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Improve tuple analysis for unused-return detector #1861

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May 15, 2023
Merged

Improve tuple analysis for unused-return detector #1861

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42 changes: 28 additions & 14 deletions slither/detectors/operations/unused_return_values.py
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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,7 @@
"""
from typing import List

from slither.core.cfg.node import Node
from slither.core.cfg.node import Node, NodeType
from slither.core.declarations import Function
from slither.core.declarations.function_contract import FunctionContract
from slither.core.variables.state_variable import StateVariable
Expand All @@ -12,8 +12,8 @@
DetectorClassification,
DETECTOR_INFO,
)
from slither.slithir.operations import HighLevelCall
from slither.slithir.operations.operation import Operation
from slither.slithir.operations import HighLevelCall, Assignment, Unpack, Operation
from slither.slithir.variables import TupleVariable
from slither.utils.output import Output


Expand Down Expand Up @@ -50,13 +50,18 @@ class UnusedReturnValues(AbstractDetector):
WIKI_RECOMMENDATION = "Ensure that all the return values of the function calls are used."

def _is_instance(self, ir: Operation) -> bool: # pylint: disable=no-self-use
return isinstance(ir, HighLevelCall) and (
(
isinstance(ir.function, Function)
and ir.function.solidity_signature
not in ["transfer(address,uint256)", "transferFrom(address,address,uint256)"]
return (
isinstance(ir, HighLevelCall)
and (
(
isinstance(ir.function, Function)
and ir.function.solidity_signature
not in ["transfer(address,uint256)", "transferFrom(address,address,uint256)"]
)
or not isinstance(ir.function, Function)
)
or not isinstance(ir.function, Function)
or ir.node.type == NodeType.TRY
and isinstance(ir, (Assignment, Unpack))
)

def detect_unused_return_values(
Expand All @@ -71,18 +76,27 @@ def detect_unused_return_values(
"""
values_returned = []
nodes_origin = {}
# pylint: disable=too-many-nested-blocks
for n in f.nodes:
for ir in n.irs:
if self._is_instance(ir):
# if a return value is stored in a state variable, it's ok
if ir.lvalue and not isinstance(ir.lvalue, StateVariable):
values_returned.append(ir.lvalue)
values_returned.append((ir.lvalue, None))
nodes_origin[ir.lvalue] = ir
if isinstance(ir.lvalue, TupleVariable):
# we iterate the number of elements the tuple has
# and add a (variable, index) in values_returned for each of them
for index in range(len(ir.lvalue.type)):
values_returned.append((ir.lvalue, index))
for read in ir.read:
if read in values_returned:
values_returned.remove(read)

return [nodes_origin[value].node for value in values_returned]
remove = (read, ir.index) if isinstance(ir, Unpack) else (read, None)
if remove in values_returned:
# this is needed to remove the tuple variable when the first time one of its element is used
if remove[1] is not None and (remove[0], None) in values_returned:
values_returned.remove((remove[0], None))
values_returned.remove(remove)
return [nodes_origin[value].node for (value, _) in values_returned]

def _detect(self) -> List[Output]:
"""Detect high level calls which return a value that are never used"""
Expand Down
8 changes: 6 additions & 2 deletions ...etectors/snapshots/detectors__detector_UnusedReturnValues_0_4_25_unused_return_sol__0.txt
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@@ -1,4 +1,8 @@
User.test(Target) (tests/e2e/detectors/test_data/unused-return/0.4.25/unused_return.sol#17-29) ignores return value by t.f() (tests/e2e/detectors/test_data/unused-return/0.4.25/unused_return.sol#18)
User.test(Target) (tests/e2e/detectors/test_data/unused-return/0.4.25/unused_return.sol#18-37) ignores return value by t.g() (tests/e2e/detectors/test_data/unused-return/0.4.25/unused_return.sol#31)

User.test(Target) (tests/e2e/detectors/test_data/unused-return/0.4.25/unused_return.sol#17-29) ignores return value by a.add(0) (tests/e2e/detectors/test_data/unused-return/0.4.25/unused_return.sol#22)
User.test(Target) (tests/e2e/detectors/test_data/unused-return/0.4.25/unused_return.sol#18-37) ignores return value by t.f() (tests/e2e/detectors/test_data/unused-return/0.4.25/unused_return.sol#19)

User.test(Target) (tests/e2e/detectors/test_data/unused-return/0.4.25/unused_return.sol#18-37) ignores return value by a.add(0) (tests/e2e/detectors/test_data/unused-return/0.4.25/unused_return.sol#23)

User.test(Target) (tests/e2e/detectors/test_data/unused-return/0.4.25/unused_return.sol#18-37) ignores return value by (e) = t.g() (tests/e2e/detectors/test_data/unused-return/0.4.25/unused_return.sol#36)

8 changes: 6 additions & 2 deletions ...etectors/snapshots/detectors__detector_UnusedReturnValues_0_5_16_unused_return_sol__0.txt
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@@ -1,4 +1,8 @@
User.test(Target) (tests/e2e/detectors/test_data/unused-return/0.5.16/unused_return.sol#17-29) ignores return value by t.f() (tests/e2e/detectors/test_data/unused-return/0.5.16/unused_return.sol#18)
User.test(Target) (tests/e2e/detectors/test_data/unused-return/0.5.16/unused_return.sol#18-37) ignores return value by (e) = t.g() (tests/e2e/detectors/test_data/unused-return/0.5.16/unused_return.sol#36)

User.test(Target) (tests/e2e/detectors/test_data/unused-return/0.5.16/unused_return.sol#17-29) ignores return value by a.add(0) (tests/e2e/detectors/test_data/unused-return/0.5.16/unused_return.sol#22)
User.test(Target) (tests/e2e/detectors/test_data/unused-return/0.5.16/unused_return.sol#18-37) ignores return value by a.add(0) (tests/e2e/detectors/test_data/unused-return/0.5.16/unused_return.sol#23)

User.test(Target) (tests/e2e/detectors/test_data/unused-return/0.5.16/unused_return.sol#18-37) ignores return value by t.g() (tests/e2e/detectors/test_data/unused-return/0.5.16/unused_return.sol#31)

User.test(Target) (tests/e2e/detectors/test_data/unused-return/0.5.16/unused_return.sol#18-37) ignores return value by t.f() (tests/e2e/detectors/test_data/unused-return/0.5.16/unused_return.sol#19)

8 changes: 6 additions & 2 deletions ...etectors/snapshots/detectors__detector_UnusedReturnValues_0_6_11_unused_return_sol__0.txt
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@@ -1,4 +1,8 @@
User.test(Target) (tests/e2e/detectors/test_data/unused-return/0.6.11/unused_return.sol#17-29) ignores return value by a.add(0) (tests/e2e/detectors/test_data/unused-return/0.6.11/unused_return.sol#22)
User.test(Target) (tests/e2e/detectors/test_data/unused-return/0.6.11/unused_return.sol#18-37) ignores return value by t.f() (tests/e2e/detectors/test_data/unused-return/0.6.11/unused_return.sol#19)

User.test(Target) (tests/e2e/detectors/test_data/unused-return/0.6.11/unused_return.sol#17-29) ignores return value by t.f() (tests/e2e/detectors/test_data/unused-return/0.6.11/unused_return.sol#18)
User.test(Target) (tests/e2e/detectors/test_data/unused-return/0.6.11/unused_return.sol#18-37) ignores return value by a.add(0) (tests/e2e/detectors/test_data/unused-return/0.6.11/unused_return.sol#23)

User.test(Target) (tests/e2e/detectors/test_data/unused-return/0.6.11/unused_return.sol#18-37) ignores return value by t.g() (tests/e2e/detectors/test_data/unused-return/0.6.11/unused_return.sol#31)

User.test(Target) (tests/e2e/detectors/test_data/unused-return/0.6.11/unused_return.sol#18-37) ignores return value by (e) = t.g() (tests/e2e/detectors/test_data/unused-return/0.6.11/unused_return.sol#36)
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It would be good if we could get this to display as (e, ) = t.g() so it's clear what is being ignored

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I agree, but this should be done in a separate PR


8 changes: 6 additions & 2 deletions ...detectors/snapshots/detectors__detector_UnusedReturnValues_0_7_6_unused_return_sol__0.txt
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@@ -1,4 +1,8 @@
User.test(Target) (tests/e2e/detectors/test_data/unused-return/0.7.6/unused_return.sol#17-29) ignores return value by a.add(0) (tests/e2e/detectors/test_data/unused-return/0.7.6/unused_return.sol#22)
User.test(Target) (tests/e2e/detectors/test_data/unused-return/0.7.6/unused_return.sol#18-37) ignores return value by t.g() (tests/e2e/detectors/test_data/unused-return/0.7.6/unused_return.sol#31)

User.test(Target) (tests/e2e/detectors/test_data/unused-return/0.7.6/unused_return.sol#17-29) ignores return value by t.f() (tests/e2e/detectors/test_data/unused-return/0.7.6/unused_return.sol#18)
User.test(Target) (tests/e2e/detectors/test_data/unused-return/0.7.6/unused_return.sol#18-37) ignores return value by a.add(0) (tests/e2e/detectors/test_data/unused-return/0.7.6/unused_return.sol#23)

User.test(Target) (tests/e2e/detectors/test_data/unused-return/0.7.6/unused_return.sol#18-37) ignores return value by t.f() (tests/e2e/detectors/test_data/unused-return/0.7.6/unused_return.sol#19)

User.test(Target) (tests/e2e/detectors/test_data/unused-return/0.7.6/unused_return.sol#18-37) ignores return value by (e) = t.g() (tests/e2e/detectors/test_data/unused-return/0.7.6/unused_return.sol#36)

8 changes: 8 additions & 0 deletions tests/e2e/detectors/test_data/unused-return/0.4.25/unused_return.sol
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Expand Up @@ -8,6 +8,7 @@ library SafeMath{

contract Target{
function f() public returns(uint);
function g() public returns(uint, uint);
}

contract User{
Expand All @@ -26,5 +27,12 @@ contract User{
// As the value returned by the call is stored
// (unused local variable should be another issue)
uint b = a.add(1);

t.g();

(uint c, uint d) = t.g();

// Detected as unused return
(uint e,) = t.g();
}
}
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8 changes: 8 additions & 0 deletions tests/e2e/detectors/test_data/unused-return/0.5.16/unused_return.sol
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Expand Up @@ -8,6 +8,7 @@ library SafeMath{

contract Target{
function f() public returns(uint);
function g() public returns(uint, uint);
}

contract User{
Expand All @@ -26,5 +27,12 @@ contract User{
// As the value returned by the call is stored
// (unused local variable should be another issue)
uint b = a.add(1);

t.g();

(uint c, uint d) = t.g();

// Detected as unused return
(uint e,) = t.g();
}
}
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8 changes: 8 additions & 0 deletions tests/e2e/detectors/test_data/unused-return/0.6.11/unused_return.sol
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Expand Up @@ -8,6 +8,7 @@ library SafeMath{

abstract contract Target{
function f() public virtual returns(uint);
function g() public virtual returns(uint, uint);
}

contract User{
Expand All @@ -26,5 +27,12 @@ contract User{
// As the value returned by the call is stored
// (unused local variable should be another issue)
uint b = a.add(1);

t.g();

(uint c, uint d) = t.g();

// Detected as unused return
(uint e,) = t.g();
}
}
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8 changes: 8 additions & 0 deletions tests/e2e/detectors/test_data/unused-return/0.7.6/unused_return.sol
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Expand Up @@ -8,6 +8,7 @@ library SafeMath{

abstract contract Target{
function f() public virtual returns(uint);
function g() public virtual returns(uint, uint);
}

contract User{
Expand All @@ -26,5 +27,12 @@ contract User{
// As the value returned by the call is stored
// (unused local variable should be another issue)
uint b = a.add(1);

t.g();

(uint c, uint d) = t.g();

// Detected as unused return
(uint e,) = t.g();
}
}
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