Re: Numeric key collision related bug in Lua 5.3

[Chris Emerson <chris-lua@...>]

On Fri, Apr 24, 2015 at 05:44:47PM -0400, Sean Conner wrote:
> Makes sense when you think about it.  Even more interesting is this bit of
> code:
[converting 2^33 to 32-bit int/unsigned int
> (Again, assumption is sizeof(int) == sizeof(float).)
> 
> The results here have me perplexed because the output is not what I
> expected:
> 
> 	8589934592.000000 -2147483648 0
> 
> Truthfully, I'm not sure what I expected, but two wildly different answers
> isn't it; perhaps INT_MAX and UINT_MAX but not INT_MIN and 0! 2^31 gave the
> expected answers, and 2^32 gave -2147483648 0.

In C, converting a float type to an integer is undefined behaviour if the
value can't be represented (after truncating fractional bits).  So any
result or behaviour is "correct".  :-)

Chris