Make None compatible with SupportsBool protocol

python · Aug 16, 2023 · bc684ea · bc684ea
1 parent 76c16a4
commit bc684ea
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Showing 2 changed files with 9 additions and 1 deletion.
diff --git a/mypy/subtypes.py b/mypy/subtypes.py
@@ -406,7 +406,9 @@ def visit_none_type(self, left: NoneType) -> bool:
                 # None is compatible with Hashable (and other similar protocols). This is
                 # slightly sloppy since we don't check the signature of "__hash__".
                 # None is also compatible with `SupportsStr` protocol.
-                return not members or all(member in ("__hash__", "__str__") for member in members)
+                return not members or all(
+                    member in ("__hash__", "__str__", "__bool__") for member in members
+                )
             return False
         else:
             return True

diff --git a/test-data/unit/check-protocols.test b/test-data/unit/check-protocols.test
@@ -2890,6 +2890,12 @@ class SupportsStr(Protocol):
 def ss(s: SupportsStr) -> None: pass
 ss(None)
 
+class SupportsBool(Protocol):
+    def __bool__(self) -> bool: ...
+
+def sb(s: SupportsBool) -> None: pass
+sb(None)
+
 class HashableStr(Protocol):
     def __str__(self) -> str: ...
     def __hash__(self) -> int: ...