make MCP510 behavior opt-in to avoid conflicts between the CLI and target flavors
Fixes#113597, which contains more details on how this happens through the code, and showcases an unexpected `Gnu(Cc::Yes, Lld::Yes)` flavor.
#112910 added support to use `lld` when the flavor requests it, but didn't explicitly do so only when using `-Clink-self-contained=+linker` or one of the unstable `-Clinker-flavor`s.
The problem: some targets have a `lld` linker and flavor, e.g. `thumbv6m-none-eabi` from that issue. Users can override the linker but there are no linker flavors precise enough to describe the linker opting out of lld: when using `-Clinker=arm-none-eabi-gcc`, we infer this is a `Cc::Yes` linker flavor, but the `lld` component is unknown and therefore defaulted to the target's linker flavor, `Lld::Yes`.
<details>
<summary>Walkthrough of how this happens</summary>
The linker flavor used is a mix between what can be inferred from the CLI (`-C linker`) and the target's default linker flavor:
- there is no linker flavor on the CLI (and that also offers another workaround on nightly: `-C linker-flavor=gnu-cc -Zunstable-options`), so it will have to be inferred [from here](5dac6b320b/compiler/rustc_codegen_ssa/src/back/link.rs (L1334-L1336)) to [here](5dac6b320b/compiler/rustc_codegen_ssa/src/back/link.rs (L1321-L1327)).
- in [`infer_linker_hints`](5dac6b320b/compiler/rustc_target/src/spec/mod.rs (L320-L352)) `-C linker=arm-none-eabi-gcc` infers a `Some(Cc::Yes)` cc hint, and no hint about lld.
- the target's `linker_flavor` is combined in `with_cli_hints` with these hints. We have our `Cc::Yes`, but there is no hint about lld, [so the target's flavor `lld` component is used](5dac6b320b/compiler/rustc_target/src/spec/mod.rs (L356-L358)). It's [`Gnu(Cc::No, Lld::Yes)`](993deaa0bf/compiler/rustc_target/src/spec/thumb_base.rs (L35)).
- so we now have our `Gnu(Cc::Yes, Lld::Yes)` flavor
</details>
This results in a `Gnu(Cc::Yes, Lld::Yes)` flavor on a non-lld linker, causing an additional unexpected `-fuse-ld=lld` argument to be passed.
I don't know if this target defaulting to `rust-lld` is expected, but until MCP510's new linker flavor are stable, when people will be able to describe their linker/flavor accurately, this PR keeps the stable behavior of not doing anything when the linker/flavor on the CLI unexpectedly conflict with the target's.
I've tested this on a `no_std` `-C linker=arm-none-eabi-gcc -C link-arg=-nostartfiles --target thumbv6m-none-eabi` example, trying to simulate one of `cortex-m`'s test mentioned in issue #113597 (I don't know how to build a local complete `thumbv6m-none-eabi` toolchain to run the exact test), and checked that `-fuse-lld` was indeed gone and the error disappeared.
r? `````@petrochenkov`````
refactor proof tree formatting
mostly:
- handle indentation via a separate formatter
- change nested to use a closure
tested it after rebasing on top of #113536 and everything looks good.
r? `````@BoxyUwU`````
Make Placeholder, GeneratorWitness*, Infer and Error unreachable on SMIR rustc_ty_to_ty
Let's remove these todos to not confuse ``@ericmarkmartin`` if they pick some conversion up.
r? ``@oli-obk``
Implement selection for `Unsize` for better coercion behavior
In order for much of coercion to succeed, we need to be able to deal with partial ambiguity of `Unsize` traits during selection. However, I pessimistically implemented selection in the new trait solver to just bail out with ambiguity if it was a built-in impl:
9227ff28af/compiler/rustc_trait_selection/src/solve/eval_ctxt/select.rs (L126)
This implements a proper "rematch" procedure for dealing with built-in `Unsize` goals, so that even if the goal is ambiguous, we are able to get nested obligations which are used in the coercion selection-like loop:
9227ff28af/compiler/rustc_hir_typeck/src/coercion.rs (L702)
Second commit just moves a `resolve_vars_if_possible` call to fix a bug where we weren't detecting a trait upcasting to occur.
r? ``@lcnr``
(re-)tighten sourceinfo span of adjustments in MIR
Diagnostics rely on the spans of MIR statements being (approximately) correct in order to give suggestions relative to that span (i.e. `shrink_to_hi` and `shrink_to_lo`).
I discovered that we're *intentionally* lowering THIR exprs with their parent expr's span if they come from adjustments that are due to a parent expression. While I understand why that may be desirable to demonstrate the relationship of an adjustment and the expression that requires it, it leads to
1. very verbose borrowck output
2. incorrect spans for suggestions
Some diagnostics get around that by giving suggestions relative to other spans we've collected during MIR lowering, such as the span of the method's identifier (e.g. `name` in `.name()`), but this doesn't work too well when things come from desugaring.
I assume it also has lead to numerous tweaks and complications to diagnostics code down the road, which this PR doesn't necessarily aim to fix but may open the gates to fixing later... The last three commits are simplifications due to the fact that we can assume that the move span actually points to what is being moved (and a test).
This regressed in #89110, which was debated somewhat in #90286. cc `@Aaron1011` who originally made this change.
r? diagnostics
Fixes#113547Fixes#111016
miri: protect Move() function arguments during the call
This gives `Move` operands a meaning specific to function calls:
- for the duration of the call, the place the operand comes from is protected, making all read and write accesses insta-UB.
- the contents of that place are reset to `Uninit`, so looking at them again after the function returns, we cannot observe their contents
Turns out we can replace the existing "retag return place" hack with the exact same sort of protection on the return place, which is nicely symmetric.
Fixes https://github.com/rust-lang/rust/issues/112564
Fixes https://github.com/rust-lang/miri/issues/2927
This starts with a Miri rustc-push, since we'd otherwise conflict with a PR that recently landed in Miri.
(The "miri tree borrows" commit is an unrelated cleanup I noticed while doing the PR. I can remove it if you prefer.)
r? `@oli-obk`
Introduce `trait DebugWithInfcx` to debug format types with universe info
Seeing universes of infer vars is valuable for debugging but currently we have no way of easily debug formatting a type with the universes of all the infer vars shown. In the future I hope to augment the new solver's proof tree output with a `DebugWithInfcx` impl so that it can show universes but I left that out of this PR as it would be non trivial and this is already large and complex enough.
The goal here is to make the various abstractions taking `T: Debug` able to use the codepath for printing out universes, that way we can do `debug!("{:?}", my_x)` and have `my_x` have universes shown, same for the `write!` macro. It's not possible to put the `Infcx: InferCtxtLike<I>` into the formatter argument to `Debug::fmt` so it has to go into the self ty. For this we introduce the type `OptWithInfcx<I: Interner, Infcx: InferCtxtLike<I>, T>` which has the data `T` optionally coupled with the infcx (more on why it's optional later).
Because of coherence/orphan rules it's not possible to write the impl `Debug for OptWithInfcx<..., MyType>` when `OptWithInfcx` is in a upstream crate. This necessitates a blanket impl in the crate defining `OptWithInfcx` like so: `impl<T: DebugWithInfcx> Debug for OptWithInfcx<..., T>`. It is not intended for people to manually call `DebugWithInfcx::fmt`, the `Debug` impl for `OptWithInfcx` should be preferred.
The infcx has to be optional in `OptWithInfcx` as otherwise we would end up with a large amount of code duplication. Almost all types that want to be used with `OptWithInfcx` do not themselves need access to the infcx so if we were to not optional we would end up with large `Debug` and `DebugWithInfcx` impls that were practically identical other than that when formatting their fields we wrap the field in `OptWithInfcx` instead of formatting it alone.
The only types that need access to the infcx themselves are ty/const/region infer vars, everything else is implemented by having the `Debug` impl defer to `OptWithInfcx` with no infcx available. The `DebugWithInfcx` impl is pretty much just the standard `Debug` impl except that instead of recursively formatting fields with `write!(f, "{x:?}")` we must do `write!(f, "{:?}", opt_infcx.wrap(x))`. This is some pretty rough boilerplate but I could not think of an alternative unfortunately.
`OptWithInfcx::wrap` is an eager `Option::map` because 99% of callsites were discarding the existing data in `OptWithInfcx` and did not need lazy evaluation.
A trait `InferCtxtLike` was added instead of using `InferCtxt<'tcx>` as we need to implement `DebugWithInfcx` for types living in `rustc_type_ir` which are generic over an interner and do not have access to `InferCtxt` since it lives in `rustc_infer`. Additionally I suspect that adding universe info to new solver proof tree output will require an implementation of `InferCtxtLike` for something that is not an `InferCtxt` although this is not the primary motivaton.
---
To summarize:
- There is a type `OptWithInfcx` which bundles some data optionally with an infcx with allows us to pass an infcx into a `Debug` impl. It's optional instead of being there unconditionally so that we can share code for `Debug` and `DebugWithInfcx` impls that don't care about whether there is an infcx available but have fields that might care.
- There is a trait `DebugWithInfcx` which allows downstream crates to add impls of the form `Debug for OptWithInfcx<...>` which would normally be forbidden by orphan rules/coherence.
- There is a trait `InferCtxtLike` to allow us to implement `DebugWithInfcx` for types that live in `rustc_type_ir`
This allows debug formatting various `ty::*` structures with universes shown by using the `Debug` impl for `OptWithInfcx::new(ty, infcx)`
---
This PR does not add `DebugWithInfcx` impls to absolutely _everything_ that should realistically have them, for example you cannot use `OptWithInfcx<Obligation<Predicate>>`. I am leaving this to a future PR to do so as it would likely be a lot more work to do.
Rollup of 4 pull requests
Successful merges:
- #112717 (Implement a few more rvalue translation to smir)
- #113310 (Don't suggest `impl Trait` in path position)
- #113497 (Support explicit 32-bit MIPS ABI for the synthetic object)
- #113560 (Lint against misplaced where-clauses on associated types in traits)
r? `@ghost`
`@rustbot` modify labels: rollup
Lint against misplaced where-clauses on associated types in traits
Extends the scope of the lint `deprecated_where_clause_location` (#89122) from associated types in impls to associated types in any location (impl or trait). This is only relevant for `#![feature(associated_type_defaults)]`. Previously we didn't warn on the following code for example:
```rs
#![feature(associated_type_defaults)]
trait Trait { type Assoc where u32: Copy = (); }
```
Personally I would've preferred to emit a *hard* error here instead of a lint warning since the feature is unstable but unfortunately we are constrained by back compat as associated type defaults won't necessarily trigger the feature-gate error if they are inside of a macro call (since they use a post-expansion feature-gate due to historical reasons, see also #66004).
I've renamed and moved related preexisting tests: 1. They test AST validation passes not the parser & thus shouldn't live in `parser/` (historical reasons?). 2. One test file was named after type aliases even though it tests assoc tys.
`@rustbot` label A-lint
Support explicit 32-bit MIPS ABI for the synthetic object
PR #95604 introduced a "synthetic object file to ensure all exported and used symbols participate in the linking". One constraint on this file is that for MIPS-based targets, its architecture-specific ELF flags must be the same as all other object files passed to the linker. That's enforced by LLD, here:
https://github.com/llvm/llvm-project/blob/llvmorg-16.0.6/lld/ELF/Arch/MipsArchTree.cpp#L77
The current approach to determining e_flags for 32-bit was implemented in PR #96930, which links to this issue that summarizes the problem well: https://github.com/ayrtonm/psx-sdk-rs/issues/9
> ... the temporary object file is created with an e_flags which is
> invalid for 32-bit MIPS targets. The main issue is that it omits the ABI
> bits (EF_MIPS_ABI_O32) which implies it uses the N64 ABI.
To enable the N32 MIPS ABI (which succeeded O32), this patch enables setting the synthetic object's ABI based on the target "llvm-abiname" field, if it's given; otherwise, the O32 ABI is assumed for 32-bit MIPS targets.
More information about the N32 ABI can be found here: https://web.archive.org/web/20160121005457/http://techpubs.sgi.com/library/manuals/2000/007-2816-005/pdf/007-2816-005.pdf
Implement a few more rvalue translation to smir
Add the implementation for a few more RValue variants. For now, I simplified the stable version of `RValue::Ref` by removing the notion of Region.
r? `@oli-obk`
Structurally resolve in pattern matching when peeling refs in new solver
Let me know if you want me to commit the minimized test:
```rust
fn test() {}
fn test2() {}
fn main() {
let tests: &[(_, fn())] = &[
("test", test),
("test2", test2),
];
for (a, b) in tests {
todo!();
}
}
```
In that test above, the match scrutinee is `<std::vec::Iter<(&'static str, fn())> as Iterator>::Item`, which we cannot peel the refs from.
We also need to structurally resolve in the loop, since structural resolve is inherently shallow. I haven't come up with a test where this matters, but I can if you care.
Also, I removed two other calls to `resolve_vars_with_obligations` in diagnostics code that I'm pretty convinced are not useful.
r? `@lcnr`
Uplift `clippy::fn_null_check` lint
This PR aims at uplifting the `clippy::fn_null_check` lint into rustc.
## `incorrect_fn_null_checks`
(warn-by-default)
The `incorrect_fn_null_checks` lint checks for expression that checks if a function pointer is null.
### Example
```rust
let fn_ptr: fn() = /* somehow obtained nullable function pointer */
if (fn_ptr as *const ()).is_null() { /* ... */ }
```
### Explanation
Function pointers are assumed to be non-null, checking for their nullity is incorrect.
-----
Mostly followed the instructions for uplifting a clippy lint described here: https://github.com/rust-lang/rust/pull/99696#pullrequestreview-1134072751
`@rustbot` label: +I-lang-nominated
r? compiler
Rewrite `UnDerefer`, again
This PR is intended to improve the perf regression introduced by #112882.
`UnDerefer` has been separated out again for borrowck reasons. It was a bit overzealous to remove it in the previous PR.
r? `@oli-obk`
- moved work from `find_local` to `gather_statement`
- created custom iterator for `iter_projections`
- reverted change from `IndexVec` to `FxIndexMap`
Dynamically size sigaltstk in rustc
rustc installs a signal stack that assumes that MINSIGSTKSZ is a constant, unchanging value. Newer hardware undermines that assumption greatly, with register files larger than glibc's traditional static MINSIGSTKZ. Properly handle this so that it is correct on all supported Linux versions with all CPUs.
rustc installs a signal stack that assumes that
MINSIGSTKSZ is a constant, unchanging value.
Newer hardware undermines that assumption greatly,
with register files larger than MINSIGSTKZ.
Properly handle this so that it is correct on
all supported Linux versions with all CPUs.
Replace RPITIT current impl with new strategy that lowers as a GAT
This PR replaces the current implementation of RPITITs with the new implementation that we had under -Zlower-impl-trait-in-trait-to-assoc-ty flag that lowers the RPIT as a GAT on the trait and on the impls that implement that trait.
Opening this PR as a draft because this goes after #112682, ~#112981~ and ~#112983~.
As soon as those are merged, I can rebase and we should run perf, crater and test a lot.
r? `@compiler-errors`
