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June 2010
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2010.06.29 18:15 "Re: libtiff 4.0 compiler warning on x64 in tif_read.c", by Edward Lam
Albert Cahalan wrote: > On Thu, Jun 17, 2010 at 6:10 PM, Edward Lam <edward@sidefx.com> wrote: >> >> tif_read.c(207) : warning C4244: '=' : conversion from 'tmsize_t' to >> 'int', possible loss of data >> >> Looking at it, it seems to me that we want "read_ahead" to be tmsize_t >> instead of int? Similarly, I think TIFFFillStripPartial() should take an >> tmsize_t instead. > > It's rather doubtful, considering the purpose of the variable. Here: > > // C4244 warning is more trouble than it's worth > #if defined(_MSC_VER) > #pragma warning(push) > #pragma warning(disable:4244) > #endif Regardless of whether the warning is "more trouble than it's worth", I think that at least for this case, it is warranted. If you examine the mentioned line, we have a 64-bit variable (tif_scanlinesize) multiplied by 2 and 5000 added to it before being assigned to a 32-bit quantity. Are you arguing that it is invalid in the BigTIFF spec to have a scanline size of greater than 2 GiB? IMHO, if the truncation is intentional, then we should be explicitly casting to signify that fact, ideally along with a comment as to why truncation is acceptable/correct behaviour. But that's probably a philosophical debate. Regards, -Edward