demote float and int

mypy/typeanal.py

@@ -648,6 +648,12 @@ def try_analyze_special_unbound_type(self, t: UnboundType, fullname: str) -> Typ
         elif fullname == "basedtyping.Intersection":
             items = self.anal_array(t.args)
             return IntersectionType.make_intersection(items)
+        elif fullname == "basedtyping.Int":
+            return self.named_type("builtins.int")
+        elif fullname == "basedtyping.Float":
+            return self.named_type("builtins.float")
+        elif fullname == "basedtyping.Complex":
+            return self.named_type("builtins.complex")
         elif fullname == "typing.Optional":
             if len(t.args) != 1:
                 self.fail(

test-data/unit/check-based-promotions.test

@@ -0,0 +1,40 @@
+[case testInference]
+i = 1
+reveal_type(i)  # N: Revealed type is "int"
+
+c = 1j
+reveal_type(c)  # N: Revealed type is "complex | float | int"
+
+f = 1.
+reveal_type(f)  # N: Revealed type is "float | int"
+
+
+[case testBasedtypingImports]
+from basedtyping import Int, Complex, Float
+
+i: Int
+i = 1
+i = 1.  # E: ...
+i = ij  # E: ...
+
+c: Complex
+c = 1  # E: ...
+c = 1.  # E: ...
+c = 1j
+
+f: Float
+c = 1  # E: ...
+c = 1.
+c = 1j  # E: ...
+
+
+[case testDisable]
+# flags: --disable-number-promotions
+i = 1
+reveal_type(i)  # N: Revealed type is "int"
+
+c = 1j
+reveal_type(c)  # N: Revealed type is "complex | float | int"
+
+f = 1.
+reveal_type(f)  # N: Revealed type is "float | int"