Split an item bounds and an item's super predicates
This is the moral equivalent of #107614, but instead for predicates this applies to **item bounds**. This PR splits out the item bounds (i.e. *all* predicates that are assumed to hold for the alias) from the item *super predicates*, which are the subset of item bounds which share the same self type as the alias.
## Why?
Much like #107614, there are places in the compiler where we *only* care about super-predicates, and considering predicates that possibly don't have anything to do with the alias is problematic. This includes things like closure signature inference (which is at its core searching for `Self: Fn(..)` style bounds), but also lints like `#[must_use]`, error reporting for aliases, computing type outlives predicates.
Even in cases where considering all of the `item_bounds` doesn't lead to bugs, unnecessarily considering irrelevant bounds does lead to a regression (#121121) due to doing extra work in the solver.
## Example 1 - Trait Aliases
This is best explored via an example:
```
type TAIT<T> = impl TraitAlias<T>;
trait TraitAlias<T> = A + B where T: C;
```
The item bounds list for `Tait<T>` will include:
* `Tait<T>: A`
* `Tait<T>: B`
* `T: C`
While `item_super_predicates` query will include just the first two predicates.
Side-note: You may wonder why `T: C` is included in the item bounds for `TAIT`? This is because when we elaborate `TraitAlias<T>`, we will also elaborate all the predicates on the trait.
## Example 2 - Associated Type Bounds
```
type TAIT<T> = impl Iterator<Item: A>;
```
The `item_bounds` list for `TAIT<T>` will include:
* `Tait<T>: Iterator`
* `<Tait<T> as Iterator>::Item: A`
But the `item_super_predicates` will just include the first bound, since that's the only bound that is relevant to the *alias* itself.
## So what
This leads to some diagnostics duplication just like #107614, but none of it will be user-facing. We only see it in the UI test suite because we explicitly disable diagnostic deduplication.
Regarding naming, I went with `super_predicates` kind of arbitrarily; this can easily be changed, but I'd consider better names as long as we don't block this PR in perpetuity.
Use hir::Node helper methods instead of repeating the same impl multiple times
I wanted to do something entirely different and stumbled upon a bunch of cleanups
hir: Remove `opt_local_def_id_to_hir_id` and `opt_hir_node_by_def_id`
Also replace a few `hir_node()` calls with `hir_node_by_def_id()`.
Follow up to https://github.com/rust-lang/rust/pull/120943.
Distinguish between library and lang UB in assert_unsafe_precondition
As described in https://github.com/rust-lang/rust/pull/121583#issuecomment-1963168186, `assert_unsafe_precondition` now explicitly distinguishes between language UB (conditions we explicitly optimize on) and library UB (things we document you shouldn't do, and maybe some library internals assume you don't do).
`debug_assert_nounwind` was originally added to avoid the "only at runtime" aspect of `assert_unsafe_precondition`. Since then the difference between the macros has gotten muddied. This totally revamps the situation.
Now _all_ preconditions shall be checked with `assert_unsafe_precondition`. If you have a precondition that's only checkable at runtime, do a `const_eval_select` hack, as done in this PR.
r? RalfJung
Lint singleton gaps after exclusive ranges
In the discussion to stabilize exclusive range patterns (https://github.com/rust-lang/rust/issues/37854), it has often come up that they're likely to cause off-by-one mistakes. We already have the `overlapping_range_endpoints` lint, so I [proposed](https://github.com/rust-lang/rust/issues/37854#issuecomment-1845580712) a lint to catch the complementary mistake.
This PR adds a new `non_contiguous_range_endpoints` lint that catches likely off-by-one errors with exclusive range patterns. Here's the idea (see the test file for more examples):
```rust
match x {
0..10 => ..., // WARN: this range doesn't match `10_u8` because `..` is an exclusive range
11..20 => ..., // this could appear to continue range `0_u8..10_u8`, but `10_u8` isn't matched by either of them
_ => ...,
}
// help: use an inclusive range instead: `0_u8..=10_u8`
```
More precisely: for any exclusive range `lo..hi`, if `hi+1` is matched by another range but `hi` isn't, we suggest writing an inclusive range `lo..=hi` instead. We also catch `lo..T::MAX`.
Refactor pre-getopts command line argument handling
Rebased version of #111658. I've also fixed the Windows CI failure (although I don't have access to Windows to test it myself).
Add asm goto support to `asm!`
Tracking issue: #119364
This PR implements asm-goto support, using the syntax described in "future possibilities" section of [RFC2873](https://rust-lang.github.io/rfcs/2873-inline-asm.html#asm-goto).
Currently I have only implemented the `label` part, not the `fallthrough` part (i.e. fallthrough is implicit). This doesn't reduce the expressive though, since you can use label-break to get arbitrary control flow or simply set a value and rely on jump threading optimisation to get the desired control flow. I can add that later if deemed necessary.
r? ``@Amanieu``
cc ``@ojeda``
Add a scheme for moving away from `extern "rust-intrinsic"` entirely
All `rust-intrinsic`s can become free functions now, either with a fallback body, or with a dummy body and an attribute, requiring backends to actually implement the intrinsic.
This PR demonstrates the dummy-body scheme with the `vtable_size` intrinsic.
cc https://github.com/rust-lang/rust/issues/63585
follow-up to #120500
MCP at https://github.com/rust-lang/compiler-team/issues/720
Existing names for values of this type are `sess`, `parse_sess`,
`parse_session`, and `ps`. `sess` is particularly annoying because
that's also used for `Session` values, which are often co-located, and
it can be difficult to know which type a value named `sess` refers to.
(That annoyance is the main motivation for this change.) `psess` is nice
and short, which is good for a name used this much.
The commit also renames some `parse_sess_created` values as
`psess_created`.
`f16` and `f128` step 2: intrinsics
Continuation of https://github.com/rust-lang/rust/pull/121728, another portion of https://github.com/rust-lang/rust/pull/114607.
This PR adds `f16` and `f128` intrinsics, and hooks them up to both HIR and LLVM. This is all still unexposed to the frontend, which will probably be the next step. Also update itanium mangling per `@rcvalle's` in https://github.com/rust-lang/rust/pull/121728/files#r1506570300, and fix a typo from step 1.
Once these types are usable in code, I will add the codegen tests from #114607 (codegen is passing on that branch)
This does add more `unimplemented!`s to Clippy, but I still don't think we can do better until library support is added.
r? `@compiler-errors`
cc `@Nilstrieb`
`@rustbot` label +T-compiler +F-f16_and_f128
Add stubs in IR and ABI for `f16` and `f128`
This is the very first step toward the changes in https://github.com/rust-lang/rust/pull/114607 and the [`f16` and `f128` RFC](https://rust-lang.github.io/rfcs/3453-f16-and-f128.html). It adds the types to `rustc_type_ir::FloatTy` and `rustc_abi::Primitive`, and just propagates those out as `unimplemented!` stubs where necessary.
These types do not parse yet so there is no feature gate, and it should be okay to use `unimplemented!`.
The next steps will probably be AST support with parsing and the feature gate.
r? `@compiler-errors`
cc `@Nilstrieb` suggested breaking the PR up in https://github.com/rust-lang/rust/pull/120645#issuecomment-1925900572
Emitter cleanups
Some cleanups I made when reading emitter code. In particular, `HumanEmitter` and `JsonEmitter` have gone from three constructors to one.
r? `@oli-obk`
Count stashed errors again
Stashed diagnostics are such a pain. Their "might be emitted, might not" semantics messes with lots of things.
#120828 and #121206 made some big changes to how they work, improving some things, but still leaving some problems, as seen by the issues caused by #121206. This PR aims to fix all of them by restricting them in a way that eliminates the "might be emitted, might not" semantics while still allowing 98% of their benefit. Details in the individual commit logs.
r? `@oli-obk`
Stashed errors used to be counted as errors, but could then be
cancelled, leading to `ErrorGuaranteed` soundness holes. #120828 changed
that, closing the soundness hole. But it introduced other difficulties
because you sometimes have to account for pending stashed errors when
making decisions about whether errors have occured/will occur and it's
easy to overlook these.
This commit aims for a middle ground.
- Stashed errors (not warnings) are counted immediately as emitted
errors, avoiding the possibility of forgetting to consider them.
- The ability to cancel (or downgrade) stashed errors is eliminated, by
disallowing the use of `steal_diagnostic` with errors, and introducing
the more restrictive methods `try_steal_{modify,replace}_and_emit_err`
that can be used instead.
Other things:
- `DiagnosticBuilder::stash` and `DiagCtxt::stash_diagnostic` now both
return `Option<ErrorGuaranteed>`, which enables the removal of two
`delayed_bug` calls and one `Ty::new_error_with_message` call. This is
possible because we store error guarantees in
`DiagCtxt::stashed_diagnostics`.
- Storing the guarantees also saves us having to maintain a counter.
- Calls to the `stashed_err_count` method are no longer necessary
alongside calls to `has_errors`, which is a nice simplification, and
eliminates two more `span_delayed_bug` calls and one FIXME comment.
- Tests are added for three of the four fixed PRs mentioned below.
- `issue-121108.rs`'s output improved slightly, omitting a non-useful
error message.
Fixes#121451.
Fixes#121477.
Fixes#121504.
Fixes#121508.
