Remove not(stage0) from deny(warnings)
Historically this was done to accommodate bugs in lints, but there hasn't been a
bug in a lint since this feature was added which the warnings affected. Let's
completely purge warnings from all our stages by denying warnings in all stages.
This will also assist in tracking down `stage0` code to be removed whenever
we're updating the bootstrap compiler.
`BoolTrie` works well for sets of code points spread out through
most of Unicode’s range, but is uses a lot of space for sets
with few, mostly low, code points.
This switches a few of its instances to a similar but simpler trie
data structure.
## Before
`size_of::<BoolTrie>()` is 1552, which is added to
`table.r3.len() * 8 + t.r5.len() + t.r6.len() * 8`:
* `Cc_table`: 1632
* `White_Space_table`: 1656
* `Pattern_White_Space_table`: 1640
* Total: 4928 bytes
## After
`size_of::<SmallBoolTrie>()` is 32, which is added to
`t.r1.len() + t.r2.len() * 8`:
* `Cc_table`: 51
* `White_Space_table`: 273
* `Pattern_White_Space_table`: 193
* Total: 517 bytes
## Difference
Every Rust program with `std` statically linked should be about 4 KB smaller.
Historically this was done to accommodate bugs in lints, but there hasn't been a
bug in a lint since this feature was added which the warnings affected. Let's
completely purge warnings from all our stages by denying warnings in all stages.
This will also assist in tracking down `stage0` code to be removed whenever
we're updating the bootstrap compiler.
