As described in https://github.com/rust-lang/rfcs/pull/1298, the idea here is to make DefIds independent of changes to the content of other items. They are also *mostly* independent from ordering, so e.g. reordering two functions will change the defids, but it will not change the paths that they expand into (but this is not the case for some things, such as impls).
This is a major refactoring, so I did it in slices. The final commit is in some sense The Big One where most of the work is done. The earlier commits just pave the way by gradually refactoring accesses to the `node` field.
This is a [breaking-change] for plugin authors. The things you need to do to migrate your code are as follows:
1. For local def-ids, rather than do `def_id.node`, call `tcx.map.as_local_node_id(def_id)`.
2. To construct a local def-id, call `tcx.map.local_def_id(node_id)`.
3. Note that you cannot make def-ids for any node, but only for "definitions" -- which include all items, as well as a number of other things, but not e.g. arbitrary expressions.
4. You can get the path to a def-id by calling `tcx.def_path(def_id)`.
One thing that is NOT part of this PR, but which I plan do in a follow-up, is converting uses of the existing `with_path` API to use `def_path`, which is basically the same.
r? @eddyb (or @nrc)
this simplifies the code while reducing the size of libcore.rlib by
3.3 MiB (~1M of which is bloat a separate patch of mine removes
too), while reducing rustc memory usage on small crates by 18MiB.
This also simplifies the code considerably.
This PR removes random remaining `Ident`s outside of libsyntax and performs general cleanup
In particular, interfaces of `Name` and `Ident` are tidied up, `Name`s and `Ident`s being small `Copy` aggregates are always passed to functions by value, and `Ident`s are never used as keys in maps, because `Ident` comparisons are tricky.
Although this PR closes https://github.com/rust-lang/rust/issues/6993 there's still work related to it:
- `Name` can be made `NonZero` to compress numerous `Option<Name>`s and `Option<Ident>`s but it requires const unsafe functions.
- Implementation of `PartialEq` on `Ident` should be eliminated and replaced with explicit hygienic, non-hygienic or member-wise comparisons.
- Finally, large parts of AST can potentially be converted to `Name`s in the same way as HIR to clearly separate identifiers used in hygienic and non-hygienic contexts.
r? @nrc
Make sure Name, SyntaxContext and Ident are passed by value
Make sure Idents don't serve as keys (or parts of keys) in maps, Ident comparison is not well defined
Currently, we're generating adjustments, for example, to get from &[u8]
to &[u8], which is unneeded and kicks us out of trans_into()
into trans() which means an additional stack slot and copy in the
unoptimized code.
Currently, we're generating adjustments, for example, to get from &[u8]
to &[u8], which is unneeded and kicks us out of trans_into() into
trans() which means an additional stack slot and copy in the unoptimized
code.
The sort key is a (DefId, Name), which is *not* stable between
runs, so we must re-sort when loading.
Fixes#24063Fixes#25467Fixes#27222Fixes#28377
r? @eddyb
