The StableOrd trait can be used to mark types as having a stable
sort order across compilation sessions. Collections that sort their
items in a stable way can safely implement HashStable by
hashing items in sort order.
Reorganizing `stacked_borrows` in anticipation of a different model
These commits reorganize all the code inside the former `stacked_borrows` module and extract the part that really is specific to Stacked Borrows inside the `borrow_tracker/stacked_borrows` submodule.
Everything not specific to SB is put in `borrow_tracker/mod.rs`.
This is so that the future Tree Borrows model can be later added as a second submodule and reuse all the contents of `borrow_tracker/mod.rs`.
This reorganization is accompanied by renamings, mostly from "stacked borrows" to "borrow tracking".
Add `type_ascribe!` macro as placeholder syntax for type ascription
This makes it still possible to test the internal semantics of type ascription even once the `:`-syntax is removed from the parser. The macro now gets used in a bunch of UI tests that test the semantics and not syntax of type ascription.
I might have forgotten a few tests but this should hopefully be most of them. The remaining ones will certainly be found once type ascription is removed from the parser altogether.
Part of #101728
rustc_ast_lowering: Stop lowering imports into multiple items
Lower them into a single item with multiple resolutions instead.
This also allows to remove additional `NodId`s and `DefId`s related to those additional items.
This avoids calling `early_lint_node` twice.
Note: one `early_lint_node` call had `!pre_expansion` for the second
argument and the other had `false`. The new single call just has
`!pre_expansion`. This results in a reduction of duplicate error
messages in some `ui-fulldeps` tests. The order of some `ui-fulldeps`
output also changes, but that doesn't matter.
The lint definitions use macros heavily. This commit merges some of them
that are split unnecessarily. I find the reduced indirection makes it
easier to imagine what the generated code will look like.
The old version of this code specified a bunch of different numbers that had
to line up just right to get the size it wanted. This version uses flexbox
centering, specifies the font size, and lets the browser figure out the
rest of the layout automatically.
