Hygiene 2.0: Avoid comparing fields by name
There are two separate commits here (not counting tests):
- The first one unifies named (`obj.name`) and numeric (`obj.0`) field access expressions in AST and HIR. Before field references in these expressions are resolved it doesn't matter whether the field is named or numeric (it's just a symbol) and 99% of code is common. After field references are resolved we work with
them by index for all fields (see the second commit), so it's again not important whether the field was named or numeric (this includes MIR where all fields were already by index).
(This refactoring actually fixed some bugs in HIR-based borrow checker where borrows through names (`S {
0: ref x }`) and indices (`&s.0`) weren't considered overlapping.)
- The second commit removes all by-name field comparison and instead resolves field references to their indices once, and then uses those resolutions. (There are still a few name comparisons in save-analysis, because save-analysis is weird, but they are made correctly hygienic).
Thus we are fixing a bunch of "secondary" field hygiene bugs (in borrow checker, lints).
Fixes https://github.com/rust-lang/rust/issues/46314
Ak 44493 infer predicate
**WIP** Implements #44493
Things to do:
- [x] add feature gate and appropriate tests (see [forge](https://forge.rust-lang.org/feature-guide.html) for some details)
- [x] add a unit testing system similar to `#[rustc_variance]`
- [x] to see how, maybe `rg rustc_variance` and take some notes
- [ ] add more tests:
- [x] we need to decide how to handle `struct Foo<'a, T> { x: &'a T::Item }`
- [x] handle explicit predicates on types
- [ ] handle explicit predicates on `dyn Trait` (this could be put off to a follow-up PR)
- [ ] handle explicit predicates on projections (this could be put off to a follow-up PR)
Deprecate offset_to; switch core&alloc to using offset_from instead
Bonus: might make code than uses `.len()` on slice iterators faster
cc https://github.com/rust-lang/rust/issues/41079
Merge the std_unicode crate into the core crate
[The standard library facade](https://github.com/rust-lang/rust/issues/27783) has historically contained a number of crates with different roles, but that number has decreased over time. `rand` and `libc` have moved to crates.io, and [`collections` was merged into `alloc`](https://github.com/rust-lang/rust/pull/42648). Today we have `core` that applies everywhere, `std` that expects a full operating system, and `alloc` in-between that only requires a memory allocator (which can be provided by users)… and `std_unicode`, which doesn’t really have a reason to be separate anymore. It contains functionality based on Unicode data tables that can be large, but as long as relevant functions are not called the tables should be removed from binaries by linkers.
This deprecates the unstable `std_unicode` crate and moves all of its contents into `core`, replacing them with `pub use` reexports. The crate can be removed later. This also removes the `CharExt` trait (replaced with inherent methods in libcore) and `UnicodeStr` trait (merged into `StrExt`). There traits were both unstable and not intended to be used or named directly.
A number of new items are newly-available in libcore and instantly stable there, but only if they were already stable in libstd.
Fixes#49319.
Rollup of 14 pull requests
Successful merges:
- #49525 (Use sort_by_cached_key where appropriate)
- #49575 (Stabilize `Option::filter`.)
- #49614 (in which the non-shorthand patterns lint keeps its own counsel in macros)
- #49665 (Small nits to make couple of tests pass on mips targets.)
- #49781 (add regression test for #16223 (NLL): use of collaterally moved value)
- #49795 (Properly look for uninhabitedness of variants in niche-filling check)
- #49809 (Stop emitting color codes on TERM=dumb)
- #49856 (Do not uppercase-lint #[no_mangle] statics)
- #49863 (fixed typo)
- #49857 (Fix "fp" target feature for AArch64)
- #49849 (Add --enable-debug flag to musl CI build script)
- #49734 (proc_macro: Generalize `FromIterator` impl)
- #49730 (Fix ICE with impl Trait)
- #48270 (Replace `structurally_resolved_type` in casts check.)
Failed merges:
Replace `structurally_resolved_type` in casts check.
The behaviour of `resolve_type_vars_if_possible` is simpler and infallible. Other minor refactorings.
I'm not sure if this is backwards compatible, in theory resolving obligations between two cast checks could solve a dependency between them, but I don't know if that's actually possible and it doesn't sound like something we'd want to support.
proc_macro: Generalize `FromIterator` impl
While never intended to be stable we forgot that trait impls are insta-stable!
This construction of `FromIterator` wasn't our first choice of how to stabilize
the impl but our hands are tied at this point, so revert back to the original
definition of `FromIterator` before #49597Closes#49725
Add --enable-debug flag to musl CI build script
Building for x86_64-unknown-linux-musl currently results in an executable lacking debug information for musl libc itself. If you request a backtrace in GDB while control flow is within musl – including sycalls made by musl – the result looks like:
```
#0 0x0000000000434b46 in __cp_end ()
#1 0x0000000000432dbd in __syscall_cp_c ()
#2 0x0000000000000000 in ?? ()
```
i.e. not very helpful. Adding --enable-debug resolves this, and --enable-optimize re-enables optimisations which default to off given the previous flag.
Fix "fp" target feature for AArch64
This fixes the following warning on AArch64:
```
'+fp' is not a recognized feature for this target (ignoring feature)
```
Fixes#49782
Do not uppercase-lint #[no_mangle] statics
The reasoning being that `#[no_mangle]` expresses enough intention that there's likely a good reason for the name.
Fixes#36258.
Blindly checkpoint status of NLL mode ui tests
This takes the next (and potentially final?) step with #48879.
Namely, this PR got things to the point where I can successfully run `compiletest` on `src/test/ui` with `--compile-mode=nll`.
Here are the main pieces of it:
1. To figure out how to even run `compiletest` normally on the ui directory, I ran `x.py test -vv`, and then looked for the `compiletest` invocation that mentioned `src/test/ui`.
2. I took the aforementioned `compiletest` invocation and used it, adding `--compile-mode=nll` to the end. It had 170 failing cases.
3. Due to #49855, I had to edit some of the tests so that they fail even under NLL, via `#[rustc_error]`. That's the first commit. (Then goto 2 to double-check no such tests remain.)
4. I took the generated `build/target/test/foo.stderr` file for every case that failed, and blindly copied it to `src/test/foo.nll.stderr`. That's the second commit.
5. Goto 2 until there were no failing cases.
6. Remove any stamp files, and re-run `x.py test` to make sure that the edits and new `.nll.stderr` files haven't broken the pre-existing test suite.
add regression test for #16223 (NLL): use of collaterally moved value
Adds regression test for https://github.com/rust-lang/rust/issues/16223 which NLL fixes.
The current downside of this test is that it uses the `#![feature(box_patterns)]` and I haven't come up with a proper test that only uses the `#![feature(nll)]` - however, I don't know if this is even possible to test without `#![feature(box_syntax)]` or `#![feature(box_patterns)]`.
in which the non-shorthand patterns lint keeps its own counsel in macros
In issue #49588, Michael Lamparski pointed out a scenario in which the
non-shorthand-field-patterns lint could be triggered by a macro-expanded
pattern, in a way which was direly unwieldy for the macro author to guard
against and unreasonable to expect the macro user to take into account. We can
avoid this by not linting patterns that come from macro-expansions. Although
this entails accepting "false negatives" where the lint could genuinely improve
macro-templated code, avoiding the reported "true-but-super-annoying positive"
may be worth the trade? (Some precedent for these relative priorities exists as
no. 47775 (5985b0b0).)
Resolves#49588.
Use sort_by_cached_key where appropriate
A follow-up to https://github.com/rust-lang/rust/pull/48639, converting various slice sorting calls to `sort_by_cached_key` when the key functions are more expensive.
