Description:
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Currently the PHP manual says the PHP7 'spaceship' comparison operator <=> returns "An integer less than, equal to, or greater than zero when $a is respectively less than, equal to, or greater than $b".

In the original RFC for this feature https://wiki.php.net/rfc/combined-comparison-operator the behavior was more specific: It returns -1, 0, or 1 depending on the result of the comparison.

It seems to me that the actual implementation matches the RFC: it always returns -1, 0, or -1. As coded it seems to return -1, 0, or -1 at least for all simple types such as numbers and strings. I would like to see it documented per the RFC, returning -1, 0, or 1, so we could rely on that behavior.

The orginal behavior was more useful, as it allowed for coding things like this:

    $table[($a <=> $b) + 1] 

to index a $table with 3 entries depending on the outcome of the 3-way comparison.