DateMalformedIntervalStringException when parsing high-precision seconds in CarbonInterval::make()

[dansleboby]

Hello,

I encountered an issue with the following code:

use Carbon\CarbonInterval;

print_r(CarbonInterval::make("PT13.516837S"));
print_r(CarbonInterval::make("PT13.000001S"));

Carbon version: 3.8.0

PHP version: 8.1.3

I expected to get:

Carbon\CarbonInterval Object
(
    [s]    13
    [f]    0.000001
)

But I actually get:

DateMalformedIntervalStringException with message 'Unknown or bad format (PT13.000001S)'

I narrow down the error is comming from:

https://github.com/briannesbitt/Carbon/blob/master/src/Carbon/CarbonInterval.php#L521-L526

echo (13 - 13.000001) . PHP_EOL; // -9.999999992516E-7

Because we are dealing with float and we do not round the result wird thing append due to how decimal and base 10 to base 2, see IEEE 754 and https://www.php.net/manual/en/language.types.float.php

Thanks!

[kylekatarnls]

Hello,

Indeed there is a bug when the rounding is below 0.000001 which is what happens with 13.000001 - 13 as in you analyze returns 0.000000999999999

I'm making a fix which will convert microseconds from the string to integer (without stepping by float type) which should avoir this rounding issue: #3098