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Emit possibly-used-before-assignment after if/else switches #8952

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merged 20 commits into from
Apr 17, 2024
Merged

Emit possibly-used-before-assignment after if/else switches #8952

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4ee174f
Emit `used-before-assignment` after if/else switches
jacobtylerwalls Aug 13, 2023
9b42d21
Update expected results
jacobtylerwalls Jan 20, 2024
f17a83c
Add news
jacobtylerwalls Jan 20, 2024
1c09c0a
Add annotation; move example to details.rst
jacobtylerwalls Jan 20, 2024
55a86e4
Merge remote-tracking branch 'origin/main' into 1727-uba-false-negative
Pierre-Sassoulas Feb 23, 2024
7a983a2
Fix false negative
jacobtylerwalls Feb 23, 2024
99b2fc9
Update output
jacobtylerwalls Feb 23, 2024
a771383
Treat continue just like break
jacobtylerwalls Feb 23, 2024
f06f2f5
Add test case
jacobtylerwalls Feb 24, 2024
8c758e2
Don't unnecessarily lower confidence level
jacobtylerwalls Feb 24, 2024
48a0f25
Add test
jacobtylerwalls Feb 24, 2024
35fb7d2
Reverse confidence order
jacobtylerwalls Apr 6, 2024
76fe5ca
First stab at distinguishing new message
jacobtylerwalls Apr 6, 2024
79fac0f
Initialize `tocheck` variable
jacobtylerwalls Apr 9, 2024
3fefce6
Add good/bad
jacobtylerwalls Apr 9, 2024
282150b
Reclassify changelog as new check
jacobtylerwalls Apr 9, 2024
a6dfb21
Move details.rst
jacobtylerwalls Apr 9, 2024
cc80eb9
Add expected msg
jacobtylerwalls Apr 9, 2024
d40710e
Update docs
jacobtylerwalls Apr 9, 2024
b362668
Apply suggestions from code review
jacobtylerwalls Apr 16, 2024
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24 changes: 20 additions & 4 deletions pylint/checkers/variables.py
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Original file line number Diff line number Diff line change
Expand Up @@ -403,6 +403,12 @@ def _has_locals_call_after_node(stmt: nodes.NodeNG, scope: nodes.FunctionDef) ->
"invalid-all-format",
"Used when __all__ has an invalid format.",
),
"E0606": (
"Possibly using variable %r before assignment",
"possibly-used-before-assignment",
"Emitted when a local variable is accessed before its assignment took place "
"in both branches of an if/else switch.",
),
"E0611": (
"No name %r in module %r",
"no-name-in-module",
Expand Down Expand Up @@ -538,6 +544,7 @@ def __init__(self, node: nodes.NodeNG, scope_type: str) -> None:
)
self.node = node
self.names_under_always_false_test: set[str] = set()
self.names_defined_under_one_branch_only: set[str] = set()

def __repr__(self) -> str:
_to_consumes = [f"{k}->{v}" for k, v in self._atomic.to_consume.items()]
Expand Down Expand Up @@ -744,9 +751,13 @@ def _inferred_to_define_name_raise_or_return(
self.names_under_always_false_test.add(name)
return self._branch_handles_name(name, node.orelse)
# Search both if and else branches
return self._branch_handles_name(name, node.body) and self._branch_handles_name(
name, node.orelse
)
if_branch_handles = self._branch_handles_name(name, node.body)
else_branch_handles = self._branch_handles_name(name, node.orelse)
if if_branch_handles ^ else_branch_handles:
self.names_defined_under_one_branch_only.add(name)
elif name in self.names_defined_under_one_branch_only:
self.names_defined_under_one_branch_only.remove(name)
return if_branch_handles and else_branch_handles

def _branch_handles_name(self, name: str, body: Iterable[nodes.NodeNG]) -> bool:
return any(
Expand Down Expand Up @@ -1996,8 +2007,13 @@ def _report_unfound_name_definition(
elif node.name in current_consumer.consumed_uncertain:
confidence = CONTROL_FLOW

if node.name in current_consumer.names_defined_under_one_branch_only:
msg = "possibly-used-before-assignment"
else:
msg = "used-before-assignment"

self.add_message(
"used-before-assignment",
msg,
args=node.name,
node=node,
confidence=confidence,
Expand Down
1 change: 1 addition & 0 deletions pylintrc
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Original file line number Diff line number Diff line change
Expand Up @@ -109,6 +109,7 @@ disable=
# We anticipate #3512 where it will become optional
fixme,
consider-using-assignment-expr,
possibly-used-before-assignment,


[REPORTS]
Expand Down
6 changes: 3 additions & 3 deletions tests/functional/u/used/used_before_assignment.py
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Expand Up @@ -60,7 +60,7 @@ def redefine_time_import_with_global():
pass
else:
VAR4 = False
if VAR4: # [used-before-assignment]
if VAR4: # [possibly-used-before-assignment]
pass

if FALSE:
Expand All @@ -70,7 +70,7 @@ def redefine_time_import_with_global():
VAR5 = True
else:
VAR5 = True
if VAR5: # [used-before-assignment]
if VAR5: # [possibly-used-before-assignment]
pass

if FALSE:
Expand Down Expand Up @@ -116,7 +116,7 @@ def redefine_time_import_with_global():
VAR11 = num
if VAR11:
VAR12 = False
print(VAR12) # [used-before-assignment]
print(VAR12) # [possibly-used-before-assignment]

def turn_on2(**kwargs):
"""https://github.com/pylint-dev/pylint/issues/7873"""
Expand Down
6 changes: 3 additions & 3 deletions tests/functional/u/used/used_before_assignment.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -5,11 +5,11 @@ used-before-assignment:19:20:19:40:ClassWithProperty:Using variable 'redefine_ti
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
used-before-assignment:63:3:63:7::Using variable 'VAR4' before assignment:INFERENCE
used-before-assignment:73:3:73:7::Using variable 'VAR5' 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
used-before-assignment:119:6:119:11::Using variable 'VAR12' before assignment:CONTROL_FLOW
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
2 changes: 1 addition & 1 deletion tests/functional/u/used/used_before_assignment_issue1081.py
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Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,7 @@ def used_before_assignment_2(a):


def used_before_assignment_3(a):
if x == a: # [used-before-assignment]
if x == a: # [possibly-used-before-assignment]
if x > 3:
x = 2 # [redefined-outer-name]
Comment on lines -19 to 21
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This is kind of a shame, but I can live with it.


Expand Down
2 changes: 1 addition & 1 deletion tests/functional/u/used/used_before_assignment_issue1081.txt
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Expand Up @@ -2,6 +2,6 @@ used-before-assignment:7:7:7:8:used_before_assignment_1:Using variable 'x' befor
redefined-outer-name:8:12:8:13:used_before_assignment_1:Redefining name 'x' from outer scope (line 3):UNDEFINED
used-before-assignment:13:7:13:8:used_before_assignment_2:Using variable 'x' before assignment:HIGH
redefined-outer-name:15:4:15:5:used_before_assignment_2:Redefining name 'x' from outer scope (line 3):UNDEFINED
used-before-assignment:19:7:19:8:used_before_assignment_3:Using variable 'x' before assignment:CONTROL_FLOW
possibly-used-before-assignment:19:7:19:8:used_before_assignment_3:Possibly using variable 'x' before assignment:CONTROL_FLOW
redefined-outer-name:21:12:21:13:used_before_assignment_3:Redefining name 'x' from outer scope (line 3):UNDEFINED
redefined-outer-name:30:4:30:5:not_used_before_assignment_2:Redefining name 'x' from outer scope (line 3):UNDEFINED
6 changes: 3 additions & 3 deletions tests/functional/u/used/used_before_assignment_typing.py
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Expand Up @@ -167,8 +167,8 @@ class ConditionalImportGuardedWhenUsed: # pylint: disable=too-few-public-method

class TypeCheckingMultiBranch: # pylint: disable=too-few-public-methods,unused-variable
"""Test for defines in TYPE_CHECKING if/elif/else branching"""
def defined_in_elif_branch(self) -> calendar.Calendar: # [used-before-assignment]
print(bisect) # [used-before-assignment]
def defined_in_elif_branch(self) -> calendar.Calendar: # [possibly-used-before-assignment]
print(bisect) # [possibly-used-before-assignment]
return calendar.Calendar()

def defined_in_else_branch(self) -> urlopen:
Expand All @@ -177,7 +177,7 @@ def defined_in_else_branch(self) -> urlopen:
print(collections())
return urlopen

def defined_in_nested_if_else(self) -> heapq: # [used-before-assignment]
def defined_in_nested_if_else(self) -> heapq: # [possibly-used-before-assignment]
print(heapq)
return heapq

Expand Down
6 changes: 3 additions & 3 deletions tests/functional/u/used/used_before_assignment_typing.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -3,10 +3,10 @@ undefined-variable:74:26:74:33:MyClass.incorrect_nested_typing_method:Undefined
undefined-variable:79:20:79:27:MyClass.incorrect_default_method:Undefined variable 'MyClass':UNDEFINED
used-before-assignment:140:35:140:39:MyFourthClass.is_close:Using variable 'math' before assignment:INFERENCE
used-before-assignment:153:20:153:28:VariableAnnotationsGuardedByTypeChecking:Using variable 'datetime' before assignment:INFERENCE
used-before-assignment:170:40:170:48:TypeCheckingMultiBranch.defined_in_elif_branch:Using variable 'calendar' before assignment:INFERENCE
used-before-assignment:171:14:171:20:TypeCheckingMultiBranch.defined_in_elif_branch:Using variable 'bisect' before assignment:INFERENCE
possibly-used-before-assignment:170:40:170:48:TypeCheckingMultiBranch.defined_in_elif_branch:Possibly using variable 'calendar' before assignment:INFERENCE
possibly-used-before-assignment:171:14:171:20:TypeCheckingMultiBranch.defined_in_elif_branch:Possibly using variable 'bisect' before assignment:INFERENCE
used-before-assignment:175:14:175:22:TypeCheckingMultiBranch.defined_in_else_branch:Using variable 'zoneinfo' before assignment:INFERENCE
used-before-assignment:180:43:180:48:TypeCheckingMultiBranch.defined_in_nested_if_else:Using variable 'heapq' before assignment:INFERENCE
possibly-used-before-assignment:180:43:180:48:TypeCheckingMultiBranch.defined_in_nested_if_else:Possibly using variable 'heapq' before assignment:INFERENCE
used-before-assignment:184:39:184:44:TypeCheckingMultiBranch.defined_in_try_except:Using variable 'array' before assignment:INFERENCE
used-before-assignment:185:14:185:19:TypeCheckingMultiBranch.defined_in_try_except:Using variable 'types' before assignment:INFERENCE
used-before-assignment:186:14:186:18:TypeCheckingMultiBranch.defined_in_try_except:Using variable 'copy' before assignment:INFERENCE
Expand Down
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