https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92220
R. Diez <rdiez-2006 at rd10 dot de> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |rdiez-2006 at rd10 dot de
--- Comment #7 from R. Diez <rdiez-2006 at rd10 dot de> ---
This shortcoming has annoyed me for quite some time.
Here is the test case I am using to convey the issue:
// Compile with -Wconversion
#include <stdint.h>
int main ( void )
{
volatile uint64_t a = 123;
volatile uint16_t b = 2;
// warning: conversion from 'long unsigned int' to 'uint16_t'
// {aka 'short unsigned int'} may change value [-Wconversion]
uint16_t result = a % b;
return result;
}
It is available here to play with:
https://godbolt.org/z/aKPqEozjW
I am trying to write a safe wrapper to prevent the warning like this:
template < typename TypeA, typename TypeB >
TypeB ModuloToSmallerSize ( const TypeA a, const TypeB b ) throw()
{
if constexpr ( sizeof( TypeA ) <= sizeof( TypeB ) )
{
// If there is no need for tricks, do not use any.
return a % b;
}
else
{
return static_cast< TypeB >( a % b );
}
}
But I am not sure whether that implementation is a good idea. Should I check
whether both integer types are signed or both are unsigned? Or does it not
matter at all?
