id,summary,reporter,owner,description,type,status,milestone,component,version,severity,resolution,keywords,cc
9740,"""-ftrapv"" + multiprecision results in crash at startup",MaxBarraclough,John Maddock,"If the following file is compiled with g++ or clang++ ''without'' using the ""-ftrapv"" flag, it runs fine, irrespective of which lines are commented out.

If we compile ''with'' ""-ftrapv"", with either of the ''causes crash'' lines uncommented, then the program will crash on start-up, before even entering the ""main"" function. (The crashy code lives in a function which is never called.)

This is true of both g++ and clang++.

I am using Boost 1.55, g++ 4.8.1, clang 3.2, on Mint GNU/Linux, x86-64.


The -ftrapv flag ( described in gcc.gnu.org/onlinedocs/gcc-4.8.1/gcc/Code-Gen-Options.html#index-ftrapv-2326 (spam-detection forced me to sabotage the link) ) ''generates traps for signed overflow on addition, subtraction, multiplication operations''.



{{{
#include <boost/multiprecision/cpp_dec_float.hpp>

#include <boost/version.hpp>

#if ( BOOST_VERSION != 105500 )
  #error Boost 1.55 please
#endif

void neverCalled() {
//boost::multiprecision::cpp_dec_float_100 e;         // ok
//boost::multiprecision::cpp_dec_float_100 f = 42;    // ok
//boost::multiprecision::cpp_dec_float_100 g = 42.0f; // causes crash if -ftrapv is used
  boost::multiprecision::cpp_dec_float_100 h = 42.0;  // causes crash if -ftrapv is used
}

int main() {
  return 0;
}
}}}
",Bugs,closed,To Be Determined,multiprecision,Boost 1.55.0,Problem,fixed,,