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Merge pull request #838 from crytic/dev-dead-code
Open source dead-code detector
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‎README.md‎

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‎slither/core/declarations/contract.py‎

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@@ -445,7 +445,7 @@ def functions_entry_points(self) -> List["FunctionContract"]:
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return [
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f
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for f in self.functions
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if f.visibility in ["public", "external"] and not f.is_shadowed
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if f.visibility in ["public", "external"] and not f.is_shadowed or f.is_fallback
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]
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@property

‎slither/detectors/all_detectors.py‎

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from .variables.predeclaration_usage_local import PredeclarationUsageLocal
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from .statements.unary import IncorrectUnaryExpressionDetection
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from .operations.missing_zero_address_validation import MissingZeroAddressValidation
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from .functions.dead_code import DeadCode
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#
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#

‎slither/detectors/functions/dead_code.py‎

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"""
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Module detecting dead code
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"""
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from typing import List, Tuple
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from slither.core.declarations import Function, FunctionContract, Contract
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from slither.detectors.abstract_detector import AbstractDetector, DetectorClassification
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class DeadCode(AbstractDetector):
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"""
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Unprotected function detector
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"""
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ARGUMENT = "dead-code"
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HELP = "Functions that are not used"
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IMPACT = DetectorClassification.INFORMATIONAL
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CONFIDENCE = DetectorClassification.MEDIUM
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WIKI = "https://github.com/crytic/slither/wiki/Detector-Documentation#dead-code"
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WIKI_TITLE = "Dead-code"
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WIKI_DESCRIPTION = "Functions that are not sued."
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WIKI_EXPLOIT_SCENARIO = """
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```solidity
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contract Contract{
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function dead_code() internal() {}
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}
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```
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`dead_code` is not used in the contract, and make the code's review more difficult."""
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WIKI_RECOMMENDATION = "Remove unused functions."
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def _detect(self):
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results = []
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functions_used = set()
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for contract in self.compilation_unit.contracts_derived:
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all_functionss_called = [
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f.all_internal_calls() for f in contract.functions_entry_points
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]
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all_functions_called = [item for sublist in all_functionss_called for item in sublist]
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functions_used |= {
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f.canonical_name for f in all_functions_called if isinstance(f, Function)
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}
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all_libss_called = [f.all_library_calls() for f in contract.functions_entry_points]
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all_libs_called: List[Tuple[Contract, Function]] = [
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item for sublist in all_libss_called for item in sublist
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]
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functions_used |= {
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lib[1].canonical_name for lib in all_libs_called if isinstance(lib, tuple)
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}
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for function in sorted(self.compilation_unit.functions, key=lambda x: x.canonical_name):
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if (
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function.visibility in ["public", "external"]
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or function.is_constructor
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or function.is_fallback
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or function.is_constructor_variables
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):
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continue
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if function.canonical_name in functions_used:
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continue
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if isinstance(function, FunctionContract) and (
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function.contract_declarer.is_from_dependency()
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):
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continue
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info = [function, " is never used and should be removed\n"]
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res = self.generate_result(info)
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results.append(res)
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return results

‎tests/detectors/dead-code/0.8.0/dead-code.sol‎

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contract Test{
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function unused() internal{
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}
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}
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contract Test2{
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function unused_but_shadowed() internal virtual{
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}
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}
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contract Test3 is Test2{
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function unused_but_shadowed() internal override{
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}
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function f() public{
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unused_but_shadowed();
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}
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}
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contract Test4 is Test2{
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function unused_but_shadowed() internal override{
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}
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}

‎tests/detectors/dead-code/0.8.0/dead-code.sol.0.8.0.DeadCode.json‎

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[
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[
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{
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"elements": [
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{
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"type": "function",
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"name": "unused",
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"source_mapping": {
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"start": 19,
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"length": 34,
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"filename_used": "/GENERIC_PATH",
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"filename_relative": "tests/detectors/dead-code/0.8.0/dead-code.sol",
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"filename_absolute": "/GENERIC_PATH",
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"filename_short": "tests/detectors/dead-code/0.8.0/dead-code.sol",
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"is_dependency": false,
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"lines": [
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2,
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3,
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4
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],
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"starting_column": 5,
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"ending_column": 6
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},
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"type_specific_fields": {
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"parent": {
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"type": "contract",
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"name": "Test",
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"source_mapping": {
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"start": 0,
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"length": 55,
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"filename_used": "/GENERIC_PATH",
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"filename_relative": "tests/detectors/dead-code/0.8.0/dead-code.sol",
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"filename_absolute": "/GENERIC_PATH",
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"filename_short": "tests/detectors/dead-code/0.8.0/dead-code.sol",
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"is_dependency": false,
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"lines": [
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1,
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2,
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3,
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4,
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5
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],
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"starting_column": 1,
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"ending_column": 2
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}
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},
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"signature": "unused()"
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}
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}
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],
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"description": "Test.unused() (tests/detectors/dead-code/0.8.0/dead-code.sol#2-4) is never used and should be removed\n",
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"markdown": "[Test.unused()](tests/detectors/dead-code/0.8.0/dead-code.sol#L2-L4) is never used and should be removed\n",
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"first_markdown_element": "tests/detectors/dead-code/0.8.0/dead-code.sol#L2-L4",
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"id": "a7c13823116566bbbbb68e8a7efa78fe64785fcb8582069373eda7f27c523cb3",
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"check": "dead-code",
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"impact": "Informational",
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"confidence": "Medium"
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},
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{
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"elements": [
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{
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"type": "function",
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"name": "unused_but_shadowed",
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"source_mapping": {
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"start": 79,
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"length": 55,
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"filename_used": "/GENERIC_PATH",
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"filename_relative": "tests/detectors/dead-code/0.8.0/dead-code.sol",
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"filename_absolute": "/GENERIC_PATH",
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"filename_short": "tests/detectors/dead-code/0.8.0/dead-code.sol",
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"is_dependency": false,
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"lines": [
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10,
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11,
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12
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],
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"starting_column": 5,
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"ending_column": 6
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},
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"type_specific_fields": {
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"parent": {
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"type": "contract",
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"name": "Test2",
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"source_mapping": {
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"start": 58,
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"length": 78,
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"filename_used": "/GENERIC_PATH",
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"filename_relative": "tests/detectors/dead-code/0.8.0/dead-code.sol",
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"filename_absolute": "/GENERIC_PATH",
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"filename_short": "tests/detectors/dead-code/0.8.0/dead-code.sol",
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"is_dependency": false,
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"lines": [
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8,
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9,
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13
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],
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"starting_column": 1,
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"ending_column": 2
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}
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},
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"signature": "unused_but_shadowed()"
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}
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}
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],
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"description": "Test2.unused_but_shadowed() (tests/detectors/dead-code/0.8.0/dead-code.sol#10-12) is never used and should be removed\n",
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"markdown": "[Test2.unused_but_shadowed()](tests/detectors/dead-code/0.8.0/dead-code.sol#L10-L12) is never used and should be removed\n",
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"first_markdown_element": "tests/detectors/dead-code/0.8.0/dead-code.sol#L10-L12",
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"id": "aaba496684b73955e90b555de174e1cd03f0fee337849c4d58c10ef76ff93582",
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"check": "dead-code",
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"impact": "Informational",
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"confidence": "Medium"
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},
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{
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"elements": [
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{
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"type": "function",
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"name": "unused_but_shadowed",
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"source_mapping": {
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"start": 319,
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"length": 56,
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"filename_used": "/GENERIC_PATH",
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"filename_relative": "tests/detectors/dead-code/0.8.0/dead-code.sol",
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"filename_absolute": "/GENERIC_PATH",
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"filename_short": "tests/detectors/dead-code/0.8.0/dead-code.sol",
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"is_dependency": false,
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"lines": [
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28
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],
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"starting_column": 5,
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"ending_column": 6
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},
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"type_specific_fields": {
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"parent": {
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"type": "contract",
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"name": "Test4",
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"source_mapping": {
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"start": 290,
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"length": 87,
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"filename_used": "/GENERIC_PATH",
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"filename_relative": "tests/detectors/dead-code/0.8.0/dead-code.sol",
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"filename_absolute": "/GENERIC_PATH",
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"filename_short": "tests/detectors/dead-code/0.8.0/dead-code.sol",
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"is_dependency": false,
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"lines": [
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25,
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26,
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29
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],
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"starting_column": 1,
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"ending_column": 2
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}
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},
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"signature": "unused_but_shadowed()"
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}
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}
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],
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"description": "Test4.unused_but_shadowed() (tests/detectors/dead-code/0.8.0/dead-code.sol#26-28) is never used and should be removed\n",
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"markdown": "[Test4.unused_but_shadowed()](tests/detectors/dead-code/0.8.0/dead-code.sol#L26-L28) is never used and should be removed\n",
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"first_markdown_element": "tests/detectors/dead-code/0.8.0/dead-code.sol#L26-L28",
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"id": "74ea8421cf7fa9e04d243014b61f3eee7a9c7648df98316c3881dd4f1f2ab3f7",
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"check": "dead-code",
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"impact": "Informational",
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"confidence": "Medium"
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}
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]
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]

‎tests/test_detectors.py‎

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@@ -1134,6 +1134,11 @@ def id_test(test_item: Test):
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"predeclaration_usage_local.sol",
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"0.4.25",
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),
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Test(
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all_detectors.DeadCode,
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"dead-code.sol",
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"0.8.0",
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),
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]
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GENERIC_PATH = "/GENERIC_PATH"
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