Fix typelias invalid-name false positives for Union variables witho…

…ut assignment. (#8541) (#8548) (cherry picked from commit cb255ea) Co-authored-by: Yilei "Dolee" Yang <[email protected]>
pylint-dev · Apr 7, 2023 · ed67cc8 · ed67cc8
1 parent 011c6ac
commit ed67cc8
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Showing 4 changed files with 11 additions and 7 deletions.
diff --git a/doc/whatsnew/fragments/8540.false_positive b/doc/whatsnew/fragments/8540.false_positive
@@ -0,0 +1,4 @@
+`Union` typed variables without assignment are no longer treated as
+`TypeAlias`.
+
+Closes #8540
diff --git a/pylint/checkers/base/name_checker/checker.py b/pylint/checkers/base/name_checker/checker.py
@@ -602,10 +602,7 @@ def _assigns_typealias(node: nodes.NodeNG | None) -> bool:
  # Union is a special case because it can be used as a type alias
  # or as a type annotation. We only want to check the former.
  assert node is not None
- return not (
- isinstance(node.parent, nodes.AnnAssign)
- and node.parent.value is not None
- )
+ return not isinstance(node.parent, nodes.AnnAssign)
  elif isinstance(inferred, nodes.FunctionDef):
  if inferred.qname() == "typing.TypeAlias":
  return True

diff --git a/tests/functional/t/typealias_naming_style_default.py b/tests/functional/t/typealias_naming_style_default.py
@@ -26,5 +26,8 @@
 ANOTHERBADNAME = Union[int, str] # [invalid-name]
 
 # Regression tests
-# This is not a TypeAlias, and thus shouldn't flag the message
+# They are not TypeAlias, and thus shouldn't flag the message
 x: Union[str, int] = 42
+y: Union[str, int]
+# But the following, using a good TypeAlias name, is:
+GoodTypeAliasToUnion: TypeAlias = Union[str, int]
diff --git a/tests/functional/t/typealias_naming_style_rgx.py b/tests/functional/t/typealias_naming_style_rgx.py
@@ -3,8 +3,8 @@
 
 # Valid
 TypeAliasShouldBeLikeThis: TypeAlias = int
-_TypeAliasShouldBeLikeThis: Union[str, int]
+_TypeAliasShouldBeLikeThis = Union[str, int]
 
 # Invalid
 TypeAliasShouldntBeLikeThis: TypeAlias = int # [invalid-name]
-_TypeAliasShouldntBeLikeThis: Union[str, int] # [invalid-name]
+_TypeAliasShouldntBeLikeThis = Union[str, int] # [invalid-name]