Improve protocol return types (#7093)

* Dunder comparisons must return bool.
* write() return type should be ignored.
* Use custom comparison protocols in _operator.pyi

stdlib/_operator.pyi

@@ -1,5 +1,4 @@
 import sys
-from _typeshed import SupportsAnyComparison
 from typing import (
     Any,
     AnyStr,
@@ -25,6 +24,24 @@ _K = TypeVar("_K")
 _V = TypeVar("_V")
 _P = ParamSpec("_P")
 
+# The following protocols return "Any" instead of bool, since the comparison
+# operators can be overloaded to return an arbitrary object. For example,
+# the numpy.array comparison dunders return another numpy.array.
+
+class _SupportsDunderLT(Protocol):
+    def __lt__(self, __other: Any) -> Any: ...
+
+class _SupportsDunderGT(Protocol):
+    def __gt__(self, __other: Any) -> Any: ...
+
+class _SupportsDunderLE(Protocol):
+    def __le__(self, __other: Any) -> Any: ...
+
+class _SupportsDunderGE(Protocol):
+    def __ge__(self, __other: Any) -> Any: ...
+
+_SupportsComparison = _SupportsDunderLE | _SupportsDunderGE | _SupportsDunderGT | _SupportsDunderLT
+
 class _SupportsInversion(Protocol[_T_co]):
     def __invert__(self) -> _T_co: ...
 
@@ -35,12 +52,12 @@ class _SupportsPos(Protocol[_T_co]):
     def __pos__(self) -> _T_co: ...
 
 # All four comparison functions must have the same signature, or we get false-positive errors
-def lt(__a: SupportsAnyComparison, __b: SupportsAnyComparison) -> Any: ...
-def le(__a: SupportsAnyComparison, __b: SupportsAnyComparison) -> Any: ...
+def lt(__a: _SupportsComparison, __b: _SupportsComparison) -> Any: ...
+def le(__a: _SupportsComparison, __b: _SupportsComparison) -> Any: ...
 def eq(__a: object, __b: object) -> Any: ...
 def ne(__a: object, __b: object) -> Any: ...
-def ge(__a: SupportsAnyComparison, __b: SupportsAnyComparison) -> Any: ...
-def gt(__a: SupportsAnyComparison, __b: SupportsAnyComparison) -> Any: ...
+def ge(__a: _SupportsComparison, __b: _SupportsComparison) -> Any: ...
+def gt(__a: _SupportsComparison, __b: _SupportsComparison) -> Any: ...
 def not_(__a: object) -> bool: ...
 def truth(__a: object) -> bool: ...
 def is_(__a: object, __b: object) -> bool: ...

stdlib/_typeshed/__init__.pyi

@@ -38,16 +38,16 @@ class SupportsAnext(Protocol[_T_co]):
 # Comparison protocols
 
 class SupportsDunderLT(Protocol):
-    def __lt__(self, __other: Any) -> Any: ...
+    def __lt__(self, __other: Any) -> bool: ...
 
 class SupportsDunderGT(Protocol):
-    def __gt__(self, __other: Any) -> Any: ...
+    def __gt__(self, __other: Any) -> bool: ...
 
 class SupportsDunderLE(Protocol):
-    def __le__(self, __other: Any) -> Any: ...
+    def __le__(self, __other: Any) -> bool: ...
 
 class SupportsDunderGE(Protocol):
-    def __ge__(self, __other: Any) -> Any: ...
+    def __ge__(self, __other: Any) -> bool: ...
 
 class SupportsAllComparisons(SupportsDunderLT, SupportsDunderGT, SupportsDunderLE, SupportsDunderGE, Protocol): ...
 
@@ -181,7 +181,7 @@ class SupportsNoArgReadline(Protocol[_T_co]):
 
 # stable
 class SupportsWrite(Protocol[_T_contra]):
-    def write(self, __s: _T_contra) -> Any: ...
+    def write(self, __s: _T_contra) -> object: ...
 
 ReadOnlyBuffer = bytes  # stable
 # Anything that implements the read-write buffer interface.