is_base<T, T> is broken on MSVC10 when T is not defined

Open
#82 0 comments 0 reactions 0 assignees View on GitHub

Nobody has claimed this yet.

Assessment

Difficulty
3/5
Estimated time
1-2 days
Newbie friendliness
35/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Stale
Tech stack
cpp
Domain
compilers

Research direction

Start by reproducing the MSVC10 example involving an incomplete class and boost::is_base_of. Read boost/type_traits/is_base_and_derived.hpp and boost/type_traits/is_base_of.hpp, especially the BOOST_IS_BASE_OF path; done means the example compiles without breaking the existing base-of behavior.

Written by the indexing model from the issue text.

Description

Currently on Windows with MSVC10 boost defines BOOST_IS_BASE_OF (which is used in is_base_and_derived, which is used in is_base_of) as follows:

#define BOOST_IS_BASE_OF(T,U) (__is_base_of(T,U) && !is_same<T,U>::value)

But microsoft's intrinsic __is_base_of cannot be used with the same type (i.e. T = U) when it (the type) is not defined.

When the following is compiled

class A;
typedef typename boost::is_base_of<A, A>::type x;

you get an error message:

...\include\boost\type_traits\is_base_and_derived.hpp(228) : error C2139: 'A' : an undefined class is not allowed as an argument to compiler intrinsic type trait '__is_base_of'
...\include\boost\type_traits\is_base_of.hpp(29) : see reference to class template instantiation 'boost::detail::is_base_and_derived_impl<B,D>' being compiled
        with
        [
            B=A,
            D=A
        ]

The same code compiles on gcc-4.8.2 and clang-3.6.

Moved from https://svn.boost.org/trac10/ticket/11422

Dominant language
C++
Stars
66
Forks
87
PR merge metrics
No merged PRs in 30d

Contributor guide

No contributing guide indexed for this repository

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

More from boostorg/type_traits

All issues in boostorg/type_traits

Similar issues

More C++ issues

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.