Merge branch 'dev' into dev-ssa

scripts/tests_generate_expected_json_4.sh

@@ -14,28 +14,29 @@ generate_expected_json(){
 
 }
 
-generate_expected_json tests/uninitialized.sol "uninitialized-state"
-generate_expected_json tests/backdoor.sol "backdoor"
-generate_expected_json tests/backdoor.sol "suicidal"
-generate_expected_json tests/pragma.0.4.24.sol "pragma"
-generate_expected_json tests/old_solc.sol.json "solc-version"
-generate_expected_json tests/reentrancy.sol "reentrancy"
-generate_expected_json tests/uninitialized_storage_pointer.sol "uninitialized-storage"
-generate_expected_json tests/tx_origin.sol "tx-origin"
-generate_expected_json tests/unused_state.sol "unused-state"
-generate_expected_json tests/locked_ether.sol "locked-ether"
-generate_expected_json tests/arbitrary_send.sol "arbitrary-send"
-generate_expected_json tests/inline_assembly_contract.sol "assembly"
-generate_expected_json tests/inline_assembly_library.sol "assembly"
-generate_expected_json tests/low_level_calls.sol "low-level-calls"
-generate_expected_json tests/const_state_variables.sol "constable-states"
-generate_expected_json tests/external_function.sol "external-function"
-generate_expected_json tests/naming_convention.sol "naming-convention"
-generate_expected_json tests/uninitialized_local_variable.sol "uninitialized-local"
-generate_expected_json tests/controlled_delegatecall.sol "controlled-delegatecall"
-generate_expected_json tests/constant.sol "constant-function"
-generate_expected_json tests/unused_return.sol "unused-return"
-generate_expected_json tests/shadowing_state_variable.sol "shadowing-state"
-generate_expected_json tests/shadowing_abstract.sol "shadowing-abstract"
-generate_expected_json tests/timestamp.sol "timestamp"
-generate_expected_json tests/multiple_calls_in_loop.sol "calls-loop"
+#generate_expected_json tests/uninitialized.sol "uninitialized-state"
+#generate_expected_json tests/backdoor.sol "backdoor"
+#generate_expected_json tests/backdoor.sol "suicidal"
+#generate_expected_json tests/pragma.0.4.24.sol "pragma"
+#generate_expected_json tests/old_solc.sol.json "solc-version"
+#generate_expected_json tests/reentrancy.sol "reentrancy"
+#generate_expected_json tests/uninitialized_storage_pointer.sol "uninitialized-storage"
+#generate_expected_json tests/tx_origin.sol "tx-origin"
+#generate_expected_json tests/unused_state.sol "unused-state"
+#generate_expected_json tests/locked_ether.sol "locked-ether"
+#generate_expected_json tests/arbitrary_send.sol "arbitrary-send"
+#generate_expected_json tests/inline_assembly_contract.sol "assembly"
+#generate_expected_json tests/inline_assembly_library.sol "assembly"
+#generate_expected_json tests/low_level_calls.sol "low-level-calls"
+#generate_expected_json tests/const_state_variables.sol "constable-states"
+#generate_expected_json tests/external_function.sol "external-function"
+generate_expected_json tests/external_function_2.sol "external-function"
+#generate_expected_json tests/naming_convention.sol "naming-convention"
+#generate_expected_json tests/uninitialized_local_variable.sol "uninitialized-local"
+#generate_expected_json tests/controlled_delegatecall.sol "controlled-delegatecall"
+#generate_expected_json tests/constant.sol "constant-function"
+#generate_expected_json tests/unused_return.sol "unused-return"
+#generate_expected_json tests/shadowing_state_variable.sol "shadowing-state"
+#generate_expected_json tests/shadowing_abstract.sol "shadowing-abstract"
+#generate_expected_json tests/timestamp.sol "timestamp"
+#generate_expected_json tests/multiple_calls_in_loop.sol "calls-loop"

scripts/tests_generate_expected_json_5.sh

@@ -14,16 +14,16 @@ generate_expected_json(){
 
 }
 
-generate_expected_json tests/uninitialized-0.5.1.sol "uninitialized-state"
+#generate_expected_json tests/uninitialized-0.5.1.sol "uninitialized-state"
 #generate_expected_json tests/backdoor.sol "backdoor"
 #generate_expected_json tests/backdoor.sol "suicidal"
 #generate_expected_json tests/pragma.0.4.24.sol "pragma"
 #generate_expected_json tests/old_solc.sol.json "solc-version"
-generate_expected_json tests/reentrancy-0.5.1.sol "reentrancy"
+#generate_expected_json tests/reentrancy-0.5.1.sol "reentrancy"
 #generate_expected_json tests/uninitialized_storage_pointer.sol "uninitialized-storage"
-generate_expected_json tests/tx_origin-0.5.1.sol "tx-origin"
-generate_expected_json tests/locked_ether-0.5.1.sol "locked-ether"
-generate_expected_json tests/arbitrary_send-0.5.1.sol "arbitrary-send"
-generate_expected_json tests/inline_assembly_contract-0.5.1.sol "assembly"
-generate_expected_json tests/inline_assembly_library-0.5.1.sol "assembly"
-generate_expected_json tests/constant-0.5.1.sol "constant-function"
+#generate_expected_json tests/tx_origin-0.5.1.sol "tx-origin"
+#generate_expected_json tests/locked_ether-0.5.1.sol "locked-ether"
+#generate_expected_json tests/arbitrary_send-0.5.1.sol "arbitrary-send"
+#generate_expected_json tests/inline_assembly_contract-0.5.1.sol "assembly"
+#generate_expected_json tests/inline_assembly_library-0.5.1.sol "assembly"
+#generate_expected_json tests/constant-0.5.1.sol "constant-function"

scripts/travis_test_4.sh

@@ -81,6 +81,7 @@ test_slither tests/inline_assembly_library.sol "assembly"
 test_slither tests/low_level_calls.sol "low-level-calls"
 test_slither tests/const_state_variables.sol "constable-states"
 test_slither tests/external_function.sol "external-function"
+test_slither tests/external_function_2.sol "external-function"
 test_slither tests/naming_convention.sol "naming-convention"
 #test_slither tests/complex_func.sol "complex-function"
 test_slither tests/controlled_delegatecall.sol "controlled-delegatecall"

scripts/travis_test_5.sh

@@ -79,8 +79,9 @@ test_slither tests/inline_assembly_library-0.5.1.sol "assembly"
 test_slither tests/low_level_calls.sol "low-level-calls"
 test_slither tests/const_state_variables.sol "constable-states"
 test_slither tests/external_function.sol "external-function"
+test_slither tests/external_function_2.sol "external-function"
 test_slither tests/naming_convention.sol "naming-convention"
-#test_slither tests/complex_func.sol "complex-function"
+##test_slither tests/complex_func.sol "complex-function"
 test_slither tests/controlled_delegatecall.sol "controlled-delegatecall"
 test_slither tests/constant-0.5.1.sol "constant-function"
 test_slither tests/unused_return.sol "unused-return"

slither/core/declarations/contract.py

@@ -70,6 +70,14 @@ class Contract(ChildSlither, SourceMapping):
     def setInheritance(self, inheritance):
         self._inheritance = inheritance
 
+    @property
+    def derived_contracts(self):
+        '''
+            list(Contract): Return the list of contracts derived from self
+        '''
+        candidates = self.slither.contracts
+        return [c for c in candidates if self in c.inheritance]
+
     @property
     def structures(self):
         '''
@@ -87,12 +95,6 @@ class Contract(ChildSlither, SourceMapping):
     def enums_as_dict(self):
         return self._enums
 
-    @property
-    def modifiers(self):
-        '''
-            list(Modifier): List of the modifiers
-        '''
-        return list(self._modifiers.values())
 
     def modifiers_as_dict(self):
         return self._modifiers
@@ -115,6 +117,75 @@ class Contract(ChildSlither, SourceMapping):
         '''
         return [f for f in self.functions if f.contract != self]
 
+    @property
+    def functions_not_inherited(self):
+        '''
+            list(Function): List of the functions defined within the contract (not inherited)
+        '''
+        return [f for f in self.functions if f.contract == self]
+
+    @property
+    def functions_entry_points(self):
+        '''
+            list(Functions): List of public and external functions
+        '''
+        return [f for f in self.functions if f.visibility in ['public', 'external']]
+
+    @property
+    def modifiers(self):
+        '''
+            list(Modifier): List of the modifiers
+        '''
+        return list(self._modifiers.values())
+
+    @property
+    def modifiers_inherited(self):
+        '''
+            list(Modifier): List of the inherited modifiers
+        '''
+        return [m for m in self.modifiers if m.contract != self]
+
+    @property
+    def modifiers_not_inherited(self):
+        '''
+            list(Modifier): List of the modifiers defined within the contract (not inherited)
+        '''
+        return [m for m in self.modifiers if m.contract == self]
+
+    @property
+    def functions_and_modifiers(self):
+        '''
+            list(Function|Modifier): List of the functions and modifiers
+        '''
+        return self.functions + self.modifiers
+
+    @property
+    def functions_and_modifiers_inherited(self):
+        '''
+            list(Function|Modifier): List of the inherited functions and modifiers
+        '''
+        return self.functions_inherited + self.modifiers_inherited
+
+    @property
+    def functions_and_modifiers_not_inherited(self):
+        '''
+            list(Function|Modifier): List of the functions and modifiers defined within the contract (not inherited)
+        '''
+        return self.functions_not_inherited + self.modifiers_not_inherited
+
+    def get_functions_overridden_by(self, function):
+        '''
+            Return the list of functions overriden by the function
+        Args:
+            (core.Function)
+        Returns:
+            list(core.Function)
+
+        '''
+        candidates = [c.functions_not_inherited for c in self.inheritance]
+        candidates = [candidate for sublist in candidates for candidate in sublist]
+        return [f for f in candidates if f.full_name == function.full_name]
+
     @property
     def all_functions_called(self):
         '''

slither/core/declarations/function.py

@@ -327,6 +327,18 @@ class Function(ChildContract, SourceMapping):
         name, parameters, _ = self.signature
         return name+'('+','.join(parameters)+')'
 
+    @property
+    def functions_shadowed(self):
+        '''
+            Return the list of functions shadowed
+        Returns:
+            list(core.Function)
+
+        '''
+        candidates = [c.functions_not_inherited for c in self.contract.inheritance]
+        candidates = [candidate for sublist in candidates for candidate in sublist]
+        return [f for f in candidates if f.full_name == self.full_name]
+
 
     @property
     def slither(self):

slither/detectors/functions/external_function.py

@@ -27,7 +27,10 @@ class ExternalFunction(AbstractDetector):
             (list): List of all InternallCall, SolidityCall
         """
         result = []
+
+        # Obtain all functions reachable by this contract.
         for func in contract.all_functions_called:
+            # Loop through all nodes in the function, add all calls to a list.
             for node in func.nodes:
                 for ir in node.irs:
                     if isinstance(ir, (InternalCall, SolidityCall)):
@@ -36,6 +39,12 @@ class ExternalFunction(AbstractDetector):
 
     @staticmethod
     def _contains_internal_dynamic_call(contract):
+        """
+        Checks if a contract contains a dynamic call either in a direct definition, or through inheritance.
+
+        Returns:
+            (boolean): True if this contract contains a dynamic call (including through inheritance).
+        """
         for func in contract.all_functions_called:
             for node in func.nodes:
                 for ir in node.irs:
@@ -43,31 +52,126 @@ class ExternalFunction(AbstractDetector):
                         return True
         return False
 
+    @staticmethod
+    def get_base_most_function(function):
+        """
+        Obtains the base function definition for the provided function. This could be used to obtain the original
+        definition of a function, if the provided function is an override.
+
+        Returns:
+            (function): Returns the base-most function of a provided function. (The original definition).
+        """
+        # Loop through the list of inherited contracts and this contract, to find the first function instance which
+        # matches this function's signature. Note here that `inheritance` is in order from most basic to most extended.
+        for contract in function.contract.inheritance + [function.contract]:
+
+            # Loop through the functions not inherited (explicitly defined in this contract).
+            for f in contract.functions_not_inherited:
+
+                # If it matches names, this is the base most function.
+                if f.full_name == function.full_name:
+                    return f
+
+        # Somehow we couldn't resolve it, which shouldn't happen, as the provided function should be found if we could
+        # not find some any more basic.
+        raise Exception("Could not resolve the base-most function for the provided function.")
+
+    @staticmethod
+    def get_all_function_definitions(base_most_function):
+        """
+        Obtains all function definitions given a base-most function. This includes the provided function, plus any
+        overrides of that function.
+
+        Returns:
+            (list): Returns any the provided function and any overriding functions defined for it.
+        """
+        # We assume the provided function is the base-most function, so we check all derived contracts
+        # for a redefinition
+        return [base_most_function] + [function for derived_contract in base_most_function.contract.derived_contracts
+                                       for function in derived_contract.functions
+                                       if function.full_name == base_most_function.full_name]
+
     def detect(self):
         results = []
 
-        public_function_calls = []
         all_info = ''
 
-        for contract in self.slither.contracts_derived:
+        # Create a set to track contracts with dynamic calls. All contracts with dynamic calls could potentially be
+        # calling functions internally, and thus we can't assume any function in such contracts isn't called by them.
+        dynamic_call_contracts = set()
+
+        # Create a completed functions set to skip over functions already processed (any functions which are the base
+        # of, or override hierarchically are processed together).
+        completed_functions = set()
+
+        # First we build our set of all contracts with dynamic calls
+        for contract in self.contracts:
             if self._contains_internal_dynamic_call(contract):
+                dynamic_call_contracts.add(contract)
+
+        # Loop through all not-inherited contracts.
+        for contract in self.slither.contracts_derived:
+
+            # Filter false-positives: Immediately filter this contract if it's in blacklist
+            if contract in dynamic_call_contracts:
                 continue
 
-            func_list = self.detect_functions_called(contract)
-            public_function_calls.extend(func_list)
-
-            for func in [f for f in contract.functions if f.visibility == 'public' and\
-                                                           not f in public_function_calls and\
-                                                           not f.is_constructor]:
-                txt = "{}.{} ({}) should be declared external\n"
-                info = txt.format(func.contract.name,
-                                  func.name,
-                                  func.source_mapping_str)
-                all_info += info
-
-                json = self.generate_json_result(info)
-                self.add_function_to_json(func, json)
-                results.append(json)
+            # Next we'll want to loop through all functions defined directly in this contract.
+            for function in contract.functions_not_inherited:
+
+                # If the function is a constructor, or is public, we skip it.
+                if function.is_constructor or function.visibility != "public":
+                    continue
+
+                # Optimization: If this function has already been processed, we stop.
+                if function in completed_functions:
+                    continue
+
+                # Get the base-most function to know our origin of this function.
+                base_most_function = self.get_base_most_function(function)
+
+                # Get all possible contracts which can call this function (or an override).
+                all_possible_sources = [base_most_function.contract] + base_most_function.contract.derived_contracts
+
+                # Get all function signatures (overloaded and not), mark as completed and we process them now.
+                # Note: We mark all function definitions as the same, as they must all share visibility to override.
+                all_function_definitions = set(self.get_all_function_definitions(base_most_function))
+                completed_functions = completed_functions.union(all_function_definitions)
+
+                # Filter false-positives: Determine if any of these sources have dynamic calls, if so, flag all of these
+                # function definitions, and then flag all functions in all contracts that make dynamic calls.
+                sources_with_dynamic_calls = set(all_possible_sources) & dynamic_call_contracts
+                if sources_with_dynamic_calls:
+                    functions_in_dynamic_call_sources = set([f for dyn_contract in sources_with_dynamic_calls
+                                                             for f in dyn_contract if not f.is_constructor])
+                    completed_functions = completed_functions.union(functions_in_dynamic_call_sources)
+                    continue
+
+                # Detect all functions called in each source, if any match our current signature, we skip
+                # otherwise, this is a candidate (in all sources) to be changed visibility for.
+                is_called = False
+                for possible_source in all_possible_sources:
+                    functions_called = self.detect_functions_called(possible_source)
+                    if set(functions_called) & all_function_definitions:
+                        is_called = True
+                        break
+
+                # If any of this function's definitions are called, we skip it.
+                if is_called:
+                    continue
+
+                # Loop for each function definition, and recommend it be declared external.
+                for function_definition in all_function_definitions:
+                    txt = "{}.{} ({}) should be declared external\n"
+                    info = txt.format(function_definition.contract.name,
+                                      function_definition.name,
+                                      function_definition.source_mapping_str)
+                    all_info += info
+
+                    json = self.generate_json_result(info)
+                    self.add_function_to_json(function_definition, json)
+                    results.append(json)
+
         if all_info != '':
             self.log(all_info)
         return results

slither/slithir/convert.py

@@ -316,10 +316,19 @@ def get_type(t):
     return str(t)
 
 def get_sig(ir):
+    '''
+        Return a list of potential signature
+        It is a list, as Constant variables can be converted to int256
+    Args:
+        ir (slithIR.operation)
+    Returns:
+        list(str)
+    '''
     sig = '{}({})'
     name = ir.function_name
 
-    args = []
+    # list of list of arguments
+    argss = [[]]
     for arg in ir.arguments:
         if isinstance(arg, (list,)):
             type_arg = '{}[{}]'.format(get_type(arg[0].type), len(arg))
@@ -327,14 +336,31 @@ def get_sig(ir):
             type_arg = arg.signature_str
         else:
             type_arg = get_type(arg.type)
-        args.append(type_arg)
-    return sig.format(name, ','.join(args))
+        if isinstance(arg, Constant) and arg.type == ElementaryType('uint256'):
+            # If it is a constant
+            # We dupplicate the existing list
+            # And we add uint256 and int256 cases
+            # There is no potential collision, as the compiler
+            # Prevent it with a 
+            # "not unique after argument-dependent loopkup" issue
+            argss_new = [list(args) for args in argss]
+            for args in argss:
+                args.append(str(ElementaryType('uint256')))
+            for args in argss_new:
+                args.append(str(ElementaryType('int256')))
+            argss = argss + argss_new
+        else:
+            for args in argss:
+                args.append(type_arg)
+    return [sig.format(name, ','.join(args)) for args in argss]
 
 def convert_type_library_call(ir, lib_contract):
-    sig = get_sig(ir)
-    func = lib_contract.get_function_from_signature(sig)
-    if not func:
-        func = lib_contract.get_state_variable_from_name(ir.function_name)
+    sigs = get_sig(ir)
+    func = None
+    for sig in sigs:
+        func = lib_contract.get_function_from_signature(sig)
+        if not func:
+            func = lib_contract.get_state_variable_from_name(ir.function_name)
     # In case of multiple binding to the same type
     if not func:
         # specific lookup when the compiler does implicit conversion
@@ -363,10 +389,12 @@ def convert_type_library_call(ir, lib_contract):
     return ir
 
 def convert_type_of_high_level_call(ir, contract):
-    sig = get_sig(ir)
-    func = contract.get_function_from_signature(sig)
-    if not func:
-        func = contract.get_state_variable_from_name(ir.function_name)
+    func = None
+    sigs = get_sig(ir)
+    for sig in sigs:
+        func = contract.get_function_from_signature(sig)
+        if not func:
+            func = contract.get_state_variable_from_name(ir.function_name)
     if not func:
         # specific lookup when the compiler does implicit conversion
         # for example

slither/slithir/operations/return_operation.py

@@ -18,6 +18,11 @@ class Return(Operation):
             else:
                 values = [values]
         else:
+            # Remove None
+            # Prior Solidity 0.5
+            # return (0,)
+            # was valid for returns(uint)
+            values = [v for v in values if not v is None]
             self._valid_value(values)
         super(Return, self).__init__()
         self._values = values

slither/solc_parsing/declarations/function.py

@@ -196,9 +196,9 @@ class FunctionSolc(Function):
 
         if loop_expression:
             node_LoopExpression = self._parse_statement(loop_expression, node_body)
-            link_nodes(node_LoopExpression, node_startLoop)
+            link_nodes(node_LoopExpression, node_condition)
         else:
-            link_nodes(node_body, node_startLoop)
+            link_nodes(node_body, node_condition)
 
         if not condition:
             if not loop_expression:
@@ -291,7 +291,7 @@ class FunctionSolc(Function):
         if not hasCondition and not hasLoopExpression:
             link_nodes(node, node_endLoop)
 
-        link_nodes(node_LoopExpression, node_startLoop)
+        link_nodes(node_LoopExpression, node_condition)
 
         return node_endLoop
 

slither/solc_parsing/expressions/expression_parsing.py

@@ -237,6 +237,35 @@ def filter_name(value):
         value = value[:idx+1]
     return value
 
+def convert_subdenomination(value, sub):
+    if sub is None:
+        return value
+    # to allow 0.1 ether conversion
+    value = float(value)
+    if sub == 'wei':
+        return int(value)
+    if sub == 'szabo':
+        return int(value * int(1e12))
+    if sub == 'finney':
+        return int(value * int(1e15))
+    if sub == 'ether':
+        return int(value * int(1e18))
+    if sub == 'seconds':
+        return int(value)
+    if sub == 'minutes':
+        return int(value * 60)
+    if sub == 'hours':
+        return int(value * 60 * 60)
+    if sub == 'days':
+        return int(value * 60 * 60 * 24)
+    if sub == 'weeks':
+        return int(value * 60 * 60 * 24 * 7)
+    if sub == 'years':
+        return int(value * 60 * 60 * 24 * 7 * 365)
+
+    logger.error('Subdemoniation not found {}'.format(sub))
+    return int(value)
+
 def parse_expression(expression, caller_context):
     """
 
@@ -380,11 +409,17 @@ def parse_expression(expression, caller_context):
 
         if is_compact_ast:
             value = expression['value']
-            if not value and value != "":
+            if value:
+                if 'subdenomination' in expression and expression['subdenomination']:
+                    value = str(convert_subdenomination(value, expression['subdenomination']))
+            elif not value and value != "":
                 value = '0x'+expression['hexValue']
         else:
             value = expression['attributes']['value']
-            if value is None:
+            if value:
+                if 'subdenomination' in expression['attributes'] and expression['attributes']['subdenomination']:
+                    value = str(convert_subdenomination(value, expression['attributes']['subdenomination']))
+            elif value is None:
                 # for literal declared as hex
                 # see https://solidity.readthedocs.io/en/v0.4.25/types.html?highlight=hex#hexadecimal-literals
                 assert 'hexvalue' in expression['attributes']

slither/solc_parsing/slitherSolc.py

@@ -11,6 +11,8 @@ from slither.core.declarations.pragma_directive import Pragma
 from slither.core.declarations.import_directive import Import
 from slither.analyses.data_depencency.data_depency import compute_dependency
 
+from slither.utils.colors import red
+
 class SlitherSolc(Slither):
 
     def __init__(self, filename):
@@ -158,11 +160,18 @@ class SlitherSolc(Slither):
         for contract in self._contractsNotParsed:
             # remove the first elem in linearizedBaseContracts as it is the contract itself
             fathers = []
-            for i in contract.linearizedBaseContracts[1:]:
-                if i in contract.remapping:
-                    fathers.append(self.get_contract_from_name(contract.remapping[i]))
-                else:
-                    fathers.append(self._contracts_by_id[i])
+            try:
+                for i in contract.linearizedBaseContracts[1:]:
+                    if i in contract.remapping:
+                        fathers.append(self.get_contract_from_name(contract.remapping[i]))
+                    else:
+                        fathers.append(self._contracts_by_id[i])
+            except KeyError:
+                logger.error(red('A contract was not find, it is likely that your codebase contains muliple contracts with the same name'))
+                logger.error(red('Truffle does not handle this case during compilation'))
+                logger.error(red('Please read https://github.com/trailofbits/slither/wiki#keyerror-or-nonetype-error'))
+                logger.error(red('And update your code to remove the dupplicate'))
+                exit(-1)
             contract.setInheritance(fathers)
 
         contracts_to_be_analyzed = self.contracts

tests/expected_json/external_function_2.external-function.json

@@ -0,0 +1 @@
+[]

tests/external_function.sol

@@ -1,6 +1,6 @@
 //pragma solidity ^0.4.24;
 
-import "./external_function_test_2.sol";
+import "./external_function_import.sol";
 
 contract ContractWithFunctionCalledSuper is ContractWithFunctionCalled {
     function callWithSuper() public {

tests/external_function_2.sol

@@ -0,0 +1,55 @@
+// This tests against false-positives. This test should output no recommendations from the external-function detector.
+
+
+contract ContractWithBaseFunctionCalled {
+    function getsCalledByBase() public;
+    function callsOverrideMe() external {
+        getsCalledByBase();
+    }
+}
+
+
+contract DerivingContractWithBaseCalled is ContractWithBaseFunctionCalled {
+    function getsCalledByBase() public {
+        // This should not be recommended to be marked external because it is called by the base class.
+    }
+}
+
+
+// All the contracts below should not recommend changing to external since inherited contracts have dynamic calls.
+contract ContractWithDynamicCall {
+    function() returns(uint) ptr;
+
+    function test1() public returns(uint){
+        return 1;
+    }
+
+    function test2() public returns(uint){
+        return 2;
+    }
+
+    function setTest1() external{
+        ptr = test1;
+    }
+
+    function setTest2() external{
+        ptr = test2;
+    }
+
+    function exec() external returns(uint){
+        return ptr();
+    }
+}
+
+contract DerivesFromDynamicCall is ContractWithDynamicCall{
+    function getsCalledDynamically() public returns (uint){
+        // This should not be recommended because it is called dynamically.
+        return 3;
+    }
+    function setTest3() public {
+        // This should not be recommended because we inherit from a contract that calls dynamically, and we cannot be
+        // sure it did not somehow call this function.
+
+        ptr = getsCalledDynamically;
+    }
+}

tests/external_function_import.sol

@@ -1,4 +1,4 @@
-//pragma solidity ^0.4.24;
+// This file is imported by external_function.sol
 
 contract ContractWithFunctionCalled {
     function funcCalled() external  {