Is it ever good to call stable_sort instead of sort on scalar types (i.e. int, long, etc.) with the default comparator?
If so, when should you do this?
If not, then why don't standard libraries just forward such calls to sort? Wouldn't that be much faster?
Stable sorts are really only useful when the items you are sorting have satellite information.
From CLRS (Introduction to Algorithms, 3rd Ed.):
"In practice, the numbers to be sorted are rarely isolated values. Each is usually part of a collection of data called a record. Each record contains a key, which is the value to be sorted. The remainder of the record consists of satellite data, which are usually carried around with the key. In practice, when a sorting algorithm permutes the keys, it must permute the satellite data as well."
When a sort is stable, it means that ties are broken in the sorted array by the items' original ordering. If you are only sorting int and long types, you don't need a stable sort.