Default `repr(C)` enums to `c_int` size
This is what ISO C strongly implies this is correct, and
many processor-specific ABIs imply or mandate this size, so
"everyone" (LLVM, gcc...) defaults to emitting enums this way.
However, this is by no means guaranteed by ISO C,
and the bare-metal Arm targets show it can be overridden,
which rustc supports via `c-enum-min-bits` in a target.json.
The override is a flag named `-fshort-enums` in clang and gcc,
but introducing a CLI flag is probably unnecessary for rustc.
This flag can be used by non-Arm microcontroller targets,
like AVR and MSP430, but it is not enabled for them by default.
Rust programmers who know the size of a target's enums
can use explicit reprs, which also lets them match C23 code.
This change is most relevant to 16-bit targets: AVR and MSP430.
Most of rustc's targets use 32-bit ints, but ILP64 does exist.
Regardless, rustc should now correctly handle enums for
both very small and very large targets.
Thanks to William for confirming MSP430 behavior,
and to Waffle for better style and no-core `size_of` asserts.
Fixesrust-lang/rust#107361Fixesrust-lang/rust#77806
Add `Clause::ConstArgHasType`
Currently the way that we check that a const arg has the correct type for the const param it is an argument for is by setting the expected type of `typeck` on the anon const of the argument to be the const param's type.
In the future for a potential `min_generic_const_exprs` we will allow providing const arguments that do not have an associated anon const that can be typeck'd which will require us to actually check that the const argument has the correct type. While it would potentially be possible to just call `eq` when creating substs this would not work if we support generics of the form `const N: T, T` (the const parameters type referencing generics declared after itself).
Additionally having `ConstArgHasType` will allow us to potentially make progress on removing the `ty` field of `Const` which may be desirable. Once progress has been made on this, `ConstArgHasType` will also be helpful in ensuring we do not make mistakes in trait/impl checking by declaring functions with the wrong const parameter types as the checks that the param env is compatible would catch it. (We have messed this up in the past, and with generic const parameter types these checks will get more complex)
There is a [document](https://hackmd.io/wuCS6CJBQ9-fWbwaW7nQRw?view) about the types of const generics that may provide some general information on this subject
---
This PR shouldn't have any impact on whether code compiles or not on stable, it primarily exists to make progress on unstable const generics features that are desirable.
This function has this line twice:
```
let bound_vars = tcx.intern_bound_variable_kinds(&bound_vars);
```
The second occurrence is effectively a no-op, because the first
occurrence interned any that needed it.
There are two traits, `InternAs` and `InternIteratorElement`. I found
them confusing to use, particularly this:
```
pub fn mk_tup<I: InternAs<Ty<'tcx>, Ty<'tcx>>>(self, iter: I) -> I::Output {
iter.intern_with(|ts| self.intern_tup(ts))
}
```
where I thought there might have been two levels of interning going on
(there isn't) due to the `intern_with`/`InternAs` + `intern_tup` naming.
And then I found the actual traits and impls themselves *very*
confusing.
- `InternAs` has a single impl, for iterators, with four type variables.
- `InternAs` is only implemented for iterators because it wouldn't
really make sense to implement for any other type. And you can't
really understand the trait without seeing that single impl, which is
suspicious.
- `InternAs` is basically just a wrapper for `InternIteratorElement`
which does all the actual work.
- Neither trait actually does any interning. They just have `Intern` in
their name because they are used *by* interning code.
- There are no comments.
So this commit improves things.
- It removes `InternAs` completely. This makes the `mk_*` function
signatures slightly more verbose -- two trait bounds instead of one --
but much easier to read, because you only need to understand one trait
instead of two.
- It renames `InternIteratorElement` as `CollectAndApply`. Likewise, it
renames its method `intern_with` as `collect_and_apply`. These names
describe better what's going on: we collect the iterator elements into
a slice and then apply a function to the slice.
- It adds comments, making clear that all this is all there just to
provide an optimized version of `f(&iter.collect::<Vec<_>>())`.
It took me a couple of attempts to come up with this commit. My initial
attempt kept `InternAs` around, but renamed things and added comments,
and I wasn't happy with it. I think this version is much better. The
resulting code is shorter, despite the addition of the comments.
`InternIteratorElement` is a trait used to intern values produces by
iterators. There are three impls, corresponding to iterators that
produce different types:
- One for `T`, which operates straightforwardly.
- One for `Result<T, E>`, which is fallible, and will fail early with an
error result if any of the iterator elements are errors.
- One for `&'a T`, which clones the items as it iterates.
That last one is bad: it's extremely easy to use it without realizing
that it clones, which goes against Rust's normal "explicit is better"
approach to cloning.
So this commit just removes it. In practice, there weren't many use
sites. For all but one of them `into_iter()` could be used, which avoids
the need for cloning. And for the one remaining case `copied()` is
used.
There are several `mk_foo`/`intern_foo` pairs, where the former takes an
iterator and the latter takes a slice. (This naming convention is bad,
but that's a fix for another PR.)
This commit changes several `mk_foo` occurrences into `intern_foo`,
avoiding the need for some `.iter()`/`.into_iter()` calls. Affected
cases:
- mk_type_list
- mk_tup
- mk_substs
- mk_const_list
Switch to `EarlyBinder` for `type_of` query
Part of the work to finish #105779 and implement https://github.com/rust-lang/types-team/issues/78.
Several queries `X` have a `bound_X` variant that wraps the output in `EarlyBinder`. This adds `EarlyBinder` to the return type of the `type_of` query and removes `bound_type_of`.
r? `@lcnr`
Do not ICE on unmet trait alias impl bounds
Fixes#108132
I've also added some documentation to the `impl_def_id` field of `DerivedObligationCause` to try and minimise the risk of such errors in future.
r? `@compiler-errors`
wasm: Register the `relaxed-simd` target feature
This WebAssembly proposal is likely to reach stage 4 soon so this starts the support in Rust for the proposal by adding a target feature that can be enabled via attributes for the stdarch project to bind the intrinsics.
Pass arguments to `x` subcommands with `--`
Fixes#107375
Any arguments passed to `x` following `--` are removed and not parsed, instead passed down to subcommands (just the ones listed in the issue, not sure if more are needed). This does not remove the existing `--args` and `--test-args` behaviour, just extends it. It's also not documented in the help, not sure of the best way to format it.
r? `@jyn514`
Implement partial support for non-lifetime binders
This implements support for non-lifetime binders. It's pretty useless currently, but I wanted to put this up so the implementation can be discussed.
Specifically, this piggybacks off of the late-bound lifetime collection code in `rustc_hir_typeck::collect::lifetimes`. This seems like a necessary step given the fact we don't resolve late-bound regions until this point, and binders are sometimes merged.
Q: I'm not sure if I should go along this route, or try to modify the earlier nameres code to compute the right bound var indices for type and const binders eagerly... If so, I'll need to rename all these queries to something more appropriate (I've done this for `resolve_lifetime::Region` -> `resolve_lifetime::ResolvedArg`)
cc rust-lang/types-team#81
r? `@ghost`
This is what ISO C strongly implies this is correct, and
many processor-specific ABIs imply or mandate this size, so
"everyone" (LLVM, gcc...) defaults to emitting enums this way.
However, this is by no means guaranteed by ISO C,
and the bare-metal Arm targets show it can be overridden,
which rustc supports via `c-enum-min-bits` in a target.json.
The override is a flag named `-fshort-enums` in clang and gcc,
but introducing a CLI flag is probably unnecessary for rustc.
This flag can be used by non-Arm microcontroller targets,
like AVR and MSP430, but it is not enabled for them by default.
Rust programmers who know the size of a target's enums
can use explicit reprs, which also lets them match C23 code.
This change is most relevant to 16-bit targets: AVR and MSP430.
Most of rustc's targets use 32-bit ints, but ILP64 does exist.
Regardless, rustc should now correctly handle enums for
both very small and very large targets.
Thanks to William for confirming MSP430 behavior,
and to Waffle for better style and no-core size_of asserts.
Co-authored-by: William D. Jones <thor0505@comcast.net>
Co-authored-by: Waffle Maybe <waffle.lapkin@gmail.com>
Factor query arena allocation out from query caches
This moves the logic for arena allocation out from the query caches into conditional code in the query system. The specialized arena caches are removed. A new `QuerySystem` type is added in `rustc_middle` which contains the arenas, providers and query caches.
Performance seems to be slightly regressed:
<table><tr><td rowspan="2">Benchmark</td><td colspan="1"><b>Before</b></th><td colspan="2"><b>After</b></th></tr><tr><td align="right">Time</td><td align="right">Time</td><td align="right">%</th></tr><tr><td>🟣 <b>clap</b>:check</td><td align="right">1.8053s</td><td align="right">1.8109s</td><td align="right"> 0.31%</td></tr><tr><td>🟣 <b>hyper</b>:check</td><td align="right">0.2600s</td><td align="right">0.2597s</td><td align="right"> -0.10%</td></tr><tr><td>🟣 <b>regex</b>:check</td><td align="right">0.9973s</td><td align="right">1.0006s</td><td align="right"> 0.34%</td></tr><tr><td>🟣 <b>syn</b>:check</td><td align="right">1.6048s</td><td align="right">1.6051s</td><td align="right"> 0.02%</td></tr><tr><td>🟣 <b>syntex_syntax</b>:check</td><td align="right">6.2992s</td><td align="right">6.3159s</td><td align="right"> 0.26%</td></tr><tr><td>Total</td><td align="right">10.9664s</td><td align="right">10.9922s</td><td align="right"> 0.23%</td></tr><tr><td>Summary</td><td align="right">1.0000s</td><td align="right">1.0017s</td><td align="right"> 0.17%</td></tr></table>
Incremental performance is a bit worse:
<table><tr><td rowspan="2">Benchmark</td><td colspan="1"><b>Before</b></th><td colspan="2"><b>After</b></th></tr><tr><td align="right">Time</td><td align="right">Time</td><td align="right">%</th></tr><tr><td>🟣 <b>clap</b>:check:initial</td><td align="right">2.2103s</td><td align="right">2.2247s</td><td align="right"> 0.65%</td></tr><tr><td>🟣 <b>hyper</b>:check:initial</td><td align="right">0.3335s</td><td align="right">0.3349s</td><td align="right"> 0.41%</td></tr><tr><td>🟣 <b>regex</b>:check:initial</td><td align="right">1.2597s</td><td align="right">1.2650s</td><td align="right"> 0.42%</td></tr><tr><td>🟣 <b>syn</b>:check:initial</td><td align="right">2.0521s</td><td align="right">2.0613s</td><td align="right"> 0.45%</td></tr><tr><td>🟣 <b>syntex_syntax</b>:check:initial</td><td align="right">7.8275s</td><td align="right">7.8583s</td><td align="right"> 0.39%</td></tr><tr><td>Total</td><td align="right">13.6832s</td><td align="right">13.7442s</td><td align="right"> 0.45%</td></tr><tr><td>Summary</td><td align="right">1.0000s</td><td align="right">1.0046s</td><td align="right"> 0.46%</td></tr></table>
It does seem like LLVM optimizers struggle a bit with the current state of the query system.
Based on top of https://github.com/rust-lang/rust/pull/107782 and https://github.com/rust-lang/rust/pull/107802.
r? `@cjgillot`
