[Boost-users] Compilation errors when trying to use range adaptors with C++11 lambdas

[Evan Driscoll]

When trying to compile the following:

std::vector<int> v;
v | boost::adaptors::transformed([] (int x) { return x; });

I get a bunch of compile errors. If I replace the lambda with a function
defined normally, it works.

Am I doing something wrong, or is this a bug/missing feature/something?
I'm compiling with GCC 4.6.1 (though 4.7.1 has the same problem) and
have Boost 1.49.


The output and full program are attached. The main part (dropping the
"instantiated from..."s) of the first error is:

boost/utility/result_of.hpp:82:8: error: no class template named
�result� in �struct main()::<lambda(int)>�

Evan

[Akira Takahashi]

Hi Evan,

2012/6/20 Evan Driscoll <dris...@cs.wisc.edu>:

> When trying to compile the following:
>
> std::vector<int> v;
> v | boost::adaptors::transformed([] (int x) { return x; });
>
> I get a bunch of compile errors. If I replace the lambda with a function
> defined normally, it works.

You must use
#define BOOST_RESULT_OF_USE_DECLTYPE

C++11 lambda can't apply non decltype-base result_of.

>>========================
Akira Takahashi
mailto:faitha...@gmail.com
https://sites.google.com/site/faithandbrave/about/en
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[Evan Driscoll]

On 06/20/2012 09:04 AM, boost-use...@lists.boost.org wrote:
> 2012/6/20 Evan Driscoll<dris...@cs.wisc.edu>:
>> When trying to compile the following:
>>
>> std::vector<int> v;
>> v | boost::adaptors::transformed([] (int x) { return x; });
>>
>> I get a bunch of compile errors. If I replace the lambda with a function
>> defined normally, it works.
>
> You must use
> #define BOOST_RESULT_OF_USE_DECLTYPE
>
> C++11 lambda can't apply non decltype-base result_of.

Thanks a lot; worked like a charm. Of course, in the interim I figured
out that the function will be rather more complicated than I thought so
I'm happier with it defined normally, but that'll be good to file away
for future reference. :-)

Evan