coverage: Allow each coverage statement to have multiple code regions
The original implementation of coverage instrumentation was built around the assumption that a coverage counter/expression would be associated with *up to one* code region. When it was discovered that *multiple* regions would sometimes need to share a counter, a workaround was found: for the remaining regions, the instrumentor would create a fresh expression that adds zero to the existing counter/expression.
That got the job done, but resulted in some awkward code, and produces unnecessarily complicated coverage maps in the final binary.
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This PR removes that tension by changing `StatementKind::Coverage`'s code region field from `Option<CodeRegion>` to `Vec<CodeRegion>`.
The changes on the codegen side are fairly straightforward. As long as each `CoverageKind::Counter` only injects one `llvm.instrprof.increment`, the rest of coverage codegen is happy to handle multiple regions mapped to the same counter/expression, with only minor option-to-vec adjustments.
On the instrumentor/mir-transform side, we can get rid of the code that creates extra (x + 0) expressions. Instead we gather all of the code regions associated with a single BCB, and inject them all into one coverage statement.
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There are several patches here but they can be divided in to three phases:
- Preparatory work
- Actually switching over to multiple regions per coverage statement
- Cleaning up
So viewing the patches individually may be easier.
non_lifetime_binders: fix ICE in lint opaque-hidden-inferred-bound
Opaque types like `impl for<T> Trait<T>` would previously lead to an ICE.
r? `@compiler-errors`
a small wf and clause cleanup
- remove `Clause::from_projection_clause`, instead use `ToPredicate`
- change `predicate_obligations` to directly take a `Clause`
- remove some unnecessary `&`
- use clause in `min_specialization` checks where easily applicable
Suggest `pin!()` instead of `Pin::new()` when appropriate
When encountering a type that needs to be pinned but that is `!Unpin`, suggest using the `pin!()` macro.
Fix#57994.
This builder tested the wasm32-unknown-emscripten target, which is tier
2 (and so not eligible for testing). In the recent beta promotion, we
ran into a problem with this target: emscripten doesn't support
passing environment variables into the std environment, so we can't
enable RUSTC_BOOTSTRAP for libtest in order to pass -Zunstable-options.
We worked around this for the beta/stable branches, but given this
problem, and its tier 2 status, just dropping the target's tests
entirely seems warranted. Downgrading to tier 3 may also be a good idea,
but that is a separate conversation not proposed here.
Rollup of 5 pull requests
Successful merges:
- #115863 (Add check_unused_messages in tidy)
- #116210 (Ensure that `~const` trait bounds on associated functions are in const traits or impls)
- #116358 (Rename both of the `Match` relations)
- #116371 (Remove unused features from `rustc_llvm`.)
- #116374 (Print normalized ty)
r? `@ghost`
`@rustbot` modify labels: rollup
Print normalized ty
Inside `mir_assign_valid_types` we are comparing normalized type of `mir_place` but in debug message we are not printing the normalized value, this changes that.
It was added in #78569. It's complicated and doesn't actually help
performance.
Also, add a comment explaining why the two `alloc_from_iter` functions
are so different.
Rollup of 6 pull requests
Successful merges:
- #113053 (add notes about non-compliant FP behavior on 32bit x86 targets)
- #115726 (For a single impl candidate, try to unify it with error trait ref)
- #116158 (Don't suggest nonsense suggestions for unconstrained type vars in `note_source_of_type_mismatch_constraint`)
- #116351 (Add `must_use` on pointer equality functions)
- #116355 (Clarify float rounding direction for signed zero)
- #116361 (Bump stdarch submodule)
r? `@ghost`
`@rustbot` modify labels: rollup
Add `must_use` on pointer equality functions
`ptr == ptr` (like all use of `==`) has a similar warning, and these functions are simple convenience wrappers over that.
Don't suggest nonsense suggestions for unconstrained type vars in `note_source_of_type_mismatch_constraint`
The way we do type inference for suggestions in `note_source_of_type_mismatch_constraint` is a bit strange. We compute the "ideal" method signature, which takes the receiver that we *want* and uses it to compute the types of the arguments that would have given us that receiver via type inference, and use *that* to suggest how to change an argument to make sure our receiver type is inferred correctly.
The problem is that sometimes we have totally unconstrained arguments (well, they're constrained by things outside of the type checker per se, like associated types), and therefore type suggestions are happy to coerce anything to that unconstrained argument. This leads to bogus suggestions, like #116155. This is partly due to above, and partly due to the fact that `emit_type_mismatch_suggestions` doesn't double check that its suggestions are actually compatible with the program other than trying to satisfy the type mismatch.
This adds a hack to make sure that at least the types are fully constrained, but I guess I could also rip out this logic altogether. There would be some sad diagnostics regressions though, such as `tests/ui/type/type-check/point-at-inference-4.rs`.
Fixes#116155
For a single impl candidate, try to unify it with error trait ref
This allows us to point out an exact type mismatch when there's only one applicable impl.
cc `@asquared31415`
r? `@estebank`
add notes about non-compliant FP behavior on 32bit x86 targets
Based on ton of prior discussion (see all the issues linked from https://github.com/rust-lang/unsafe-code-guidelines/issues/237), the consensus seems to be that these targets are simply cursed and we cannot implement the desired semantics for them. I hope I properly understood what exactly the extent of the curse is here, let's make sure people with more in-depth FP knowledge take a close look!
In particular for the tier 3 targets I have no clue which target is affected by which particular variant of the x86_32 FP curse. I assumed that `i686` meant SSE is used so the "floating point return value" is the only problem, while everything lower (`i586`, `i386`) meant x87 is used.
I opened https://github.com/rust-lang/rust/issues/114479 to concisely describe and track the issue.
Cc `@workingjubilee` `@thomcc` `@chorman0773` `@rust-lang/opsem`
Fixes https://github.com/rust-lang/rust/issues/73288
Fixes https://github.com/rust-lang/rust/issues/72327
When these methods were originally written, I wasn't aware that
`newtype_index!` already supports addition with ordinary numbers, without
needing to unwrap and re-wrap.
If a BCB has more than one code region, those extra regions can now all be
stored in the same coverage statement, instead of being stored in additional
statements.
The concrete type `CoverageSpan` is no longer used outside of the `spans`
module.
This is a separate patch to avoid noise in the preceding patch that actually
encapsulates coverage spans.
By encapsulating the coverage spans in a struct, we can change the internal
representation without disturbing existing call sites. This will be useful for
grouping coverage spans by BCB.
This patch includes some changes that were originally in #115912, which avoid
the need for a particular test to deal with coverage spans at all.
(Comments/logs referring to `CoverageSpan` are updated in a subsequent patch.)
We're stabilizing `async fn` in trait (AFIT), but we have some
reservations about how people might use this in the definitions of
publicly-visible traits, so we're going to lint about that.
This is a bit of an odd lint for `rustc`. We normally don't lint just
to have people confirm that they understand how Rust works. But in
this one exceptional case, this seems like the right thing to do as
compared to the other plausible alternatives.
In this commit, we describe the nature of this odd lint.
