Re: [Boost-bugs] [Boost C++ Libraries] #11800: Boost Convert fails on user defined types with no value_type

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #11800: Boost Convert fails on user defined types with no value_type
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2015-11-19 01:59:27

#11800: Boost Convert fails on user defined types with no value_type
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  Reporter:  Brad Anderson <eco@…>  |      Owner:
      Type:  Bugs                   |     Status:  new
 Milestone:  To Be Determined       |  Component:  None
   Version:  Boost 1.59.0           |   Severity:  Problem
Resolution:                         |   Keywords:
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Comment (by Vladimir Batov):

 Thank you for the analysis and the code snippet. It's much appreciated.
 Unfortunately, I have no access to MSVC 2013. So, my reasoning is based on
 the information provided and my looking at the code. There I see that the
 mentioned code causing compilation error:

 template<typename T> struct is_string<T, /*is_range_class=*/true>
 {
     static bool const value = cnv::is_char<typename T::value_type>::value;
 };

 only kicks in if T is a class (checked by boost::is_class<T>) and T is a
 range (checked by cnv::is_range<T>). The "struct change" is a class.
 However, it is not a range and, therefore, cnv::is_range<T> should fail
 for the class as it does not have begin() and end() methods (see range.hpp
 lines 19-26). That mentioned check does correctly fail with the compilers
 (gcc and clang) available to me. More so, judging from
 http://www.boost.org/development/tests/develop/developer/convert.html, the
 respective test (convert_test_has_member) also works on msvc-12.0 (aka
 MSVC-2013, aka BOOST_MSVC=1800) correctly. However, it is known that
 earlier versions are broken and fail to compile convert_test_has_member.

 However, I understand you are using msvc-12.0 (MSVC-2013, BOOST_MSVC=1800)
 which seems to work in regression tests but fails for you. Could that be
 that your version of MSVC-2013 needs an update that would bring its
 behavior in line with msvc-12.0 in the regression tests?

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/11800#comment:3>
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