Add support for index on anonymous arrays (close #139)

slither/core/solidity_types/array_type.py

@@ -1,12 +1,15 @@
 from slither.core.variables.variable import Variable
 from slither.core.solidity_types.type import Type
 from slither.core.expressions.expression import Expression
+from slither.core.expressions import Literal
 
 class ArrayType(Type):
 
     def __init__(self, t, length):
         assert isinstance(t, Type)
         if length:
+            if isinstance(length, int):
+                length = Literal(length)
             assert isinstance(length, Expression)
         super(ArrayType, self).__init__()
         self._type = t

slither/visitors/slithir/expression_to_slithir.py

@@ -160,6 +160,14 @@ class ExpressionToSlithIR(ExpressionVisitor):
         left = get(expression.expression_left)
         right = get(expression.expression_right)
         val = ReferenceVariable(self._node)
+        # access to anonymous array
+        # such as [0,1][x]
+        if isinstance(left, list):
+            init_array_val = TemporaryVariable(self._node)
+            init_array_right = left
+            left = init_array_val
+            operation = InitArray(init_array_right, init_array_val)
+            self._result.append(operation)
         operation = Index(val, left, right, expression.type)
         self._result.append(operation)
         set_val(expression, val)