pythonnet · lostmsu · Jan 5, 2022 · Jan 4, 2022
diff --git a/src/runtime/methodbinder.cs b/src/runtime/methodbinder.cs
@@ -86,16 +86,17 @@ internal void AddMethod(MethodBase m)
 
         /// <summary>
         /// Given a sequence of MethodInfo and a sequence of type parameters,
-        /// return the MethodInfo that represents the matching closed generic.
+        /// return the MethodInfo(s) that represents the matching closed generic.
         /// If unsuccessful, returns null and may set a Python error.
         /// </summary>
-        internal static MethodInfo? MatchParameters(MethodBase[] mi, Type[]? tp)
+        internal static MethodInfo[] MatchParameters(MethodBase[] mi, Type[]? tp)
         {
             if (tp == null)
             {
-                return null;
+                return Array.Empty<MethodInfo>();
             }
             int count = tp.Length;
+            var result = new List<MethodInfo>();
             foreach (MethodInfo t in mi)
             {
                 if (!t.IsGenericMethodDefinition)
@@ -111,16 +112,14 @@ internal void AddMethod(MethodBase m)
                 {
                     // MakeGenericMethod can throw ArgumentException if the type parameters do not obey the constraints.
                     MethodInfo method = t.MakeGenericMethod(tp);
-                    Exceptions.Clear();
-                    return method;
+                    result.Add(method);
                 }
-                catch (ArgumentException e)
+                catch (ArgumentException)
                 {
-                    Exceptions.SetError(e);
                     // The error will remain set until cleared by a successful match.
                 }
             }
-            return null;
+            return result.ToArray();
         }
 
 
@@ -381,9 +380,6 @@ public MismatchedMethod(Exception exception, MethodBase mb)
                 }
             }
 
-            var pynargs = (int)Runtime.PyTuple_Size(args);
-            var isGeneric = false;
-
             MethodBase[] _methods;
             if (info != null)
             {
@@ -395,11 +391,19 @@ public MismatchedMethod(Exception exception, MethodBase mb)
                 _methods = GetMethods();
             }
 
-            var argMatchedMethods = new List<MatchedMethod>(_methods.Length);
+            return Bind(inst, args, kwargDict, _methods, matchGenerics: true);
+        }
+
+        static Binding? Bind(BorrowedReference inst, BorrowedReference args, Dictionary<string, PyObject> kwargDict, MethodBase[] methods, bool matchGenerics)
+        {
+            var pynargs = (int)Runtime.PyTuple_Size(args);
+            var isGeneric = false;
+
+            var argMatchedMethods = new List<MatchedMethod>(methods.Length);
             var mismatchedMethods = new List<MismatchedMethod>();
 
             // TODO: Clean up
-            foreach (MethodBase mi in _methods)
+            foreach (MethodBase mi in methods)
             {
                 if (mi.IsGenericMethod)
                 {
@@ -535,17 +539,17 @@ public MismatchedMethod(Exception exception, MethodBase mb)
 
                 return new Binding(mi, target, margs, outs);
             }
-            else if (isGeneric && info == null && methodinfo != null)
+            else if (matchGenerics && isGeneric)
             {
                 // We weren't able to find a matching method but at least one
                 // is a generic method and info is null. That happens when a generic
                 // method was not called using the [] syntax. Let's introspect the
                 // type of the arguments and use it to construct the correct method.
                 Type[]? types = Runtime.PythonArgsToTypeArray(args, true);
-                MethodInfo? mi = MatchParameters(methodinfo, types);
-                if (mi != null)
+                MethodInfo[] overloads = MatchParameters(methods, types);
+                if (overloads.Length != 0)
                 {
-                    return Bind(inst, args, kw, mi, null);
+                    return Bind(inst, args, kwargDict, overloads, matchGenerics: false);
                 }
             }
             if (mismatchedMethods.Count > 0)

diff --git a/src/runtime/methodbinding.cs b/src/runtime/methodbinding.cs
@@ -43,15 +43,18 @@ public static NewReference mp_subscript(BorrowedReference tp, BorrowedReference
                 return Exceptions.RaiseTypeError("type(s) expected");
             }
 
-            MethodBase? mi = self.m.IsInstanceConstructor
-                ? self.m.type.Value.GetConstructor(types)
+            MethodBase[] overloads = self.m.IsInstanceConstructor
+                ? self.m.type.Value.GetConstructor(types) is { } ctor
+                    ? new[] { ctor }
+                    : Array.Empty<MethodBase>()
                 : MethodBinder.MatchParameters(self.m.info, types);
-            if (mi == null)
+            if (overloads.Length == 0)
             {
                 return Exceptions.RaiseTypeError("No match found for given type params");
             }
 
-            var mb = new MethodBinding(self.m, self.target, self.targetType) { info = mi };
+            MethodObject overloaded = self.m.WithOverloads(overloads);
+            var mb = new MethodBinding(overloaded, self.target, self.targetType);
             return mb.Alloc();
         }
 

diff --git a/src/runtime/methodobject.cs b/src/runtime/methodobject.cs
@@ -27,7 +27,7 @@ internal class MethodObject : ExtensionType
         internal PyString? doc;
         internal MaybeType type;
 
-        public MethodObject(Type type, string name, MethodBase[] info, bool allow_threads = MethodBinder.DefaultAllowThreads)
+        public MethodObject(MaybeType type, string name, MethodBase[] info, bool allow_threads = MethodBinder.DefaultAllowThreads)
         {
             this.type = type;
             this.name = name;
@@ -47,6 +47,9 @@ public MethodObject(Type type, string name, MethodBase[] info, bool allow_thread
 
         public bool IsInstanceConstructor => name == "__init__";
 
+        public MethodObject WithOverloads(MethodBase[] overloads)
+            => new(type, name, overloads, allow_threads: binder.allow_threads);
+
         internal MethodBase[] info
         {
             get

diff --git a/src/testing/methodtest.cs b/src/testing/methodtest.cs
@@ -646,6 +646,9 @@ public static int Overloaded(int i, string s)
             return i;
         }
 
+        public virtual void OverloadedConstrainedGeneric<T>(T generic) where T : MethodTest { }
+        public virtual void OverloadedConstrainedGeneric<T>(T generic, string str) where T: MethodTest { }
+
         public static string CaseSensitive()
         {
             return "CaseSensitive";

diff --git a/tests/test_generic.py b/tests/test_generic.py
@@ -762,6 +762,18 @@ def test_missing_generic_type():
     with pytest.raises(TypeError):
         IList[bool]
 
+# https://github.com/pythonnet/pythonnet/issues/1522
+def test_overload_generic_parameter():
+    from Python.Test import MethodTest, MethodTestSub
+
+    inst = MethodTest()
+    generic = MethodTestSub()
+    inst.OverloadedConstrainedGeneric(generic)
+    inst.OverloadedConstrainedGeneric[MethodTestSub](generic)
+
+    inst.OverloadedConstrainedGeneric[MethodTestSub](generic, '42')
+    inst.OverloadedConstrainedGeneric[MethodTestSub](generic, System.String('42'))
+
 def test_invalid_generic_type_parameter():
     from Python.Test import GenericTypeWithConstraint
     with pytest.raises(TypeError):