Improve reentrancy heuristic: ignore call to this. if the destination is reentrancy-safe (close #127)

slither/detectors/reentrancy/reentrancy.py

@@ -6,7 +6,7 @@
 """
 
 from slither.core.cfg.node import NodeType
-from slither.core.declarations import Function, SolidityFunction
+from slither.core.declarations import Function, SolidityFunction, SolidityVariable
 from slither.core.expressions import UnaryOperation, UnaryOperationType
 from slither.detectors.abstract_detector import (AbstractDetector,
                                                  DetectorClassification)
@@ -55,6 +55,13 @@ class Reentrancy(AbstractDetector):
                         continue
                     if isinstance(ir.function, Variable):
                         continue
+                # If there is a call to itself
+                # We can check that the function called is
+                # reentrancy-safe
+                if ir.destination == SolidityVariable('this'):
+                    if not ir.function.all_high_level_calls():
+                        if not ir.function.all_low_level_calls():
+                            continue
                 return True
         return False