Very strange problem with comparing floating point numbers

[so]

On Sunday, 30 September 2012 at 17:07:19 UTC, monarch_dodra wrote:
> On Sunday, 30 September 2012 at 01:29:24 UTC, Ivan Agafonov 
> wrote:
>> // Tell me about this sutation, may be it is a bug?
>>
>> [SNIP]
>> 	// all of this fails!!!
>> 	assert (a.length == a.length); // This is really shocking
>> 	assert (a.length == a3.length);
>> [SNIP]
>
> This is just a fact of life regarding how floating point types 
> work. Here is a well documented explanation. It pertains to 
> C++, but applies.
>
> http://www.parashift.com/c++-faq/floating-point-arith2.html
>
> As a rule of thumb, NEVER use opEqual with floating point types 
> aniways. You need to use some sort of comparison with leway for 
> error, such as std.math.approxEqual.

Floating point types are trouble enough without these
optimization failures.
There are many unsolved problems, things like approxEqual are far
from answering them. Whatever the justifications they come up
with, "a.len == a.len" failure is IMO unacceptable, an opEqual
like this must not fail.

A suggestion: do what i do and have this in your config files.

alias real evil;