TYP: Type MaskedArray.swapaxes (numpy#28850)

Author: MarcoGorelli

numpy/ma/core.pyi

@@ -793,7 +793,14 @@ class MaskedArray(ndarray[_ShapeT_co, _DTypeT_co]):
     ) -> MaskedArray[_Shape, _DTypeT_co]: ...
 
     squeeze: Any
-    swapaxes: Any
+
+    def swapaxes(
+        self,
+        axis1: SupportsIndex,
+        axis2: SupportsIndex,
+        /
+    ) -> MaskedArray[_Shape, _DTypeT_co]: ...
+
     T: Any
     transpose: Any
 

numpy/typing/tests/data/fail/ma.pyi

@@ -122,3 +122,5 @@ np.ma.allequal(m, [1,2,3], fill_value=1.5)  # E: No overload variant
 np.ma.allclose(m, [1,2,3], masked_equal=4.5)  # E: No overload variant
 np.ma.allclose(m, [1,2,3], rtol='.4')  # E: No overload variant
 np.ma.allclose(m, [1,2,3], atol='.5')  # E: No overload variant
+
+m.swapaxes(axis1=1, axis2=0)  # E: No overload variant

numpy/typing/tests/data/reveal/ma.pyi

@@ -308,6 +308,9 @@ def func(x: object) -> None:
     else:
         assert_type(x, object)
 
+assert_type(MAR_b.swapaxes(0, 1), MaskedArray[np.bool])
+assert_type(MAR_2d_f4.swapaxes(1, 0), MaskedArray[np.float32])
+
 assert_type(np.ma.nomask, np.bool[Literal[False]])
 # https://github.com/python/mypy/issues/18974
 assert_type(np.ma.MaskType, type[np.bool])  # type: ignore[assert-type]