rust/library
Mara Bos 3601f9d40b
Rollup merge of #78581 - a1phyr:const_btree_more, r=dtolnay
Constantify more BTreeMap and BTreeSet functions

Just because we can:

- `BTreeMap::len`
- `BTreeMap::is_empty`
- `BTreeSet::len`
- `BTreeSet::is_empty`

Note that I put the `const` under `const_btree_new`, because I don't think their is a need to create another feature flag for that.

cc #71835
2020-10-31 09:49:39 +01:00
..