{MSVC} Building with /W4 results in warning C4127

[asmaloney]

...
\...\extern\CRCpp\inc\CRC.h(904): warning C4127: conditional expression is constant
\...\extern\CRCpp\inc\CRC.h(501): note: see reference to function template instantiation 'CRCType CRC::CalculateRemainder<CRCType,32>(const void *,size_t,const CRC::Table<CRCType,32> &,CRCType)' being compiled
        with
        [
            CRCType=uint32_t
        ]
...

Right above line 904, an MSVC warning is explicitly disabled. I wonder if the same should be done here?

Happy to create a PR if so.

Workaround is to disable it for the entire include:

#if defined( WIN32 ) || defined( _WIN32 ) || defined( WINCE )
// Disable warning about "conditional expression is constant".
#pragma warning( push )
#pragma warning( disable : 4127 )
#endif
#include "CRC.h"
#if defined( WIN32 ) || defined( _WIN32 ) || defined( WINCE )
#pragma warning( pop )
#endif

[d-bahr]

There are a couple of places where this is the case, I think, not just line 904. if constexpr would be the C++17 way of solving this but would still break for older compilers.

I think disabling the warning for the whole file is acceptable. I'll fix it shortly.

[asmaloney]

👍 I found another solution in case you want another option.

You can assign to a var and then check it like this (from my own code):

   // Assign to var to avoid MSVC warning
   // This section can be simplified in C++17 using a "constexpr if".
   constexpr bool cSizeCheck = ( sizeof( size_t ) >= sizeof( int64_t ) );
   if ( cSizeCheck )
...

MSVC only complains if it's in the conditional expression.

Thanks Daniel!

[d-bahr]

Decided to go with the #ifdef solution. If compiled with C++03 then the constexpr solutions may not work.

MSVC should be smart enough to optimize out the branches that are not invoked. In any case, issue closed.

[asmaloney]

If compiled with C++03 then the constexpr solutions may not work.

Ah right. Could use static instead.

Anyways - thanks for the great lib!