Make sure to instantiate placeholders correctly in old solver
When creating the query substitution guess for an input placeholder type like `!1_T` (in universe 1), we were guessing the response substitution with something like `!0_T`. This failed to unify with `!1_T`, causing an ICE.
This PR reworks the query substitution guess code to work a bit more like the new solver. I'm *pretty* sure this is correct, though I'd really appreciate some scrutiny from someone (*cough* lcnr) who knows a bit more about query instantiation :)
Fixes#119941
r? lcnr
Sandwich MIR optimizations between DSE.
This PR reorders MIR optimization passes in an attempt to increase their efficiency.
- Stop running CopyProp before GVN, it's useless as GVN will do the same thing anyway. Instead, we perform CopyProp at the end of the pipeline, to ensure we do not emit copy/move chains.
- Run DSE before GVN, as it increases the probability to have single-assignment locals.
- Run DSE after the final CopyProp to turn copies into moves.
r? `@ghost`
Avoid some redundant work in GVN
The first 2 commits are about reducing the perf effect.
Third commit avoids doing redundant work: is a local is SSA, it already has been simplified, and the resulting value is in `self.locals`. No need to call any code on it.
The last commit avoids removing some storage statements.
r? wg-mir-opt
Foreign maps are used to cache external DefIds, typically backed by
metadata decoding. In the future we might skip caching `V` there (since
loading from metadata usually is already cheap enough), but for now this
cuts down on the impact to memory usage and time to None-init a bunch of
memory. Foreign data is usually much sparser, since we're not usually
loading *all* entries from the foreign crate(s).
never patterns: Check bindings wrt never patterns
Never patterns:
- Shouldn't contain bindings since they never match anything;
- Don't count when checking that or-patterns have consistent bindings.
r? `@compiler-errors`
Tune the inlinability of `unwrap`
Fixes#115463
cc `@thomcc`
This tweaks `unwrap` on ~~`Option` &~~ `Result` to be two parts:
- `#[inline(always)]` for checking the discriminant
- `#[cold]` for actually panicking
The idea here is that checking the discriminant on a `Result` ~~or `Option`~~ should always be trivial enough to be worth inlining, even in `opt-level=z`, especially compared to passing it to a function.
As seen in the issue and codegen test, this will hopefully help particularly for things like `.try_into().unwrap()`s that are actually infallible, but in a way that's only visible with the inlining.
EDIT: I've restricted this to `Result` to avoid combining effects
Use `zip_eq` to enforce that things being zipped have equal sizes
Some `zip`s are best enforced to be equal, since size mismatches suggest deeper bugs in the compiler.
Fix `allow_internal_unstable` for `(min_)specialization`
Fixes#119950
Blocked on #119949 (comment doesn't make sense until that merges)
I'd like to follow this up and look for more instances of not properly checking spans for features but I wanted to fix the motivating issue.
`OutputTypeParameterMismatch` -> `SignatureMismatch`
I'm probably missing something that made this rename more complicated. What did you end up getting stuck on when renaming this selection error, `@lcnr?`
**also** I renamed the `FulfillmentErrorCode` variants. This is just churn but I wanted to do it forever. I can move it out of this PR if desired.
r? lcnr
std: Doc blocking behavior of LazyLock
Adding notes about blocking behavior of calls that can block the current thread, similar to those on https://doc.rust-lang.org/std/sync/struct.OnceLock.html
I'm not sure if the "This method never blocks." counterparts would be desired. If so, can add those, as well.
Silence some follow-up errors [3/x]
this is one piece of the requested cleanups from https://github.com/rust-lang/rust/pull/117449
Keep error types around, even in obligations.
These help silence follow-up errors, as we now figure out that some types (most notably inference variables) are equal to an error type.
But it also allows figuring out more types in the presence of errors, possibly causing more errors.
coverage: Simplify building the coverage graph with `CoverageSuccessors`
This is a collection of simplifications to the code that builds the *basic coverage block* graph, which is a simplified view of the MIR control-flow graph that ignores panics and merges straight-line sequences of blocks into a single BCB node.
The biggest change is to how we determine the coverage-relevant successors of a block. Previously we would call `Terminator::successors` and apply some ad-hoc postprocessing, but with this PR we instead have our own `match` on the terminator kind that produces a coverage-specific enum `CoverageSuccessors`. That enum also includes information about whether a block has exactly one successor that it can be chained into as part of a single BCB.
Exhaustiveness: remove the need for arena-allocation within the algorithm
After https://github.com/rust-lang/rust/pull/119688, exhaustiveness checking doesn't need access to the arena anymore. This simplifies the lifetime story and makes it compile on stable without the extra dependency.
r? `@compiler-errors`
Inverting the condition lets us merge the two `Ok(false)` paths. I also
find the inverted condition easier to read: "all the things that must be
true for trimming to occur", instead of "any of the things that must be
true for trimming to not occur".
ARMv6K HorizonOS - Fix backlog for UnixListener
Simple `#[cfg]` fix to avoid using `libc::SOMAXCONN`, which isn't defined for the `armv6k-nintendo-3ds` target.
Edit: This is similar to #119632.
