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Emit using-constant-test when testing truth value of a call returning a generator #6911

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merged 4 commits into from
Jun 11, 2022
Merged

Emit using-constant-test when testing truth value of a call returning a generator #6911

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21f2709
Emit `using-constant-test` when testing truth value of a call returni…
jacobtylerwalls Jun 10, 2022
bf7f322
don't say "truthy"
jacobtylerwalls Jun 10, 2022
cc90541
avoid two iterations
jacobtylerwalls Jun 10, 2022
7272b43
add comment
jacobtylerwalls Jun 11, 2022
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4 changes: 4 additions & 0 deletions doc/whatsnew/2/2.15/index.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -36,6 +36,10 @@ False negatives fixed

Closes #6648

* Emit ``using-constant-test`` when testing the truth value of a call that only returns generators.

Closes #6909


Other bug fixes
===============
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19 changes: 16 additions & 3 deletions pylint/checkers/base/basic_checker.py
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Expand Up @@ -17,7 +17,7 @@

from pylint import utils as lint_utils
from pylint.checkers import BaseChecker, utils
from pylint.interfaces import HIGH
from pylint.interfaces import HIGH, INFERENCE
from pylint.reporters.ureports import nodes as reporter_nodes
from pylint.utils import LinterStats

Expand Down Expand Up @@ -317,6 +317,17 @@ def _check_using_constant_test(
emit = isinstance(test, (nodes.Const,) + structs + const_nodes)
if not isinstance(test, except_nodes):
inferred = utils.safe_infer(test)
# Emit if the call is to a function that only returns GeneratorExp (always truthy)
elif isinstance(test, nodes.Call):
inferred_call = utils.safe_infer(test.func)
if isinstance(inferred_call, nodes.FunctionDef):
return_nodes = list(inferred_call._get_return_nodes_skip_functions())
if return_nodes and all(
isinstance(n.value, nodes.GeneratorExp) for n in return_nodes
):
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self.add_message(
"using-constant-test", node=node, confidence=INFERENCE
)

if emit:
self.add_message("using-constant-test", node=test)
Expand All @@ -336,12 +347,14 @@ def _check_using_constant_test(
for inf_call in call_inferred:
if inf_call != astroid.Uninferable:
self.add_message(
"missing-parentheses-for-call-in-test", node=test
"missing-parentheses-for-call-in-test",
node=test,
confidence=INFERENCE,
)
break
except astroid.InferenceError:
pass
self.add_message("using-constant-test", node=test)
self.add_message("using-constant-test", node=test, confidence=INFERENCE)

def visit_module(self, _: nodes.Module) -> None:
"""Check module name, docstring and required arguments."""
Expand Down
30 changes: 15 additions & 15 deletions tests/functional/m/missing/missing_parentheses_for_call_in_test.txt
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Original file line number Diff line number Diff line change
@@ -1,15 +1,15 @@
missing-parentheses-for-call-in-test:29:3:29:16::Using a conditional statement with potentially wrong function or method call due to missing parentheses:UNDEFINED
missing-parentheses-for-call-in-test:35:3:35:19::Using a conditional statement with potentially wrong function or method call due to missing parentheses:UNDEFINED
missing-parentheses-for-call-in-test:43:3:43:23::Using a conditional statement with potentially wrong function or method call due to missing parentheses:UNDEFINED
missing-parentheses-for-call-in-test:51:5:51:25::Using a conditional statement with potentially wrong function or method call due to missing parentheses:UNDEFINED
missing-parentheses-for-call-in-test:56:3:56:14::Using a conditional statement with potentially wrong function or method call due to missing parentheses:UNDEFINED
missing-parentheses-for-call-in-test:64:3:64:17::Using a conditional statement with potentially wrong function or method call due to missing parentheses:UNDEFINED
missing-parentheses-for-call-in-test:70:17:70:30::Using a conditional statement with potentially wrong function or method call due to missing parentheses:UNDEFINED
missing-parentheses-for-call-in-test:72:23:72:34::Using a conditional statement with potentially wrong function or method call due to missing parentheses:UNDEFINED
missing-parentheses-for-call-in-test:73:24:73:38::Using a conditional statement with potentially wrong function or method call due to missing parentheses:UNDEFINED
missing-parentheses-for-call-in-test:75:26:75:39::Using a conditional statement with potentially wrong function or method call due to missing parentheses:UNDEFINED
missing-parentheses-for-call-in-test:76:26:76:37::Using a conditional statement with potentially wrong function or method call due to missing parentheses:UNDEFINED
missing-parentheses-for-call-in-test:79:26:79:40::Using a conditional statement with potentially wrong function or method call due to missing parentheses:UNDEFINED
missing-parentheses-for-call-in-test:80:26:80:42::Using a conditional statement with potentially wrong function or method call due to missing parentheses:UNDEFINED
missing-parentheses-for-call-in-test:85:3:85:26::Using a conditional statement with potentially wrong function or method call due to missing parentheses:UNDEFINED
missing-parentheses-for-call-in-test:91:3:91:20::Using a conditional statement with potentially wrong function or method call due to missing parentheses:UNDEFINED
missing-parentheses-for-call-in-test:29:3:29:16::Using a conditional statement with potentially wrong function or method call due to missing parentheses:INFERENCE
missing-parentheses-for-call-in-test:35:3:35:19::Using a conditional statement with potentially wrong function or method call due to missing parentheses:INFERENCE
missing-parentheses-for-call-in-test:43:3:43:23::Using a conditional statement with potentially wrong function or method call due to missing parentheses:INFERENCE
missing-parentheses-for-call-in-test:51:5:51:25::Using a conditional statement with potentially wrong function or method call due to missing parentheses:INFERENCE
missing-parentheses-for-call-in-test:56:3:56:14::Using a conditional statement with potentially wrong function or method call due to missing parentheses:INFERENCE
missing-parentheses-for-call-in-test:64:3:64:17::Using a conditional statement with potentially wrong function or method call due to missing parentheses:INFERENCE
missing-parentheses-for-call-in-test:70:17:70:30::Using a conditional statement with potentially wrong function or method call due to missing parentheses:INFERENCE
missing-parentheses-for-call-in-test:72:23:72:34::Using a conditional statement with potentially wrong function or method call due to missing parentheses:INFERENCE
missing-parentheses-for-call-in-test:73:24:73:38::Using a conditional statement with potentially wrong function or method call due to missing parentheses:INFERENCE
missing-parentheses-for-call-in-test:75:26:75:39::Using a conditional statement with potentially wrong function or method call due to missing parentheses:INFERENCE
missing-parentheses-for-call-in-test:76:26:76:37::Using a conditional statement with potentially wrong function or method call due to missing parentheses:INFERENCE
missing-parentheses-for-call-in-test:79:26:79:40::Using a conditional statement with potentially wrong function or method call due to missing parentheses:INFERENCE
missing-parentheses-for-call-in-test:80:26:80:42::Using a conditional statement with potentially wrong function or method call due to missing parentheses:INFERENCE
missing-parentheses-for-call-in-test:85:3:85:26::Using a conditional statement with potentially wrong function or method call due to missing parentheses:INFERENCE
missing-parentheses-for-call-in-test:91:3:91:20::Using a conditional statement with potentially wrong function or method call due to missing parentheses:INFERENCE
16 changes: 16 additions & 0 deletions tests/functional/u/using_constant_test.py
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Expand Up @@ -147,3 +147,19 @@ def test_good_comprehension_checks():
{data for data in range(100) if abs(data)}
{data: 1 for data in range(100) if data}
{data: 1 for data in range(100)}


# Calls to functions returning generator expressions are always truthy
def get_generator():
return (x for x in range(0))

if get_generator(): # [using-constant-test]
pass

def maybe_get_generator(arg):
if arg:
return (x for x in range(0))
return None

if maybe_get_generator(None):
pass
21 changes: 11 additions & 10 deletions tests/functional/u/using_constant_test.txt
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Original file line number Diff line number Diff line change
@@ -1,8 +1,8 @@
using-constant-test:22:3:22:14::Using a conditional statement with a constant value:UNDEFINED
using-constant-test:22:3:22:14::Using a conditional statement with a constant value:INFERENCE
using-constant-test:26:3:26:31::Using a conditional statement with a constant value:UNDEFINED
using-constant-test:29:3:29:15:<lambda>:Using a conditional statement with a constant value:UNDEFINED
using-constant-test:32:3:32:11::Using a conditional statement with a constant value:UNDEFINED
using-constant-test:35:3:35:8::Using a conditional statement with a constant value:UNDEFINED
using-constant-test:32:3:32:11::Using a conditional statement with a constant value:INFERENCE
using-constant-test:35:3:35:8::Using a conditional statement with a constant value:INFERENCE
using-constant-test:38:3:38:4::Using a conditional statement with a constant value:UNDEFINED
using-constant-test:41:3:41:7::Using a conditional statement with a constant value:UNDEFINED
using-constant-test:44:3:44:5::Using a conditional statement with a constant value:UNDEFINED
Expand All @@ -14,14 +14,15 @@ using-constant-test:59:3:59:12::Using a conditional statement with a constant va
using-constant-test:62:3:62:5::Using a conditional statement with a constant value:UNDEFINED
using-constant-test:65:3:65:12::Using a conditional statement with a constant value:UNDEFINED
using-constant-test:68:3:68:5::Using a conditional statement with a constant value:UNDEFINED
using-constant-test:73:3:73:12::Using a conditional statement with a constant value:UNDEFINED
using-constant-test:73:3:73:12::Using a conditional statement with a constant value:INFERENCE
using-constant-test:76:8:76:9::Using a conditional statement with a constant value:UNDEFINED
using-constant-test:80:36:80:39:test_comprehensions:Using a conditional statement with a constant value:UNDEFINED
using-constant-test:80:36:80:39:test_comprehensions:Using a conditional statement with a constant value:INFERENCE
using-constant-test:81:36:81:37:test_comprehensions:Using a conditional statement with a constant value:UNDEFINED
using-constant-test:82:36:82:39:test_comprehensions:Using a conditional statement with a constant value:UNDEFINED
using-constant-test:82:36:82:39:test_comprehensions:Using a conditional statement with a constant value:INFERENCE
using-constant-test:83:36:83:37:test_comprehensions:Using a conditional statement with a constant value:UNDEFINED
using-constant-test:84:36:84:39:test_comprehensions:Using a conditional statement with a constant value:UNDEFINED
using-constant-test:85:39:85:42:test_comprehensions:Using a conditional statement with a constant value:UNDEFINED
using-constant-test:89:3:89:15::Using a conditional statement with a constant value:UNDEFINED
using-constant-test:93:3:93:18::Using a conditional statement with a constant value:UNDEFINED
using-constant-test:84:36:84:39:test_comprehensions:Using a conditional statement with a constant value:INFERENCE
using-constant-test:85:39:85:42:test_comprehensions:Using a conditional statement with a constant value:INFERENCE
using-constant-test:89:3:89:15::Using a conditional statement with a constant value:INFERENCE
using-constant-test:93:3:93:18::Using a conditional statement with a constant value:INFERENCE
comparison-of-constants:117:3:117:8::"Comparison between constants: '2 < 3' has a constant value":HIGH
using-constant-test:156:0:157:8::Using a conditional statement with a constant value:INFERENCE