fix reportInvalidCast false positive when casting to/from None

DetachHead · Aug 14, 2024 · 223ebe0 · 223ebe0
1 parent 5ca0b65
commit 223ebe0
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diff --git a/packages/pyright-internal/src/analyzer/typeEvaluator.ts b/packages/pyright-internal/src/analyzer/typeEvaluator.ts
@@ -10328,7 +10328,7 @@ export function createTypeEvaluator(
             return isTypeSame(leftType, rightType);
         }
 
-        if (isNoneInstance(leftType) || isNoneInstance(rightType)) {
+        if (checkEq && (isNoneInstance(leftType) || isNoneInstance(rightType))) {
             return isTypeSame(leftType, rightType);
         }
 

diff --git a/packages/pyright-internal/src/tests/samples/cast.py b/packages/pyright-internal/src/tests/samples/cast.py
@@ -8,6 +8,8 @@ def foo(str_: str, int_or_str: int | str, dict_int_or_none: dict[str, int | None
     cast(int | str, str_) # wider, no error
     cast(Never, int_or_str) # narrower, no error
     cast(int, int_or_str) # narrower, no error
+    cast(None, object()) # narrower, no error
+    cast(object, None) # wider, no error
     cast(Mapping[str, int], dict_int_or_none) # wider (ignore type parameters), no error
     cast(dict[str, int], mapping) # wider, no error
     cast(dict[str, bytes], mapping) # xfail, https://github.com/DetachHead/basedpyright/issues/259