[release/7.0] [Mono] Fix function pointer check

src/coreclr/tools/Common/Compiler/NativeAotNameMangler.cs

@@ -303,9 +303,8 @@ private string ComputeMangledTypeName(TypeDesc type)
  mangledName = GetMangledTypeName(((PointerType)type).ParameterType) + NestMangledName("Pointer");
  break;
  case TypeFlags.FunctionPointer:
- // TODO: need to also encode calling convention (or all modopts?)
  var fnPtrType = (FunctionPointerType)type;
- mangledName = "__FnPtr" + EnterNameScopeSequence;
+ mangledName = "__FnPtr_" + ((int)fnPtrType.Signature.Flags).ToString("X2") + EnterNameScopeSequence;
  mangledName += GetMangledTypeName(fnPtrType.Signature.ReturnType);
 
  mangledName += EnterNameScopeSequence;

src/mono/mono/metadata/class.c

@@ -4218,11 +4218,11 @@ mono_class_is_assignable_from_general (MonoClass *klass, MonoClass *oklass, gboo
  }
 
  if (m_class_get_byval_arg (klass)->type == MONO_TYPE_FNPTR) {
-/*
- * if both klass and oklass are fnptr, and they're equal, we would have returned at the
- * beginning.
- */
- /* Is this right? or do we need to look at signature compatibility? */
+if (mono_metadata_signature_equal (klass_byval_arg->data.method, oklass_byval_arg->data.method)) {
+	*result = TRUE;
+	return;
+}
+
  *result = FALSE;
  return;
  }

src/mono/mono/metadata/marshal.c

@@ -4618,6 +4618,8 @@ is_monomorphic_array (MonoClass *klass)
  return FALSE;
 
 	element_class = m_class_get_element_class (klass);
+	if (m_class_get_byval_arg (element_class)->type == MONO_TYPE_FNPTR)
+ return FALSE;
 	return mono_class_is_sealed (element_class) || m_class_is_valuetype (element_class);
 }
 

src/tests/Loader/classloader/Casting/Functionpointer.cs

@@ -0,0 +1,46 @@
+using System;
+using System.Runtime.InteropServices;
+
+namespace TestFunctionPointer
+{
+ unsafe class TestThings
+ {
+ public static delegate* managed<int>[][] Functions = {
+ new delegate* managed<int>[]
+ {
+ &Function,
+ },
+ };
+
+ public static int Function() => 100;
+
+ public static delegate* unmanaged<int>[][] Functions1 = {
+ new delegate* unmanaged<int>[]
+ {
+ &Function1,
+ },
+ };
+
+ [UnmanagedCallersOnly]
+ public static int Function1() => 100;
+
+ public static delegate* managed<int, int>[][] Functions2 = {
+ new delegate* managed<int, int>[]
+ {
+ &Function2,
+ },
+ };
+
+ public static int Function2(int a) {
+ return a;
+ }
+ }
+
+ unsafe class Program
+ {
+ public static int Main()
+ {
+ return TestThings.Functions2[0][0](TestThings.Functions[0][0]());
+ }
+ }
+}

src/tests/Loader/classloader/Casting/Functionpointer.csproj

@@ -0,0 +1,9 @@
+<Project Sdk="Microsoft.NET.Sdk">
+ <PropertyGroup>
+ <OutputType>Exe</OutputType>
+ <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
+ </PropertyGroup>
+ <ItemGroup>
+ <Compile Include="Functionpointer.cs" />
+ </ItemGroup>
+</Project>