Inline a bunch of trivial conditions in parser
It is often the case that these small, conditional functions, when inlined, reveal notable optimization opportunities to LLVM. While saethlin has done a lot of good work on making these kinds of small functions not need `#[inline]` tags as much, being clearer about what we want inlined will get both the MIR opts and LLVM to pursue it more aggressively.
On local perf runs, this seems fruitful. Let's see what rust-timer says.
r? `@ghost`
There are a bunch of small helper conditionals we use.
Inline them to get slightly better perf in a few cases,
especially when rustc is compiled without PGO.
Ensure stack before parsing dot-or-call
There are many cases where, due to codegen or a massively unruly codebase, a deeply nested `call(call(call(call(call(call(call(call(call(f())))))))))` can happen. This is a spot where it would be good to grow our stack, so that we can survive to tell the programmer their code is dubiously written.
Closes https://github.com/rust-lang/rust/issues/122715
There are many cases where, due to codegen or a massively unruly codebase,
a deeply nested call(call(call(call(call(call(call(call(call(f())))))))))
can happen. This is a spot where it would be good to grow our stack, so that
we can survive to tell the programmer their code is dubiously written.
Stabilize associated type bounds (RFC 2289)
This PR stabilizes associated type bounds, which were laid out in [RFC 2289]. This gives us a shorthand to express nested type bounds that would otherwise need to be expressed with nested `impl Trait` or broken into several `where` clauses.
### What are we stabilizing?
We're stabilizing the associated item bounds syntax, which allows us to put bounds in associated type position within other bounds, i.e. `T: Trait<Assoc: Bounds...>`. See [RFC 2289] for motivation.
In all position, the associated type bound syntax expands into a set of two (or more) bounds, and never anything else (see "How does this differ[...]" section for more info).
Associated type bounds are stabilized in four positions:
* **`where` clauses (and APIT)** - This is equivalent to breaking up the bound into two (or more) `where` clauses. For example, `where T: Trait<Assoc: Bound>` is equivalent to `where T: Trait, <T as Trait>::Assoc: Bound`.
* **Supertraits** - Similar to above, `trait CopyIterator: Iterator<Item: Copy> {}`. This is almost equivalent to breaking up the bound into two (or more) `where` clauses; however, the bound on the associated item is implied whenever the trait is used. See #112573/#112629.
* **Associated type item bounds** - This allows constraining the *nested* rigid projections that are associated with a trait's associated types. e.g. `trait Trait { type Assoc: Trait2<Assoc2: Copy>; }`.
* **opaque item bounds (RPIT, TAIT)** - This allows constraining associated types that are associated with the opaque without having to *name* the opaque. For example, `impl Iterator<Item: Copy>` defines an iterator whose item is `Copy` without having to actually name that item bound.
The latter three are not expressible in surface Rust (though for associated type item bounds, this will change in #120752, which I don't believe should block this PR), so this does represent a slight expansion of what can be expressed in trait bounds.
### How does this differ from the RFC?
Compared to the RFC, the current implementation *always* desugars associated type bounds to sets of `ty::Clause`s internally. Specifically, it does *not* introduce a position-dependent desugaring as laid out in [RFC 2289], and in particular:
* It does *not* desugar to anonymous associated items in associated type item bounds.
* It does *not* desugar to nested RPITs in RPIT bounds, nor nested TAITs in TAIT bounds.
This position-dependent desugaring laid out in the RFC existed simply to side-step limitations of the trait solver, which have mostly been fixed in #120584. The desugaring laid out in the RFC also added unnecessary complication to the design of the feature, and introduces its own limitations to, for example:
* Conditionally lowering to nested `impl Trait` in certain positions such as RPIT and TAIT means that we inherit the limitations of RPIT/TAIT, namely lack of support for higher-ranked opaque inference. See this code example: https://github.com/rust-lang/rust/pull/120752#issuecomment-1979412531.
* Introducing anonymous associated types makes traits no longer object safe, since anonymous associated types are not nameable, and all associated types must be named in `dyn` types.
This last point motivates why this PR is *not* stabilizing support for associated type bounds in `dyn` types, e.g, `dyn Assoc<Item: Bound>`. Why? Because `dyn` types need to have *concrete* types for all associated items, this would necessitate a distinct lowering for associated type bounds, which seems both complicated and unnecessary compared to just requiring the user to write `impl Trait` themselves. See #120719.
### Implementation history:
Limited to the significant behavioral changes and fixes and relevant PRs, ping me if I left something out--
* #57428
* #108063
* #110512
* #112629
* #120719
* #120584Closes#52662
[RFC 2289]: https://rust-lang.github.io/rfcs/2289-associated-type-bounds.html
Eagerly translate `HelpUseLatestEdition` in parser diagnostics
Fixes#122130.
This makes me suspicious of these other two usage of `add_to_diagnostic()`. Would they *also* crash? I haven't attempted to construct test cases for them.
```
compiler/rustc_parse/src/parser/expr.rs
3453: errors::HelpUseLatestEdition::new().add_to_diagnostic(e);
compiler/rustc_hir_typeck/src/expr.rs
2603: HelpUseLatestEdition::new().add_to_diagnostic(&mut err);
```
This also seems like a footgun?
Use `ControlFlow` in visitors.
Follow up to #121256
This does have a few small behaviour changes in some diagnostic output where the visitor will now find the first match rather than the last match. The change in `find_anon_types.rs` has the only affected test. I don't see this being an issue as the last occurrence isn't any better of a choice than the first.
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``
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`.
Detect more cases of `=` to `:` typo
When a `Local` is fully parsed, but not followed by a `;`, keep the `:` span arround and mention it. If the type could continue being parsed as an expression, suggest replacing the `:` with a `=`.
```
error: expected one of `!`, `+`, `->`, `::`, `;`, or `=`, found `.`
--> file.rs:2:32
|
2 | let _: std::env::temp_dir().join("foo");
| - ^ expected one of `!`, `+`, `->`, `::`, `;`, or `=`
| |
| while parsing the type for `_`
| help: use `=` if you meant to assign
```
Fix#119665.
When a `Local` is fully parsed, but not followed by a `;`, keep the `:` span
arround and mention it. If the type could continue being parsed as an
expression, suggest replacing the `:` with a `=`.
```
error: expected one of `!`, `+`, `->`, `::`, `;`, or `=`, found `.`
--> file.rs:2:32
|
2 | let _: std::env::temp_dir().join("foo");
| - ^ expected one of `!`, `+`, `->`, `::`, `;`, or `=`
| |
| while parsing the type for `_`
| help: use `=` if you meant to assign
```
Fix#119665.
Detect empty leading where clauses on type aliases
1. commit: refactor the AST of type alias where clauses
* I could no longer bear the look of `.0.1` and `.1.0`
* Arguably moving `split` out of `TyAlias` into a substruct might not make that much sense from a semantic standpoint since it reprs an index into `TyAlias.predicates` but it's alright and it cleans up the usage sites of `TyAlias`
2. commit: fix an oversight: An empty leading where clause is still a leading where clause
* semantically reject empty leading where clauses on lazy type aliases
* e.g., on `#![feature(lazy_type_alias)] type X where = ();`
* make empty leading where clauses on assoc types trigger lint `deprecated_where_clause_location`
* e.g., `impl Trait for () { type X where = (); }`
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.
Delayed bug audit
I went through all the calls to `delayed_bug` and `span_delayed_bug` and found a few places where they could be avoided.
r? `@compiler-errors`
Add newtypes for bool fields/params/return types
Fixed all the cases of this found with some simple searches for `*/ bool` and `bool /*`; probably many more
Remove an `unchecked_error_guaranteed` call.
If we abort immediately after complaining about the obsolete `impl Trait for ..` syntax, then we avoid reaching HIR lowering. This means we can use `TyKind::Dummy` instead of `TyKind::Err`.
r? `@oli-obk`
If we abort immediately after complaining about the obsolete `impl Trait
for ..` syntax, then we avoid reaching HIR lowering. This means we can
use `TyKind::Dummy` instead of `TyKind::Err`.
There are lots of functions that modify a diagnostic. This can be via a
`&mut Diagnostic` or a `&mut DiagnosticBuilder`, because the latter type
wraps the former and impls `DerefMut`.
This commit converts all the `&mut Diagnostic` occurrences to `&mut
DiagnosticBuilder`. This is a step towards greatly simplifying
`Diagnostic`. Some of the relevant function are made generic, because
they deal with both errors and warnings. No function bodies are changed,
because all the modifier methods are available on both `Diagnostic` and
`DiagnosticBuilder`.
errors: only eagerly translate subdiagnostics
Subdiagnostics don't need to be lazily translated, they can always be eagerly translated. Eager translation is slightly more complex as we need to have a `DiagCtxt` available to perform the translation, which involves slightly more threading of that context.
This slight increase in complexity should enable later simplifications - like passing `DiagCtxt` into `AddToDiagnostic` and moving Fluent messages into the diagnostic structs rather than having them in separate files (working on that was what led to this change).
r? ```@nnethercote```
Add an ErrorGuaranteed to ast::TyKind::Err (attempt 2)
This makes it more like `hir::TyKind::Err`, and avoids a `has_errors` assertion in `LoweringContext::lower_ty_direct`.
r? ```@oli-obk```
Subdiagnostics don't need to be lazily translated, they can always be
eagerly translated. Eager translation is slightly more complex as we need
to have a `DiagCtxt` available to perform the translation, which involves
slightly more threading of that context.
This slight increase in complexity should enable later simplifications -
like passing `DiagCtxt` into `AddToDiagnostic` and moving Fluent messages
into the diagnostic structs rather than having them in separate files
(working on that was what led to this change).
Signed-off-by: David Wood <david@davidtw.co>
This mostly works well, and eliminates a couple of delayed bugs.
One annoying thing is that we should really also add an
`ErrorGuaranteed` to `proc_macro::bridge::LitKind::Err`. But that's
difficult because `proc_macro` doesn't have access to `ErrorGuaranteed`,
so we have to fake it.
This makes it more like `hir::TyKind::Err`, and avoids a
`span_delayed_bug` call in `LoweringContext::lower_ty_direct`.
It also requires adding `ast::TyKind::Dummy`, now that
`ast::TyKind::Err` can't be used for that purpose in the absence of an
error emission.
There are a couple of cases that aren't as neat as I would have liked,
marked with `FIXME` comments.
