Consider Enums when checking for duplicate dictionary keys

CONTRIBUTORS.txt

@@ -552,3 +552,5 @@ contributors:
 * Jaehoon Hwang (jaehoonhwang): contributor
 
 * Samuel Forestier: contributor
+
+* James DesLauriers: contributor

ChangeLog

@@ -40,6 +40,10 @@ Release date: TBA
   * Added ``using-f-string-in-unsupported-version`` checker. Issued when ``py-version``
     is set to a version that does not support f-strings (< 3.6)
 
+* Properly emit ``duplicate-key`` when Enum members are duplicate dictionary keys
+
+  Closes #5150
+
 * Use ``py-version`` setting for alternative union syntax check (PEP 604),
   instead of the Python interpreter version.
 

pylint/checkers/base.py

@@ -1452,9 +1452,13 @@ def visit_dict(self, node: nodes.Dict) -> None:
         for k, _ in node.items:
             if isinstance(k, nodes.Const):
                 key = k.value
-                if key in keys:
-                    self.add_message("duplicate-key", node=node, args=key)
-                keys.add(key)
+            elif isinstance(k, nodes.Attribute):
+                key = k.as_string()
+            else:
+                continue
+            if key in keys:
+                self.add_message("duplicate-key", node=node, args=key)
+            keys.add(key)
 
     def visit_tryfinally(self, node: nodes.TryFinally) -> None:
         """update try...finally flag"""

tests/functional/d/duplicate_dict_literal_key.py

@@ -1,11 +1,25 @@
 """Check multiple key definition"""
 # pylint: disable=pointless-statement, redundant-u-string-prefix
 
+from enum import Enum
+
+
+class MyEnum(Enum):
+    """ Sample Enum for testing duplicate keys"""
+    KEY = "key"
+
+
+
 correct_dict = {
     'tea': 'for two',
     'two': 'for tea',
 }
 
+wrong_with_enum = {  # [duplicate-key]
+    MyEnum.KEY: "value 1",
+    MyEnum.KEY: "value 2",
+}
+
 wrong_dict = {  # [duplicate-key]
     'tea': 'for two',
     'two': 'for tea',

tests/functional/d/duplicate_dict_literal_key.txt

@@ -1,3 +1,4 @@
-duplicate-key:9:13::Duplicate key 'tea' in dictionary
-duplicate-key:16:0::Duplicate key 1 in dictionary
-duplicate-key:17:0::Duplicate key 1.0 in dictionary
+duplicate-key:18:18::Duplicate key 'MyEnum.KEY' in dictionary:HIGH
+duplicate-key:23:13::Duplicate key 'tea' in dictionary:HIGH
+duplicate-key:30:0::Duplicate key 1 in dictionary:HIGH
+duplicate-key:31:0::Duplicate key 1.0 in dictionary:HIGH