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authorDaniël van Noord <13665637+DanielNoord@users.noreply.github.com>2023-03-23 22:53:01 +0100
committerDaniël van Noord <13665637+DanielNoord@users.noreply.github.com>2023-03-23 23:48:41 +0100
commitebf1952eb5b4bac46751d91181a62bea4bd6599f (patch)
treecb0c911b3cdc70cd82610ab716bb12ccdc1f522b
parentb9c1ab3cd5323f5cb305a12c9e105102e4200ead (diff)
downloadpylint-git-ebf1952eb5b4bac46751d91181a62bea4bd6599f.tar.gz
Don't consider ``Union`` to always be a type alias (#8489)
Co-authored-by: Pierre Sassoulas <pierre.sassoulas@gmail.com> (cherry picked from commit 07127ee75f3456920ff5117cdbaf8697744b6cfc)
-rw-r--r--doc/whatsnew/fragments/8487.false_positive3
-rw-r--r--pylint/checkers/base/name_checker/checker.py8
-rw-r--r--tests/functional/t/typealias_naming_style_default.py4
3 files changed, 14 insertions, 1 deletions
diff --git a/doc/whatsnew/fragments/8487.false_positive b/doc/whatsnew/fragments/8487.false_positive
new file mode 100644
index 000000000..9ff5e3482
--- /dev/null
+++ b/doc/whatsnew/fragments/8487.false_positive
@@ -0,0 +1,3 @@
+No longer consider ``Union`` as type annotation as type alias for naming checks.
+
+Closes #8487
diff --git a/pylint/checkers/base/name_checker/checker.py b/pylint/checkers/base/name_checker/checker.py
index 1341edc96..616067d1f 100644
--- a/pylint/checkers/base/name_checker/checker.py
+++ b/pylint/checkers/base/name_checker/checker.py
@@ -597,7 +597,13 @@ class NameChecker(_BasicChecker):
inferred = utils.safe_infer(node)
if isinstance(inferred, nodes.ClassDef):
if inferred.qname() == ".Union":
- return True
+ # 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
+ )
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
index 45f801521..a2d02c0c6 100644
--- a/tests/functional/t/typealias_naming_style_default.py
+++ b/tests/functional/t/typealias_naming_style_default.py
@@ -21,3 +21,7 @@ BAD_NAME = Union[int, str] # [invalid-name]
_BAD_NAME = Union[int, str] # [invalid-name]
__BAD_NAME = Union[int, str] # [invalid-name]
ANOTHERBADNAME = Union[int, str] # [invalid-name]
+
+# Regression tests
+# This is not a TypeAlias, and thus shouldn't flag the message
+x: Union[str, int] = 42