No longer emit invalid-name for non-constants found at module level.

Pylint was taking the following statement from PEP-8 too far, considering
all module level variables as constants, which is not what the statement is saying:

`Constants are usually defined on a module level and written in
all capital letters with underscores separating words.`

Close #3111
Close #3132

ChangeLog

@@ -11,6 +11,17 @@ Release date: TBA
 
   Close #3224
 
+* No longer emit ``invalid-name`` for non-constants found at module level.
+
+  Pylint was taking the following statement from PEP-8 too far, considering
+  all module level variables as constants, which is not what the statement is saying:
+
+  `Constants are usually defined on a module level and written in
+  all capital letters with underscores separating words.`
+
+  Close #3111
+  Close #3132
+
 * Allow ``implicit-str-concat-in-sequence`` to be emitted for string juxtaposition
 
   Close #3030

pylint/checkers/base.py

@@ -1886,9 +1886,11 @@ def visit_assignname(self, node):
                 if isinstance(utils.safe_infer(assign_type.value), astroid.ClassDef):
                     self._check_name("class", node.name, node)
                 else:
-                    if not _redefines_import(node):
-                        # Don't emit if the name redefines an import
-                        # in an ImportError except handler.
+                    # Don't emit if the name redefines an import
+                    # in an ImportError except handler.
+                    if not _redefines_import(node) and isinstance(
+                        utils.safe_infer(assign_type.value), astroid.Const
+                    ):
                         self._check_name("const", node.name, node)
             elif isinstance(assign_type, astroid.ExceptHandler):
                 self._check_name("variable", node.name, node)

tests/functional/n/name_styles.py

@@ -134,6 +134,9 @@ def _private_scope_function_with_long_descriptive_name():
     return 12
 
 LONG_CONSTANT_NAME_IN_PUBLIC_SCOPE_ARE_OKAY = True
+# We don't emit for non-const nodes
+good_name_for_funcs = lambda: None
+good_name_for_lists = [1, 2, 3]
 
 class _AnExceptionalExceptionThatOccursVeryVeryRarely(Exception):
     """A very exceptional exception with a nice descriptive name"""