Some cleanups around diagnostic levels.
Plus some refactoring in and around diagnostic levels and emission. Details in the individual commit logs.
r? ````@oli-obk````
Rework support for async closures; allow them to return futures that borrow from the closure's captures
This PR implements a new lowering for async closures via `TyKind::CoroutineClosure` which handles the curious relationship between the closure and the coroutine that it returns.
I wrote up a bunch in [this hackmd](https://hackmd.io/`@compiler-errors/S1HvqQxca)` which will be copied to the dev guide after this PR lands, and hopefully left sufficient comments in the source code explaining why this change is as large as it is.
This also necessitates that they begin implementing the `AsyncFn`-family of traits, rather than the `Fn`-family of traits -- if you need `Fn` implementations, you should probably use the non-sugar `|| async {}` syntax instead.
Notably this PR does not yet implement `async Fn()` syntax sugar for bounds, but I expect to add those soon (**edit:** #120392). For now, users must use `AsyncFn()` traits directly, which necessitates adding the `async_fn_traits` feature gate as well. I will add this as a follow-up very soon.
r? oli-obk
This is based on top of #120322, but that PR is minimal.
This rewrite makes the cache-updating nature of the function slightly clearer, using the Entry API into the hash table for region names to capture the update-insert nature of the method. May be marginally more efficient since it only runtime-borrows the map once, but in this context the performance impact is almost certainly completely negligible.
When encountering an `if let` tail expression without an `else` arm for an
enum with a single variant, suggest writing an irrefutable `let` binding
instead.
```
error[E0317]: `if` may be missing an `else` clause
--> $DIR/irrefutable-if-let-without-else.rs:8:5
|
LL | fn foo(x: Enum) -> i32 {
| --- expected `i32` because of this return type
LL | / if let Enum::Variant(value) = x {
LL | | value
LL | | }
| |_____^ expected `i32`, found `()`
|
= note: `if` expressions without `else` evaluate to `()`
= help: consider adding an `else` block that evaluates to the expected type
help: consider using an irrefutable `let` binding instead
|
LL ~ let Enum::Variant(value) = x;
LL ~ value
|
```
Fix#61788.
That is, change `diagnostic_outside_of_impl` and
`untranslatable_diagnostic` from `allow` to `deny`, because more than
half of the compiler has be converted to use translated diagnostics.
This commit removes more `deny` attributes than it adds `allow`
attributes, which proves that this change is warranted.
Introduce support for `async` bound modifier on `Fn*` traits
Adds `async` to the list of `TraitBoundModifiers`, which instructs AST lowering to map the trait to an async flavor of the trait. For now, this is only supported for `Fn*` to `AsyncFn*`, and I expect that this manual mapping via lang items will be replaced with a better system in the future.
The motivation for adding these bounds is to separate the users of async closures from the exact trait desugaring of their callable bounds. Instead of users needing to be concerned with the `AsyncFn` trait, they should be able to write `async Fn()` and it will desugar to whatever underlying trait we decide is best for the lowering of async closures.
Note: rustfmt support can be done in the rustfmt repo after a subtree sync.
pattern_analysis: Gracefully abort on type incompatibility
This leaves the option for a consumer of the crate to return `Err` instead of panicking on type error. rust-analyzer could use that (e.g. https://github.com/rust-lang/rust-analyzer/issues/15808).
Since the only use of `TypeCx::bug` is in `Constructor::is_covered_by`, it is tempting to return `false` instead of `Err()`, but that would cause "non-exhaustive match" false positives.
r? `@compiler-errors`
All the other `emit`/`emit_diagnostic` methods were recently made
consuming (e.g. #119606), but this one wasn't. But it makes sense to.
Much of this is straightforward, and lots of `clone` calls are avoided.
There are a couple of tricky bits.
- `Emitter::primary_span_formatted` no longer takes a `Diagnostic` and
returns a pair. Instead it takes the two fields from `Diagnostic` that
it used (`span` and `suggestions`) as `&mut`, and modifies them. This
is necessary to avoid the cloning of `diag.children` in two emitters.
- `from_errors_diagnostic` is rearranged so various uses of `diag` occur
before the consuming `emit_diagnostic` call.
target: default to the medium code model on LoongArch targets
The Rust LoongArch targets have been using the default LLVM code model so far, which is "small" in LLVM-speak and "normal" in LoongArch-speak. As [described][1] in the "Code Model" section of LoongArch ELF psABI spec v20231219, one can only make function calls as far as ±128MiB with the "normal" code model; this is insufficient for very large software containing Rust components that needs to be linked into the big text section, such as Chromium.
Because:
* we do not want to ask users to recompile std if they are to build such software,
* objects compiled with larger code models can be linked with those with smaller code models without problems, and
* the "medium" code model is comparable to the "small"/"normal" one performance-wise (same data access pattern; each function call becomes 2-insn long and indirect, but this may be relaxed back into the direct 1-insn form in a future LLVM version), but is able to perform function calls within ±128GiB,
it is better to just switch the targets to the "medium" code model, which is also "medium" in LLVM-speak.
[1]: https://github.com/loongson/la-abi-specs/blob/v2.30/laelf.adoc#code-models
riscv only supports split_debuginfo=off for now
Disable packed/unpacked options for riscv linux/android. Other riscv targets already only have the off option.
The packed/unpacked options might be supported in the future. See upstream issue for more details:
https://github.com/llvm/llvm-project/issues/56642Fixes#110224
make matching on NaN a hard error, and remove the rest of illegal_floating_point_literal_pattern
These arms would never be hit anyway, so the pattern makes little sense. We have had a future-compat lint against float matches in general for a *long* time, so I hope we can get away with immediately making this a hard error.
This is part of implementing https://github.com/rust-lang/rfcs/pull/3535.
Closes https://github.com/rust-lang/rust/issues/41620 by removing the lint.
https://github.com/rust-lang/reference/pull/1456 updates the reference to match.
The Rust LoongArch targets have been using the default LLVM code model
so far, which is "small" in LLVM-speak and "normal" in LoongArch-speak.
As described in the "Code Model" section of LoongArch ELF psABI spec
v20231219 [1], one can only make function calls as far as ±128MiB with
the "normal" code model; this is insufficient for very large software
containing Rust components that needs to be linked into the big text
section, such as Chromium.
Because:
* we do not want to ask users to recompile std if they are to build
such software,
* objects compiled with larger code models can be linked with those
with smaller code models without problems, and
* the "medium" code model is comparable to the "small"/"normal" one
performance-wise (same data access pattern; each function call
becomes 2-insn long and indirect, but this may be relaxed back into
the direct 1-insn form in a future LLVM version), but is able to
perform function calls within ±128GiB,
it is better to just switch the targets to the "medium" code model,
which is also "medium" in LLVM-speak.
[1]: https://github.com/loongson/la-abi-specs/blob/v2.30/laelf.adoc#code-models
coverage: Improve handling of function/closure spans
This is a combination of some loosely-related changes that touch the same code:
1. Make unexpansion of closure bodies more precise, by unexpanding back to the context of the closure declaration, instead of unexpanding all the way back to the top-level context. This preserves the way we handle async desugaring and closures containing a single bang-macro, while also giving better results for closures defined in macros.
2. Skip the normal span-refinement code when dealing with the trivial outer part of an async function.
3. Be more explicit about the fact that `fn_sig_span` has been extended to the start of the function body, and is not necessarily present.
---
`@rustbot` label +A-code-coverage
Move predicate, region, and const stuff into their own modules in middle
This PR mostly moves things around, and in a few cases adds some `ty::` to the beginning of names to avoid one-off imports.
I don't mean this to be the most *thorough* move/refactor. I just generally wanted to begin to split up `ty/mod.rs` and `ty/sty.rs` which are huge and hard to distinguish, and have a lot of non-ty stuff in them.
r? lcnr
