Check that nested statics in thread locals are duplicated per thread.
follow-up to #123310
cc ``@compiler-errors`` ``@RalfJung``
fwiw: I have no idea how thread local statics make that work under LLVM, and miri fails on this example, which I would have expected to be the correct behaviour.
Since the `#[thread_local]` attribute is just an internal implementation detail, I'm just going to start hard erroring on nested mutable statics in thread locals.
Make sure to insert `Sized` bound first into clauses list
#120323 made it so that we don't insert an implicit `Sized` bound whenever we see an *explicit* `Sized` bound. However, since the code that inserts implicit sized bounds puts the bound as the *first* in the list, that means that it had the **side-effect** of possibly meaning we check `Sized` *after* checking other trait bounds.
If those trait bounds result in ambiguity or overflow or something, it may change how we winnow candidates. (**edit: SEE** #123303) This is likely the cause for the regression in https://github.com/rust-lang/rust/issues/123279#issuecomment-2028899598, since the impl...
```rust
impl<T: Job + Sized> AsJob for T { // <----- changing this to `Sized + Job` or just `Job` (which turns into `Sized + Job`) will FIX the issue.
}
```
...looks incredibly suspicious.
Fixes [after beta-backport] #123279.
Alternative is to revert #120323. I don't have a strong opinion about this, but think it may be nice to keep the diagnostic changes around.
De-LLVM the unchecked shifts [MCP#693]
This is just one part of the MCP (https://github.com/rust-lang/compiler-team/issues/693), but it's the one that IMHO removes the most noise from the standard library code.
Seems net simpler this way, since MIR already supported heterogeneous shifts anyway, and thus it's not more work for backends than before.
r? WaffleLapkin
Add `Ord::cmp` for primitives as a `BinOp` in MIR
Update: most of this OP was written months ago. See https://github.com/rust-lang/rust/pull/118310#issuecomment-2016940014 below for where we got to recently that made it ready for review.
---
There are dozens of reasonable ways to implement `Ord::cmp` for integers using comparison, bit-ops, and branches. Those differences are irrelevant at the rust level, however, so we can make things better by adding `BinOp::Cmp` at the MIR level:
1. Exactly how to implement it is left up to the backends, so LLVM can use whatever pattern its optimizer best recognizes and cranelift can use whichever pattern codegens the fastest.
2. By not inlining those details for every use of `cmp`, we drastically reduce the amount of MIR generated for `derive`d `PartialOrd`, while also making it more amenable to MIR-level optimizations.
Having extremely careful `if` ordering to μoptimize resource usage on broadwell (#63767) is great, but it really feels to me like libcore is the wrong place to put that logic. Similarly, using subtraction [tricks](https://graphics.stanford.edu/~seander/bithacks.html#CopyIntegerSign) (#105840) is arguably even nicer, but depends on the optimizer understanding it (https://github.com/llvm/llvm-project/issues/73417) to be practical. Or maybe [bitor is better than add](https://discourse.llvm.org/t/representing-in-ir/67369/2?u=scottmcm)? But maybe only on a future version that [has `or disjoint` support](https://discourse.llvm.org/t/rfc-add-or-disjoint-flag/75036?u=scottmcm)? And just because one of those forms happens to be good for LLVM, there's no guarantee that it'd be the same form that GCC or Cranelift would rather see -- especially given their very different optimizers. Not to mention that if LLVM gets a spaceship intrinsic -- [which it should](https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/Suboptimal.20inlining.20in.20std.20function.20.60binary_search.60/near/404250586) -- we'll need at least a rustc intrinsic to be able to call it.
As for simplifying it in Rust, we now regularly inline `{integer}::partial_cmp`, but it's quite a large amount of IR. The best way to see that is with 8811efa88b (diff-d134c32d028fbe2bf835fef2df9aca9d13332dd82284ff21ee7ebf717bfa4765R113) -- I added a new pre-codegen MIR test for a simple 3-tuple struct, and this PR change it from 36 locals and 26 basic blocks down to 24 locals and 8 basic blocks. Even better, as soon as the construct-`Some`-then-match-it-in-same-BB noise is cleaned up, this'll expose the `Cmp == 0` branches clearly in MIR, so that an InstCombine (#105808) can simplify that to just a `BinOp::Eq` and thus fix some of our generated code perf issues. (Tracking that through today's `if a < b { Less } else if a == b { Equal } else { Greater }` would be *much* harder.)
---
r? `@ghost`
But first I should check that perf is ok with this
~~...and my true nemesis, tidy.~~
Adds support for both CFI and KCFI for attaching concrete and abstract
types to functions. KCFI does this through generation of `ReifyShim` on
any function pointer that could go in a vtable, and checking the
`ReifyReason` when emitting the instance. CFI does this by attaching
both the concrete and abstract type to every instance.
TypeID codegen tests are switched to be anchored on the left rather than
the right in order to allow emission of additional type attachments.
Fixes#115953
Previously, we assumed all `ty::Coroutine` were general coroutines and
attempted to generalize them through the `Coroutine` trait. Select
appropriate traits for each kind of coroutine.
Update to new browser-ui-test version
This new version brings a lot of new internal improvements (mostly around validating the commands input).
It also improved some command names and arguments.
r? `@notriddle`
rustdoc-search: shard the search result descriptions
## Preview
This makes no visual changes to rustdoc search. It's a pure perf improvement.
<details><summary>old</summary>
Preview: <http://notriddle.com/rustdoc-html-demo-10/doc/std/index.html?search=vec>
WebPageTest Comparison with before branch on a sort of worst case (searching `vec`, winds up downloading most of the shards anyway): <https://www.webpagetest.org/video/compare.php?tests=240317_AiDc61_2EM,240317_AiDcM0_2EN>
Waterfall diagram:
</details>
Preview: <http://notriddle.com/rustdoc-html-demo-10/doc2/std/index.html?search=vec>
WebPageTest Comparison with before branch on a sort of worst case (searching `vec`, winds up downloading most of the shards anyway): <https://www.webpagetest.org/video/compare.php?tests=240322_BiDcCH_13R,240322_AiDcJY_104>
## Description
r? `@GuillaumeGomez`
The descriptions are, on almost all crates[^1], the majority of the size of the search index, even though they aren't really used for searching. This makes it relatively easy to separate them into their own files.
Additionally, this PR pulls out information about whether there's a description into a bitmap. This allows us to sort, truncate, *then* download.
This PR also bumps us to ES8. Out of the browsers we support, all of them support async functions according to caniuse.
https://caniuse.com/async-functions
[^1]:
<https://microsoft.github.io/windows-docs-rs/>, a crate with
44MiB of pure names and no descriptions for them, is an outlier
and should not be counted. But this PR should improve it, by replacing a long line of empty strings with a compressed bitmap with a single Run section. Just not very much.
## Detailed sizes
```console
$ cat test.sh
set -ex
cp ../search-index*.js search-index.js
awk 'FNR==NR {a++;next} FNR<a-3' search-index.js{,} | awk 'NR>1 {gsub(/\],\\$/,""); gsub(/^\["[^"]+",/,""); print} {next}' | sed -E "s:\\\\':':g" > search-index.json
jq -c '.t' search-index.json > t.json
jq -c '.n' search-index.json > n.json
jq -c '.q' search-index.json > q.json
jq -c '.D' search-index.json > D.json
jq -c '.e' search-index.json > e.json
jq -c '.i' search-index.json > i.json
jq -c '.f' search-index.json > f.json
jq -c '.c' search-index.json > c.json
jq -c '.p' search-index.json > p.json
jq -c '.a' search-index.json > a.json
du -hs t.json n.json q.json D.json e.json i.json f.json c.json p.json a.json
$ bash test.sh
+ cp ../search-index1.78.0.js search-index.js
+ awk 'FNR==NR {a++;next} FNR<a-3' search-index.js search-index.js
+ awk 'NR>1 {gsub(/\],\\$/,""); gsub(/^\["[^"]+",/,""); print} {next}'
+ sed -E 's:\\'\'':'\'':g'
+ jq -c .t search-index.json
+ jq -c .n search-index.json
+ jq -c .q search-index.json
+ jq -c .D search-index.json
+ jq -c .e search-index.json
+ jq -c .i search-index.json
+ jq -c .f search-index.json
+ jq -c .c search-index.json
+ jq -c .p search-index.json
+ jq -c .a search-index.json
+ du -hs t.json n.json q.json D.json e.json i.json f.json c.json p.json a.json
64K t.json
800K n.json
8.0K q.json
4.0K D.json
16K e.json
192K i.json
544K f.json
4.0K c.json
36K p.json
20K a.json
```
These are, roughly, the size of each section in the standard library (this tool actually excludes libtest, for parsing-json-with-awk reasons, but libtest is tiny so it's probably not important).
t = item type, like "struct", "free fn", or "type alias". Since one byte is used for every item, this implies that there are approximately 64 thousand items in the standard library.
n = name, and that's now the largest section of the search index with the descriptions removed from it
q = parent *module* path, stored parallel to the items within
D = the size of each description shard, stored as vlq hex numbers
e = empty description bit flags, stored as a roaring bitmap
i = parent *type* index as a link into `p`, stored as decimal json numbers; used only for associated types; might want to switch to vlq hex, since that's shorter, but that would be a separate pr
f = function signature, stored as lists of lists that index into `p`
c = deprecation flag, stored as a roaring bitmap
p = parent *type*, stored separately and linked into from `i` and `f`
a = alias, as [[key, value]] pairs
## Search performance
http://notriddle.com/rustdoc-html-demo-11/perf-shard/index.html
For example, in stm32f4:
<table><thead><tr><th>before<th>after</tr></thead>
<tbody><tr><td>
```
Testing T -> U ... in_args = 0, returned = 0, others = 200
wall time = 617
Testing T, U ... in_args = 0, returned = 0, others = 200
wall time = 198
Testing T -> T ... in_args = 0, returned = 0, others = 200
wall time = 282
Testing crc32 ... in_args = 0, returned = 0, others = 0
wall time = 426
Testing spi::pac ... in_args = 0, returned = 0, others = 0
wall time = 673
```
</td><td>
```
Testing T -> U ... in_args = 0, returned = 0, others = 200
wall time = 716
Testing T, U ... in_args = 0, returned = 0, others = 200
wall time = 207
Testing T -> T ... in_args = 0, returned = 0, others = 200
wall time = 289
Testing crc32 ... in_args = 0, returned = 0, others = 0
wall time = 418
Testing spi::pac ... in_args = 0, returned = 0, others = 0
wall time = 687
```
</td></tr><tr><td>
```
user: 005.345 s
sys: 002.955 s
wall: 006.899 s
child_RSS_high: 583664 KiB
group_mem_high: 557876 KiB
```
</td><td>
```
user: 004.652 s
sys: 000.565 s
wall: 003.865 s
child_RSS_high: 538696 KiB
group_mem_high: 511724 KiB
```
</td></tr>
</table>
This perf tester is janky and unscientific enough that the apparent differences might just be noise. If it's not an order of magnitude, it's probably not real.
## Future possibilities
* Currently, results are not shown until the descriptions are downloaded. Theoretically, the description-less results could be shown. But actually doing that, and making sure it works properly, would require extra work (we have to be careful to avoid layout jumps).
* More than just descriptions can be sharded this way. But we have to be careful to make sure the size wins are worth the round trips. Ideally, data that’s needed only for display should be sharded while data needed for search isn’t.
* [Full text search](https://internals.rust-lang.org/t/full-text-search-for-rustdoc-and-doc-rs/20427) also needs this kind of infrastructure. A good implementation might store a compressed bloom filter in the search index, then download the full keyword in shards. But, we have to be careful not just of the amount readers have to download, but also of the amount that [publishers](https://gist.github.com/notriddle/c289e77f3ed469d1c0238d1d135d49e1) have to store.
rustdoc: heavily simplify the synthesis of auto trait impls
`gd --numstat HEAD~2 HEAD src/librustdoc/clean/auto_trait.rs`
**+315 -705** 🟩🟥🟥🟥⬛
---
As outlined in issue #113015, there are currently 3[^1] large separate routines that “clean” `rustc_middle::ty` data types related to generics & predicates to rustdoc data types. Every single one has their own kinds of bugs. While I've patched a lot of bugs in each of the routines in the past, it's about time to unify them. This PR is only the first in a series. It completely **yanks** the custom “bounds cleaning” of mod `auto_trait` and reuses the routines found in mod `simplify`. As alluded to, `simplify` is also flawed but it's still more complete than `auto_trait`'s routines. [See also my review comment over at `tests/rustdoc/synthetic_auto/bounds.rs`](https://github.com/rust-lang/rust/pull/123340#discussion_r1546900539).
This is preparatory work for rewriting “bounds cleaning” from scratch in follow-up PRs in order to finally [fix] #113015.
Apart from that, I've eliminated all potential sources of *instability* in the rendered output.
See also #119597. I'm pretty sure this fixes#119597.
This PR does not attempt to fix [any other issues related to synthetic auto trait impls](https://github.com/rust-lang/rust/issues?q=is%3Aissue+is%3Aopen+label%3AA-synthetic-impls%20label%3AA-auto-traits).
However, it's definitely meant to be a *stepping stone* by making `auto_trait` more contributor-friendly.
---
* Replace `FxHash{Map,Set}` with `FxIndex{Map,Set}` to guarantee a stable iteration order
* Or as a perf opt, `UnordSet` (a thin wrapper around `FxHashSet`) in cases where we never iterate over the set.
* Yes, we do make use of `swap_remove` but that shouldn't matter since all the callers are deterministic. It does make the output less “predictable” but it's still better than before. Ofc, I rely on `rustc_infer` being deterministic. I hope that holds.
* Utilizing `clean::simplify` over the custom “bounds cleaning” routines wipes out the last reference to `collect_referenced_late_bound_regions` in rustdoc (`simplify` uses `bound_vars`) which was a source of instability / unpredictability (cc #116388)
* Remove the types `RegionTarget` and `RegionDeps` from `librustdoc`. They were duplicates of the identical types found in `rustc`. Just import them from `rustc`. For some reason, they were duplicated when splitting `auto_trait` in two in #49711.
* Get rid of the useless “type namespace” `AutoTraitFinder` in `librustdoc`
* The struct only held a `DocContext`, it was over-engineered
* Turn the associated functions into free ones
* Eliminates rightward drift; increases legibility
* `rustc` also contains a useless `AutoTraitFinder` struct but I plan on removing that in a follow-up PR
* Rename a bunch of methods to be way more descriptive
* Eliminate `use super::*;`
* Lead to `clean/mod.rs` accumulating a lot of unnecessary imports
* Made `auto_traits` less modular
* Eliminate a custom `TypeFolder`: We can just use the rustc helper `fold_regions` which does that for us
I plan on adding extensive documentation to `librustdoc`'s `auto_trait` in follow-up PRs.
I don't want to do that in this PR because further refactoring & bug fix PRs may alter the overall structure of `librustdoc`'s & `rustc`'s `auto_trait` modules to a great degree. I'm slowly digging into the dark details of `rustc`'s `auto_trait` module again and once I have the full picture I will be able to provide proper docs.
---
While this PR does indeed touch `rustc`'s `auto_trait` — mostly tiny refactorings — I argue this PR doesn't need any compiler reviewers next to rustdoc ones since that module falls under the purview of rustdoc — it used to be part of `librustdoc` after all (#49711).
Sorry for not having split this into more commits. If you'd like me to I can try to split it into more atomic commits retroactively. However, I don't know if that would actually make reviewing easier. I think the best way to review this might just be to place the master version of `auto_trait` on the left of your screen and the patched one on the right, not joking.
r? `@GuillaumeGomez`
[^1]: Or even 4 depending on the way you're counting.
Refactor stack overflow handling
Currently, every platform must implement a `Guard` that protects a thread from stack overflow. However, UNIX is the only platform that actually does so. Windows has a different mechanism for detecting stack overflow, while the other platforms don't detect it at all. Also, the UNIX stack overflow handling is split between `sys::pal::unix::stack_overflow`, which implements the signal handler, and `sys::pal::unix::thread`, which detects/installs guard pages.
This PR cleans this by getting rid of `Guard` and unifying UNIX stack overflow handling inside `stack_overflow` (commit 1). Therefore we can get rid of `sys_common::thread_info`, which stores `Guard` and the current `Thread` handle and move the `thread::current` TLS variable into `thread` (commit 2).
The second commit is not strictly speaking necessary. To keep the implementation clean, I've included it here, but if it causes too much noise, I can split it out without any trouble.
Don't inherit codegen attrs from parent static
Putting this up partly for discussion and partly for review. Specifically, in #121644, `@oli-obk` designed a system that creates new static items for representing nested allocations in statics. However, in that PR, oli made it so that these statics inherited the codegen attrs from the parent.
This causes problems such as colliding symbols with `#[export_name]` and ICEs with `#[no_mangle]` since these synthetic statics have no `tcx.item_name(..)`.
So the question is, is there any case where we *do* want to inherit codegen attrs from the parent? The only one that seems a bit suspicious is the thread-local attribute. And there may be some interesting interactions with the coverage attributes as well...
Fixes (after backport) #123274. Fixes#123243. cc #121644.
r? `@oli-obk` cc `@nnethercote` `@RalfJung` (reviewers on that pr)
Fix error message for `env!` when env var is not valid Unicode
Currently (without this PR) the `env!` macro emits an ```environment variable `name` not defined at compile time``` error when the environment variable is defined, but not a valid Unicode string. This PR introduces a separate more accurate error message, and a test to verify this behaviour.
For reference, before this PR, the new test would have outputted:
```
error: environment variable `NON_UNICODE_VAR` not defined at compile time
--> non_unicode_env.rs:2:13
|
2 | let _ = env!("NON_UNICODE_VAR");
| ^^^^^^^^^^^^^^^^^^^^^^^
|
= help: use `std::env::var("NON_UNICODE_VAR")` to read the variable at run time
= note: this error originates in the macro `env` (in Nightly builds, run with -Z macro-backtrace for more info)
error: aborting due to 1 previous error
```
whereas with this PR, the test ouputs:
```
error: environment variable `NON_UNICODE_VAR` is not a valid Unicode string
--> non_unicode_env.rs:2:13
|
2 | let _ = env!("NON_UNICODE_VAR");
| ^^^^^^^^^^^^^^^^^^^^^^^
|
= note: this error originates in the macro `env` (in Nightly builds, run with -Z macro-backtrace for more info)
error: aborting due to 1 previous error
```
Use the `Align` type when parsing alignment attributes
Use the `Align` type in `rustc_attr::parse_alignment`, removing the need to call `Align::from_bytes(...).unwrap()` later in the compilation process.
Rewrite `core-no-fp-fmt-parse` test in Rust
Claiming the simple "core-no-fp-fmt-parse" test from #121876. `run_make_support` was altered with `arg_path` written in #121918 by `@abhay-51,` with additional doc comment.
Preliminary GSoC contribution for the project proposal mentored by `@jieyouxu.`
match lowering: sort `Eq` candidates in the failure case too
This is a slight tweak to MIR gen of matches. Take a match like:
```rust
match (s, flag) {
("a", _) if foo() => 1,
("b", true) => 2,
("a", false) => 3,
(_, true) => 4,
_ => 5,
}
```
If we switch on `s == "a"`, the first candidate matches, and we learn almost nothing about the second candidate. So there's a choice:
1. (what we do today) stop sorting candidates, keep the "b" case grouped with everything below. This could allow us to be clever here and test on `flag == true` next.
2. (what this PR does) sort "b" into the failure case. The "b" will be alone (fewer opportunities for picking a good test), but that means the two "a" cases require a single test.
Today, we aren't clever in which tests we pick, so this is an unambiguous win. In a future where we pick tests better, idk. Grouping tests as much as possible feels like a generally good strategy.
This was proposed in https://github.com/rust-lang/rust/issues/29623 (9 years ago :D)
The original proposal allows reference patterns
with "compatible" mutability, however it's not clear
what that means so for now we require an exact match.
I don't know the type system code well, so if something
seems to not make sense it's probably because I made a
mistake
CFI: Abstract Closures and Coroutines
This will abstract coroutines in a moment, it's just abstracting closures for now to show `@rcvalle`
This uses the same principal as the methods on traits - figure out the `dyn` type representing the fn trait, instantiate it, and attach that alias set. We're essentially just computing how we would be called in a dynamic context, and attaching that.
Similar to methods on a trait object, the most common way to indirectly
call a closure or coroutine is through the vtable on the appropriate
trait. This uses the same approach as we use for trait methods, after
backing out the trait arguments from the type.
Add support for `NonNull`s in the `ambiguous_wide_ptr_comparisions` lint
This PR add support for `NonNull` pointers in the `ambiguous_wide_ptr_comparisions` lint.
Fixes https://github.com/rust-lang/rust/issues/121264
r? `@Nadrieril` (since you just reviewed #121268, feel free to reassign)
KCFI: Require -C panic=abort
While the KCFI scheme is not incompatible with unwinding, LLVM's `invoke` instruction does not currently support KCFI bundles. While it likely will in the near future, we won't be able to assume that in Rust for a while.
We encountered this problem while [turning on closure support](https://github.com/rust-lang/rust/pull/123106#issuecomment-2027436640).
r? ``@workingjubilee``
Replace regions in const canonical vars' types with `'static` in next-solver canonicalizer
We shouldn't ever have non-static regions in consts on stable (or really any regions at all, lol).
The test I committed is less minimal than, e.g., https://github.com/rust-lang/rust/issues/123155?notification_referrer_id=NT_kwDOADgQyrMxMDAzNDU4MDI0OTozNjc0MzE0#issuecomment-2025472029 -- however, I believe that it actually portrays the underlying issue here a bit better than that one.
In the linked issue, we end up emitting a normalizes-to predicate for a const placeholder because we don't actually unify `false` and `""`. In the test I committed, we emit a normalizes-to predicate as a part of actually solving a negative coherence goal.
Fixes#123155Fixes#118783
r? lcnr
This is just one part of the MCP, but it's the one that IMHO removes the most noise from the standard library code.
Seems net simpler this way, since MIR already supported heterogeneous shifts anyway, and thus it's not more work for backends than before.
CFI: Support calling methods on supertraits
Automatically adjust `Virtual` calls to supertrait functions to use the supertrait's trait object type as the receiver rather than the child trait.
cc `@compiler-errors` - this is the next usage of `trait_object_ty` I intend to have, so I thought it might be relevant while reviewing the existing one.
Remove len argument from RawVec::reserve_for_push
Removes `RawVec::reserve_for_push`'s `len` argument since it's always the same as capacity.
Also makes `Vec::insert` use `RawVec::reserve_for_push`.
Stabilize `unchecked_{add,sub,mul}`
Tracking issue: #85122
I think we might as well just stabilize these basic three. They're the ones that have `nuw`/`nsw` flags in LLVM.
Notably, this doesn't include the potentially-more-complex or -more-situational things like `unchecked_neg` or `unchecked_shr` that are under different feature flags.
To quote Ralf https://github.com/rust-lang/rust/issues/85122#issuecomment-1681669646,
> Are there any objections to stabilizing at least `unchecked_{add,sub,mul}`? For those there shouldn't be any surprises about what their safety requirements are.
*Semantially* these are [already available on stable, even in `const`, via](https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=bdb1ff889b61950897f1e9f56d0c9a36) `checked_*`+`unreachable_unchecked`. So IMHO we might as well just let people write them directly, rather than try to go through a `let Some(x) = x.checked_add(y) else { unsafe { hint::unreachable_unchecked() }};` dance.
I added additional text to each method to attempt to better describe the behaviour and encourage `wrapping_*` instead.
r? rust-lang/libs-api
Add detection of [Partial]Ord methods in the `ambiguous_wide_pointer_comparisons` lint
Partially addresses https://github.com/rust-lang/rust/issues/121264 by adding diagnostics items for PartialOrd and Ord methods, detecting such diagnostics items as "binary operation" and suggesting the correct replacement.
I also took the opportunity to change the suggestion to use new methods `.cast()` on `*mut T` an d `*const T`.
While the KCFI scheme is not incompatible with unwinding, LLVM's
`invoke` instruction does not currently support KCFI bundles. While it
likely will in the near future, we won't be able to assume that in Rust
for a while.
Rollup of 4 pull requests
Successful merges:
- #123176 (Normalize the result of `Fields::ty_with_args`)
- #123186 (copy any file from stage0/lib to stage0-sysroot/lib)
- #123187 (Forward port 1.77.1 release notes)
- #123188 (compiler: fix few unused_peekable and needless_pass_by_ref_mut clippy lints)
r? `@ghost`
`@rustbot` modify labels: rollup
Normalize the result of `Fields::ty_with_args`
We were only instantiating before, which would leak an AliasTy. I added a test case that reproduce the issue seen here:
https://github.com/model-checking/kani/issues/3113
r? ``@oli-obk``
Simplify trim-paths feature by merging all debuginfo options together
This PR simplifies the trim-paths feature by merging all debuginfo options together, as described in https://github.com/rust-lang/rust/issues/111540#issuecomment-1994010274.
And also do some correctness fixes found during the review.
cc `@weihanglo`
r? `@michaelwoerister`
Match ergonomics 2024: implement mutable by-reference bindings
Implements the mutable by-reference bindings portion of match ergonomics 2024 (#123076), with the `mut ref`/`mut ref mut` syntax, under feature gate `mut_ref`.
r? `@Nadrieril`
`@rustbot` label A-patterns A-edition-2024
CFI: Fix methods as function pointer cast
Fix casting between methods and function pointers by assigning a secondary type id to methods with their concrete self so they can be used as function pointers.
This was split off from #116404.
cc `@compiler-errors` `@workingjubilee`
Eliminate `UbChecks` for non-standard libraries
The purpose of this PR is to allow other passes to treat `UbChecks` as constants in MIR for optimization after #122629.
r? RalfJung
Codegen const panic messages as function calls
This skips emitting extra arguments at every callsite (of which there
can be many). For a librustc_driver build with overflow checks enabled,
this cuts 0.7MB from the resulting shared library (see [perf]).
A sample improvement from nightly:
```
leaq str.0(%rip), %rdi
leaq .Lalloc_d6aeb8e2aa19de39a7f0e861c998af13(%rip), %rdx
movl $25, %esi
callq *_ZN4core9panicking5panic17h17cabb89c5bcc999E@GOTPCREL(%rip)
```
to this PR:
```
leaq .Lalloc_d6aeb8e2aa19de39a7f0e861c998af13(%rip), %rdi
callq *_RNvNtNtCsduqIKoij8JB_4core9panicking11panic_const23panic_const_div_by_zero@GOTPCREL(%rip)
```
[perf]: https://perf.rust-lang.org/compare.html?start=a7e4de13c1785819f4d61da41f6704ed69d5f203&end=64fbb4f0b2d621ff46d559d1e9f5ad89a8d7789b&stat=instructions:u
Rollup of 6 pull requests
Successful merges:
- #123063 (Function ABI is irrelevant for reachability)
- #123096 (Don't check match scrutinee of postfix match for unused parens)
- #123146 (Use compiletest directives instead of manually checking TARGET / tools)
- #123160 (remove `def_id_to_node_id` in ast lowering)
- #123162 (Correctly get complete intra-doc link data)
- #123164 (Bump Unicode printables to version 15.1, align to unicode_data)
r? `@ghost`
`@rustbot` modify labels: rollup
Correctly get complete intra-doc link data
Fixes https://github.com/rust-lang/rust/issues/123158.
The problem was that we didn't take into account cases where there would be content other than backticks into the intra doc link definition.
r? `@notriddle`
Use compiletest directives instead of manually checking TARGET / tools
Changes:
- Accept `ignore-wasm32-wasip1` and `needs-wasmtime` directives.
- Add support for needing `wasmtime` as a runner.
- Update wasm/compiler_builtin tests to use compiletest directives over manual checks.
Don't check match scrutinee of postfix match for unused parens
We only check the scrutinees of block-like constructs and a few others (return/index/assign/method calls). Just don't do it for postfix match at all.
Fixes#123064
r? fmease
Suggest correct path in include_bytes!
`include_bytes!` paths are relative, and I'm often not sure how nested is the `.rs` file that I'm editing, so I have to guess the number of `"../.."`. This change searches `..` and `../..` for the given file and offers corrected path as a suggestion.
I wasn't sure how to get the right span, and how to properly escape it.
```text
error: couldn't read src/file.txt: No such file or directory (os error 2)
--> src/main.rs:2:13
|
2 | let x = include_bytes!("file.txt");
| ^^^^^^^^^^^^^^^----------^
| |
| help: it's in a parent directory: `"../../file.txt"`
```
Fix casting between methods and function pointers by assigning a
secondary type id to methods with their concrete self so they can be
used as function pointers.
Delegation: fix ICE on wrong `Self` instantiation
fixes https://github.com/rust-lang/rust/issues/119921
fixes https://github.com/rust-lang/rust/issues/119919
There is no way to instantiate `Self` param for caller in delegation item if
1. callee is a trait method && callee contains `Self` param
2. delegation item isn't an associative item
In general, we can consider `Self` param as independent type param in these cases:
```rust
trait Trait {
fn foo(_: Option<&Self>) {...}
}
reuse Trait::foo;
// will be desugared to:
fn foo<T: Trait>(x: Option<&T>) { Trait::foo(x) }
```
But this requires early bound parameters support. For now, I suggest banning such cases to avoid ICE's.
r? ``@petrochenkov``
CFI: Fix drop and drop_in_place
Fix drop and drop_in_place by transforming self of drop and drop_in_place methods into a Drop trait objects.
This was split off from https://github.com/rust-lang/rust/pull/116404.
cc `@compiler-errors` `@workingjubilee`
Rework rmake support library API
### Take 1: Strongly-typed API
Context: https://github.com/rust-lang/rust/pull/122448#discussion_r1523774427
> My 2 cents: from my experience with writing similar "test DSLs", I would suggest to create these helpers as soon as possible in the process (basically the first time someone needs them, not only after N similar usages), and basically treat any imperative code in these high-level tests as a maintenance burden, basically making them as declarative as possible. Otherwise it might be a bit annoying to keep refactoring the tests later once such helpers are available.
>
> I would even discourage the arg method and create explicit methods for setting things like unpretty, the output file etc., but this might be more controversial, as it will make the invoked command-line arguments more opaque.
cc `@Kobzol` for the testing DSL suggestion.
Example:
```rs
let output = Rustc::new()
.input_file("main.rs")
.emit(&[EmitKind::Metadata])
.extern_("stable", &stable_path)
.output();
```
### Take 2: xshell-based macro API
Example:
```rs
let sh = Shell::new()?;
let stable_path = stable_path.to_string_lossy();
let output = cmd!(sh, "rustc main.rs --emit=metadata --extern stable={stable_path}").output()?;
```
### Take 3: Weakly-typed API with a few helper methods
```rs
let output = Rustc::new()
.input("main.rs")
.emit("metadata")
.extern_("stable", &stable_path)
.output();
```
CFI: Enable KCFI testing of run-pass tests
This enables KCFI-based testing for all the CFI run-pass tests in the suite today. We can add the test header on top of in-flight CFI tests once they land. This is becoming more important as we get closer to leveraging CFI's multiple type attachment feature, as that is where the implementations will have a divergence.
It also enables KCFI as a sanitizer for x86_64 and aarch64 Linux to make this possible. The sanitizer should likely be available for all aarch64, x86_64, and riscv targets, but that isn't critical for initial testing.
coverage: Re-enable `UnreachablePropagation` for coverage builds
This is a sequence of 3 related changes:
- Clean up the existing code that scans for unused functions
- Detect functions that were instrumented for coverage, but have had all their coverage statements removed by later MIR transforms (e.g. `UnreachablePropagation`)
- Re-enable `UnreachablePropagation` in coverage builds
Because we now detect functions that have lost their coverage statements, and treat them as unused, we don't need to worry about `UnreachablePropagation` removing all of those statements. This is demonstrated by `tests/coverage/unreachable.rs`.
Fixes#116171.
Soft-destabilize `RustcEncodable` & `RustcDecodable`, remove from prelude in next edition
cc rust-lang/libs-team#272
Any use of `RustcEncodable` and `RustcDecodable` now triggers a deny-by-default lint. The derives have been removed from the 2024 prelude. I specifically chose **not** to document this in the module-level documentation, as the presence in existing preludes is not documented (which I presume is intentional).
This does not implement the proposed change for `rustfix`, which I will be looking into shortly.
With regard to the items in the preludes being stable, this should not be an issue because #15702 has been resolved.
r? libs-api
Rollup of 9 pull requests
Successful merges:
- #108675 (Document `adt_const_params` feature in Unstable Book)
- #122120 (Suggest associated type bounds on problematic associated equality bounds)
- #122589 (Fix diagnostics for async block cloning)
- #122835 (Require `DerefMut` and `DerefPure` on `deref!()` patterns when appropriate)
- #123049 (In `ConstructCoroutineInClosureShim`, pass receiver by mut ref, not mut pointer)
- #123055 (enable cargo miri test doctests)
- #123057 (unix fs: Make hurd using explicit new rather than From)
- #123087 (Change `f16` and `f128` clippy stubs to be nonpanicking)
- #123103 (Rename `Inherited` -> `TypeckRootCtxt`)
r? `@ghost`
`@rustbot` modify labels: rollup
In `ConstructCoroutineInClosureShim`, pass receiver by mut ref, not mut pointer
The receivers were compatible at codegen time, but did not necessarily have the same layouts due to niches, which was caught by miri.
Fixesrust-lang/miri#3400
r? oli-obk
Suggest associated type bounds on problematic associated equality bounds
Fixes#105056. TL;DR: Suggest `Trait<Ty: Bound>` on `Trait<Ty = Bound>` in Rust >=2021.
~~Blocked on #122055 (stabilization of `associated_type_bounds`), I'd say.~~ (merged)
Delegation: fix ICE on wrong `self` resolution
fixes https://github.com/rust-lang/rust/issues/122874
Delegation item should be wrapped in a `rib` to behave like a regular function during name resolution.
r? `@petrochenkov`
match lowering: consistently merge simple or-patterns
There are two places where we expand or-patterns in match lowering: the main one is `test_candidates_with_or`, and there's one in `match_candidates` that's an optimization for the simple case where the whole pattern is just one or-pattern.
To reduce duplication, we merge or-pattern alternatives into a single block when possible, but we only to that in `test_candidates_with_or`. This PR fixes this oversight and merges them in `match_candidates` too.
This is a part of splitting up https://github.com/rust-lang/rust/pull/122046 into smaller bits.
CFI: (actually) check that methods are object-safe before projecting their receivers to `dyn Trait` in CFI
`trait_object_ty` assumed that associated types would be fully determined by the trait. This is *almost* true - const parameters and type parameters are no longer allowed, but lifetime parameters are. Since we erase all lifetime parameters anyways, instantiate it with as many erased regions as it needs.
Fixes: #123053
r? `@compiler-errors`
Avoid some unnecessary query invocations.
Specifically this inlines `const_eval_poly` and avoids computing the generic params, the param env, normalizing the param env and erasing lifetimes on everything.
should fix the perf regression from https://github.com/rust-lang/rust/pull/121087
This enables KCFI-based testing for all the CFI run-pass tests in the
suite today. We can add the test header on top of in-flight CFI tests
once they land.
It also enables KCFI as a sanitizer for x86_64 and aarch64 Linux to make
this possible. The sanitizer should likely be available for all aarch64,
x86_64, and riscv targets, but that isn't critical for initial testing.
Rollup of 10 pull requests
Successful merges:
- #122707 (Fix a typo in the alloc::string::String docs)
- #122769 (extend comments for reachability set computation)
- #122892 (fix(bootstrap/dist): use versioned dirs when vendoring)
- #122896 (Update stdarch submodule)
- #122923 (In `pretty_print_type()`, print `async fn` futures' paths instead of spans.)
- #122950 (Add regression tests for #101903)
- #123039 (Update books)
- #123042 (Import the 2021 prelude in the core crate)
- #123044 (`Instance` is `Copy`)
- #123051 (did I mention that tests are super cool? )
r? `@ghost`
`@rustbot` modify labels: rollup
Print a backtrace in const eval if interrupted
Demo:
```rust
#![feature(const_eval_limit)]
#![const_eval_limit = "0"]
const OW: u64 = {
let mut res: u64 = 0;
let mut i = 0;
while i < u64::MAX {
res = res.wrapping_add(i);
i += 1;
}
res
};
fn main() {
println!("{}", OW);
}
```
```
╭ ➜ ben@archlinux:~/rust
╰ ➤ rustc +stage1 spin.rs
^Cerror[E0080]: evaluation of constant value failed
--> spin.rs:8:33
|
8 | res = res.wrapping_add(i);
| ^ Compilation was interrupted
note: erroneous constant used
--> spin.rs:15:20
|
15 | println!("{}", OW);
| ^^
note: erroneous constant used
--> spin.rs:15:20
|
15 | println!("{}", OW);
| ^^
|
= note: this note originates in the macro `$crate::format_args_nl` which comes from the expansion of the macro `println` (in Nightly builds, run with -Z macro-backtrace for more info)
error: aborting due to previous error
For more information about this error, try `rustc --explain E0080`.
```
`trait_object_ty` assumed that associated types would be fully
determined by the trait. This is *almost* true - const parameters and
type parameters are no longer allowed, but lifetime parameters are.
Since we erase all lifetime parameters anyways, instantiate it with as
many erased regions as it needs.
Fixes: #123053
In `pretty_print_type()`, print `async fn` futures' paths instead of spans.
This makes `-Zprint-type-sizes`'s output easier to read, because the name of an `async fn` is more immediately recognizable than its span. This change will also synergize with my other `-Zprint-type-sizes` PR #122922 which prints the type of child futures being awaited.
I also deleted the comment "FIXME(eddyb) should use `def_span`." because it appears to have already been fixed by commit 67727aa7c3.
Validate that we're only matching on unit struct for path pattern
Resolution doesn't validate that we only really take `CtorKind::Unit` in path patterns, since all it sees is `Res::SelfCtor(def_id)`. Check this instead during pattern typeck.
r? petrochenkov
Fixes#122809
Delegation: fix ICE on `bound_vars` divergence
Fixes https://github.com/rust-lang/rust/issues/122550.
Bug was caused by divergence between lowered type and corresponding `bound_vars` in `late_bound_vars_map`. In this patch `bound_vars` calculation for delegation item is moved from `lower_fn_ty` to `resolve_bound_vars` query.
r? `@petrochenkov`
Don't emit an error about failing to produce a file with a specific name if user never gave an explicit name
Fixes#122509
You can ask `rustc` to produce some intermediate results with `--emit foo`, this operation comes in two flavors: `--emit asm` and `--emit asm=foo.s`. First one produces one or more `.s` files without any name guarantees, second one renames it into `foo.s`. Second version only works when compiler produces a single file - for asm files this means using a single compilation unit for example.
In case compilation produced more than a single file `rustc` runs following check to emit some warnings:
```rust
if crate_output.outputs.contains_key(&output_type) {
// 2) Multiple codegen units, with `--emit foo=some_name`. We have
// no good solution for this case, so warn the user.
sess.dcx().emit_warn(errors::IgnoringEmitPath { extension });
} else if crate_output.single_output_file.is_some() {
// 3) Multiple codegen units, with `-o some_name`. We have
// no good solution for this case, so warn the user.
sess.dcx().emit_warn(errors::IgnoringOutput { extension });
} else {
// 4) Multiple codegen units, but no explicit name. We
// just leave the `foo.0.x` files in place.
// (We don't have to do any work in this case.)
}
```
Comment in the final `else` branch implies that if user didn't ask for a specific name - there's no need to emit warnings. However because of the internal representation of `crate_output.outputs` - this doesn't work as expected: if user asked to produce an asm file without giving it an implicit name it will contain `Some(None)`.
To fix the problem new code actually checks if user gave an explicit name. I think this was an original intentional behavior, at least comments imply that.
This makes `-Zprint-type-sizes`'s output easier to read, because the
name of an `async fn` is more immediately recognizable than its span.
I also deleted the comment "FIXME(eddyb) should use `def_span`." because
it appears to have already been fixed by commit 67727aa7c3.
CFI: Support complex receivers
Right now, we only support rewriting `&self` and `&mut self` into `&dyn MyTrait` and `&mut dyn MyTrait`. This expands it to handle the full gamut of receivers by calculating the receiver based on *substitution* rather than based on a rewrite. This means that, for example, `Arc<Self>` will become `Arc<dyn MyTrait>` appropriately with this change.
This approach also allows us to support associated type constraints as well, so we will correctly rewrite `&self` into `&dyn MyTrait<T=i32>`, for example.
r? ```@workingjubilee```
CFI: Handle dyn with no principal
In user-facing Rust, `dyn` always has at least one predicate following it. Unfortunately, because we filter out marker traits from receivers at callsites and `dyn Sync` is, for example, legal, this results in us having `dyn` types with no predicates on occasion in our alias set encoding. This patch handles cases where there are no predicates in a `dyn` type which are relevant to its alias set.
Fixes#122998
r? workingjubilee
Clean up unnecessary headers/flags in coverage mir-opt tests
During #122542, I noticed that some of the headers and flags I had copied over from `tests/mir-opt/instrument_coverage.rs` were unnecessary. And while working to remove those, I noticed even more that could be removed or replaced.
Replace `mir_built` query with a hook and use mir_const everywhere instead
A small perf improvement due to less dep graph handling.
Mostly just a cleanup to get rid of one of our many mir queries
Previously, we only rewrote `&self` and `&mut self` receivers. By
instantiating the method from the trait definition, we can make this
work work with arbitrary legal receivers instead.
This saves some debug and scope metadata in every single function that calls it.
Normally wouldn't be worth it, but with the derives there's *so* many of these.
In user-facing Rust, `dyn` always has at least one predicate following
it. Unfortunately, because we filter out marker traits from receivers at
callsites and `dyn Sync` is, for example, legal, this results in us
having `dyn` types with no predicates on occasion in our alias set
encoding. This patch handles cases where there are no predicates in a
`dyn` type which are relevant to its alias set.
Fixes#122998
panic-in-panic-hook: formatting a message that's just a string is risk-free
This slightly improves the output in the 'panic while processing panic' case if the panic message does not involve any formatting. Follow-up to https://github.com/rust-lang/rust/pull/122930.
r? ``@Amanieu``
Add a regression test for #117310Closes#117310
It seems to have been fixed in `rustc 1.79.0-nightly (1388d7a06 2024-03-20)` or before, so just adding a regression test for it.
Fixed the `private-dependency` bug
Fixed the private-dependency bug: If the directly dependent crate is loaded last and is not configured with `--extern`, it may be incorrectly set to `private-dependency`
Fixes#122756
Encode implied predicates for traits
In #112629, we decided to make associated type bounds in the "supertrait" AST position *implied* even though they're not supertraits themselves.
This means that the `super_predicates` and `implied_predicates` queries now differ for regular traits. The assumption that they didn't differ was hard-coded in #107614, so in cross-crate positions this means that we forget the implied predicates from associated type bounds.
This isn't unsound, just kind of annoying. This should be backported since associated type bounds are slated to stabilize for 1.78 -- either that, or associated type bounds can be reverted on beta and re-shipped in 1.79 with this patch.
Fixes#122859
CFI: Strip auto traits off Virtual calls
We already use `Instance` at declaration sites when available to glean additional information about possible abstractions of the type in use. This does the same when possible at callsites as well.
The primary purpose of this change is to allow CFI to alter how it generates type information for indirect calls through `Virtual` instances.
This is needed for the "separate machinery" version of my approach to the vtable issues (#122573), because we need to respond differently to a `Virtual` call to the same type as a non-virtual call, specifically [stripping auto traits off the receiver's `Self`](54b15b0c36) because there isn't a separate vtable for `Foo` vs `Foo + Send`.
This would also make a more general underlying mechanism that could be used by rcvalle's [proposed drop detection / encoding](edcd1e20a1) if we end up using his approach, as we could condition out on the `def_id` in the CFI code rather than requiring the generating code to explicitly note whether it was calling drop.
CFI: Support self_cell-like recursion
Current `transform_ty` attempts to avoid cycles when normalizing `#[repr(transparent)]` types to their interior, but runs afoul of this pattern used in `self_cell`:
```
struct X<T> {
x: u8,
p: PhantomData<T>,
}
#[repr(transparent)]
struct Y(X<Y>);
```
When attempting to normalize Y, it will still cycle indefinitely. By using a types-visited list, this will instead get expanded exactly one layer deep to X<Y>, and then stop, not attempting to normalize `Y` any further.
This PR was split off from #121962 as part of fixing the larger vtable compatibility issues.
r? ``````@workingjubilee``````
Mention Register Size in `#[warn(asm_sub_register)]`
Fixes#121593
Displays the register size information obtained from `suggest_modifier()` and `default_modifier()`.
Add test in higher ranked subtype
I'm a beginner in this repository, and there are some things I'm not sure about:
- Is it okay that there is a warning:
```
rustc_infer::infer::relate::generalize may incompletely handle alias type: AliasTy { args: [?1t, '^0.Named(DefId(0:15 ~ structually_relate_aliases[de75]::{impl#1}::'a), "'a")], def_id: DefId(0:5 ~ structually_relate_aliases[de75]::ToUnit::Unit) }
```
- Is it okay that there are two duplicate errors in the same line?
- Did I put the test in the right place?
Any suggestions would be appreciated.
Fixes#121649
`rustdoc --test`: Prevent reaching the maximum size of command-line by using files for arguments if there are too many
Fixes#122722.
Thanks to this I discovered that rust was using ``@`` to add arguments from a file, quite convenient.
If there are too many `cfg` arguments given to `rustdoc --test`, it'll now put them into a temporary file and passing it as argument to the rustc command.
I added a test with 100_000 `cfg` arguments to ensure it'll not break again.
r? `@notrid`
Handle str literals written with `'` lexed as lifetime
Given `'hello world'` and `'1 str', provide a structured suggestion for a valid string literal:
```
error[E0762]: unterminated character literal
--> $DIR/lex-bad-str-literal-as-char-3.rs:2:26
|
LL | println!('hello world');
| ^^^^
|
help: if you meant to write a `str` literal, use double quotes
|
LL | println!("hello world");
| ~ ~
```
```
error[E0762]: unterminated character literal
--> $DIR/lex-bad-str-literal-as-char-1.rs:2:20
|
LL | println!('1 + 1');
| ^^^^
|
help: if you meant to write a `str` literal, use double quotes
|
LL | println!("1 + 1");
| ~ ~
```
Fix#119685.
Fix validation on substituted callee bodies in MIR inliner
When inlining a coroutine, we will substitute the MIR body with the args of the call. There is code in the MIR validator that attempts to prevent query cycles, and will use the coroutine body directly when it detects that's the body that's being validated. That means that when inlining a coroutine body that has been substituted, it may no longer be parameterized over the original args of the coroutine, which will lead to substitution ICEs.
Fixes#119064
refactor check_{lang,library}_ub: use a single intrinsic
This enacts the plan I laid out [here](https://github.com/rust-lang/rust/pull/122282#issuecomment-1996917998): use a single intrinsic, called `ub_checks` (in aniticpation of https://github.com/rust-lang/compiler-team/issues/725), that just exposes the value of `debug_assertions` (consistently implemented in both codegen and the interpreter). Put the language vs library UB logic into the library.
This makes it easier to do something like https://github.com/rust-lang/rust/pull/122282 in the future: that just slightly alters the semantics of `ub_checks` (making it more approximating when crates built with different flags are mixed), but it no longer affects whether these checks can happen in Miri or compile-time.
The first commit just moves things around; I don't think these macros and functions belong into `intrinsics.rs` as they are not intrinsics.
r? `@saethlin`
Additional trait bounds beyond the principal trait and its implications
are not possible in the vtable. This means that if a receiver is
`&dyn Foo + Send`, the function will only be expecting `&dyn Foo`.
This strips those auto traits off before CFI encoding.
Rollup of 11 pull requests
Successful merges:
- #120577 (Stabilize slice_split_at_unchecked)
- #122698 (Cancel `cargo update` job if there's no updates)
- #122780 (Rename `hir::Local` into `hir::LetStmt`)
- #122915 (Delay a bug if no RPITITs were found)
- #122916 (docs(sync): normalize dot in fn summaries)
- #122921 (Enable more mir-opt tests in debug builds)
- #122922 (-Zprint-type-sizes: print the types of awaitees and unnamed coroutine locals.)
- #122927 (Change an ICE regression test to use the original reproducer)
- #122930 (add panic location to 'panicked while processing panic')
- #122931 (Fix some typos in the pin.rs)
- #122933 (tag_for_variant follow-ups)
r? `@ghost`
`@rustbot` modify labels: rollup
Change an ICE regression test to use the original reproducer
The ICE was fixed in PR https://github.com/rust-lang/rust/pull/122370, but the test used a different reproducer than the one originally reported. This PR changes it to the original one, giving us more confidence that the fix works.
Fixes#122199
-Zprint-type-sizes: print the types of awaitees and unnamed coroutine locals.
This should assist comprehending the size of coroutines. In particular, whenever a future is suspended while awaiting another future, the latter is given the special name `__awaitee`, and now the type of the awaited future will be printed, allowing identifying caller/callee — er, I mean, poller/pollee — relationships.
It would be possible to include the type name in more cases, but I thought that that might be overly verbose (`print-type-sizes` is already a lot of text) and ordinary named fields or variables are easier for readers to discover the types of.
This change will also synergize with my other PR #122923 which changes type printing to print the path of the `async fn` instead of the span.
Implementation note: I'm not sure if `Symbol::intern` is appropriate for this application, but it was the obvious way to not have to remove the `Copy` implementation from `FieldInfo`, or add a `'tcx` lifetime, while avoiding keeping a lot of possibly redundant strings in memory. I don't know what the proper tradeoff to make here is (though presumably it is not too important for a `-Z` debugging option).
Let codegen decide when to `mem::swap` with immediates
Making `libcore` decide this is silly; the backend has so much better information about when it's a good idea.
Thus this PR introduces a new `typed_swap` intrinsic with a fallback body, and replaces that fallback implementation when swapping immediates or scalar pairs.
r? oli-obk
Replaces #111744, and means we'll never need more libs PRs like #111803 or #107140
