shenanigans.

I've pushed a new tag, v1.1. Hopefully when the build ends a new version is published: https://github.com/mono/CppSharp/actions/runs/6560441820

[Saalvage]

Thank you very much!!

[tritao]

Should be up now.

https://github.com/mono/CppSharp/releases/tag/v1.1
https://www.nuget.org/packages/CppSharp/1.0.76.8341

There is some kind of mismatch in the package/release version name, will have to figure that out, but should be good enough to use for now.

[Saalvage]

Hmmm, it doesn't seem to be working for me. The CppSharp namespace appears to just be missing with 1.0.76.8341, changing it to 1.0.54.626 makes it work as normal again.
Might be nuget taking a while to correctly serve the package??

[tritao]

Hmmm, it doesn't seem to be working for me. The CppSharp namespace appears to just be missing with 1.0.76.8341, changing it to 1.0.54.626 makes it work as normal again. Might be nuget taking a while to correctly serve the package??

Not sure, everything looks fine when I download the package and check its contents. The process is the same that the previous release was created with so dunno.