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Compile warnings in 64-bit builds, mostly re. loss-of-data #93
Description
I'm able to compile and run pForth for Windows/AMD64 using Visual Studio 2019. I'm seeing several compiler warnings though:
philburk-pforth-dd36def\csrc\pf_inner.c(204,69): warning C4293: '>>': shift count negative or too big, undefined behavior
philburk-pforth-dd36def\csrc\pf_save.c(410,75): warning C4244: '=': conversion from 'cell_t' to 'uint32_t', possible loss of data
philburk-pforth-dd36def\csrc\pf_save.c(412,102): warning C4267: '=': conversion from 'size_t' to 'int32_t', possible loss of data
philburk-pforth-dd36def\csrc\pf_save.c(413,106): warning C4267: '=': conversion from 'size_t' to 'int32_t', possible loss of data
philburk-pforth-dd36def\csrc\pf_save.c(414,41): warning C4244: '=': conversion from 'cell_t' to 'int32_t', possible loss of data
philburk-pforth-dd36def\csrc\pf_save.c(438,38): warning C4244: '=': conversion from 'ExecToken' to 'int32_t', possible loss of data
philburk-pforth-dd36def\csrc\pf_save.c(456,55): warning C4244: '=': conversion from 'cell_t' to 'int32_t', possible loss of data
philburk-pforth-dd36def\csrc\pf_save.c(457,78): warning C4244: '=': conversion from 'cell_t' to 'uint32_t', possible loss of data
philburk-pforth-dd36def\csrc\pf_save.c(469,34): warning C4244: '=': conversion from 'cell_t' to 'int32_t', possible loss of data
philburk-pforth-dd36def\csrc\pf_save.c(476,30): warning C4244: '=': conversion from 'cell_t' to 'int32_t', possible loss of data
Regarding the possible loss of data warnings: these seem, at a glance, to be well-founded. For instance, peering through the typedefs, the conversion from 'ExecToken' to 'int32_t' boils down to a uintptr_t being converted to an int32_t.
There are also some compiler warnings on 32-bit builds, but these ones seem spurious, as all 4 of the lines are wrapped within if( sizeof(ucell_t) == 8 ) { and so will not be executed on 32-bit builds.
philburk-pforth-dd36def\csrc\pf_save.c(223,38): warning C4293: '>>': shift count negative or too big, undefined behavior
philburk-pforth-dd36def\csrc\pf_save.c(224,38): warning C4293: '>>': shift count negative or too big, undefined behavior
philburk-pforth-dd36def\csrc\pf_save.c(225,38): warning C4293: '>>': shift count negative or too big, undefined behavior
philburk-pforth-dd36def\csrc\pf_save.c(226,38): warning C4293: '>>': shift count negative or too big, undefined behavior
It's possible to get rid of these warnings using the preprocessor, following this documentation, something like this (non-Windows builds will be unaffected):
/* 32-bit Windows builds definitely don't need the first
sequence. This avoid spurious Visual Studio warnings. */
#if (!defined _WIN32) || (defined _WIN64)
if( sizeof(ucell_t) == 8 )
{
*addr++ = (uint8_t) (data>>56);
*addr++ = (uint8_t) (data>>48);
*addr++ = (uint8_t) (data>>40);
*addr++ = (uint8_t) (data>>32);
}
#endif
*addr++ = (uint8_t) (data>>24);
*addr++ = (uint8_t) (data>>16);
*addr++ = (uint8_t) (data>>8);
*addr = (uint8_t) (data);
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