ref STRUCT* now generated as STRUCT**

[Rans4ckeR]

Actual behavior

It seems I can no longer use several functions (BCryptEnumContexts, BCryptEnumContextFunctions, BCryptResolveProviders) because of invalid signatures.

The DllImport now has an [Optional] attribute and seems to cause the overloads that previously were generated as ref STRUCT* now to be generated as STRUCT**.

Example below for BCryptEnumContexts ppBuffer.

0.2.206-beta generates:

[SupportedOSPlatform("windows6.0.6000")]
internal static unsafe winmdroot.Foundation.NTSTATUS BCryptEnumContexts(winmdroot.Security.Cryptography.BCRYPT_TABLE dwTable, ref uint pcbBuffer, winmdroot.Security.Cryptography.CRYPT_CONTEXTS** ppBuffer)
{
    fixed (uint* pcbBufferLocal = &pcbBuffer)
    {
        winmdroot.Foundation.NTSTATUS __result = PInvoke.BCryptEnumContexts(dwTable, pcbBufferLocal, ppBuffer);
        return __result;
    }
}

[DllImport("bcrypt.dll", ExactSpelling = true)]
[DefaultDllImportSearchPaths(DllImportSearchPath.System32)]
[SupportedOSPlatform("windows6.0.6000")]
internal static extern unsafe winmdroot.Foundation.NTSTATUS BCryptEnumContexts(winmdroot.Security.Cryptography.BCRYPT_TABLE dwTable, uint* pcbBuffer, [Optional] winmdroot.Security.Cryptography.CRYPT_CONTEXTS** ppBuffer);

Expected behavior

0.2.188-beta generates:

[SupportedOSPlatform("windows6.0.6000")]
internal static unsafe winmdroot.Foundation.NTSTATUS BCryptEnumContexts(winmdroot.Security.Cryptography.BCRYPT_TABLE dwTable, ref uint pcbBuffer, ref winmdroot.Security.Cryptography.CRYPT_CONTEXTS* ppBuffer)
{
    fixed (winmdroot.Security.Cryptography.CRYPT_CONTEXTS** ppBufferLocal = &ppBuffer)
    {
        fixed (uint* pcbBufferLocal = &pcbBuffer)
        {
            winmdroot.Foundation.NTSTATUS __result = PInvoke.BCryptEnumContexts(dwTable, pcbBufferLocal, ppBufferLocal);
            return __result;
        }
    }
}

[DllImport("bcrypt.dll", ExactSpelling = true)]
[DefaultDllImportSearchPaths(DllImportSearchPath.System32)]
[SupportedOSPlatform("windows6.0.6000")]
internal static extern unsafe winmdroot.Foundation.NTSTATUS BCryptEnumContexts(winmdroot.Security.Cryptography.BCRYPT_TABLE dwTable, uint* pcbBuffer, winmdroot.Security.Cryptography.CRYPT_CONTEXTS** ppBuffer);

Repro steps

1. NativeMethods.txt content:

   BCryptAddContextFunction
   BCryptEnumContextFunctions
   BCryptEnumContexts
   BCryptFreeBuffer
   BCryptRemoveContextFunction
   BCryptResolveProviders
   NCryptOpenStorageProvider
   NCryptEnumAlgorithms
   NCRYPT_KEY_HANDLE
   IGroupPolicyObject
   CoInitializeEx
   CoCreateInstance
   CoUninitialize
   RegCreateKeyEx
   RegOpenKeyEx
   RegDeleteValue
   RegSetKeyValue
   RegGetValue
   CryptEnumOIDInfo
   BCRYPT_ECCKEY_BLOB
   PCSTR
   CRYPT_INTEGER_BLOB
   NTE_NO_MORE_ITEMS
   szOID_ECC_CURVE_*
   CLSID_GroupPolicyObject
   NCryptProviderName
   BCryptGetProperty
   BCryptOpenAlgorithmProvider
   BCryptCloseAlgorithmProvider
   BCRYPT_ECC_CURVE_NAMES
   CryptFindOIDInfo
   BCryptGenerateKeyPair
   BCryptSetProperty
   BCryptDestroyKey
   BCRYPT_KEY_LENGTHS_STRUCT
   ECC_CURVE_TYPE_ENUM
   ECC_CURVE_ALG_ID_ENUM
   ALG_CLASS_*
   ALG_TYPE_*
   ALG_SID_*
   CALG_*
   CRYPT_*
   BCRYPT_*
   NCRYPT_*
   MS_PRIMITIVE_PROVIDER
   MS_PLATFORM_CRYPTO_PROVIDER
   GPO_OPEN_*
   GPO_SECTION_*
   HKEY_*
   REG_VALUE_TYPE
   SSL_F12_EXTRA_CERT_CHAIN_POLICY_STATUS
   CERT_INFO

2. NativeMethods.json content (if present):

3. Any of your own code that should be shared?

Context

• CsWin32 version: 0.2.206-beta
• Win32Metadata version (if explicitly set by project):
• Target Framework: net7.0
• LangVersion: preview

[AArnott]

I'm afraid this is by design, since the ppBuffer is in fact allowed to be NULL and the C# ref syntax doesn't make it intuitive as to how to pass NULL in. All such optional parameters are therefore declared as pointers instead of using ref, in or out. This shouldn't block any of your scenarios, as far as we're aware. It does unfortunately mean you'll need to update your callers. One thing you could do is add a partial class to declare your own overload of this method that doesacceptref, and internally obtain its pointer and pass it on to theextern` method. If you have a lot of callers of this method, this will allow you to avoid fixing them all up individually.

[AArnott]

137 tracks improving usability of this and possibly bringing ref parameters back.