Add basic Serde serialization capabilities to Stable MIR
This PR adds basic Serde serialization capabilities to Stable MIR. It is intentionally minimal (just wrapping all stable MIR types with a Serde `derive`), so that any important design decisions can be discussed before going further. A simple test is included with this PR to validate that JSON can actually be emitted.
## Notes
When I wrapped the Stable MIR error types in `compiler/stable_mir/src/error.rs`, it caused test failures (though I'm not sure why) so I backed those out.
## Future Work
So, this PR will support serializing basic stable MIR, but it _does not_ support serializing interned values beneath `Ty`s and `AllocId`s, etc... My current thinking about how to handle this is as follows:
1. Add new `visited_X` fields to the `Tables` struct for each interned category of interest.
2. As serialization is occuring, serialize interned values as usual _and_ also record the interned value we referenced in `visited_X`.
(Possibly) In addition, if an interned value recursively references other interned values, record those interned values as well.
3. Teach the stable MIR `Context` how to access the `visited_X` values and expose them with wrappers in `stable_mir/src/lib.rs` to users (e.g. to serialize and/or further analyze them).
### Pros
This approach does not commit to any specific serialization format regarding interned values or other more complex cases, which avoids us locking into any behaviors that may not be desired long-term.
### Cons
The user will need to manually handle serializing interned values.
### Alternatives
1. We can directly provide access to the underlying `Tables` maps for interned values; the disadvantage of this approach is that it either requires extra processing for users to filter out to only use the values that they need _or_ users may serialize extra values that they don't need. The advantage is that the implementation is even simpler. The other pros/cons are similar to the above.
2. We can directly serialize interned values by expanding them in-place. The pro is that this may make some basic inputs easier to consume. However, the cons are that there will need to be special provisions for dealing with cyclical values on both the producer and consumer _and_ global values will possibly need to be de-duplicated on the consumer side.
Rollup of 6 pull requests
Successful merges:
- #126908 (Use Cow<'static, str> for InlineAsmTemplatePiece::String)
- #127999 (Inject arm32 shims into Windows metadata generation)
- #128137 (CStr: derive PartialEq, Eq; add test for Ord)
- #128185 (Fix a span error when parsing a wrong param of function.)
- #128187 (Fix 1.80.0 version in RELEASES.md)
- #128189 (Turn an unreachable code path into an ICE)
r? `@ghost`
`@rustbot` modify labels: rollup
Turn an unreachable code path into an ICE
We're probably replacing the resolution with a `Res::Err` nowadays instead of just erroring but keeping the `Res`, so this code path should be unreachable
Fix a span error when parsing a wrong param of function.
fixes#128042
Before this change, the span of param `*mut Self` in `fn oof(*mut Self)` contains `(` before it, so the suggestion in E0424 will be error.
Don't ICE if HIR and middle types disagree in borrowck error reporting
We try to match up the `middle::ty::Ty` and `hir::Ty` types in borrowck error reporting, but due to things like `Self` self type alias, or regular type aliases, these might not match up. Don't ICE.
This PR also tries to recover the error by looking up the self type of the impl in case we see `Self`. The diagnostic is frankly quite confusing, but I also didn't really want to look at it because I don't understand the conflict error reporting logic. 🤷Fixes#121816
Make sure that args are compatible in `resolve_associated_item`
Implements a similar check to the one that we have in projection for GATs (#102488, #123240), where we check that the args of an impl item are compatible before returning it. This is done in `resolve_assoc_item`, which is backing `Instance::resolve`, so this is conceptually generalizing the check from GATs to methods/assoc consts. This is important to make sure that the inliner will only visit and substitute MIR bodies that are compatible w/ their trait definitions.
This shouldn't happen in codegen, but there are a few ways to get the inliner to be invoked (via calls to `optimized_mir`) before codegen, namely polymorphization and CTFE.
Fixes#121957Fixes#120792Fixes#120793Fixes#121063
`#[naked]`: use an allowlist for allowed options on `asm!` in naked functions
tracking issue: https://github.com/rust-lang/rust/issues/90957
this is mostly just a refactor, but using an allowlist (rather than a denylist) for which asm options are allowed in naked functions is a little safer.
These options are disallowed because naked functions are effectively global asm, but defined using inline asm.
Implement lint against ambiguous negative literals
This PR implements a lint against ambiguous negative literals with a literal and method calls right after it.
## `ambiguous_negative_literals`
(deny-by-default)
The `ambiguous_negative_literals` lint checks for cases that are confusing between a negative literal and a negation that's not part of the literal.
### Example
```rust,compile_fail
-1i32.abs(); // equals -1, while `(-1i32).abs()` equals 1
```
### Explanation
Method calls take precedence over unary precedence. Setting the precedence explicitly makes the code clearer and avoid potential bugs.
<details>
<summary>Old proposed lint</summary>
## `ambiguous_unary_precedence`
(deny-by-default)
The `ambiguous_unary_precedence` lint checks for use the negative unary operator with a literal and method calls.
### Example
```rust
-1i32.abs(); // equals -1, while `(-1i32).abs()` equals 1
```
### Explanation
Unary operations take precedence on binary operations and method calls take precedence over unary precedence. Setting the precedence explicitly makes the code clearer and avoid potential bugs.
</details>
-----
Note: This is a strip down version of https://github.com/rust-lang/rust/pull/117161, without the binary op precedence.
Fixes https://github.com/rust-lang/rust/issues/117155
`@rustbot` labels +I-lang-nominated
cc `@scottmcm`
r? compiler
compiler: Never debug_assert in codegen
In the name of Turing and his Hoarey heralds, assert our truths before creating a monster!
The `rustc_codegen_llvm` and `rustc_codegen_ssa` crates are fairly critical for rustc's correctness. Small mistakes here can easily result in undefined behavior, since a "small mistake" can mean something like "link and execute the wrong code". We should probably run any and all asserts in these modules unconditionally on whether this is a "debug build", and damn the costs in performance.
...Especially because the costs in performance seem to be *nothing*. It is not clear how much correctness we gain here, but I'll take free correctness improvements.
Don't ICE when auto trait has assoc ty in old solver
Kinda a pointless change to make, but it's observable w/o the feature gate, so let's just fix it. I reintroduced this ICE when I removed the "auto impl" kind from `ImplSource` in #112687.
Fixes#117829Fixes#127746
Do not use question as label
We don't want to have questions in the diagnostic output. Instead, we use wording that communicates uncertainty, like "might":
```
error[E0432]: unresolved import `spam`
--> $DIR/import-from-missing-star-3.rs:2:9
|
LL | use spam::*;
| ^^^^ you might be missing crate `spam`
|
= help: consider adding `extern crate spam` to use the `spam` crate
```
Replace ASCII control chars with Unicode Control Pictures
Replace ASCII control chars like `CR` with Unicode Control Pictures like `␍`:
```
error: bare CR not allowed in doc-comment
--> $DIR/lex-bare-cr-string-literal-doc-comment.rs:3:32
|
LL | /// doc comment with bare CR: '␍'
| ^
```
Centralize the checking of unicode char width for the purposes of CLI display in one place. Account for the new replacements. Remove unneeded tracking of "zero-width" unicode chars, as we calculate these in the `SourceMap` as needed now.
Reorder trait bound modifiers *after* `for<...>` binder in trait bounds
This PR suggests changing the grammar of trait bounds from:
```
[CONSTNESS] [ASYNCNESS] [?] [BINDER] [TRAIT_PATH]
const async ? for<'a> Sized
```
to
```
([BINDER] [CONSTNESS] [ASYNCNESS] | [?]) [TRAIT_PATH]
```
i.e., either
```
? Sized
```
or
```
for<'a> const async Sized
```
(but not both)
### Why?
I think it's strange that the binder applies "more tightly" than the `?` trait polarity. This becomes even weirder when considering that we (or at least, I) want to have `async` trait bounds expressed like:
```
where T: for<'a> async Fn(&'a ()) -> i32,
```
and not:
```
where T: async for<'a> Fn(&'a ()) -> i32,
```
### Fallout
No crates on crater use this syntax, presumably because it's literally useless. This will require modifying the reference grammar, though.
### Alternatives
If this is not desirable, then we can alternatively keep parsing `for<'a>` after the `?` but deprecate it with either an FCW (or an immediate hard error), and begin parsing `for<'a>` *before* the `?`.
We don't want to have questions in the diagnostic output. Instead, we use wording that communicates uncertainty, like "might":
```
error[E0432]: unresolved import `spam`
--> $DIR/import-from-missing-star-3.rs:2:9
|
LL | use spam::*;
| ^^^^ you might be missing crate `spam`
|
= help: consider adding `extern crate spam` to use the `spam` crate
```
Mark `missing_fragment_specifier` as `FutureReleaseErrorReportInDeps`
We are moving toward forbidding `missing_fragment_specifier` either in edition 2024 or unconditionally. Make a first step toward this by ensuring crates that rely on the old behavior are reported when used as dependencies.
Tracking issue: <https://github.com/rust-lang/rust/issues/128143>
Fix malformed suggestion for repeated maybe unsized bounds
Fixes#127441
Now when we encounter something like `foo(a : impl ?Sized + ?Sized)`, instead of suggesting removal of both bounds and leaving `foo(a: impl )` behind, we suggest changing the first bound to `Sized` and removing the second bound, resulting in `foo(a: impl Sized)`.
Although the issue was reported for impl trait types, it also occurred with regular param bounds. So if we encounter `foo<T: ?Sized + ?Sized>(a: T)` we now detect that all the bounds are `?Sized` and therefore emit the suggestion to remove the entire predicate `: ?Sized + ?Sized` resulting in `foo<T>(a: T)`.
Lastly, if we encounter a situation where some of the bounds are something other than `?Sized`, then we emit separate removal suggestions for each `?Sized` bound. E.g. if we see `foo(a: impl ?Sized + Bar + ?Sized)` or `foo<T: ?Sized + Bar + ?Sized>(a: T)` we emit suggestions such that the user will be left with `foo(a : impl Bar)` or `foo<T: Bar>(a: T)` respectively.
Do not try to reveal hidden types when trying to prove auto-traits in the defining scope
fixes#99793
this avoids the cycle error by just causing a selection error, which is not fatal. We pessimistically assume that freeze does not hold, which is always a safe assumption.
We are moving toward forbidding `missing_fragment_specifier` either in
edition 2024 or unconditionally. Make a first step toward this by
ensuring crates that rely on the old behavior are reported when used as
dependencies.
Tracking issue: <https://github.com/rust-lang/rust/issues/128143>
Improve spans on evaluated `cfg_attr`s.
When converting something like `#![cfg_attr(cond, attr)]` into `#![attr]`, we currently duplicate the `#` token and the `!` token. But weirdly, there is also this comment:
// We don't really have a good span to use for the synthesized `[]`
// in `#[attr]`, so just use the span of the `#` token.
Maybe that comment used to be true? But now it is false: we can duplicate the existing delimiters (and their spans and spacing), much like we do for the `#` and `!`.
This commit does that, thus removing the incorrect comment, and improving the spans on `Group`s in a few proc-macro tests.
`@petrochenkov`
Gate `AsyncFn*` under `async_closure` feature
T-lang has not come to a consensus on the naming of async closure callable bounds, and as part of allowing the async closures RFC merge, we agreed to place `AsyncFn` under the same gate as `async Fn` so that these syntaxes can be evaluated in parallel.
See https://github.com/rust-lang/rfcs/pull/3668#issuecomment-2246435537
r? oli-obk
Do not use global caches if opaque types can be defined
fixes#119272
r? `@lcnr`
This is certainly a crude way to make the cache sound wrt opaque types, but since perf lets us get away with this, let's do it in the old solver and let the new solver fix this correctly once and for all.
cc https://github.com/rust-lang/rust/pull/122192#issuecomment-2149252655
When converting something like `#![cfg_attr(cond, attr)]` into
`#![attr]`, we currently duplicate the `#` token and the `!` token. But
weirdly, there is also this comment:
// We don't really have a good span to use for the synthesized `[]`
// in `#[attr]`, so just use the span of the `#` token.
Maybe that comment used to be true? But now it is false: we can
duplicate the existing delimiters (and their spans and spacing), much
like we do for the `#` and `!`.
This commit does that, thus removing the incorrect comment, and
improving the spans on `Group`s in a few proc-macro tests.
Make ast `MutVisitor` have the same method name and style as `Visitor`
It doesn't map 100% because some `MutVisitor` methods can filter or even expand to multiple items, but consistency seems nicer.
tracking issue: https://github.com/rust-lang/rust/issues/127615
Note closure captures when reporting cast to fn ptr failed
Fixes#128078
We already had logic to point out a closure having captures when that's possibly the source of a coercion error to `fn()`, but we weren't reporting it during an explicit `as` cast.
Reword E0626 to mention static coroutine, add structured suggestion for adding `static`
Not certain how to make the example feel less artificial. 🤷
My main point though is that we should probably emphasize that the first solution to making a coroutine allow a borrow across an await is making it `static`.
Also adds a structured suggestion.
treat `&raw (const|mut) UNSAFE_STATIC` implied deref as safe
Fixesrust-lang/rust#125833
As reported in that and related issues, `static mut STATIC_MUT: T` is very often used in embedded code, and is in many ways equivalent to `static STATIC_CELL: SyncUnsafeCell<T>`. The Rust expression of `&raw mut STATIC_MUT` and `SyncUnsafeCell::get(&STATIC_CELL)` are approximately equal, and both evaluate to `*mut T`. The library function is safe because it has *declared itself* to be safe. However, the raw ref operator is unsafe because all uses of `static mut` are considered unsafe, even though the static's value is not used by this expression (unlike, for example, `&STATIC_MUT`).
We can fix this unnatural difference by simply adding the proper exclusion for the safety check inside the THIR unsafeck, so that we do not declare it unsafe if it is not.
While the primary concern here is `static mut`, this change is made for all instances of an "unsafe static", which includes a static declared inside `extern "abi" {}`. Hypothetically, we could go as far as generalizing this to all instances of `&raw (const|mut) *ptr`, but today we do not, as we have not actually considered the range of possible expressions that use a similar encoding. We do not even extend this to thread-local equivalents, because they have less clear semantics.
Add NuttX based targets for RISC-V and ARM
Apache NuttX is a real-time operating system (RTOS) with an emphasis on standards compliance and small footprint. It is scalable from 8-bit to 64-bit microcontroller environments. The primary governing standards in NuttX are POSIX and ANSI standards.
NuttX adopts additional standard APIs from Unix and other common RTOSs, such as VxWorks. These APIs are used for functionality not available under the POSIX and ANSI standards. However, some APIs, like fork(), are not appropriate for deeply-embedded environments and are not implemented in NuttX.
For brevity, many parts of the documentation will refer to Apache NuttX as simply NuttX.
I'll be adding libstd support for NuttX in the future, but for now I'll just add the targets.
Tier 3 policy:
> 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.)
I will be the target maintainer for this target on matters that pertain to the NuttX part of the triple. For matters pertaining to the riscv or arm part of the triple, there should be no difference from all other targets. If there are issues, I will address issues regarding the target.
> 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.
This is a new supported OS, so I have taken the origin target like `riscv32imac-unknown-none-elf` or `thumbv7m-none-eabi` and changed the `os` section to `nuttx`.
> 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.
I feel that the target name does not introduce any ambiguity.
> 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 only unusual requirement for building the compiler-builtins crate is a standard RISC-V or ARM C compiler supported by cc-rs, and using this target does not require any additional software beyond what is shipped by rustup.
> The target must not introduce license incompatibilities.
All of the additional code will use Apache-2.0.
> Anything added to the Rust repository must be under the standard Rust
> license (`MIT OR Apache-2.0`).
Agreed, and there is no problem here.
> 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.
No new dependencies are added.
> 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.
Linking is performed by rust-lld
> "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.
There are no terms. NuttX is distributed under the Apache 2.0 license.
> 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.
I'm not the reviewer here.
> 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.
Again I'm not the reviewer here.
> 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.
> 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.
Building is described in platform support doc, but libstd is not supported now, I'll implement it later.
> 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.
Understood.
> 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.
Understood.
> 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.
I believe I didn't break any other 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.
I think there are no such problems in this PR.
> Tier 3 targets must be able to produce assembly using at least one of
> rustc's supported backends from any host target. (Having support in a fork
> of the backend is not sufficient, it must be upstream.)
Yes, it use standard RISCV or ARM backend to generate assembly.
match exhaustiveness: Expand or-patterns as a separate step
To compute exhaustiveness, we must expand or-patterns. Previously, we expanded them at the same time that we pushed patterns into the matrix. This made it harder to track pattern reachability, because the or-pattern itself would never show up in the matrix so we had to recover missing information.
This PR changes that: we no longer expand or-patterns as we push them into the matrix. Instead, if we find an or-pattern in the matrix we expand them in a step very much like the specialization we already do. This simplifies a bunch of things, and should greatly simplify the implementation of https://github.com/rust-lang/rust/issues/127870.
r? `@compiler-errors`
