We all know dates are hard, which is why we let libraries and built-in language features handle them. Right?

Well, turns out you can’t even trust those. I was just writing the following code, that needed to determine the first day of the next month for me. Using PHP’s strtotime function, this oughtta be easy, right?

$firstDateOfNextMonth = date('Y-m-01', strtotime('+1 month'));

Only, today is August 31st, so PHP actually turned this into 2017-10-01, because obviously that is correct. And yes, my timezone settings are local – var_dump(date('Y-m-d H:i:s')) gave me 2017-08-31 17:28:22.

For comparison, PostgreSQL does what I expect:

# select NOW()+'1 month'::interval;
           ?column?            
-------------------------------
 2017-09-30 17:31:25.025405+02
(1 row)

Sighs time to file a bug I guess…