Re: [Boost-bugs] [Boost C++ Libraries] #10109: Wrong overflow checking with uint_parser<int>

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #10109: Wrong overflow checking with uint_parser<int>
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2014-06-10 16:59:16

#10109: Wrong overflow checking with uint_parser<int>
----------------------------------------------+---------------------
  Reporter:  Giulio Franco <giulio_franco@…>  |      Owner:  djowel
      Type:  Bugs                             |     Status:  new
 Milestone:  To Be Determined                 |  Component:  spirit
   Version:  Boost Release Branch             |   Severity:  Problem
Resolution:                                   |   Keywords:
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Comment (by Giulio Franco <giulio_franco@…>):

 According to the docs, `uint_parser` is supposed to parse an unsigned
 value, it doesn't make any restriction on the type it will read the value
 into. In fact, you can also create a uint_parser<double>, and in that case
 `int_extractor::call(Char, size_t, T&)` will use a different
 implementation, that just adds the digits without checking for overflow.

 As I wrote, the current implementations already checks for wrap around, by
 using `std::numeric_limits<T>::max` in
 {{{
 #!c++
 template<typename T, typename Char>
 positive_accumulator::add(T&, Char, mpl::true_)
 }}}

 The only issue is that it's using the wrong `T`. It uses
 `numeric_limits<unsigned int>`, because it is passed an `unsigned int&`.
 If it used `numeric_limits<signed int>` with the very same algorithm it
 would probably work perfectly.
 It looks like it only involves template work, which means no performance
 impact for those who aren't using it.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/10109#comment:2>
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