[cfe-dev] libc++, std::bind, and <random>

[Howard Hinnant]

On Apr 11, 2011, at 11:30 AM, Steven Watanabe wrote:

> AMDG
> 
> On 04/10/2011 10:18 PM, Seth Cantrell wrote:
>> Should the following work with clang and libc++?
>> 
>>> #include<functional>
>>> #include<random>
>>> 
>>> int main(int argc,char const *argv[]) {
>>>     std::mt19937 re;
>>>     std::normal_distribution<>  di(30,8);
>>>     auto rand = std::bind(di,re);
>>> }
>> 
>> Clang outputs the following error for this program:
>> 
>>> In file included from test.c++:2:
>>> /usr/include/c++/v1/random:2234:9: error: no member named 'generate' in 'std::__1::mersenne_twister_engine<unsigned int, 32, 624, 397, 31, 2567483615, 11,
>>>       4294967295, 7, 2636928640, 15, 4022730752, 18, 1812433253>'
>>>     __q.generate(__ar, __ar + __n * __k);
>>>     ~~~ ^
>> 
>> It looks to me like clang supports all the features necessary, and the code runs as expected in VS2010. Here's the command line I used:
>> 
> 
> When calling the copy constructor of a Random
> Number Engine with a non-const argument, the library is
> incorrectly treating the argument as a SeedSeq.
> The two declarations in question are:
> 
> mersenne_twister(const mersenne_twister&);
> template<typename SeedSeq> mersenne_twister(SeedSeq&);

Thanks Steven.  I'm working on an improved constraint for the SeedSeq template parameter.  The current constraint is simply that it is not implicitly convertible to the engine's result_type.

Howard