boost :: multiprecision从整型转换为cpp_dec_float编译错误

Question

我遇到了将代码移动到服务器的问题。

问题的最小工作实例是下面的代码（文件名mp2.cpp）：

#include <boost/multiprecision/cpp_int.hpp> 
#include <boost/multiprecision/cpp_dec_float.hpp> 
#include <iostream> 

using namespace std; 
using namespace boost::multiprecision; 

int main() { 
    uint128_t a = 1; 
    uint128_t b = 2; 
    cpp_dec_float_50 fa = static_cast<cpp_dec_float_50>(a); 
    cpp_dec_float_50 fb = static_cast<cpp_dec_float_50>(b); 
    cout << fa/fb << endl; 
    return 0; 
} 

编译和按预期运行，我开发机（克++ 4.6.3上在标准输出写0.5，升压1.55 ，32位CPU）。

对于相同的代码，G ++失败，此错误在服务器上编译：

In file included from /usr/local/include/boost/multiprecision/number.hpp:22:0, 
       from /usr/local/include/boost/multiprecision/cpp_int.hpp:12, 
       from mp2.cpp:1: 
/usr/local/include/boost/multiprecision/detail/generic_interconvert.hpp: In instantiation of 'void boost::multiprecision::detail::generic_interconvert(To&, const From&, const mpl_::int_<1>&, const mpl_::int_<0>&) [with To = boost::multiprecision::backends::cpp_dec_float<50u>; From = boost::multiprecision::backends::cpp_int_backend<128u, 128u, (boost::multiprecision::cpp_integer_type)0u, (boost::multiprecision::cpp_int_check_type)0u, void>]': 
/usr/local/include/boost/multiprecision/number.hpp:108:7: required from 'boost::multiprecision::number<Backend, ExpressionTemplates>::number(const boost::multiprecision::number<Other, ET>&, typename boost::enable_if_c<(! boost::multiprecision::detail::is_explicitly_convertible<Other, Backend>::value)>::type*) [with Other = boost::multiprecision::backends::cpp_int_backend<128u, 128u, (boost::multiprecision::cpp_integer_type)0u, (boost::multiprecision::cpp_int_check_type)0u, void>; boost::multiprecision::expression_template_option ET = (boost::multiprecision::expression_template_option)0u; Backend = boost::multiprecision::backends::cpp_dec_float<50u>; boost::multiprecision::expression_template_option ExpressionTemplates = (boost::multiprecision::expression_template_option)1u; typename boost::enable_if_c<(! boost::multiprecision::detail::is_explicitly_convertible<Other, Backend>::value)>::type = void]' 
mp2.cpp:11:55: required from here 
/usr/local/include/boost/multiprecision/detail/generic_interconvert.hpp:43:4: error: no matching function for call to 'eval_is_zero(boost::multiprecision::backends::cpp_int_backend<128u, 128u, (boost::multiprecision::cpp_integer_type)0u, (boost::multiprecision::cpp_int_check_type)0u, void>&)' 
/usr/local/include/boost/multiprecision/detail/generic_interconvert.hpp:43:4: note: candidates are: 
In file included from mp2.cpp:2:0: 
/usr/local/include/boost/multiprecision/cpp_dec_float.hpp:2905:13: note: template<unsigned int Digits10, class ExponentType, class Allocator> bool boost::multiprecision::backends::eval_is_zero(const boost::multiprecision::backends::cpp_dec_float<Digits10, ExponentType, Allocator>&) 
/usr/local/include/boost/multiprecision/cpp_dec_float.hpp:2905:13: note: template argument deduction/substitution failed: 
In file included from /usr/local/include/boost/multiprecision/number.hpp:22:0, 
       from /usr/local/include/boost/multiprecision/cpp_int.hpp:12, 
       from mp2.cpp:1: 
/usr/local/include/boost/multiprecision/detail/generic_interconvert.hpp:43:4: note: 'boost::multiprecision::backends::cpp_int_backend<128u, 128u, (boost::multiprecision::cpp_integer_type)0u, (boost::multiprecision::cpp_int_check_type)0u, void>' is not derived from 'const boost::multiprecision::backends::cpp_dec_float<Digits10, ExponentType, Allocator>' 
In file included from /usr/local/include/boost/multiprecision/cpp_int.hpp:1787:0, 
       from mp2.cpp:1: 
/usr/local/include/boost/multiprecision/cpp_int/misc.hpp:94:4: note: template<unsigned int MinBits1, unsigned int MaxBits1, boost::multiprecision::cpp_integer_type SignType1, boost::multiprecision::cpp_int_check_type Checked1, class Allocator1> typename boost::enable_if_c<(! boost::multiprecision::backends::is_trivial_cpp_int<boost::multiprecision::backends::cpp_int_backend<MinBits, MaxBits, SignType, Checked, Allocator> >::value), bool>::type boost::multiprecision::backends::eval_is_zero(const boost::multiprecision::backends::cpp_int_backend<MinBits, MaxBits, SignType, Checked, Allocator>&) 
/usr/local/include/boost/multiprecision/cpp_int/misc.hpp:94:4: note: template argument deduction/substitution failed: 
/usr/local/include/boost/multiprecision/cpp_int/misc.hpp: In substitution of 'template<unsigned int MinBits1, unsigned int MaxBits1, boost::multiprecision::cpp_integer_type SignType1, boost::multiprecision::cpp_int_check_type Checked1, class Allocator1> typename boost::enable_if_c<(! boost::multiprecision::backends::is_trivial_cpp_int<boost::multiprecision::backends::cpp_int_backend<MinBits, MaxBits, SignType, Checked, Allocator> >::value), bool>::type boost::multiprecision::backends::eval_is_zero(const boost::multiprecision::backends::cpp_int_backend<MinBits, MaxBits, SignType, Checked, Allocator>&) [with unsigned int MinBits1 = 128u; unsigned int MaxBits1 = 128u; boost::multiprecision::cpp_integer_type SignType1 = (boost::multiprecision::cpp_integer_type)0u; boost::multiprecision::cpp_int_check_type Checked1 = (boost::multiprecision::cpp_int_check_type)0u; Allocator1 = void]': 
/usr/local/include/boost/multiprecision/detail/generic_interconvert.hpp:43:4: required from 'void boost::multiprecision::detail::generic_interconvert(To&, const From&, const mpl_::int_<1>&, const mpl_::int_<0>&) [with To = boost::multiprecision::backends::cpp_dec_float<50u>; From = boost::multiprecision::backends::cpp_int_backend<128u, 128u, (boost::multiprecision::cpp_integer_type)0u, (boost::multiprecision::cpp_int_check_type)0u, void>]' 
/usr/local/include/boost/multiprecision/number.hpp:108:7: required from 'boost::multiprecision::number<Backend, ExpressionTemplates>::number(const boost::multiprecision::number<Other, ET>&, typename boost::enable_if_c<(! boost::multiprecision::detail::is_explicitly_convertible<Other, Backend>::value)>::type*) [with Other = boost::multiprecision::backends::cpp_int_backend<128u, 128u, (boost::multiprecision::cpp_integer_type)0u, (boost::multiprecision::cpp_int_check_type)0u, void>; boost::multiprecision::expression_template_option ET = (boost::multiprecision::expression_template_option)0u; Backend = boost::multiprecision::backends::cpp_dec_float<50u>; boost::multiprecision::expression_template_option ExpressionTemplates = (boost::multiprecision::expression_template_option)1u; typename boost::enable_if_c<(! boost::multiprecision::detail::is_explicitly_convertible<Other, Backend>::value)>::type = void]' 
mp2.cpp:11:55: required from here 
/usr/local/include/boost/multiprecision/cpp_int/misc.hpp:94:4: error: no type named 'type' in 'struct boost::enable_if_c<false, bool>' 
In file included from /usr/local/include/boost/multiprecision/cpp_int.hpp:18:0, 
       from mp2.cpp:1: 
/usr/local/include/boost/multiprecision/detail/generic_interconvert.hpp: In instantiation of 'void boost::multiprecision::detail::generic_interconvert(To&, const From&, const mpl_::int_<1>&, const mpl_::int_<0>&) [with To = boost::multiprecision::backends::cpp_dec_float<50u>; From = boost::multiprecision::backends::cpp_int_backend<128u, 128u, (boost::multiprecision::cpp_integer_type)0u, (boost::multiprecision::cpp_int_check_type)0u, void>]': 
/usr/local/include/boost/multiprecision/number.hpp:108:7: required from 'boost::multiprecision::number<Backend, ExpressionTemplates>::number(const boost::multiprecision::number<Other, ET>&, typename boost::enable_if_c<(! boost::multiprecision::detail::is_explicitly_convertible<Other, Backend>::value)>::type*) [with Other = boost::multiprecision::backends::cpp_int_backend<128u, 128u, (boost::multiprecision::cpp_integer_type)0u, (boost::multiprecision::cpp_int_check_type)0u, void>; boost::multiprecision::expression_template_option ET = (boost::multiprecision::expression_template_option)0u; Backend = boost::multiprecision::backends::cpp_dec_float<50u>; boost::multiprecision::expression_template_option ExpressionTemplates = (boost::multiprecision::expression_template_option)1u; typename boost::enable_if_c<(! boost::multiprecision::detail::is_explicitly_convertible<Other, Backend>::value)>::type = void]' 
mp2.cpp:11:55: required from here 
/usr/local/include/boost/multiprecision/rational_adaptor.hpp:252:13: note: template<class IntBackend> bool boost::multiprecision::backends::eval_is_zero(const boost::multiprecision::backends::rational_adaptor<IntBackend>&) 
/usr/local/include/boost/multiprecision/rational_adaptor.hpp:252:13: note: template argument deduction/substitution failed: 
In file included from /usr/local/include/boost/multiprecision/number.hpp:22:0, 
       from /usr/local/include/boost/multiprecision/cpp_int.hpp:12, 
       from mp2.cpp:1: 
/usr/local/include/boost/multiprecision/detail/generic_interconvert.hpp:43:4: note: 'boost::multiprecision::backends::cpp_int_backend<128u, 128u, (boost::multiprecision::cpp_integer_type)0u, (boost::multiprecision::cpp_int_check_type)0u, void>' is not derived from 'const boost::multiprecision::backends::rational_adaptor<IntBackend>' 

服务器运行克++ 4.7.2和升压1.56，在64位CPU。我已经安装了相同的g ++和boost版本来查看这是否是问题，但事实并非如此。

从实验来源看，每当我尝试将整数转换为浮点数时，就会出现问题。但是，正如in the documentation所提到的，这是正确的方法。

有人知道问题是怎么回事，以及如何解决它？

Answer 1

我不知道这个库，但似乎问题来自x86-64体系结构的错误（？）。

应该注意的是：

1. 我有同样的问题，我的64位操作系统（Linux Mint的16 - G ++ 4.8.1 - 提升1.53）。
2. 作为解决方法，您可以使用-m32标志（成功进行测试）将代码交叉编译为32位二进制文​​件。
3. 问题使用uint128_t的cpp_int intead消失。

4. 奇怪的是，有使用下述自定义类型没有编译错误：当该分配器是由空隙替换（由uint128_t定义）

   typedef number<cpp_int_backend<128, 128, signed_magnitude, unchecked, std::allocator<limb_type> > > t128_custom; 
   

   问题出现，或者当使用usigned_magnitude。

也许您应该联系boost社区获取更多信息。