[possibly-used-before-assignment] Fix FP for sys.exit() (#9634)

Author: jacobtylerwalls

doc/whatsnew/fragments/9627.false_positive

@@ -0,0 +1,4 @@
+Exclude if/else branches containing terminating functions (e.g. `sys.exit()`)
+from `possibly-used-before-assignment` checks.
+
+Closes #9627

pylint/checkers/variables.py

@@ -940,6 +940,12 @@ def _uncertain_nodes_in_except_blocks(
     def _defines_name_raises_or_returns(name: str, node: nodes.NodeNG) -> bool:
         if isinstance(node, (nodes.Raise, nodes.Assert, nodes.Return, nodes.Continue)):
             return True
+        if (
+            isinstance(node, nodes.Expr)
+            and isinstance(node.value, nodes.Call)
+            and utils.is_terminating_func(node.value)
+        ):
+            return True
         if (
             isinstance(node, nodes.AnnAssign)
             and node.value

tests/functional/u/used/used_before_assignment.py

@@ -1,6 +1,7 @@
 """Miscellaneous used-before-assignment cases"""
 # pylint: disable=consider-using-f-string, missing-function-docstring
 import datetime
+import sys
 
 MSG = "hello %s" % MSG  # [used-before-assignment]
 
@@ -118,6 +119,12 @@ def redefine_time_import_with_global():
         VAR12 = False
 print(VAR12)  # [possibly-used-before-assignment]
 
+if input("This tests terminating functions: "):
+    sys.exit()
+else:
+    VAR13 = 1
+print(VAR13)
+
 def turn_on2(**kwargs):
     """https://github.com/pylint-dev/pylint/issues/7873"""
     if "brightness" in kwargs:

tests/functional/u/used/used_before_assignment.txt

@@ -1,15 +1,15 @@
-used-before-assignment:5:19:5:22::Using variable 'MSG' before assignment:HIGH
-used-before-assignment:7:20:7:24::Using variable 'MSG2' before assignment:HIGH
-used-before-assignment:10:4:10:9:outer:Using variable 'inner' before assignment:HIGH
-used-before-assignment:19:20:19:40:ClassWithProperty:Using variable 'redefine_time_import' before assignment:HIGH
-used-before-assignment:23:0:23:9::Using variable 'calculate' before assignment:HIGH
-used-before-assignment:31:10:31:14:redefine_time_import:Using variable 'time' before assignment:HIGH
-used-before-assignment:45:3:45:7::Using variable 'VAR2' before assignment:INFERENCE
-possibly-used-before-assignment:63:3:63:7::Possibly using variable 'VAR4' before assignment:INFERENCE
-possibly-used-before-assignment:73:3:73:7::Possibly using variable 'VAR5' before assignment:INFERENCE
-used-before-assignment:78:3:78:7::Using variable 'VAR6' before assignment:INFERENCE
-used-before-assignment:113:6:113:11::Using variable 'VAR10' before assignment:INFERENCE
-possibly-used-before-assignment:119:6:119:11::Possibly using variable 'VAR12' before assignment:CONTROL_FLOW
-used-before-assignment:144:10:144:14::Using variable 'SALE' before assignment:INFERENCE
-used-before-assignment:176:10:176:18::Using variable 'ALL_DONE' before assignment:INFERENCE
-used-before-assignment:187:6:187:24::Using variable 'NOT_ALWAYS_DEFINED' before assignment:INFERENCE
+used-before-assignment:6:19:6:22::Using variable 'MSG' before assignment:HIGH
+used-before-assignment:8:20:8:24::Using variable 'MSG2' before assignment:HIGH
+used-before-assignment:11:4:11:9:outer:Using variable 'inner' before assignment:HIGH
+used-before-assignment:20:20:20:40:ClassWithProperty:Using variable 'redefine_time_import' before assignment:HIGH
+used-before-assignment:24:0:24:9::Using variable 'calculate' before assignment:HIGH
+used-before-assignment:32:10:32:14:redefine_time_import:Using variable 'time' before assignment:HIGH
+used-before-assignment:46:3:46:7::Using variable 'VAR2' before assignment:INFERENCE
+possibly-used-before-assignment:64:3:64:7::Possibly using variable 'VAR4' before assignment:INFERENCE
+possibly-used-before-assignment:74:3:74:7::Possibly using variable 'VAR5' before assignment:INFERENCE
+used-before-assignment:79:3:79:7::Using variable 'VAR6' before assignment:INFERENCE
+used-before-assignment:114:6:114:11::Using variable 'VAR10' before assignment:INFERENCE
+possibly-used-before-assignment:120:6:120:11::Possibly using variable 'VAR12' before assignment:CONTROL_FLOW
+used-before-assignment:151:10:151:14::Using variable 'SALE' before assignment:INFERENCE
+used-before-assignment:183:10:183:18::Using variable 'ALL_DONE' before assignment:INFERENCE
+used-before-assignment:194:6:194:24::Using variable 'NOT_ALWAYS_DEFINED' before assignment:INFERENCE