[jnimarshalmethod-gen] Create delegate types for marshaling methods with 15+ parameters

[radekdoulik]

Context: #709

Generate delegate types for marshaling methods. We generate them
in cases where we cannot use Func<> or Action<> delegates
because of too many parameters (more than 14) and when we don't
have special custom delegate type available - like
_JniMarshal_PPZBCSIJFDLLLLLDFJ_Z delegate type in our tests.

Let the TypeMover move these delegate types to the original
assembly as well.

Added test to check marshaling with auto-generated delegate types.

Example of generated delegate type:

.class private auto ansi sealed '__<$>_jni_marshal_LLZBCSIJFDLLLLLDFJII_I'
       extends [mscorlib]System.MulticastDelegate
{
  .method public hidebysig specialname rtspecialname 
          instance void  .ctor(object A_1,
                               native int A_2) runtime managed
  {
  } // end of method '__<$>_jni_marshal_LLZBCSIJFDLLLLLDFJII_I'::.ctor

  .method public hidebysig newslot virtual 
          instance bool  Invoke(native int A_1,
                                native int A_2,
                                bool A_3,
                                int8 A_4,
                                char A_5,
                                int16 A_6,
                                int32 A_7,
                                int64 A_8,
                                float32 A_9,
                                float64 A_10,
                                native int A_11,
                                native int A_12,
                                native int A_13,
                                native int A_14,
                                native int A_15,
                                float64 A_16,
                                float32 A_17,
                                int64 A_18,
                                int32 A_19,
                                int32 A_20) runtime managed
  {
  } // end of method '__<$>_jni_marshal_LLZBCSIJFDLLLLLDFJII_I'::Invoke

  .method public hidebysig newslot virtual 
          instance [mscorlib]System.IAsyncResult 
          BeginInvoke(native int A_1,
                      native int A_2,
                      bool A_3,
                      int8 A_4,
                      char A_5,
                      int16 A_6,
                      int32 A_7,
                      int64 A_8,
                      float32 A_9,
                      float64 A_10,
                      native int A_11,
                      native int A_12,
                      native int A_13,
                      native int A_14,
                      native int A_15,
                      float64 A_16,
                      float32 A_17,
                      int64 A_18,
                      int32 A_19,
                      int32 A_20,
                      [mscorlib]System.AsyncCallback A_21,
                      object A_22) runtime managed
  {
  } // end of method '__<$>_jni_marshal_LLZBCSIJFDLLLLLDFJII_I'::BeginInvoke

  .method public hidebysig newslot virtual 
          instance bool  EndInvoke([mscorlib]System.IAsyncResult A_1) runtime managed
  {
  } // end of method '__<$>_jni_marshal_LLZBCSIJFDLLLLLDFJII_I'::EndInvoke

} // end of class '__<$>_jni_marshal_LLZBCSIJFDLLLLLDFJII_I'

An example of the optimized code in the registration __<$>_jni_marshal_methods'::__RegisterNativeMembers method:

...
  IL_0181:  dup
  IL_0182:  ldc.i4.s   11
  IL_0184:  ldstr      "staticManyParametersWithAutogeneratedDelegateType"
  IL_0189:  ldstr      "(ZBCSIJFDLjava/lang/Object;Ljava/lang/String;Ljava"
  + "/util/ArrayList;Ljava/lang/String;Ljava/lang/Object;DFJII)I"
  IL_018e:  ldnull
  IL_018f:  ldftn      int32 Java.InteropTests.ExportTest/'__<$>_jni_marshal_methods'::staticManyParametersWithAutogeneratedDelegateType(native int,
                                                                                                                                         native int,
                                                                                                                                         bool,
                                                                                                                                         int8,
                                                                                                                                         char,
                                                                                                                                         int16,
                                                                                                                                         int32,
                                                                                                                                         int64,
                                                                                                                                         float32,
                                                                                                                                         float64,
                                                                                                                                         native int,
                                                                                                                                         native int,
                                                                                                                                         native int,
                                                                                                                                         native int,
                                                                                                                                         native int,
                                                                                                                                         float64,
                                                                                                                                         float32,
                                                                                                                                         int64,
                                                                                                                                         int32,
                                                                                                                                         int32)
  IL_0195:  newobj     instance void '__<$>_jni_marshal_LLZBCSIJFDLLLLLDFJII_I'::.ctor(object,
                                                                                       native int)
  IL_019a:  newobj     instance void [Java.Interop]Java.Interop.JniNativeMethodRegistration::.ctor(string,
                                                                                                   string,
                                                                                                   [mscorlib]System.Delegate)
  IL_019f:  stelem     [Java.Interop]Java.Interop.JniNativeMethodRegistration
...

[jonpryor]

Is there a reason to generate these new __<$>_jni_marshal_-prefixed delegate types instead of using the same types -- or same naming convention? -- as the _JniMarshal_-prefixed types?

[jonpryor]

…I ask because I'm wondering if there's some way to not add this public export, or at least find a "more suitable" location for it?

[jonpryor]

I don't understand how this method differs from the existing "lots of parameters" test:

https://github.com/xamarin/java.interop/blob/03c227228955622511bafabe61a12e30e45dc6f7/tests/Java.Interop.Export-Tests/Java.Interop/ExportTest.cs#L109-L162

How does this (pair of) method(s) differ from the current ExportType.staticFuncThisMethodTakesLotsOfParameters() method? They both have lots of parameters, and they both appear to have "similar" [JavaCallable] custom attribute values. How does this test differ?

[jonpryor]

Do we need to declare BeginInvoke() and EndInvoke() if these are generated types, with type names that are "inaccessible", and jnimarshalmethod-gen isn't emitting references to these methods?

[jonpryor]

Closing as this is largely moot as of #1046 + dependencies.