Re: [Boost-bugs] [Boost C++ Libraries] #11047: Valgrind warning "uninitialized variable" with lexical_cast on empty string as target

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #11047: Valgrind warning "uninitialized variable" with lexical_cast on empty string as target
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2015-09-30 20:16:31

#11047: Valgrind warning "uninitialized variable" with lexical_cast on empty string
as target
-------------------------+-------------------------------------------------
  Reporter:  aedo99@…    |      Owner:  apolukhin
      Type:  Bugs        |     Status:  closed
 Milestone:  Boost       |  Component:  lexical_cast
  1.60.0                 |   Severity:  Problem
   Version:  Boost       |   Keywords:  lexical_cast uninitialized variable
  1.47.0                 |  valgrind
Resolution:  obsolete    |
-------------------------+-------------------------------------------------
Changes (by apolukhin):

 * status:  assigned => closed
 * resolution:   => obsolete

Comment:

 Looks like this issue was fixed somewhere between 1.47-1.59.

 New code correctly handles empty strings:
 * on empty string `m_begin == m_end`
 *
 [https://github.com/boostorg/lexical_cast/blob/master/include/boost/lexical_cast/detail/lcast_unsigned_converters.hpp#L186

 Decrementing `m_end` without dereferencing]
 *
 [https://github.com/boostorg/lexical_cast/blob/master/include/boost/lexical_cast/detail/lcast_unsigned_converters.hpp#L189

 `m_begin > m_end` is `true`], which will prevent the compiler from
 evaluating the expression further, `false` will be returned.
 * exception is thrown

 Thanks for reporting this issue anyway!

 If you need a fix for Boost 1.47, then just replace the line
 {{{
 if ( *end < czero || *end >= czero + 10 || begin > end)
 }}}
 with
 {{{
 if (begin > end || *end < czero || *end >= czero + 10)
 }}}

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/11047#comment:4>
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