select Vec::from_iter impls in a const block to optimize compile times
Ignoring whitespace diffs should make this easier to review.
This relies on the trick from #122301
Split out from #120682
Remove `target_override`
Because the "target can override the backend" and "backend can override the target" situation is a mess. Details in the individual commits.
r? `@WaffleLapkin`
Implement macro-based deref!() syntax for deref patterns
Stop using `box PAT` syntax for deref patterns, and instead use a perma-unstable macro.
Blocked on #122222
r? `@Nadrieril`
Interpolated cleanups
Various cleanups I made while working on attempts to remove `Interpolated`, that are worth merging now. Best reviewed one commit at a time.
r? `@petrochenkov`
Strip placeholders from hidden types before remapping generic parameter
When remapping generic parameters in the hidden type to the generic parameters of the definition of the opaque, we assume that placeholders cannot exist. Instead of just patching that site, I decided to handle it earlier, directly in `infer_opaque_types`, where we are already doing all the careful lifetime handling.
fixes#122694
the reason that ICE now occurred was that we stopped treating `operation` as being in the defining scope, so the TAIT became part of the hidden type of the `async fn`'s opaque type instead of just bailing out as ambiguos
I think
```rust
use std::future::Future;
mod foo {
type FutNothing<'a> = impl 'a + Future<Output = ()>;
//~^ ERROR: unconstrained opaque type
}
async fn operation(_: &mut ()) -> () {
//~^ ERROR: concrete type differs from previous
call(operation).await
//~^ ERROR: concrete type differs from previous
}
async fn call<F>(_f: F)
where
for<'any> F: FnMut(&'any mut ()) -> foo::FutNothing<'any>,
{
//~^ ERROR: expected generic lifetime parameter, found `'any`
}
```
would have already had the same ICE before https://github.com/rust-lang/rust/pull/121796
pattern analysis: add a custom test harness
There are two features of the pattern analysis code that are hard to test: the newly-added pattern complexity limit, and the computation of arm intersections. This PR adds some crate-specific tests for that, including an unmaintainable but pretty macro to help construct patterns.
r? `````@compiler-errors`````
Make `#[diagnostic::on_unimplemented]` format string parsing more robust
This commit fixes several issues with the format string parsing of the `#[diagnostic::on_unimplemented]` attribute that were pointed out by `@ehuss.`
In detail it fixes:
* Appearing format specifiers (display, etc). For these we generate a warning that the specifier is unsupported. Otherwise we ignore them
* Positional arguments. For these we generate a warning that positional arguments are unsupported in that location and replace them with the format string equivalent (so `{}` or `{n}` where n is the index of the positional argument)
* Broken format strings with enclosed }. For these we generate a warning about the broken format string and set the emitted message literally to the provided unformatted string
* Unknown format specifiers. For these we generate an additional warning about the unknown specifier. Otherwise we emit the literal string as message.
This essentially makes those strings behave like `format!` with the minor difference that we do not generate hard errors but only warnings. After that we continue trying to do something unsuprising (mostly either ignoring the broken parts or falling back to just giving back the literal string as provided).
Fix#122391
r? `@compiler-errors`
Use MSVC-style escaping when passing a response/@ file to lld on windows
LLD parses @ files like the command arguments on the platform it's on, so on windows it needs to follow the MSVC style to work correctly. Otherwise builds can fail if the linker command gets too long and the build path contains spaces.
Make `type_ascribe!` not a built-in
The only weird thing is the macro expansion note. I wonder if we should suppress these 🤔
r? ````@fmease```` since you told me about builtin# lol
Fix misc printing issues in emit=stable_mir
Trying to continue the work that ````@ouz-a```` started here: https://github.com/rust-lang/rust/pull/118364
Few modifications beyond fixes:
1. I made the `pretty_*` functions private.
2. I added a function to print the instance body
3. Changed a bunch of signatures to write to the writer directly.
4. Added a function to translate the place to its internal representation, so we could use the internal debug implementation.
5. Also removed `pretty_ty`, replaced by Display implementation of Ty which uses the internal display.
Inherit `RUSTC_BOOTSTRAP` when testing wasm
This is implemented with the freshly-released Wasmtime 19 and should prevent beta breakage from wasm tests that was observed and fixed in #122640 again.
Add bare metal riscv32 target.
I asked in the embedded Rust matrix if it would be OK to clone a PR to add another riscv32 configuration. The riscv32ima in this case. ``````@MabezDev`````` was open to this suggestion as a maintainer for the Riscv targets.
I now took https://github.com/rust-lang/rust/pull/117958/ for inspiration and added/edited the appropriate files.
# [Tier 3 target policy](https://doc.rust-lang.org/nightly/rustc/target-tier-policy.html#tier-3-target-policy)
> At this tier, the Rust project provides no official support for a target, so we place minimal requirements on the introduction of targets.
>
> A proposed new tier 3 target must be reviewed and approved by a member of the compiler team based on these requirements. The reviewer may choose to gauge broader compiler team consensus via a [Major Change Proposal (MCP)](https://forge.rust-lang.org/compiler/mcp.html).
>
> A proposed target or target-specific patch that substantially changes code shared with other targets (not just target-specific code) must be reviewed and approved by the appropriate team for that shared code before acceptance.
> * A tier 3 target must have a designated developer or developers (the "target maintainers") on record to be CCed when issues arise regarding the target. (The mechanism to track and CC such developers may evolve over time.)
The target being added is using riscv32 as a basis, with added extensions. The riscv32 targets already have a maintainer and are named in the description file.
> * Targets must use naming consistent with any existing targets; for instance, a target for the same CPU or OS as an existing Rust target should use the same name for that CPU or OS. Targets should normally use the same names and naming conventions as used elsewhere in the broader ecosystem beyond Rust (such as in other toolchains), unless they have a very good reason to diverge. Changing the name of a target can be highly disruptive, especially once the target reaches a higher tier, so getting the name right is important even for a tier 3 target.
> * Target names should not introduce undue confusion or ambiguity unless absolutely necessary to maintain ecosystem compatibility. For example, if the name of the target makes people extremely likely to form incorrect beliefs about what it targets, the name should be changed or augmented to disambiguate it.
> * If possible, use only letters, numbers, dashes and underscores for the name. Periods (.) are known to cause issues in Cargo.
Name is derived from the extensions used in the target.
> * Tier 3 targets may have unusual requirements to build or use, but must not create legal issues or impose onerous legal terms for the Rust project or for Rust developers or users.
> * The target must not introduce license incompatibilities.
Same conditions apply compared to other riscv32 targets.
> * Anything added to the Rust repository must be under the standard Rust license (MIT OR Apache-2.0).
Same conditions apply compared to other riscv32 targets.
> * The target must not cause the Rust tools or libraries built for any other host (even when supporting cross-compilation to the target) to depend on any new dependency less permissive than the Rust licensing policy. This applies whether the dependency is a Rust crate that would require adding new license exceptions (as specified by the tidy tool in the rust-lang/rust repository), or whether the dependency is a native library or binary. In other words, the introduction of the target must not cause a user installing or running a version of Rust or the Rust tools to be subject to any new license requirements.
Same conditions apply compared to other riscv32 targets.
> * Compiling, linking, and emitting functional binaries, libraries, or other code for the target (whether hosted on the target itself or cross-compiling from another target) must not depend on proprietary (non-FOSS) libraries. Host tools built for the target itself may depend on the ordinary runtime libraries supplied by the platform and commonly used by other applications built for the target, but those libraries must not be required for code generation for the target; cross-compilation to the target must not require such libraries at all. For instance, rustc built for the target may depend on a common proprietary C runtime library or console output library, but must not depend on a proprietary code generation library or code optimization library. Rust's license permits such combinations, but the Rust project has no interest in maintaining such combinations within the scope of Rust itself, even at tier 3.
Same conditions apply compared to other riscv32 targets.
> * "onerous" here is an intentionally subjective term. At a minimum, "onerous" legal/licensing terms include but are not limited to: non-disclosure requirements, non-compete requirements, contributor license agreements (CLAs) or equivalent, "non-commercial"/"research-only"/etc terms, requirements conditional on the employer or employment of any particular Rust developers, revocable terms, any requirements that create liability for the Rust project or its developers or users, or any requirements that adversely affect the livelihood or prospects of the Rust project or its developers or users.
Same conditions apply compared to other riscv32 targets.
> * Neither this policy nor any decisions made regarding targets shall create any binding agreement or estoppel by any party. If any member of an approving Rust team serves as one of the maintainers of a target, or has any legal or employment requirement (explicit or implicit) that might affect their decisions regarding a target, they must recuse themselves from any approval decisions regarding the target's tier status, though they may otherwise participate in discussions.
> * This requirement does not prevent part or all of this policy from being cited in an explicit contract or work agreement (e.g. to implement or maintain support for a target). This requirement exists to ensure that a developer or team responsible for reviewing and approving a target does not face any legal threats or obligations that would prevent them from freely exercising their judgment in such approval, even if such judgment involves subjective matters or goes beyond the letter of these requirements.
Same conditions apply compared to other riscv32 targets.
> * Tier 3 targets should attempt to implement as much of the standard libraries as possible and appropriate (core for most targets, alloc for targets that can support dynamic memory allocation, std for targets with an operating system or equivalent layer of system-provided functionality), but may leave some code unimplemented (either unavailable or stubbed out as appropriate), whether because the target makes it impossible to implement or challenging to implement. The authors of pull requests are not obligated to avoid calling any portions of the standard library on the basis of a tier 3 target not implementing those portions.
This target is build on top of existing riscv32 targets and inherits these implementations.
> * The target must provide documentation for the Rust community explaining how to build for the target, using cross-compilation if possible. If the target supports running binaries, or running tests (even if they do not pass), the documentation must explain how to run such binaries or tests for the target, using emulation if possible or dedicated hardware if necessary.
The documentation of this target is shared along with targets that target riscv32 with a different configuration of extensions.
> * Tier 3 targets must not impose burden on the authors of pull requests, or other developers in the community, to maintain the target. In particular, do not post comments (automated or manual) on a PR that derail or suggest a block on the PR based on a tier 3 target. Do not send automated messages or notifications (via any medium, including via ``````@)`````` to a PR author or others involved with a PR regarding a tier 3 target, unless they have opted into such messages.
I now understand, apologies for the mention before.
> * Backlinks such as those generated by the issue/PR tracker when linking to an issue or PR are not considered a violation of this policy, within reason. However, such messages (even on a separate repository) must not generate notifications to anyone involved with a PR who has not requested such notifications.
I now understand, apologies for the link to a similar PR before.
> * Patches adding or updating tier 3 targets must not break any existing tier 2 or tier 1 target, and must not knowingly break another tier 3 target without approval of either the compiler team or the maintainers of the other tier 3 target.
> * In particular, this may come up when working on closely related targets, such as variations of the same architecture with different features. Avoid introducing unconditional uses of features that another variation of the target may not have; use conditional compilation or runtime detection, as appropriate, to let each target run code supported by that target.
This should not cause issues, as the target has similarities to other configurations of the riscv32 targets.
> * Tier 3 targets must be able to produce assembly using at least one of rustc's supported backends from any host target.
This should not cause issues, as the target has similarities to other configurations of the riscv32 targets.
Don't ICE when encountering bound regions in generator interior type
I'm pretty sure this meant to say "`has_free_regions`", probably just a typo in 4a4fc3bb5b. We can have bound regions (because we only convert non-bound regions into existential regions in generator interiors), but we can't have (non-ReErased) free regions.
r? lcnr
deref patterns: bare-bones feature gate and typechecking
I am restarting the deref patterns experimentation. This introduces a feature gate under the lang-team [experimental feature](https://github.com/rust-lang/lang-team/blob/master/src/how_to/experiment.md) process, with [````@cramertj```` as lang-team liaison](https://github.com/rust-lang/lang-team/issues/88) (it's been a while though, you still ok with this ````@cramertj?).```` Tracking issue: https://github.com/rust-lang/rust/issues/87121.
This is the barest-bones implementation I could think of:
- explicit syntax, reusing `box <pat>` because that saves me a ton of work;
- use `Deref` as a marker trait (instead of a yet-to-design `DerefPure`);
- no support for mutable patterns with `DerefMut` for now;
- MIR lowering will come in the next PR. It's the trickiest part.
My goal is to let us figure out the MIR lowering part, which might take some work. And hopefully get something working for std types soon.
This is in large part salvaged from ````@fee1-dead's```` https://github.com/rust-lang/rust/pull/119467.
r? ````@compiler-errors````
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`
recursively evaluate the constants in everything that is 'mentioned'
This is another attempt at fixing https://github.com/rust-lang/rust/issues/107503. The previous attempt at https://github.com/rust-lang/rust/pull/112879 seems stuck in figuring out where the [perf regression](https://perf.rust-lang.org/compare.html?start=c55d1ee8d4e3162187214692229a63c2cc5e0f31&end=ec8de1ebe0d698b109beeaaac83e60f4ef8bb7d1&stat=instructions:u) comes from. In https://github.com/rust-lang/rust/pull/122258 I learned some things, which informed the approach this PR is taking.
Quoting from the new collector docs, which explain the high-level idea:
```rust
//! One important role of collection is to evaluate all constants that are used by all the items
//! which are being collected. Codegen can then rely on only encountering constants that evaluate
//! successfully, and if a constant fails to evaluate, the collector has much better context to be
//! able to show where this constant comes up.
//!
//! However, the exact set of "used" items (collected as described above), and therefore the exact
//! set of used constants, can depend on optimizations. Optimizing away dead code may optimize away
//! a function call that uses a failing constant, so an unoptimized build may fail where an
//! optimized build succeeds. This is undesirable.
//!
//! To fix this, the collector has the concept of "mentioned" items. Some time during the MIR
//! pipeline, before any optimization-level-dependent optimizations, we compute a list of all items
//! that syntactically appear in the code. These are considered "mentioned", and even if they are in
//! dead code and get optimized away (which makes them no longer "used"), they are still
//! "mentioned". For every used item, the collector ensures that all mentioned items, recursively,
//! do not use a failing constant. This is reflected via the [`CollectionMode`], which determines
//! whether we are visiting a used item or merely a mentioned item.
//!
//! The collector and "mentioned items" gathering (which lives in `rustc_mir_transform::mentioned_items`)
//! need to stay in sync in the following sense:
//!
//! - For every item that the collector gather that could eventually lead to build failure (most
//! likely due to containing a constant that fails to evaluate), a corresponding mentioned item
//! must be added. This should use the exact same strategy as the ecollector to make sure they are
//! in sync. However, while the collector works on monomorphized types, mentioned items are
//! collected on generic MIR -- so any time the collector checks for a particular type (such as
//! `ty::FnDef`), we have to just onconditionally add this as a mentioned item.
//! - In `visit_mentioned_item`, we then do with that mentioned item exactly what the collector
//! would have done during regular MIR visiting. Basically you can think of the collector having
//! two stages, a pre-monomorphization stage and a post-monomorphization stage (usually quite
//! literally separated by a call to `self.monomorphize`); the pre-monomorphizationn stage is
//! duplicated in mentioned items gathering and the post-monomorphization stage is duplicated in
//! `visit_mentioned_item`.
//! - Finally, as a performance optimization, the collector should fill `used_mentioned_item` during
//! its MIR traversal with exactly what mentioned item gathering would have added in the same
//! situation. This detects mentioned items that have *not* been optimized away and hence don't
//! need a dedicated traversal.
enum CollectionMode {
/// Collect items that are used, i.e., actually needed for codegen.
///
/// Which items are used can depend on optimization levels, as MIR optimizations can remove
/// uses.
UsedItems,
/// Collect items that are mentioned. The goal of this mode is that it is independent of
/// optimizations: the set of "mentioned" items is computed before optimizations are run.
///
/// The exact contents of this set are *not* a stable guarantee. (For instance, it is currently
/// computed after drop-elaboration. If we ever do some optimizations even in debug builds, we
/// might decide to run them before computing mentioned items.) The key property of this set is
/// that it is optimization-independent.
MentionedItems,
}
```
And the `mentioned_items` MIR body field docs:
```rust
/// Further items that were mentioned in this function and hence *may* become monomorphized,
/// depending on optimizations. We use this to avoid optimization-dependent compile errors: the
/// collector recursively traverses all "mentioned" items and evaluates all their
/// `required_consts`.
///
/// This is *not* soundness-critical and the contents of this list are *not* a stable guarantee.
/// All that's relevant is that this set is optimization-level-independent, and that it includes
/// everything that the collector would consider "used". (For example, we currently compute this
/// set after drop elaboration, so some drop calls that can never be reached are not considered
/// "mentioned".) See the documentation of `CollectionMode` in
/// `compiler/rustc_monomorphize/src/collector.rs` for more context.
pub mentioned_items: Vec<Spanned<MentionedItem<'tcx>>>,
```
Fixes#107503
This commit fixes several issues with the format string parsing of the
`#[diagnostic::on_unimplemented]` attribute that were pointed out by
@ehuss.
In detail it fixes:
* Appearing format specifiers (display, etc). For these we generate a
warning that the specifier is unsupported. Otherwise we ignore them
* Positional arguments. For these we generate a warning that positional
arguments are unsupported in that location and replace them with the
format string equivalent (so `{}` or `{n}` where n is the index of the
positional argument)
* Broken format strings with enclosed }. For these we generate a warning
about the broken format string and set the emitted message literally to
the provided unformatted string
* Unknown format specifiers. For these we generate an additional warning
about the unknown specifier. Otherwise we emit the literal string as
message.
This essentially makes those strings behave like `format!` with the
minor difference that we do not generate hard errors but only warnings.
After that we continue trying to do something unsuprising (mostly either
ignoring the broken parts or falling back to just giving back the
literal string as provided).
Fix#122391
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.
Fix bad span for explicit lifetime suggestions
Fixes#121267
Current explicit lifetime suggestions are not showing correct spans for some lifetimes - e.g. elided lifetime generic parameters;
This should be done correctly regarding elided lifetime kind like the following code
43fdd4916d/compiler/rustc_resolve/src/late/diagnostics.rs (L3015-L3044)
Backend and target selection is a mess: the target can override the
backend (via `Target::default_codegen_backend`), *and* the backend can
override the target (via `CodegenBackend::target_override`).
The code that handles this is ugly. It calls `build_target_config`
twice, once before getting the backend and once again afterward. It also
must check that both overrides aren't triggering at the same time.
This commit removes the latter override. It's used in rust-gpu but
@eddyb said via Zulip that removing it would be ok. This simplifies the
code greatly, and will allow some nice follow-up refactorings.
compiletest: Introduce `remove_and_create_dir_all()` helper
The code
let _ = fs::remove_dir_all(&dir);
create_dir_all(&dir).unwrap();
is duplicated in 7 places. Let's introduce a helper.
Add `usize::MAX` arg tests for Vec
Tests to prevent recurrence of the UB from the rust-lang/rust#122760 issue.
I skipped the `with_capacity`, `drain`, `reserve`, etc. APIs because they actually had a good assortment of tests earlier in the same file.
r? Nilstrieb
coverage: Remove incorrect assertions from counter allocation
These assertions detect situations where a BCB node (in the coverage graph) would have both a physical counter and one or more in-edge counters/expressions.
For most BCBs that situation would indicate an implementation bug. However, it's perfectly fine in the case of a BCB having an edge that loops back to itself.
Given the complexity and risk involved in fixing the assertions, and the fact that nothing relies on them actually being true, this patch just removes them instead.
Fixes#122738.
`````@rustbot````` label +A-code-coverage
Relax SeqCst ordering in standard library.
Every single SeqCst in the standard library is unnecessary. In all cases, Relaxed or Release+Acquire was sufficient.
As I [wrote](https://marabos.nl/atomics/memory-ordering.html#common-misconceptions) in my book on atomics:
> [..] when reading code, SeqCst basically tells the reader: "this operation depends on the total order of every single SeqCst operation in the program," which is an incredibly far-reaching claim. The same code would likely be easier to review and verify if it used weaker memory ordering instead, if possible. For example, Release effectively tells the reader: "this relates to an acquire operation on the same variable," which involves far fewer considerations when forming an understanding of the code.
>
> It is advisable to see SeqCst as a warning sign. Seeing it in the wild often means that either something complicated is going on, or simply that the author did not take the time to analyze their memory ordering related assumptions, both of which are reasons for extra scrutiny.
r? ````@Amanieu```` ````@joboet````
Ignore paths from expansion in `unused_qualifications`
If any of the path segments are from an expansion the lint is skipped currently, but a path from an expansion where all of the segments are passed in would not be. Doesn't seem that likely to occur but it could happen
LLD parses @ files like the command arguments on the platform it's on,
so on windows it needs to follow the MSVC style to work correctly.
Otherwise builds can fail if the linker command gets too long and the
build path contains spaces.
