Allow implicit safe conversion to System.Double/Single in method calls

filmor · filmor · commit c4325dd1b167 · 2022-09-19T14:11:51.000+02:00
Checking the exact type beforehand is unnecessary and `AsDouble` will
check whether `__float__` is available and call it.

This is not yet supported for integer types, which would use `__int__`
or `__index__` (for Python &gt;=3.10), as the respective logic is for some
reason only implemented for `AsLongLong` and `AsLong`, not for the
unsigned counterparts and also not for the `AsSize_t` variants that we
are using.
diff --git a/src/runtime/Converter.cs b/src/runtime/Converter.cs
@@ -777,12 +777,8 @@ internal static bool ToPrimitive(BorrowedReference value, Type obType, out objec
 
                 case TypeCode.Single:
                     {
-                        if (!Runtime.PyFloat_Check(value) && !Runtime.PyInt_Check(value))
-                        {
-                            goto type_error;
-                        }
                         double num = Runtime.PyFloat_AsDouble(value);
-                        if (num == -1.0 && Exceptions.ErrorOccurred())
+                        if (Exceptions.ErrorOccurred())
                         {
                             goto convert_error;
                         }
@@ -799,12 +795,8 @@ internal static bool ToPrimitive(BorrowedReference value, Type obType, out objec
 
                 case TypeCode.Double:
                     {
-                        if (!Runtime.PyFloat_Check(value) && !Runtime.PyInt_Check(value))
-                        {
-                            goto type_error;
-                        }
                         double num = Runtime.PyFloat_AsDouble(value);
-                        if (num == -1.0 && Exceptions.ErrorOccurred())
+                        if (Exceptions.ErrorOccurred())
                         {
                             goto convert_error;
                         }
diff --git a/tests/test_method.py b/tests/test_method.py
@@ -1256,3 +1256,28 @@ def test_method_encoding():
 def test_method_with_pointer_array_argument():
     with pytest.raises(TypeError):
         MethodTest.PointerArray([0])
+
+def test_method_call_implicit_conversion():
+
+    class Answer:
+        # For Python >= 3.8
+        def __index__(self):
+            return 42
+
+        # For Python < 3.10
+        def __int__(self):
+            return 42
+
+    class FloatAnswer(Answer):
+        def __float__(self):
+            return 42.0
+
+    # TODO: This should also work for integer types but due to some complexities
+    # in the C-API functions (some call __int__/__index__, some don't), it's not
+    # supported, yet.
+    for v in [Answer(), FloatAnswer()]:
+        for t in [System.Double, System.Single]:
+            min_value = t(t.MinValue)
+            compare_to = min_value.CompareTo.__overloads__[t]
+
+            assert compare_to(v) == -1

Original file line number	Diff line number	Diff line change
`@@ -777,12 +777,8 @@ internal static bool ToPrimitive(BorrowedReference value, Type obType, out objec`
`777`	`777`
`778`	`778`	`case TypeCode.Single:`
`779`	`779`	`{`
`780`		`- if (!Runtime.PyFloat_Check(value) && !Runtime.PyInt_Check(value))`
`781`		`- {`
`782`		`- goto type_error;`
`783`		`- }`
`784`	`780`	`double num = Runtime.PyFloat_AsDouble(value);`
`785`		`- if (num == -1.0 && Exceptions.ErrorOccurred())`
	`781`	`+ if (Exceptions.ErrorOccurred())`
`786`	`782`	`{`
`787`	`783`	`goto convert_error;`
`788`	`784`	`}`
`@@ -799,12 +795,8 @@ internal static bool ToPrimitive(BorrowedReference value, Type obType, out objec`
`799`	`795`
`800`	`796`	`case TypeCode.Double:`
`801`	`797`	`{`
`802`		`- if (!Runtime.PyFloat_Check(value) && !Runtime.PyInt_Check(value))`
`803`		`- {`
`804`		`- goto type_error;`
`805`		`- }`
`806`	`798`	`double num = Runtime.PyFloat_AsDouble(value);`
`807`		`- if (num == -1.0 && Exceptions.ErrorOccurred())`
	`799`	`+ if (Exceptions.ErrorOccurred())`
`808`	`800`	`{`
`809`	`801`	`goto convert_error;`
`810`	`802`	`}`