Temporary fix divide by zero crash.

Exposed by a case in test/runtime-errors.sh

Add TODOs for a better fix.

core/expr_eval.py

@@ -125,6 +125,8 @@ def _StringToIntegerOrError(self, s):
        raise
      else:
        i = 0
        # TODO: Need the arena for printing this error?
        #ui.PrettyPrintError(e)
        warn(e.UserErrorString())
    return i

@@ -394,10 +396,19 @@ def Eval(self, node):
        try:
          return lhs / rhs
        except ZeroDivisionError:
          # TODO: Instead of op_id, I should have the token
          # node.right.w crashes if it's not a constant!
          e_die('Divide by zero', word=node.right.w)
          # TODO: _ErrorWithLocation should also accept arith_expr ?  I
          # think I needed that for other stuff.
          # Or I could blame the '/' token, instead of op_id.
          error_expr = node.right  # node is ArithBinary
          if error_expr.tag == arith_expr_e.ArithVarRef:
            # TODO: ArithVarRef should store a token instead of a string!
            e_die('Divide by zero (name)')
          elif error_expr.tag == arith_expr_e.ArithWord:
            e_die('Divide by zero', word=node.right.w)
          else:
            e_die('Divide by zero')
      if op_id == Id.Arith_Percent:

        return lhs % rhs
      if op_id == Id.Arith_DStar:
        return lhs ** rhs

core/tdop.py

@@ -125,6 +125,7 @@ def LeftError(p, t, left, rbp):

def LeftBinaryOp(p, w, left, rbp):
  """ Normal binary operator like 1+2 or 2*3, etc. """
  # TODO: w shoudl be a TokenWord, and we should extract the token from it.
  return ast.ArithBinary(word.ArithId(w), left, p.ParseUntil(rbp))