Normalize opaques with late-bound vars again
We have a hack in the compiler where if an opaque has escaping late-bound vars, we skip revealing it even though we *could* reveal it from a technical perspective. First of all, this is weird, since we really should be revealing all opaques in `Reveal::All` mode. Second of all, it causes subtle bugs (linked below).
I attempted to fix this in #100980, which was unfortunately reverted due to perf regressions on codebases that used really deeply nested futures in some interesting ways. The worst of which was #103423, which caused the project to hang on build. Another one was #104842, which was just a slow-down, but not a hang. I took some time afterwards to investigate how to rework `normalize_erasing_regions` to take advantage of better caching, but that effort kinda fizzled out (#104133).
However, recently, I was made aware of more bugs whose root cause is not revealing opaques during codegen. That made me want to fix this again -- in the process, interestingly, I took the the minimized example from https://github.com/rust-lang/rust/issues/103423#issuecomment-1292947043, and it doesn't seem to hang any more...
Thinking about this harder, there have been some changes to the way we lower and typecheck async futures that may have reduced the pathologically large number of outlives obligations (see description of #103423) that we were encountering when normalizing opaques with bound vars the last time around:
* #104321 (lower `async { .. }` directly as a generator that implements `Future`, removing the `from_generator` shim)
* #104833 (removing an `identity_future` fn that was wrapping desugared future generators)
... so given that I can see:
* No significant regression on rust perf bot (https://github.com/rust-lang/rust/pull/107620#issuecomment-1600070317)
* No timeouts in crater run I did (https://github.com/rust-lang/rust/pull/107620#issuecomment-1605428952, rechecked failing crates in https://github.com/rust-lang/rust/pull/107620#issuecomment-1605973434)
... and given that this PR:
* Fixes#104601
* Fixes#107557
* Fixes#109464
* Allows us to remove a `DefiningAnchor::Bubble` from codegen (75a8f68183)
I'm inclined to give this another shot at landing this. Best case, it just works -- worst case, we get more examples to study how we need to improve the compiler to make this work.
r? types
Rollup of 5 pull requests
Successful merges:
- #112946 (Improve cgu naming and ordering)
- #113048 (Fix build on Solaris where fd-lock cannot be used.)
- #113100 (Fix display of long items in search results)
- #113107 (add check for ConstKind::Value(_) to in_operand())
- #113119 (rustdoc: Reduce internal function visibility.)
r? `@ghost`
`@rustbot` modify labels: rollup
Test that we require implementing trait items whose bounds don't hold in the current impl
I initially tried to make most of these pass, but that's a big can of worms, so I'm just adding them as tests, considering we have no tests for these things.
Make associated type bounds in supertrait position implied
`trait A: B<Assoc: C> {}` should be able to imply both `Self: B` and `<Self as B>::Assoc: C`. Adjust the way that we collect implied predicates to do so.
Fixes#112573Fixes#112568
add check for ConstKind::Value(_) to in_operand()
Added check for valtree value to close#113012 which fixes the issue, although I am not sure if adding the check there is sound or not cc `@oli-obk`
add note for non-exhaustive matches with guards
Associated issue: #92197
When a match statement includes guards on every match arm (and is therefore necessarily non-exhaustive), add a note to the error E0004 diagnostic noting this.
Validate fluent variable references in tests
Closes#101109
Under `cfg(test)`, the `fluent_messages` macro will emit a list of variables referenced by each message and its attributes. The derive attribute will now emit a `#[test]` that checks that each referenced variable exists in the structure it's applied to.
mir opt + codegen: handle subtyping
fixes#107205
the same issue was caused in multiple places:
- mir opts: both copy and destination propagation
- codegen: assigning operands to locals (which also propagates values)
I changed codegen to always update the type in the operands used for locals which should guard against any new occurrences of this bug going forward. I don't know how to make mir optimizations more resilient here. Hopefully the added tests will be enough to detect any trivially wrong optimizations going forward.
Add tests impl via obj unless denied
Fixes#112737
Add simple tests to check feature change in #112320 is performing as expected.
Note:
- Unsure about filenames, locations & function signature names (tried to make them something sensible)
Make `UnwindAction::Continue` explicit in MIR dump
Makes it easier to spot unwinding related issues in MIR by making `UnwindAction::Continue` explicit, just like all other `UnwindAction`s.
Make compiletest aware of targets without dynamic linking
Some parts of the compiletest internals and some tests require dynamic linking to work, which is not supported by all targets. Before this PR, this was handled by if branches matching on the target name.
This PR loads whether a target supports dynamic linking or not from the target spec, and adds a `// needs-dynamic-linking` attribute for tests that require it. Note that I was not able to replace all the old conditions based on the target name, as some targets have `dynamic_linking: true` in their spec but pretend they don't have it in compiletest.
Also, to get this to work I had to *partially* revert #111472 (cc `@djkoloski` `@tmandry` `@bjorn3).` On one hand, only the target spec contains whether a target supports dynamic linking, but on the other hand a subset of the fields can be overridden through `-C` flags (as far as I'm aware only `-C panic=$strategy`). The solution I came up with is to take the target spec as the base, and then override the panic strategy based on `--print=cfg`. Hopefully that should not break y'all again.
rustdoc: render generic params & where-clauses of cross-crate assoc tys in impls
We used to only ever render generic parameters & where-clauses of cross-crate associated types when the item was located inside of a trait and we used to just drop them when it was inside of an impl block (trait or inherent).
Fixes#112904.
`@rustbot` label A-cross-crate-reexports
`hir`: Add `Become` expression kind (explicit tail calls experiment)
This adds `hir::ExprKind::Become` alongside ast lowering. During hir-thir lowering we currently lower `become` as `return`, so that we can partially test `become` without ICEing.
cc `@scottmcm`
r? `@Nilstrieb`
Rollup of 5 pull requests
Successful merges:
- #112976 (Add test for futures with HRTB)
- #113013 (rustdoc: get rid of extra line when line-wrapping fn decls with empty arg list)
- #113030 (Add a regression test for #109071)
- #113031 (Add a regression test for #110933)
- #113036 (Accept `ReStatic` for RPITIT)
r? `@ghost`
`@rustbot` modify labels: rollup
