Make global-variable-not-assigned check functions

This checker now also checks function defintions in the module and local scope
This closes pylint-dev#330

ChangeLog

@@ -78,9 +78,10 @@ Release date: TBA
   Closes #4900
 
 * The ``global-variable-not-assigned`` checker now catches global variables that are never reassigned in a
-  local scope
+  local scope and catches (reassigned) functions
 
   Closes #1375
+  Closes #330
 
 * Fix ``no-self-use`` and ``docparams extension`` for async functions and methods.
 

doc/whatsnew/2.11.rst

@@ -81,6 +81,7 @@ Other Changes
   Closes #4900
 
 * The ``global-variable-not-assigned`` checker now catches global variables that are never reassigned in a
-  local scope
+  local scope and catches (reassigned) functions
 
   Closes #1375
+  Closes #330

pylint/checkers/utils.py

@@ -1564,5 +1564,5 @@ def is_reassigned_after_current(node: nodes.NodeNG, varname: str) -> bool:
     """Check if the given variable name is reassigned in the same scope after the current node"""
     return any(
         a.name == varname and a.lineno > node.lineno
-        for a in node.scope().nodes_of_class(nodes.AssignName)
+        for a in node.scope().nodes_of_class((nodes.AssignName, nodes.FunctionDef))
     )

pylint/checkers/variables.py

@@ -949,6 +949,9 @@ def visit_global(self, node: nodes.Global) -> None:
                 if anode.frame() is module:
                     # module level assignment
                     break
+                if isinstance(anode, nodes.FunctionDef) and anode.parent is module:
+                    # module level function assignment
+                    break
             else:
                 if not_defined_locally_by_import:
                     # global undefined at the module scope

tests/functional/g/globals.py

@@ -1,10 +1,13 @@
 """Warnings about global statements and usage of global variables."""
+# pylint: disable=invalid-name, redefined-outer-name, missing-function-docstring
 from __future__ import print_function
 
 global CSTE  # [global-at-module-level]
 print(CSTE)  # [undefined-variable]
 
 CONSTANT = 1
+def FUNC():
+    pass
 
 def fix_contant(value):
     """all this is ok, but try not using global ;)"""
@@ -25,7 +28,6 @@ def define_constant():
     SOMEVAR = 2
 
 
-# pylint: disable=invalid-name
 def global_with_import():
     """should only warn for global-statement"""
     global sys  # [global-statement]
@@ -43,3 +45,23 @@ def global_operator_assign():
     global CONSTANT  # [global-statement]
     print(CONSTANT)
     CONSTANT += 1
+
+
+def global_function_assign():
+    """Function assigns should only throw a global statement error"""
+    global CONSTANT  # [global-statement]
+
+    def CONSTANT():
+        pass
+
+    CONSTANT()
+
+
+def override_func():
+    """Overriding a function should only throw a global statement error"""
+    global FUNC # [global-statement]
+
+    def FUNC():
+        pass
+
+    FUNC()

tests/functional/g/globals.txt

@@ -1,9 +1,11 @@
-global-at-module-level:4:0::Using the global statement at the module level
-undefined-variable:5:6::Undefined variable 'CSTE'
-global-statement:11:4:fix_contant:Using the global statement
-global-variable-not-assigned:18:4:other:Using global for 'HOP' but no assignment is done
-undefined-variable:19:10:other:Undefined variable 'HOP'
-global-variable-undefined:24:4:define_constant:Global variable 'SOMEVAR' undefined at the module level
-global-statement:31:4:global_with_import:Using the global statement
-global-variable-not-assigned:37:4:global_no_assign:Using global for 'CONSTANT' but no assignment is done:HIGH
-global-statement:43:4:global_operator_assign:Using the global statement:HIGH
+global-at-module-level:5:0::Using the global statement at the module level:HIGH
+undefined-variable:6:6::Undefined variable 'CSTE':HIGH
+global-statement:14:4:fix_contant:Using the global statement:HIGH
+global-variable-not-assigned:21:4:other:Using global for 'HOP' but no assignment is done:HIGH
+undefined-variable:22:10:other:Undefined variable 'HOP':HIGH
+global-variable-undefined:27:4:define_constant:Global variable 'SOMEVAR' undefined at the module level:HIGH
+global-statement:33:4:global_with_import:Using the global statement:HIGH
+global-variable-not-assigned:39:4:global_no_assign:Using global for 'CONSTANT' but no assignment is done:HIGH
+global-statement:45:4:global_operator_assign:Using the global statement:HIGH
+global-statement:52:4:global_function_assign:Using the global statement:HIGH
+global-statement:62:4:override_func:Using the global statement:HIGH