a first very simple implementation of reachable/unreachable return statements.

jedi/evaluate/compiled/__init__.py

@@ -48,6 +48,9 @@ class CompiledObject(Base):
     def py__mro__(self, evaluator):
         return tuple(create(evaluator, cls) for cls in self.obj.__mro__)
 
+    def py__bool__(self):
+        return bool(self.obj)
+
     @property
     def doc(self):
         return inspect.getdoc(self.obj) or ''

jedi/evaluate/flow_analysis.py

@@ -2,8 +2,12 @@ from jedi.parser.representation import Flow
 
 
 class Status(object):
-    def __init__(self, value):
+    lookup_table = {}
+
+    def __init__(self, value, name):
         self._value = value
+        self._name = name
+        Status.lookup_table[value] = self
 
     def __eq__(self, other):
         return self._value == other.value
@@ -15,20 +19,27 @@ class Status(object):
         if UNSURE in (self, other):
             return other
         else:
-            return REACHABLE if self._value and other._value else NOT_REACHABLE
+            return REACHABLE if self._value and other._value else UNREACHABLE
+
+    def __repr__(self):
+        return '<%s: %s>' % (type(self).__name__, self._name)
 
 
-NOT_REACHABLE = Status(True)
-REACHABLE = Status(False)
-UNSURE = Status(None)
+REACHABLE = Status(True, 'reachable')
+UNREACHABLE = Status(False, 'unreachable')
+UNSURE = Status(None, 'unsure')
 
 
 def break_check(evaluator, base_scope, element_scope):
     reachable = REACHABLE
     if isinstance(element_scope, Flow):
         if element_scope.command == 'if' and element_scope.inputs:
-            result = evaluator.eval_statement(element_scope.inputs[0])
-            print(result)
+            types = evaluator.eval_statement(element_scope.inputs[0])
+            values = set(x.py__bool__() for x in types)
+            if len(values) == 1:
+                return Status.lookup_table[values.pop()]
+            else:
+                return UNSURE
 
     if base_scope != element_scope.parent:
         return reachable & break_check(base_scope, element_scope.parent)

jedi/evaluate/representation.py

@@ -476,7 +476,7 @@ class FunctionExecution(Executed):
                 continue
 
             check = flow_analysis.break_check(self._evaluator, self, r.parent.parent)
-            if check is not flow_analysis.NOT_REACHABLE:
+            if check is not flow_analysis.UNREACHABLE:
                 types += self._evaluator.eval_statement(r)
             if check is flow_analysis.REACHABLE:
                 break