From 08b47954cdf280aee415449594519f95efef572a Mon Sep 17 00:00:00 2001
From: Goran Vladika <goran.vladika@gmail.com>
Date: Thu, 12 Sep 2024 12:56:57 +0200
Subject: [PATCH 01/16] Initial skeleton for unused custom errors detector

---
 slither/detectors/all_detectors.py            |   1 +
 .../variables/unused_custom_errors.py         |  45 ++++++++++++++++++
 .../0.8.15/unused_custom_errors.sol           |  11 +++++
 .../unused_custom_errors.sol-0.8.15.zip       | Bin 0 -> 1127 bytes
 tests/e2e/detectors/test_detectors.py         |   5 ++
 5 files changed, 62 insertions(+)
 create mode 100644 slither/detectors/variables/unused_custom_errors.py
 create mode 100644 tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/unused_custom_errors.sol
 create mode 100644 tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/unused_custom_errors.sol-0.8.15.zip

diff --git a/slither/detectors/all_detectors.py b/slither/detectors/all_detectors.py
index 44a168c2b..3b1ecd150 100644
--- a/slither/detectors/all_detectors.py
+++ b/slither/detectors/all_detectors.py
@@ -19,6 +19,7 @@
 from .reentrancy.reentrancy_no_gas import ReentrancyNoGas
 from .reentrancy.reentrancy_events import ReentrancyEvent
 from .variables.unused_state_variables import UnusedStateVars
+from .variables.unused_custom_errors import UnusedCustomErrors
 from .variables.could_be_constant import CouldBeConstant
 from .variables.could_be_immutable import CouldBeImmutable
 from .statements.tx_origin import TxOrigin
diff --git a/slither/detectors/variables/unused_custom_errors.py b/slither/detectors/variables/unused_custom_errors.py
new file mode 100644
index 000000000..76bf0f2e1
--- /dev/null
+++ b/slither/detectors/variables/unused_custom_errors.py
@@ -0,0 +1,45 @@
+"""
+Module detecting unused custom errors
+"""
+from typing import List, Dict
+
+from slither.core.compilation_unit import SlitherCompilationUnit
+from slither.detectors.abstract_detector import (
+    AbstractDetector,
+    DetectorClassification,
+    DETECTOR_INFO,
+)
+from slither.formatters.variables.unused_state_variables import custom_format
+from slither.utils.output import Output
+
+class UnusedCustomErrors(AbstractDetector):
+    """
+    Unused custom errors detector
+    """
+
+    ARGUMENT = "unused-custom-errors"
+    HELP = "Unused Custom Errors"
+    IMPACT = DetectorClassification.INFORMATIONAL
+    CONFIDENCE = DetectorClassification.HIGH
+
+    WIKI = "https://github.com/crytic/slither/wiki/Detector-Documentation#unused-state-variable"
+
+    WIKI_TITLE = "Unused state variable"
+    WIKI_DESCRIPTION = "Unused state variable."
+    WIKI_EXPLOIT_SCENARIO = ""
+    WIKI_RECOMMENDATION = "Remove unused state variables."
+
+    def _detect(self) -> List[Output]:
+        """Detect unused state variables"""
+        results = []
+        for c in self.compilation_unit.contracts_derived:
+            for custom_error in c.custom_errors:
+                info: DETECTOR_INFO = [custom_error.name, " is never used in ", c, "\n"]
+                json = self.generate_result(info)
+                results.append(json)
+
+        return results
+
+    @staticmethod
+    def _format(compilation_unit: SlitherCompilationUnit, result: Dict) -> None:
+        custom_format(compilation_unit, result)
diff --git a/tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/unused_custom_errors.sol b/tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/unused_custom_errors.sol
new file mode 100644
index 000000000..e337f8925
--- /dev/null
+++ b/tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/unused_custom_errors.sol
@@ -0,0 +1,11 @@
+//pragma solidity ^0.4.24;
+
+contract A {
+    error Unused1();
+    error Unused2();
+    error Unused3();
+
+    function x() public pure {
+        revert Unused1();
+    }
+}
diff --git a/tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/unused_custom_errors.sol-0.8.15.zip b/tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/unused_custom_errors.sol-0.8.15.zip
new file mode 100644
index 0000000000000000000000000000000000000000..61cc0dca55f66d3153dc0732a80e5fd0b31f1796
GIT binary patch
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diff --git a/tests/e2e/detectors/test_detectors.py b/tests/e2e/detectors/test_detectors.py
index 2c6a5f55a..1dc3fe07e 100644
--- a/tests/e2e/detectors/test_detectors.py
+++ b/tests/e2e/detectors/test_detectors.py
@@ -401,6 +401,11 @@ def id_test(test_item: Test):
         "unused_state.sol",
         "0.7.6",
     ),
+    Test(
+        all_detectors.UnusedCustomErrors,
+        "unused_custom_errors.sol",
+        "0.8.15",
+    ),
     Test(all_detectors.LockedEther, "locked_ether.sol", "0.4.25"),
     Test(all_detectors.LockedEther, "locked_ether.sol", "0.5.16"),
     Test(all_detectors.LockedEther, "locked_ether.sol", "0.6.11"),

From 617fe8b6faf0f372fc2f072260dbd2db9e4b940d Mon Sep 17 00:00:00 2001
From: Goran Vladika <goran.vladika@gmail.com>
Date: Tue, 17 Sep 2024 12:17:26 +0200
Subject: [PATCH 02/16] Add function that checks if custom error is unused

---
 .../variables/unused_custom_errors.py         | 34 ++++++++++++-------
 1 file changed, 21 insertions(+), 13 deletions(-)

diff --git a/slither/detectors/variables/unused_custom_errors.py b/slither/detectors/variables/unused_custom_errors.py
index 76bf0f2e1..f0b61dd3e 100644
--- a/slither/detectors/variables/unused_custom_errors.py
+++ b/slither/detectors/variables/unused_custom_errors.py
@@ -4,12 +4,13 @@
 from typing import List, Dict
 
 from slither.core.compilation_unit import SlitherCompilationUnit
+from slither.core.declarations.custom_error import CustomError
+from slither.core.declarations.solidity_variables import SolidityCustomRevert
 from slither.detectors.abstract_detector import (
     AbstractDetector,
     DetectorClassification,
     DETECTOR_INFO,
 )
-from slither.formatters.variables.unused_state_variables import custom_format
 from slither.utils.output import Output
 
 class UnusedCustomErrors(AbstractDetector):
@@ -22,24 +23,31 @@ class UnusedCustomErrors(AbstractDetector):
     IMPACT = DetectorClassification.INFORMATIONAL
     CONFIDENCE = DetectorClassification.HIGH
 
-    WIKI = "https://github.com/crytic/slither/wiki/Detector-Documentation#unused-state-variable"
+    WIKI = "https://github.com/crytic/slither/wiki/Detector-Documentation#unused-custom-error"
 
-    WIKI_TITLE = "Unused state variable"
-    WIKI_DESCRIPTION = "Unused state variable."
+    WIKI_TITLE = "Unused custom error"
+    WIKI_DESCRIPTION = "Unused custom error."
     WIKI_EXPLOIT_SCENARIO = ""
-    WIKI_RECOMMENDATION = "Remove unused state variables."
+    WIKI_RECOMMENDATION = "Remove unused custom errors."
 
     def _detect(self) -> List[Output]:
-        """Detect unused state variables"""
+
+
+        """Detect unused custom errors"""
         results = []
         for c in self.compilation_unit.contracts_derived:
             for custom_error in c.custom_errors:
-                info: DETECTOR_INFO = [custom_error.name, " is never used in ", c, "\n"]
-                json = self.generate_result(info)
-                results.append(json)
-
+                if not self._isCustomErrorUsed(custom_error):
+                    info: DETECTOR_INFO = ["Unused custom error: ", custom_error.name, "\n"]
+                    json = self.generate_result(info)
+                    results.append(json)
         return results
 
-    @staticmethod
-    def _format(compilation_unit: SlitherCompilationUnit, result: Dict) -> None:
-        custom_format(compilation_unit, result)
+    def _isCustomErrorUsed(self, custom_error: CustomError) -> bool:
+        for c in self.compilation_unit.contracts_derived:
+            for f in c.functions:
+                for int_call in f._internal_calls:
+                    print("Comparing: ", int_call.name, custom_error.name)
+                    if type(int_call) is SolidityCustomRevert and custom_error.name in int_call.name:
+                        return True
+        return False
\ No newline at end of file

From 0edd70c1a81f8fe52e4564e0f4edaa0cca585082 Mon Sep 17 00:00:00 2001
From: Goran Vladika <goran.vladika@gmail.com>
Date: Tue, 17 Sep 2024 12:17:50 +0200
Subject: [PATCH 03/16] Add first sol contract for testing unused custom errors

---
 .../0.8.15/unused_custom_errors.sol           |  13 +++++++++----
 .../unused_custom_errors.sol-0.8.15.zip       | Bin 1127 -> 2624 bytes
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/unused_custom_errors.sol b/tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/unused_custom_errors.sol
index e337f8925..b8e24a971 100644
--- a/tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/unused_custom_errors.sol
+++ b/tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/unused_custom_errors.sol
@@ -2,10 +2,15 @@
 
 contract A {
     error Unused1();
-    error Unused2();
-    error Unused3();
+    error UsedError(address x);
 
-    function x() public pure {
-        revert Unused1();
+    constructor() public {}
+
+    function x() public view {
+        uint256 d = 7;
+        if (msg.sender == address(0)) {
+            d = 100;
+            revert UsedError(msg.sender);
+        }
     }
 }
diff --git a/tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/unused_custom_errors.sol-0.8.15.zip b/tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/unused_custom_errors.sol-0.8.15.zip
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From 82dfd33ec0590bda7a543e6997e32f611454d2c1 Mon Sep 17 00:00:00 2001
From: Goran Vladika <goran.vladika@gmail.com>
Date: Tue, 17 Sep 2024 15:13:27 +0200
Subject: [PATCH 04/16] Refactor and include errors defined outside of
 contracts

---
 .../variables/unused_custom_errors.py         | 50 ++++++++++++-------
 1 file changed, 32 insertions(+), 18 deletions(-)

diff --git a/slither/detectors/variables/unused_custom_errors.py b/slither/detectors/variables/unused_custom_errors.py
index f0b61dd3e..d6dfaf41d 100644
--- a/slither/detectors/variables/unused_custom_errors.py
+++ b/slither/detectors/variables/unused_custom_errors.py
@@ -1,7 +1,7 @@
 """
 Module detecting unused custom errors
 """
-from typing import List, Dict
+from typing import List, Set
 
 from slither.core.compilation_unit import SlitherCompilationUnit
 from slither.core.declarations.custom_error import CustomError
@@ -13,6 +13,7 @@
 )
 from slither.utils.output import Output
 
+
 class UnusedCustomErrors(AbstractDetector):
     """
     Unused custom errors detector
@@ -31,23 +32,36 @@ class UnusedCustomErrors(AbstractDetector):
     WIKI_RECOMMENDATION = "Remove unused custom errors."
 
     def _detect(self) -> List[Output]:
+        """Detect unused custom errors"""
+        defined_custom_errors: Set[CustomError] = set()
+        custom_reverts: Set[SolidityCustomRevert] = set()
+        unused_custom_errors: Set[CustomError] = set()
 
+        # Collect all custom errors defined in the contracts
+        for contract in self.compilation_unit.contracts:
+            for custom_error in contract.custom_errors:
+                defined_custom_errors.add(custom_error)
+
+        # Add custom errors defined outside of contracts
+        for custom_error in self.compilation_unit.custom_errors:
+            defined_custom_errors.add(custom_error)
+
+        # Collect all used custom errors
+        for contract in self.compilation_unit.contracts:
+            for function in contract.functions_and_modifiers:
+                for internal_call in function.internal_calls:
+                    if isinstance(internal_call, SolidityCustomRevert):
+                        custom_reverts.add(internal_call)
+
+        # Find unused custom errors
+        for defined_error in defined_custom_errors:
+            if not any(defined_error.name in custom_revert.name for custom_revert in custom_reverts):
+                unused_custom_errors.add(defined_error)
 
-        """Detect unused custom errors"""
         results = []
-        for c in self.compilation_unit.contracts_derived:
-            for custom_error in c.custom_errors:
-                if not self._isCustomErrorUsed(custom_error):
-                    info: DETECTOR_INFO = ["Unused custom error: ", custom_error.name, "\n"]
-                    json = self.generate_result(info)
-                    results.append(json)
-        return results
-
-    def _isCustomErrorUsed(self, custom_error: CustomError) -> bool:
-        for c in self.compilation_unit.contracts_derived:
-            for f in c.functions:
-                for int_call in f._internal_calls:
-                    print("Comparing: ", int_call.name, custom_error.name)
-                    if type(int_call) is SolidityCustomRevert and custom_error.name in int_call.name:
-                        return True
-        return False
\ No newline at end of file
+        for custom_error in unused_custom_errors:
+            info: DETECTOR_INFO = ["Unused custom error: # ", custom_error.full_name, "\n"]
+            json = self.generate_result(info)
+            results.append(json)
+
+        return results
\ No newline at end of file

From a6b84cfc8a7fc157133128da76475029e915b112 Mon Sep 17 00:00:00 2001
From: Goran Vladika <goran.vladika@gmail.com>
Date: Wed, 18 Sep 2024 14:29:09 +0200
Subject: [PATCH 05/16] Change format

---
 slither/detectors/variables/unused_custom_errors.py | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/slither/detectors/variables/unused_custom_errors.py b/slither/detectors/variables/unused_custom_errors.py
index d6dfaf41d..3db6c021f 100644
--- a/slither/detectors/variables/unused_custom_errors.py
+++ b/slither/detectors/variables/unused_custom_errors.py
@@ -46,7 +46,7 @@ def _detect(self) -> List[Output]:
         for custom_error in self.compilation_unit.custom_errors:
             defined_custom_errors.add(custom_error)
 
-        # Collect all used custom errors
+        # Collect all custom errors used in revertsCustomError
         for contract in self.compilation_unit.contracts:
             for function in contract.functions_and_modifiers:
                 for internal_call in function.internal_calls:
@@ -59,9 +59,10 @@ def _detect(self) -> List[Output]:
                 unused_custom_errors.add(defined_error)
 
         results = []
-        for custom_error in unused_custom_errors:
-            info: DETECTOR_INFO = ["Unused custom error: # ", custom_error.full_name, "\n"]
-            json = self.generate_result(info)
-            results.append(json)
+        if len(unused_custom_errors) > 0:
+            info: DETECTOR_INFO = ["The following unused error(s) should be removed:"]
+            for custom_error in unused_custom_errors:
+                info += ["\n\t-", custom_error.full_name, " ", custom_error.compilation_unit, "\n"]
+            results.append(self.generate_result(info))
 
         return results
\ No newline at end of file

From 0efbf5ccc08a5379193b4830e44cc0cb1aa40aaf Mon Sep 17 00:00:00 2001
From: Goran Vladika <goran.vladika@gmail.com>
Date: Tue, 24 Sep 2024 11:54:22 +0200
Subject: [PATCH 06/16] Add filename to the output

---
 .../variables/unused_custom_errors.py         | 23 ++++++++++---------
 1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/slither/detectors/variables/unused_custom_errors.py b/slither/detectors/variables/unused_custom_errors.py
index 3db6c021f..913374438 100644
--- a/slither/detectors/variables/unused_custom_errors.py
+++ b/slither/detectors/variables/unused_custom_errors.py
@@ -1,7 +1,7 @@
 """
 Module detecting unused custom errors
 """
-from typing import List, Set
+from typing import List, Tuple
 
 from slither.core.compilation_unit import SlitherCompilationUnit
 from slither.core.declarations.custom_error import CustomError
@@ -33,36 +33,37 @@ class UnusedCustomErrors(AbstractDetector):
 
     def _detect(self) -> List[Output]:
         """Detect unused custom errors"""
-        defined_custom_errors: Set[CustomError] = set()
-        custom_reverts: Set[SolidityCustomRevert] = set()
-        unused_custom_errors: Set[CustomError] = set()
+        defined_custom_errors: List[Tuple[CustomError,str]] = []
+        custom_reverts: List[SolidityCustomRevert] = []
+        unused_custom_errors: List[Tuple[CustomError,str]] = []
 
         # Collect all custom errors defined in the contracts
         for contract in self.compilation_unit.contracts:
+            contract.custom_errors_declared
             for custom_error in contract.custom_errors:
-                defined_custom_errors.add(custom_error)
+                defined_custom_errors.append((custom_error, custom_error.contract.file_scope.filename.short))
 
         # Add custom errors defined outside of contracts
         for custom_error in self.compilation_unit.custom_errors:
-            defined_custom_errors.add(custom_error)
+            defined_custom_errors.append((custom_error, custom_error.file_scope.filename.short))
 
         # Collect all custom errors used in revertsCustomError
         for contract in self.compilation_unit.contracts:
             for function in contract.functions_and_modifiers:
                 for internal_call in function.internal_calls:
                     if isinstance(internal_call, SolidityCustomRevert):
-                        custom_reverts.add(internal_call)
+                        custom_reverts.append(internal_call)
 
         # Find unused custom errors
-        for defined_error in defined_custom_errors:
+        for defined_error, file_name in defined_custom_errors:
             if not any(defined_error.name in custom_revert.name for custom_revert in custom_reverts):
-                unused_custom_errors.add(defined_error)
+                unused_custom_errors.append((defined_error, file_name))
 
         results = []
         if len(unused_custom_errors) > 0:
             info: DETECTOR_INFO = ["The following unused error(s) should be removed:"]
-            for custom_error in unused_custom_errors:
-                info += ["\n\t-", custom_error.full_name, " ", custom_error.compilation_unit, "\n"]
+            for custom_error, file_name in unused_custom_errors:
+                info += ["\n\t-", custom_error.full_name, " (", file_name, ")\n"]
             results.append(self.generate_result(info))
 
         return results
\ No newline at end of file

From 53e896ce3bd01a75bd2d700c47c9b1332281bc82 Mon Sep 17 00:00:00 2001
From: Goran Vladika <goran.vladika@gmail.com>
Date: Tue, 24 Sep 2024 12:01:15 +0200
Subject: [PATCH 07/16] Simplify fetching the file name

---
 .../variables/unused_custom_errors.py         | 22 +++++++++----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/slither/detectors/variables/unused_custom_errors.py b/slither/detectors/variables/unused_custom_errors.py
index 913374438..f4262ac72 100644
--- a/slither/detectors/variables/unused_custom_errors.py
+++ b/slither/detectors/variables/unused_custom_errors.py
@@ -1,10 +1,9 @@
 """
 Module detecting unused custom errors
 """
-from typing import List, Tuple
-
-from slither.core.compilation_unit import SlitherCompilationUnit
+from typing import List
 from slither.core.declarations.custom_error import CustomError
+from slither.core.declarations.custom_error_top_level import CustomErrorTopLevel
 from slither.core.declarations.solidity_variables import SolidityCustomRevert
 from slither.detectors.abstract_detector import (
     AbstractDetector,
@@ -33,19 +32,19 @@ class UnusedCustomErrors(AbstractDetector):
 
     def _detect(self) -> List[Output]:
         """Detect unused custom errors"""
-        defined_custom_errors: List[Tuple[CustomError,str]] = []
+        declared_custom_errors: List[CustomError] = []
         custom_reverts: List[SolidityCustomRevert] = []
-        unused_custom_errors: List[Tuple[CustomError,str]] = []
+        unused_custom_errors: List[CustomError] = []
 
         # Collect all custom errors defined in the contracts
         for contract in self.compilation_unit.contracts:
             contract.custom_errors_declared
             for custom_error in contract.custom_errors:
-                defined_custom_errors.append((custom_error, custom_error.contract.file_scope.filename.short))
+                declared_custom_errors.append(custom_error)
 
         # Add custom errors defined outside of contracts
         for custom_error in self.compilation_unit.custom_errors:
-            defined_custom_errors.append((custom_error, custom_error.file_scope.filename.short))
+            declared_custom_errors.append(custom_error)
 
         # Collect all custom errors used in revertsCustomError
         for contract in self.compilation_unit.contracts:
@@ -55,15 +54,16 @@ def _detect(self) -> List[Output]:
                         custom_reverts.append(internal_call)
 
         # Find unused custom errors
-        for defined_error, file_name in defined_custom_errors:
+        for defined_error in declared_custom_errors:
             if not any(defined_error.name in custom_revert.name for custom_revert in custom_reverts):
-                unused_custom_errors.append((defined_error, file_name))
+                unused_custom_errors.append(defined_error)
 
         results = []
         if len(unused_custom_errors) > 0:
             info: DETECTOR_INFO = ["The following unused error(s) should be removed:"]
-            for custom_error, file_name in unused_custom_errors:
-                info += ["\n\t-", custom_error.full_name, " (", file_name, ")\n"]
+            for custom_error in unused_custom_errors:
+                file_scope = custom_error.file_scope if isinstance(custom_error, CustomErrorTopLevel) else custom_error.contract.file_scope
+                info += ["\n\t-", custom_error.full_name, " (", file_scope.filename.short, ")\n"]
             results.append(self.generate_result(info))
 
         return results
\ No newline at end of file

From acc542e3eee61b1907ddd004ffac190fdebc3f14 Mon Sep 17 00:00:00 2001
From: Goran Vladika <goran.vladika@gmail.com>
Date: Tue, 24 Sep 2024 12:32:57 +0200
Subject: [PATCH 08/16] Add wiki docs

---
 .../variables/unused_custom_errors.py         | 28 +++++++++++++++----
 1 file changed, 22 insertions(+), 6 deletions(-)

diff --git a/slither/detectors/variables/unused_custom_errors.py b/slither/detectors/variables/unused_custom_errors.py
index f4262ac72..6f9545544 100644
--- a/slither/detectors/variables/unused_custom_errors.py
+++ b/slither/detectors/variables/unused_custom_errors.py
@@ -19,16 +19,32 @@ class UnusedCustomErrors(AbstractDetector):
     """
 
     ARGUMENT = "unused-custom-errors"
-    HELP = "Unused Custom Errors"
+    HELP = "Detects unused custom errors"
     IMPACT = DetectorClassification.INFORMATIONAL
     CONFIDENCE = DetectorClassification.HIGH
 
-    WIKI = "https://github.com/crytic/slither/wiki/Detector-Documentation#unused-custom-error"
+    WIKI = "https://github.com/crytic/slither/wiki/Detector-Documentation#unused-custom-errors"
 
-    WIKI_TITLE = "Unused custom error"
-    WIKI_DESCRIPTION = "Unused custom error."
-    WIKI_EXPLOIT_SCENARIO = ""
-    WIKI_RECOMMENDATION = "Remove unused custom errors."
+    WIKI_TITLE = "Unused Custom Errors"
+    WIKI_DESCRIPTION = "Declaring a custom error, but never using it might indicate a mistake."
+    
+    # region wiki_exploit_scenario
+    WIKI_EXPLOIT_SCENARIO = """
+    ```solidity
+    contract A {
+        error ZeroAddressNotAllowed();
+        
+        address public owner;
+        
+        constructor(address _owner) {
+            owner = _owner;
+        }
+    }
+    ```
+    Custom error `ZeroAddressNotAllowed` is declared but never used. It shall be either invoked where needed, or removed if there's no need for it.
+    """
+    # endregion wiki_exploit_scenario = ""
+    WIKI_RECOMMENDATION = "Remove the unused custom errors."
 
     def _detect(self) -> List[Output]:
         """Detect unused custom errors"""

From cacb154802d049a527f237dc0500ad8ddd0fb16f Mon Sep 17 00:00:00 2001
From: Goran Vladika <goran.vladika@gmail.com>
Date: Tue, 24 Sep 2024 14:06:47 +0200
Subject: [PATCH 09/16] Make test contract(s) more complete

---
 ...5_ContractToTestForCustomErrors_sol__0.txt |  15 +++++++
 .../0.8.15/ContractToTestForCustomErrors.sol  |  41 ++++++++++++++++++
 ...ntractToTestForCustomErrors.sol-0.8.15.zip | Bin 0 -> 5968 bytes
 .../0.8.15/CustomErrorsLib.sol                |   8 ++++
 .../0.8.15/ErrorLibConsumer.sol               |  17 ++++++++
 .../0.8.15/unused_custom_errors.sol           |  16 -------
 .../unused_custom_errors.sol-0.8.15.zip       | Bin 2624 -> 0 bytes
 tests/e2e/detectors/test_detectors.py         |   2 +-
 8 files changed, 82 insertions(+), 17 deletions(-)
 create mode 100644 tests/e2e/detectors/snapshots/detectors__detector_UnusedCustomErrors_0_8_15_ContractToTestForCustomErrors_sol__0.txt
 create mode 100644 tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/ContractToTestForCustomErrors.sol
 create mode 100644 tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/ContractToTestForCustomErrors.sol-0.8.15.zip
 create mode 100644 tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/CustomErrorsLib.sol
 create mode 100644 tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/ErrorLibConsumer.sol
 delete mode 100644 tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/unused_custom_errors.sol
 delete mode 100644 tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/unused_custom_errors.sol-0.8.15.zip

diff --git a/tests/e2e/detectors/snapshots/detectors__detector_UnusedCustomErrors_0_8_15_ContractToTestForCustomErrors_sol__0.txt b/tests/e2e/detectors/snapshots/detectors__detector_UnusedCustomErrors_0_8_15_ContractToTestForCustomErrors_sol__0.txt
new file mode 100644
index 000000000..c62cbd5ec
--- /dev/null
+++ b/tests/e2e/detectors/snapshots/detectors__detector_UnusedCustomErrors_0_8_15_ContractToTestForCustomErrors_sol__0.txt
@@ -0,0 +1,15 @@
+The following unused error(s) should be removed:
+	-UnusedParentErr() (tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/ContractToTestForCustomErrors.sol)
+
+	-UnusedParentErrWithArg(uint256) (tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/ContractToTestForCustomErrors.sol)
+
+	-UnusedParentErr() (tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/ContractToTestForCustomErrors.sol)
+
+	-UnusedParentErrWithArg(uint256) (tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/ContractToTestForCustomErrors.sol)
+
+	-UnusedLibError() (tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/CustomErrorsLib.sol)
+
+	-UnusedErrorLibConsumerErr() (tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/ErrorLibConsumer.sol)
+
+	-UnusedTopLevelErr() (tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/ContractToTestForCustomErrors.sol)
+
diff --git a/tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/ContractToTestForCustomErrors.sol b/tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/ContractToTestForCustomErrors.sol
new file mode 100644
index 000000000..c59f3505c
--- /dev/null
+++ b/tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/ContractToTestForCustomErrors.sol
@@ -0,0 +1,41 @@
+// SPDX-License-Identifier: Unlicense
+pragma solidity 0.8.15;
+
+error UnusedTopLevelErr();
+error UsedTopLevelErr();
+
+import "./ErrorLibConsumer.sol";
+
+contract ParentContract {
+    error UnusedParentErr();
+    error UnusedParentErrWithArg(uint256 x);
+    error UsedParentErr(address x);
+    error UsedParentErrInChild(uint256 x);
+
+    constructor() {
+        new ErrorLibConsumer();
+    }
+
+    function x() public view {
+        uint256 d = 7;
+        if (msg.sender == address(0)) {
+            d = 100;
+            revert UsedParentErr(msg.sender);
+        }
+    }
+}
+
+contract ContractToTestForCustomErrors is ParentContract {
+    function y() public {
+        address f = msg.sender;
+        (bool s,) = f.call("");
+        if (!s) {
+            revert UsedParentErrInChild(1);
+        }
+        revert UsedTopLevelErr();
+    }
+
+    function z() public {
+        revert Lib.UsedLibErrorB(8);
+    }
+}
diff --git a/tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/ContractToTestForCustomErrors.sol-0.8.15.zip b/tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/ContractToTestForCustomErrors.sol-0.8.15.zip
new file mode 100644
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HcmV?d00001

diff --git a/tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/CustomErrorsLib.sol b/tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/CustomErrorsLib.sol
new file mode 100644
index 000000000..7c81c5026
--- /dev/null
+++ b/tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/CustomErrorsLib.sol
@@ -0,0 +1,8 @@
+// SPDX-License-Identifier: Unlicense
+pragma solidity 0.8.15;
+
+library Lib {
+    error UnusedLibError();
+    error UsedLibErrorA();
+    error UsedLibErrorB(uint256 x);
+}
\ No newline at end of file
diff --git a/tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/ErrorLibConsumer.sol b/tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/ErrorLibConsumer.sol
new file mode 100644
index 000000000..9f173a721
--- /dev/null
+++ b/tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/ErrorLibConsumer.sol
@@ -0,0 +1,17 @@
+// SPDX-License-Identifier: Unlicense
+pragma solidity 0.8.15;
+
+import "./CustomErrorsLib.sol";
+
+contract ErrorLibConsumer {
+    error UnusedErrorLibConsumerErr();
+    error UsedErrorLibConsumerErr();
+
+    constructor() {
+        revert Lib.UsedLibErrorA();
+    }
+
+    function a() public pure {
+        revert UsedErrorLibConsumerErr();
+    }
+}
diff --git a/tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/unused_custom_errors.sol b/tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/unused_custom_errors.sol
deleted file mode 100644
index b8e24a971..000000000
--- a/tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/unused_custom_errors.sol
+++ /dev/null
@@ -1,16 +0,0 @@
-//pragma solidity ^0.4.24;
-
-contract A {
-    error Unused1();
-    error UsedError(address x);
-
-    constructor() public {}
-
-    function x() public view {
-        uint256 d = 7;
-        if (msg.sender == address(0)) {
-            d = 100;
-            revert UsedError(msg.sender);
-        }
-    }
-}
diff --git a/tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/unused_custom_errors.sol-0.8.15.zip b/tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/unused_custom_errors.sol-0.8.15.zip
deleted file mode 100644
index f03b01102c4e89e91dc6633fbb2752406d997b14..0000000000000000000000000000000000000000
GIT binary patch
literal 0
HcmV?d00001

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z^pg9beUdKf)J@RSK$k(@uyYjBi+f0q2$FCKGdq-z@n~wVZrbRPvPgoC;7b~1JEt+b
znC`YLH_I@3Cc4nVi%7K2v9&Ej^^e;`YG^Qs%43zGo@**6OQWwDpk7sBEm2>D9Ef+4
ztyiIY$?DS@y4xmL?RDQKpL~}_<MVgAFUQ{HtxS<Q_u=KC5B(2ObE4iw299xV<AYvN
zacJhRaOIjyes&?e(HFDbXc1fchLhcC{U)p*z1pY89^u*wHZZ3or=np!=~%H~2CjMx
zlmDJEbtbX(!Ie5T_Q$XoLekaWeLt%LwyYjQzqe|AUe0(J<|r5M=#(a7Op!V!SpkBp
z_RVPvW|Ta`CYw$~Z4W5lhm?M(l5U5Z&1iYhJGu(3$BLJ)IV2zZwQtzF-u>wg{C)r^
z@X<6wbS6(e2BE6dcpbLG0~#&52h#B5-8P$V@M=LUp(tw2<YAeI<*fcYWkGmB^YXnp
z%N(Y)b5;k4-Jp_((wX4i1s*%99aDT^Z^OcB#P+{M_ZM~l4Uy&F`G0(8Z^Oa)?}z1Y
M-Tp59uM+{_KRu)4r~m)}

diff --git a/tests/e2e/detectors/test_detectors.py b/tests/e2e/detectors/test_detectors.py
index 1dc3fe07e..cd9ef2c02 100644
--- a/tests/e2e/detectors/test_detectors.py
+++ b/tests/e2e/detectors/test_detectors.py
@@ -403,7 +403,7 @@ def id_test(test_item: Test):
     ),
     Test(
         all_detectors.UnusedCustomErrors,
-        "unused_custom_errors.sol",
+        "ContractToTestForCustomErrors.sol",
         "0.8.15",
     ),
     Test(all_detectors.LockedEther, "locked_ether.sol", "0.4.25"),

From c61e536a115de241d08fff8bb109a81c87040776 Mon Sep 17 00:00:00 2001
From: Goran Vladika <goran.vladika@gmail.com>
Date: Tue, 24 Sep 2024 14:17:19 +0200
Subject: [PATCH 10/16] Lint

---
 .../detectors/variables/unused_custom_errors.py    | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/slither/detectors/variables/unused_custom_errors.py b/slither/detectors/variables/unused_custom_errors.py
index 6f9545544..cde22cc00 100644
--- a/slither/detectors/variables/unused_custom_errors.py
+++ b/slither/detectors/variables/unused_custom_errors.py
@@ -27,7 +27,7 @@ class UnusedCustomErrors(AbstractDetector):
 
     WIKI_TITLE = "Unused Custom Errors"
     WIKI_DESCRIPTION = "Declaring a custom error, but never using it might indicate a mistake."
-    
+
     # region wiki_exploit_scenario
     WIKI_EXPLOIT_SCENARIO = """
     ```solidity
@@ -71,15 +71,21 @@ def _detect(self) -> List[Output]:
 
         # Find unused custom errors
         for defined_error in declared_custom_errors:
-            if not any(defined_error.name in custom_revert.name for custom_revert in custom_reverts):
+            if not any(
+                defined_error.name in custom_revert.name for custom_revert in custom_reverts
+            ):
                 unused_custom_errors.append(defined_error)
 
         results = []
         if len(unused_custom_errors) > 0:
             info: DETECTOR_INFO = ["The following unused error(s) should be removed:"]
             for custom_error in unused_custom_errors:
-                file_scope = custom_error.file_scope if isinstance(custom_error, CustomErrorTopLevel) else custom_error.contract.file_scope
+                file_scope = (
+                    custom_error.file_scope
+                    if isinstance(custom_error, CustomErrorTopLevel)
+                    else custom_error.contract.file_scope
+                )
                 info += ["\n\t-", custom_error.full_name, " (", file_scope.filename.short, ")\n"]
             results.append(self.generate_result(info))
 
-        return results
\ No newline at end of file
+        return results

From 3d68770e9f7ae4e0a355a593404c268d8d8f10a1 Mon Sep 17 00:00:00 2001
From: Goran Vladika <goran.vladika@gmail.com>
Date: Tue, 24 Sep 2024 14:22:07 +0200
Subject: [PATCH 11/16] Move detector to another folder

---
 slither/detectors/all_detectors.py                              | 2 +-
 .../detectors/{variables => statements}/unused_custom_errors.py | 0
 2 files changed, 1 insertion(+), 1 deletion(-)
 rename slither/detectors/{variables => statements}/unused_custom_errors.py (100%)

diff --git a/slither/detectors/all_detectors.py b/slither/detectors/all_detectors.py
index 3b1ecd150..9bfdc5cd4 100644
--- a/slither/detectors/all_detectors.py
+++ b/slither/detectors/all_detectors.py
@@ -19,7 +19,6 @@
 from .reentrancy.reentrancy_no_gas import ReentrancyNoGas
 from .reentrancy.reentrancy_events import ReentrancyEvent
 from .variables.unused_state_variables import UnusedStateVars
-from .variables.unused_custom_errors import UnusedCustomErrors
 from .variables.could_be_constant import CouldBeConstant
 from .variables.could_be_immutable import CouldBeImmutable
 from .statements.tx_origin import TxOrigin
@@ -98,5 +97,6 @@
 from .statements.tautological_compare import TautologicalCompare
 from .statements.return_bomb import ReturnBomb
 from .functions.out_of_order_retryable import OutOfOrderRetryable
+from .statements.unused_custom_errors import UnusedCustomErrors
 
 # from .statements.unused_import import UnusedImport
diff --git a/slither/detectors/variables/unused_custom_errors.py b/slither/detectors/statements/unused_custom_errors.py
similarity index 100%
rename from slither/detectors/variables/unused_custom_errors.py
rename to slither/detectors/statements/unused_custom_errors.py

From 3c18062b0697cddda8ca14c8a7461f491301a507 Mon Sep 17 00:00:00 2001
From: Goran Vladika <goran.vladika@gmail.com>
Date: Tue, 24 Sep 2024 14:26:59 +0200
Subject: [PATCH 12/16] Update comments

---
 slither/detectors/statements/unused_custom_errors.py | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/slither/detectors/statements/unused_custom_errors.py b/slither/detectors/statements/unused_custom_errors.py
index cde22cc00..d73111a1f 100644
--- a/slither/detectors/statements/unused_custom_errors.py
+++ b/slither/detectors/statements/unused_custom_errors.py
@@ -62,7 +62,7 @@ def _detect(self) -> List[Output]:
         for custom_error in self.compilation_unit.custom_errors:
             declared_custom_errors.append(custom_error)
 
-        # Collect all custom errors used in revertsCustomError
+        # Collect all custom errors invoked in revert statements
         for contract in self.compilation_unit.contracts:
             for function in contract.functions_and_modifiers:
                 for internal_call in function.internal_calls:
@@ -70,11 +70,11 @@ def _detect(self) -> List[Output]:
                         custom_reverts.append(internal_call)
 
         # Find unused custom errors
-        for defined_error in declared_custom_errors:
+        for declared_error in declared_custom_errors:
             if not any(
-                defined_error.name in custom_revert.name for custom_revert in custom_reverts
+                declared_error.name in custom_revert.name for custom_revert in custom_reverts
             ):
-                unused_custom_errors.append(defined_error)
+                unused_custom_errors.append(declared_error)
 
         results = []
         if len(unused_custom_errors) > 0:

From 415e65e910266bf41e5083ac87660595947c3ddf Mon Sep 17 00:00:00 2001
From: Goran Vladika <goran.vladika@gmail.com>
Date: Tue, 24 Sep 2024 15:17:11 +0200
Subject: [PATCH 13/16] Remove leftovers

---
 slither/detectors/statements/unused_custom_errors.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/slither/detectors/statements/unused_custom_errors.py b/slither/detectors/statements/unused_custom_errors.py
index d73111a1f..b3873ec57 100644
--- a/slither/detectors/statements/unused_custom_errors.py
+++ b/slither/detectors/statements/unused_custom_errors.py
@@ -54,7 +54,6 @@ def _detect(self) -> List[Output]:
 
         # Collect all custom errors defined in the contracts
         for contract in self.compilation_unit.contracts:
-            contract.custom_errors_declared
             for custom_error in contract.custom_errors:
                 declared_custom_errors.append(custom_error)
 
@@ -76,6 +75,7 @@ def _detect(self) -> List[Output]:
             ):
                 unused_custom_errors.append(declared_error)
 
+        # Format results
         results = []
         if len(unused_custom_errors) > 0:
             info: DETECTOR_INFO = ["The following unused error(s) should be removed:"]

From b63e62a0f0f6871749dc973e72a6c9d7902a2dbd Mon Sep 17 00:00:00 2001
From: Goran Vladika <goran.vladika@gmail.com>
Date: Thu, 26 Sep 2024 14:00:51 +0200
Subject: [PATCH 14/16] Use sets to avoid duplicates

---
 .../detectors/statements/unused_custom_errors.py | 16 ++++++++--------
 ...8_15_ContractToTestForCustomErrors_sol__0.txt | 10 +++-------
 2 files changed, 11 insertions(+), 15 deletions(-)

diff --git a/slither/detectors/statements/unused_custom_errors.py b/slither/detectors/statements/unused_custom_errors.py
index b3873ec57..0f0a73640 100644
--- a/slither/detectors/statements/unused_custom_errors.py
+++ b/slither/detectors/statements/unused_custom_errors.py
@@ -1,7 +1,7 @@
 """
 Module detecting unused custom errors
 """
-from typing import List
+from typing import List, Set
 from slither.core.declarations.custom_error import CustomError
 from slither.core.declarations.custom_error_top_level import CustomErrorTopLevel
 from slither.core.declarations.solidity_variables import SolidityCustomRevert
@@ -48,32 +48,32 @@ class UnusedCustomErrors(AbstractDetector):
 
     def _detect(self) -> List[Output]:
         """Detect unused custom errors"""
-        declared_custom_errors: List[CustomError] = []
-        custom_reverts: List[SolidityCustomRevert] = []
-        unused_custom_errors: List[CustomError] = []
+        declared_custom_errors: Set[CustomError] = set()
+        custom_reverts: Set[SolidityCustomRevert] = set()
+        unused_custom_errors: Set[CustomError] = set()
 
         # Collect all custom errors defined in the contracts
         for contract in self.compilation_unit.contracts:
             for custom_error in contract.custom_errors:
-                declared_custom_errors.append(custom_error)
+                declared_custom_errors.add(custom_error)
 
         # Add custom errors defined outside of contracts
         for custom_error in self.compilation_unit.custom_errors:
-            declared_custom_errors.append(custom_error)
+            declared_custom_errors.add(custom_error)
 
         # Collect all custom errors invoked in revert statements
         for contract in self.compilation_unit.contracts:
             for function in contract.functions_and_modifiers:
                 for internal_call in function.internal_calls:
                     if isinstance(internal_call, SolidityCustomRevert):
-                        custom_reverts.append(internal_call)
+                        custom_reverts.add(internal_call)
 
         # Find unused custom errors
         for declared_error in declared_custom_errors:
             if not any(
                 declared_error.name in custom_revert.name for custom_revert in custom_reverts
             ):
-                unused_custom_errors.append(declared_error)
+                unused_custom_errors.add(declared_error)
 
         # Format results
         results = []
diff --git a/tests/e2e/detectors/snapshots/detectors__detector_UnusedCustomErrors_0_8_15_ContractToTestForCustomErrors_sol__0.txt b/tests/e2e/detectors/snapshots/detectors__detector_UnusedCustomErrors_0_8_15_ContractToTestForCustomErrors_sol__0.txt
index c62cbd5ec..4c7643166 100644
--- a/tests/e2e/detectors/snapshots/detectors__detector_UnusedCustomErrors_0_8_15_ContractToTestForCustomErrors_sol__0.txt
+++ b/tests/e2e/detectors/snapshots/detectors__detector_UnusedCustomErrors_0_8_15_ContractToTestForCustomErrors_sol__0.txt
@@ -1,15 +1,11 @@
 The following unused error(s) should be removed:
-	-UnusedParentErr() (tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/ContractToTestForCustomErrors.sol)
-
-	-UnusedParentErrWithArg(uint256) (tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/ContractToTestForCustomErrors.sol)
+	-UnusedLibError() (tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/CustomErrorsLib.sol)
 
-	-UnusedParentErr() (tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/ContractToTestForCustomErrors.sol)
+	-UnusedErrorLibConsumerErr() (tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/ErrorLibConsumer.sol)
 
 	-UnusedParentErrWithArg(uint256) (tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/ContractToTestForCustomErrors.sol)
 
-	-UnusedLibError() (tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/CustomErrorsLib.sol)
-
-	-UnusedErrorLibConsumerErr() (tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/ErrorLibConsumer.sol)
+	-UnusedParentErr() (tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/ContractToTestForCustomErrors.sol)
 
 	-UnusedTopLevelErr() (tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/ContractToTestForCustomErrors.sol)
 

From 44de39b8452a92ad20307c49b8e60eb5a351b6e8 Mon Sep 17 00:00:00 2001
From: Goran Vladika <goran.vladika@gmail.com>
Date: Thu, 26 Sep 2024 14:54:28 +0200
Subject: [PATCH 15/16] Use sorted list to get deterministic order in output

---
 slither/detectors/statements/unused_custom_errors.py       | 7 +++++--
 ...mErrors_0_8_15_ContractToTestForCustomErrors_sol__0.txt | 6 +++---
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/slither/detectors/statements/unused_custom_errors.py b/slither/detectors/statements/unused_custom_errors.py
index 0f0a73640..a1d64b4b3 100644
--- a/slither/detectors/statements/unused_custom_errors.py
+++ b/slither/detectors/statements/unused_custom_errors.py
@@ -50,7 +50,7 @@ def _detect(self) -> List[Output]:
         """Detect unused custom errors"""
         declared_custom_errors: Set[CustomError] = set()
         custom_reverts: Set[SolidityCustomRevert] = set()
-        unused_custom_errors: Set[CustomError] = set()
+        unused_custom_errors: List[CustomError] = []
 
         # Collect all custom errors defined in the contracts
         for contract in self.compilation_unit.contracts:
@@ -73,7 +73,10 @@ def _detect(self) -> List[Output]:
             if not any(
                 declared_error.name in custom_revert.name for custom_revert in custom_reverts
             ):
-                unused_custom_errors.add(declared_error)
+                unused_custom_errors.append(declared_error)
+
+        # Sort by error name
+        unused_custom_errors = sorted(unused_custom_errors, key=lambda err: err.name)
 
         # Format results
         results = []
diff --git a/tests/e2e/detectors/snapshots/detectors__detector_UnusedCustomErrors_0_8_15_ContractToTestForCustomErrors_sol__0.txt b/tests/e2e/detectors/snapshots/detectors__detector_UnusedCustomErrors_0_8_15_ContractToTestForCustomErrors_sol__0.txt
index 4c7643166..5b3870de4 100644
--- a/tests/e2e/detectors/snapshots/detectors__detector_UnusedCustomErrors_0_8_15_ContractToTestForCustomErrors_sol__0.txt
+++ b/tests/e2e/detectors/snapshots/detectors__detector_UnusedCustomErrors_0_8_15_ContractToTestForCustomErrors_sol__0.txt
@@ -1,11 +1,11 @@
 The following unused error(s) should be removed:
-	-UnusedLibError() (tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/CustomErrorsLib.sol)
-
 	-UnusedErrorLibConsumerErr() (tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/ErrorLibConsumer.sol)
 
-	-UnusedParentErrWithArg(uint256) (tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/ContractToTestForCustomErrors.sol)
+	-UnusedLibError() (tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/CustomErrorsLib.sol)
 
 	-UnusedParentErr() (tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/ContractToTestForCustomErrors.sol)
 
+	-UnusedParentErrWithArg(uint256) (tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/ContractToTestForCustomErrors.sol)
+
 	-UnusedTopLevelErr() (tests/e2e/detectors/test_data/unused-custom-errors/0.8.15/ContractToTestForCustomErrors.sol)
 

From 9af60e669cf8a16eb056dc0d725ad01cdc970655 Mon Sep 17 00:00:00 2001
From: Goran Vladika <goran.vladika@gmail.com>
Date: Thu, 10 Oct 2024 13:10:03 +0200
Subject: [PATCH 16/16] internal_call.function is instance of
 SolidityCustomRevert

---
 slither/detectors/statements/unused_custom_errors.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/slither/detectors/statements/unused_custom_errors.py b/slither/detectors/statements/unused_custom_errors.py
index a1d64b4b3..356c2c6a1 100644
--- a/slither/detectors/statements/unused_custom_errors.py
+++ b/slither/detectors/statements/unused_custom_errors.py
@@ -65,8 +65,8 @@ def _detect(self) -> List[Output]:
         for contract in self.compilation_unit.contracts:
             for function in contract.functions_and_modifiers:
                 for internal_call in function.internal_calls:
-                    if isinstance(internal_call, SolidityCustomRevert):
-                        custom_reverts.add(internal_call)
+                    if isinstance(internal_call.function, SolidityCustomRevert):
+                        custom_reverts.add(internal_call.function)
 
         # Find unused custom errors
         for declared_error in declared_custom_errors: