Boost::crc fails if Visual C++'s "/RTCc Convert to smaller type checks" is enabled

[anonymous]

Boost::crc fails if Visual C++'s "/RTCc Convert to smaller type checks" is enabled

I would suggest to change crc_helper::index() from

static  unsigned char  index( value_type rem, unsigned char x )
{ return x ^ rem; }

to

static  unsigned char  index( value_type rem, unsigned char x )
{ return x ^ (rem & 0xFF); }

[Steven Watanabe]

x ^ static_cast<unsigned char>(rem)

would be slightly better.

[Steven Watanabe]

/RTCc yields non-conformant behavior. The behavior of the following program is well-defined (technically implementation defined since sizeof(short) is implementation defined) according to the C++ standard. In most implementations it will print 1.

#include <iostream>

int main() {
    unsigned int i = 65537;
    unsigned short s = static_cast<unsigned short>(i);
    std::cout << s << std::endl;
}