[Boost-bugs] [Boost C++ Libraries] #2558: Unnecessary conversion warning in lexical_cast

Subject: [Boost-bugs] [Boost C++ Libraries] #2558: Unnecessary conversion warning in lexical_cast
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2008-12-01 23:58:26

#2558: Unnecessary conversion warning in lexical_cast
-------------------------------------------------+--------------------------
 Reporter:  Yang Zhang <yanghatespam_at_[hidden]>  |       Owner:  nasonov     
     Type:  Bugs                                 |      Status:  new         
Milestone:  Boost 1.38.0                         |   Component:  lexical_cast
  Version:  Boost Development Trunk              |    Severity:  Problem     
 Keywords:                                       |  
-------------------------------------------------+--------------------------
 When trying to compile the following against r50058 with g++
 -Wconversion:

 {{{
 #include <boost/lexical_cast.hpp>
 #include <string>
 using namespace boost;
 using namespace std;
 int main() {
   lexical_cast<string>(3);
   return 0;
 }
 }}}

 I get:

 {{{
 /home/yang/work/boost/boost/lexical_cast.hpp: In function ‘CharT*
 boost::detail::lcast_put_unsigned(T, CharT*) [with Traits =
 std::char_traits<char>, T = unsigned int, CharT = char]’:
 /home/yang/work/boost/boost/lexical_cast.hpp:848:   instantiated from
 ‘bool boost::detail::lexical_stream_limited_src<CharT, Base,
 Traits>::operator<<(int) [with CharT = char, Base =
 boost::detail::lexical_streambuf_fake, Traits = std::char_traits<char>]’
 /home/yang/work/boost/boost/lexical_cast.hpp:1142:   instantiated from
 ‘Target boost::detail::lexical_cast(typename
 boost::call_traits<Source>::param_type, CharT*, size_t) [with Target =
 std::basic_string<char, std::char_traits<char>, std::allocator<char> >,
 Source = int, bool Unlimited = false, CharT =
 boost::lexical_cast::char_type]’
 /home/yang/work/boost/boost/lexical_cast.hpp:1166:   instantiated from
 ‘Target boost::lexical_cast(const Source&) [with Target =
 std::basic_string<char, std::char_traits<char>, std::allocator<char> >,
 Source = int]’
 blah.cc:6:   instantiated from here
 /home/yang/work/boost/boost/lexical_cast.hpp:510: warning: conversion to
 ‘char’ from ‘int’ may alter its value
 /home/yang/work/boost/boost/lexical_cast.hpp:848:   instantiated from
 ‘bool boost::detail::lexical_stream_limited_src<CharT, Base,
 Traits>::operator<<(int) [with CharT = char, Base =
 boost::detail::lexical_streambuf_fake, Traits = std::char_traits<char>]’
 /home/yang/work/boost/boost/lexical_cast.hpp:1142:   instantiated from
 ‘Target boost::detail::lexical_cast(typename
 boost::call_traits<Source>::param_type, CharT*, size_t) [with Target =
 std::basic_string<char, std::char_traits<char>, std::allocator<char> >,
 Source = int, bool Unlimited = false, CharT =
 boost::lexical_cast::char_type]’
 /home/yang/work/boost/boost/lexical_cast.hpp:1166:   instantiated from
 ‘Target boost::lexical_cast(const Source&) [with Target =
 std::basic_string<char, std::char_traits<char>, std::allocator<char> >,
 Source = int]’
 blah.cc:6:   instantiated from here
 /home/yang/work/boost/boost/lexical_cast.hpp:512: warning: conversion to
 ‘char’ from ‘int’ may alter its value
 /home/yang/work/boost/boost/lexical_cast.hpp:536: warning: conversion to
 ‘char’ from ‘int’ may alter its value
 }}}

 It seems this is because the header is using CHAR_MAX as-is and
 expecting it to be a char.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/2558>
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