[bgen] Add support for delegates with pointer types. (#21159)

src/bgen/Generator.cs

@@ -718,6 +718,14 @@ public partial class Generator : IMemberGatherer {
 				}
 			}
 
+			if (pi.ParameterType.IsPointer && pi.ParameterType.GetElementType ().IsValueType) {
+				// Technically we should only allow blittable types here, but the C# compiler shows an error later on if any non-blittable types
+				// are used, because this ends up in the signature of a UnmanagedCallersOnly method.
+				pars.Add (new TrampolineParameterInfo (TypeManager.FormatType (null, pi.ParameterType), safe_name));
+				invoke.Append (safe_name);
+				continue;
+			}
+
 			if (pi.ParameterType.IsSubclassOf (TypeCache.System_Delegate)) {
 				if (!delegate_types.ContainsKey (pi.ParameterType.Name)) {
 					delegate_types [pi.ParameterType.FullName] = pi.ParameterType.GetMethod ("Invoke");
@@ -4731,11 +4739,13 @@ public partial class Generator : IMemberGatherer {
 					print ("[MonoNativeFunctionWrapper]\n");
 
 				var accessibility = mi.DeclaringType.IsInternal (this) ? "internal" : "public";
-				print ("{3} delegate {0} {1} ({2});",
+				var isUnsafe = mi.GetParameters ().Any ((v => v.ParameterType.IsPointer)) || mi.ReturnType.IsPointer;
+				print ("{3}{4} delegate {0} {1} ({2});",
 					   TypeManager.RenderType (mi.ReturnType, mi.ReturnTypeCustomAttributes),
 					   shortName,
 					   RenderParameterDecl (mi.GetParameters ()),
-					   accessibility);
+					   accessibility,
+					   isUnsafe ? " unsafe" : string.Empty);
 			}
 
 			if (group.Namespace is not null) {

tests/generator/BGenTests.cs

@@ -1719,5 +1719,20 @@ namespace GeneratorTests {
 			var delegateCallback = bgen.ApiAssembly.MainModule.GetType ("NS", "MyCallback").Methods.First ((v) => v.Name == "EndInvoke");
 			Assert.That (delegateCallback.MethodReturnType.CustomAttributes.Any (v => v.AttributeType.Name == "NullableAttribute"), "Nullable return type");
 		}
+
+		[Test]
+		[TestCase (Profile.iOS)]
+		public void DelegatesWithPointerTypes (Profile profile)
+		{
+			Configuration.IgnoreIfIgnoredPlatform (profile.AsPlatform ());
+			var bgen = BuildFile (profile, "tests/delegate-types.cs");
+			bgen.AssertNoWarnings ();
+
+			var delegateCallback = bgen.ApiAssembly.MainModule.GetType ("NS", "MyCallback").Methods.First ((v) => v.Name == "EndInvoke");
+			Assert.IsTrue (delegateCallback.MethodReturnType.ReturnType.IsPointer, "Pointer return type");
+			foreach (var p in delegateCallback.Parameters.Where (v => v.Name != "result")) {
+				Assert.IsTrue (p.ParameterType.IsPointer, $"Pointer parameter type: {p.Name}");
+			}
+		}
 	}
 }

tests/generator/tests/delegate-types.cs

@@ -0,0 +1,15 @@
+using System;
+
+using Foundation;
+using ObjCRuntime;
+
+namespace NS {
+	unsafe delegate byte* MyCallback (sbyte* a, short* b, ushort* c, int* d, uint* e, long* f, ulong* g, float* h, double* i);
+
+	[BaseType (typeof (NSObject))]
+	interface Widget {
+		[Export ("foo")]
+		[NullAllowed]
+		MyCallback Foo { get; set; }
+	}
+}