Shorten `rustc_middle::ty::mod`
Related to #60302.
This PR moves all `Adt*`, `Assoc*`, `Generic*`, and `UpVar*` types to separate files.
This, alongside some `use` reordering, puts `mod.rs` at ~2,200 lines, thus removing the `// ignore-tidy-filelength`.
The particular groups were chosen as they had 4 or more "substantive" members.
This essentially switches search-index.js from a "array of struct"
to a "struct of array" format, like this:
{
"doc": "Crate documentation",
"t": [ 1, 1, 2, 3, ... ],
"n": [ "Something", "SomethingElse", "whatever", "do_stuff", ... ],
"q": [ "a::b", "", "", "", ... ],
"d": [ "A Struct That Does Something", "Another Struct", "a function", "another function", ... ],
"i": [ 0, 0, 1, 1, ... ],
"f": [ null, null, [], [], ... ],
"p": ...,
"a": ...
}
So `{ty: 1, name: "Something", path: "a::b", desc: "A Struct That Does Something", parent_idx: 0, search_type: null}` is the first item.
This makes the uncompressed version smaller, but it really shows on the
compressed version:
notriddle:rust$ wc -c new-search-index1.52.0.js
2622427 new-search-index1.52.0.js
notriddle:rust$ wc -c old-search-index1.52.0.js
2725046 old-search-index1.52.0.js
notriddle:rust$ gzip new-search-index1.52.0.js
notriddle:rust$ gzip old-search-index1.52.0.js
notriddle:rust$ wc -c new-search-index1.52.0.js.gz
239385 new-search-index1.52.0.js.gz
notriddle:rust$ wc -c old-search-index1.52.0.js.gz
296328 old-search-index1.52.0.js.gz
notriddle:rust$
That's a 4% improvement on the uncompressed version (fewer `[]`),
and 20% improvement after gzipping it, thanks to putting like-typed
data next to each other. Any compression algorithm based on a sliding
window will probably show this kind of improvement.
This pulls in rust-lang/rustc-rayon#8 to fix#81425. (h/t @ammaraskar)
That revealed weak constraints on `rustc_arena::DropArena`, because its
`DropType` was holding type-erased raw pointers to generic `T`. We can
implement `Send` for `DropType` (under `cfg(parallel_compiler)`) by
requiring all `T: Send` before they're type-erased.
