From d4f04a79219c4ea12f013ff19cd7a98c215ea53e Mon Sep 17 00:00:00 2001
From: Mark Byrne <mbyrnepr2@gmail.com>
Date: Mon, 10 Jan 2022 00:00:04 +0100
Subject: [PATCH] Fixed false positive for ``global-variable-not-assigned``
 when the `del` statement is used

Closes #5333
---
 ChangeLog                      | 4 ++++
 doc/whatsnew/2.13.rst          | 4 ++++
 pylint/checkers/utils.py       | 9 +++++++++
 pylint/checkers/variables.py   | 1 +
 tests/functional/g/globals.py  | 7 +++++++
 tests/functional/g/globals.txt | 9 +++++----
 6 files changed, 30 insertions(+), 4 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 2bf37a089a..79d0f7b3bf 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -47,6 +47,10 @@ Release date: TBA
 
   Closes #5499
 
+* Fixed false positive for ``global-variable-not-assigned`` when the ``del`` statement is used
+
+  Closes #5333
+
 * By default, pylint does no longer take files starting with ``.#`` into account. Those are
   considered `emacs file locks`. See
   https://www.gnu.org/software/emacs/manual/html_node/elisp/File-Locks.html.
diff --git a/doc/whatsnew/2.13.rst b/doc/whatsnew/2.13.rst
index c1b5922378..284d68f292 100644
--- a/doc/whatsnew/2.13.rst
+++ b/doc/whatsnew/2.13.rst
@@ -180,3 +180,7 @@ Other Changes
       raise ValueError
 
   Closes #4955
+
+* Fixed false positive for ``global-variable-not-assigned`` when the ``del`` statement is used
+
+  Closes #5333
diff --git a/pylint/checkers/utils.py b/pylint/checkers/utils.py
index c20342c82e..105a39bb39 100644
--- a/pylint/checkers/utils.py
+++ b/pylint/checkers/utils.py
@@ -1672,6 +1672,15 @@ def is_reassigned_after_current(node: nodes.NodeNG, varname: str) -> bool:
     )
 
 
+def is_deleted_after_current(node: nodes.NodeNG, varname: str) -> bool:
+    """Check if the given variable name is deleted in the same scope after the current node"""
+    return any(
+        getattr(target, "name", None) == varname and target.lineno > node.lineno
+        for del_node in node.scope().nodes_of_class(nodes.Delete)
+        for target in del_node.targets
+    )
+
+
 def is_function_body_ellipsis(node: nodes.FunctionDef) -> bool:
     """Checks whether a function body only consists of a single Ellipsis"""
     return (
diff --git a/pylint/checkers/variables.py b/pylint/checkers/variables.py
index ae01a65d18..584a5cc4fe 100644
--- a/pylint/checkers/variables.py
+++ b/pylint/checkers/variables.py
@@ -1083,6 +1083,7 @@ def visit_global(self, node: nodes.Global) -> None:
             )
             if (
                 not utils.is_reassigned_after_current(node, name)
+                and not utils.is_deleted_after_current(node, name)
                 and not_defined_locally_by_import
             ):
                 self.add_message("global-variable-not-assigned", args=name, node=node)
diff --git a/tests/functional/g/globals.py b/tests/functional/g/globals.py
index a5e4b4bffc..56c852d8a6 100644
--- a/tests/functional/g/globals.py
+++ b/tests/functional/g/globals.py
@@ -40,6 +40,13 @@ def global_no_assign():
     print(CONSTANT)
 
 
+def global_del():
+    """Deleting the global name prevents `global-variable-not-assigned`"""
+    global CONSTANT  # [global-statement]
+    print(CONSTANT)
+    del CONSTANT
+
+
 def global_operator_assign():
     """Operator assigns should only throw a global statement error"""
     global CONSTANT  # [global-statement]
diff --git a/tests/functional/g/globals.txt b/tests/functional/g/globals.txt
index 0559eea213..4e3f6dca43 100644
--- a/tests/functional/g/globals.txt
+++ b/tests/functional/g/globals.txt
@@ -6,7 +6,8 @@ undefined-variable:22:10:22:13:other:Undefined variable 'HOP':UNDEFINED
 global-variable-undefined:27:4:27:18:define_constant:Global variable 'SOMEVAR' undefined at the module level:UNDEFINED
 global-statement:33:4:33:14:global_with_import:Using the global statement:UNDEFINED
 global-variable-not-assigned:39:4:39:19:global_no_assign:Using global for 'CONSTANT' but no assignment is done:UNDEFINED
-global-statement:45:4:45:19:global_operator_assign:Using the global statement:UNDEFINED
-global-statement:52:4:52:19:global_function_assign:Using the global statement:UNDEFINED
-global-statement:62:4:62:15:override_func:Using the global statement:UNDEFINED
-global-statement:71:4:71:14:func:Using the global statement:UNDEFINED
+global-statement:45:4:45:19:global_del:Using the global statement:UNDEFINED
+global-statement:52:4:52:19:global_operator_assign:Using the global statement:UNDEFINED
+global-statement:59:4:59:19:global_function_assign:Using the global statement:UNDEFINED
+global-statement:69:4:69:15:override_func:Using the global statement:UNDEFINED
+global-statement:78:4:78:14:func:Using the global statement:UNDEFINED