Re: [boost] [test] Boost.Test fails to build with gcc-4.6

Subject: Re: [boost] [test] Boost.Test fails to build with gcc-4.6
From: Andrey Semashev (andrey.semashev_at_[hidden])
Date: 2016-03-05 10:26:09

On 2016-03-03 23:32, Raffi Enficiaud wrote:
> Le 03/03/16 12:04, John Maddock a écrit :
>> See
>> http://www.boost.org/development/tests/develop/developer/output/igaztanaga-gcc-4-6c++11-boost-bin-v2-libs-test-test-doc-boost_test_container_default-test-gcc-mngw-4-6c+-dbg-dbg-symbl-off.html
>>
>>
>
> The compiler looked broken to me (works eg. in 4.7), so I did not pay
> that much attention to that, but maybe I should reconsider.
>
> An example of error says this:
>
> ========
> test_case_template-test.cpp:38:5: error:
>
> 'boost::test_tools::assertion::binary_expr<Lhs, Rhs,OP>::evaluate(bool)
> const
>
> [with
> LExpr = boost::test_tools::assertion::value_expr<int>,
> Rhs = int&,
> OP = boost::test_tools::assertion::op::EQ<int, int, void>
> ]'
>
> is not a member of
>
> 'boost::test_tools::assertion::binary_expr<
>     boost::test_tools::assertion::value_expr<int>,
>     int,
>     boost::test_tools::assertion::op::EQ<int, int, void> >'
>
> ========
>
> note that "Rhs = int&" for the first expression, while "int" in
> "binary_expr<..., int>" for the second expression.
>
> The corresponding code is
>
> ========
> template<typename LExpr, typename Rhs, typename OP>
> class binary_expr : public
> expression_base<binary_expr<LExpr,Rhs,OP>,typename OP::result_type> {
> public:
>     // snip
>
>     assertion_result evaluate( bool no_message = false ) const
>     {
>       // ....
>
> ========
>
> This is an issue I was trying to fix for some time now. It appeared so
> far only for gcc in C++0X mode and not in C++11. This is the following:
>
> Say I have this:
>
> template<typename T>
> binary_expr<
>    ExprType,
>    T,
>    op::name<ValType,typename RhsT<T>::type> >
> operator ==( T&& rhs ) {
>    return binary_expr<ExprType,
>                       T,
>                       op::name<ValType,typename RhsT<T>::type> >
>             ( /* ... */ )
> }
>
> The compiler complains because the type in the declaration and inside
> the function mismatch, for some reason I do not get. Especially the type
> "T" is seen as eg. "int&" from outside the function (eg. from "auto"),
> while "T" is seen as "int" at the return statement.
>
> Maybe this is a known issue in gcc and easy to fix?

Is there any progress? I'm seeing these failures:

http://www.boost.org/development/tests/develop/developer/output/igaztanaga-gcc-4-6c++11-boost-bin-v2-libs-log-test-attr_attribute_set-test-gcc-mngw-4-6c+-dbg-bld-no-dbg-symbl-off-thrd-mlt.html

 From the look at the code I might suggest two solutions. First is easy, 
just add a check for gcc > 4.6 to 
boost/test/utils/runtime/errors.hpp:81. The second approach is to make 
the operator<<'s members of specific_param_error. This would also allow 
to remove the preprocessor check altogether.