Fix isinstance-second-argument-not-valid-type for union types with None

(cherry picked from commit b5f2b01)
pylint-dev · Apr 7, 2023 · bcceff6 · bcceff6
1 parent ed67cc8
commit bcceff6
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Showing 4 changed files with 19 additions and 9 deletions.
diff --git a/doc/whatsnew/fragments/8424.false_positive b/doc/whatsnew/fragments/8424.false_positive
@@ -0,0 +1,3 @@
+Fix false positive for isinstance-second-argument-not-valid-type when union types contains None.
+
+Closes #8424
diff --git a/pylint/checkers/typecheck.py b/pylint/checkers/typecheck.py
@@ -37,6 +37,7 @@
  is_mapping,
  is_module_ignored,
  is_node_in_type_annotation_context,
+ is_none,
  is_overload_stub,
  is_postponed_evaluation_enabled,
  is_super,
@@ -798,8 +799,9 @@ def _is_c_extension(module_node: InferenceResult) -> bool:
 def _is_invalid_isinstance_type(arg: nodes.NodeNG) -> bool:
  # Return True if we are sure that arg is not a type
  if PY310_PLUS and isinstance(arg, nodes.BinOp) and arg.op == "|":
- return _is_invalid_isinstance_type(arg.left) or _is_invalid_isinstance_type(
- arg.right
+ return any(
+ _is_invalid_isinstance_type(elt) and not is_none(elt)
+ for elt in (arg.left, arg.right)
  )
  inferred = utils.safe_infer(arg)
  if not inferred:
@@ -812,9 +814,10 @@ def _is_invalid_isinstance_type(arg: nodes.NodeNG) -> bool:
  if isinstance(inferred, astroid.Instance) and inferred.qname() == BUILTIN_TUPLE:
  return False
  if PY310_PLUS and isinstance(inferred, bases.UnionType):
- return _is_invalid_isinstance_type(
- inferred.left
- ) or _is_invalid_isinstance_type(inferred.right)
+ return any(
+ _is_invalid_isinstance_type(elt) and not is_none(elt)
+ for elt in (inferred.left, inferred.right)
+ )
  return True
 
 

diff --git a/tests/functional/i/isinstance_second_argument_py310.py b/tests/functional/i/isinstance_second_argument_py310.py
@@ -1,13 +1,17 @@
-'''Tests for invalid isinstance with compound types'''
+"""Tests for invalid isinstance with compound types"""
 
 # True negatives
 isinstance(0, int | str)
 isinstance(0, int | int | int)
 isinstance(0, int | str | list | float)
 isinstance(0, (int | str) | (list | float))
+isinstance(0, int | None)
+isinstance(0, None | int)
 
 IntOrStr = int | str
 isinstance(0, IntOrStr)
+IntOrNone = int | None
+isinstance(0, IntOrNone)
 ListOrDict = list | dict
 isinstance(0, (float | ListOrDict) | IntOrStr)
 

diff --git a/tests/functional/i/isinstance_second_argument_py310.txt b/tests/functional/i/isinstance_second_argument_py310.txt
@@ -1,3 +1,3 @@
-isinstance-second-argument-not-valid-type:15:0:15:22::Second argument of isinstance is not a type:INFERENCE
-isinstance-second-argument-not-valid-type:16:0:16:28::Second argument of isinstance is not a type:INFERENCE
-isinstance-second-argument-not-valid-type:18:0:18:24::Second argument of isinstance is not a type:INFERENCE
+isinstance-second-argument-not-valid-type:19:0:19:22::Second argument of isinstance is not a type:INFERENCE
+isinstance-second-argument-not-valid-type:20:0:20:28::Second argument of isinstance is not a type:INFERENCE
+isinstance-second-argument-not-valid-type:22:0:22:24::Second argument of isinstance is not a type:INFERENCE