`struct*` return types on extern methods generated without pointer when marshaling is allowed

[Nuklon]

Actual behavior

It's generated like this:

		[DllImport("WINTRUST.dll", ExactSpelling = true)]
		[DefaultDllImportSearchPaths(DllImportSearchPath.System32)]
		[SupportedOSPlatform("windows5.1.2600")]
		internal static extern winmdroot.Security.WinTrust.CRYPT_PROVIDER_DATA WTHelperProvDataFromStateData(winmdroot.Foundation.HANDLE hStateData);

But it should return a pointer to CRYPT_PROVIDER_DATA.

In the metadata this is OK:

		[SupportedOSPlatform("windows5.1.2600")]
		[Documentation("https://docs.microsoft.com/windows/win32/api/wintrust/nf-wintrust-wthelperprovdatafromstatedata")]
		[DllImport("WINTRUST.dll", ExactSpelling = true, PreserveSig = false)]
		public unsafe static extern CRYPT_PROVIDER_DATA* WTHelperProvDataFromStateData([In] HANDLE hStateData);

Expected behavior

A clear and concise description of what you expected to happen.

Repro steps

1. NativeMethods.txt content:

WTHelperProvDataFromStateData

Context

• CsWin32 version: 0.3.18-beta+dc807e7787
• Target Framework: net 6.0
• LangVersion (if explicitly set by project): latest

[Nuklon]

WTHelperGetProvSignerFromChain should also take a pointer.

[Nuklon]

A workaround is to set allowMarshaling to false. It seems there's some logic wrong there as this shouldn't be done here.

[AArnott]

Thanks for the excellent bug report. I was able to repro.

[Nuklon]

@AArnott, what would be needed to get this fixed somehow? I'm not entirely sure where to fix this in the code.

[AArnott]

Fixes always start with a test case added to the repo that fails. Then the challenge is to understand the problem enough to change the source generator to recognize the scenario and fix it -- without breaking any other tests. That's usually not too hard. I just haven't had time to take this one on yet. Anything you can do toward it though would be most welcome.

[Nuklon]

Wow, thanks @jevansaks!