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2025-03-14also skip abi_required_features check in rustdocRalf Jung-6/+11
(cherry picked from commit 4c939db0e775df21a0b409b7603eaaf0056e8f86)
2025-03-14also fix potential issues with mixed stable/unstable target features in rustdocRalf Jung-12/+33
(cherry picked from commit 039af88e09f4f4beb47406f4771bffc2e61d800a)
2025-03-14rustdoc: disable forbidden #[target_feature] checkRalf Jung-3/+9
(cherry picked from commit b6f22400002f7921feed13e35852e3041cf2b145)
2025-03-07Revert "Auto merge of #135335 - oli-obk:push-zxwssomxxtnq, r=saethlin"Michael Goulet-62/+24
This reverts commit a7a6c64a657f68113301c2ffe0745b49a16442d1, reversing changes made to ebbe63891f1fae21734cb97f2f863b08b1d44bf8. (cherry picked from commit a59a8f9e7579b4346eb6b00c3809d04986dcfcee)
2025-02-14Auto merge of #136575 - scottmcm:nsuw-math, r=nikicbors-14/+32
Set both `nuw` and `nsw` in slice size calculation There's an old note in the code to do this, and now that [LLVM-C has an API for it](https://github.com/llvm/llvm-project/blob/f0b8ff12519270adcfef93410abff76ab073476a/llvm/include/llvm-c/Core.h#L4403-L4408), we might as well. And it's been there since what looks like LLVM 17 https://github.com/llvm/llvm-project/commit/de9b6aa341d8951625d62ae3dac8670ebb3eb006 so doesn't even need to be conditional. (There's other places, like `RawVecInner` or `Layout`, that might want to do things like this too, but I'll leave those for a future PR.)
2025-02-14Auto merge of #136735 - scottmcm:transmute-nonnull, r=oli-obkbors-9/+26
`transmute` should also assume non-null pointers Previously it only did integer-ABI things, but this way it does data pointers too. That gives more information in general to the backend, and allows slightly simplifying one of the helpers in slice iterators.
2025-02-13Set both `nuw` and `nsw` in slice size calculationScott McMurray-14/+32
There's an old note in the code to do this, and now that LLVM-C has an API for it, we might as well.
2025-02-13Make `-O` mean `-C opt-level=3`clubby789-13/+13
2025-02-12`transmute` should also assume non-null pointersScott McMurray-9/+26
Previously it only did integer-ABI things, but this way it does data pointers too. That gives more information in general to the backend, and allows slightly simplifying one of the helpers in slice iterators.
2025-02-13Auto merge of #136954 - jhpratt:rollup-koefsot, r=jhprattbors-19/+8
Rollup of 12 pull requests Successful merges: - #134090 (Stabilize target_feature_11) - #135025 (Cast allocas to default address space) - #135841 (Reject `?Trait` bounds in various places where we unconditionally warned since 1.0) - #136217 (Mark condition/carry bit as clobbered in C-SKY inline assembly) - #136699 (std: replace the `FromInner` implementation for addresses with private conversion functions) - #136806 (Fix cycle when debug-printing opaque types from RPITIT) - #136807 (compiler: internally merge `PtxKernel` into `GpuKernel`) - #136818 (Implement `read*_exact` for `std:io::repeat`) - #136927 (Correctly escape hashtags when running `invalid_rust_codeblocks` lint) - #136937 (Update books) - #136945 (Add diagnostic item for `std::io::BufRead`) - #136947 (Reinstate nnethercote in the review rotation.) r? `@ghost` `@rustbot` modify labels: rollup
2025-02-12Rollup merge of #134090 - veluca93:stable-tf11, r=oli-obkJacob Pratt-19/+8
Stabilize target_feature_11 # Stabilization report This is an updated version of https://github.com/rust-lang/rust/pull/116114, which is itself a redo of https://github.com/rust-lang/rust/pull/99767. Most of this commit and report were copied from those PRs. Thanks ```@LeSeulArtichaut``` and ```@calebzulawski!``` ## Summary Allows for safe functions to be marked with `#[target_feature]` attributes. Functions marked with `#[target_feature]` are generally considered as unsafe functions: they are unsafe to call, cannot *generally* be assigned to safe function pointers, and don't implement the `Fn*` traits. However, calling them from other `#[target_feature]` functions with a superset of features is safe. ```rust // Demonstration function #[target_feature(enable = "avx2")] fn avx2() {} fn foo() { // Calling `avx2` here is unsafe, as we must ensure // that AVX is available first. unsafe { avx2(); } } #[target_feature(enable = "avx2")] fn bar() { // Calling `avx2` here is safe. avx2(); } ``` Moreover, once https://github.com/rust-lang/rust/pull/135504 is merged, they can be converted to safe function pointers in a context in which calling them is safe: ```rust // Demonstration function #[target_feature(enable = "avx2")] fn avx2() {} fn foo() -> fn() { // Converting `avx2` to fn() is a compilation error here. avx2 } #[target_feature(enable = "avx2")] fn bar() -> fn() { // `avx2` coerces to fn() here avx2 } ``` See the section "Closures" below for justification of this behaviour. ## Test cases Tests for this feature can be found in [`tests/ui/target_feature/`](https://github.com/rust-lang/rust/tree/f6cb952dc115fd1311b02b694933e31d8dc8b002/tests/ui/target-feature). ## Edge cases ### Closures * [target-feature 1.1: should closures inherit target-feature annotations? #73631](https://github.com/rust-lang/rust/issues/73631) Closures defined inside functions marked with #[target_feature] inherit the target features of their parent function. They can still be assigned to safe function pointers and implement the appropriate `Fn*` traits. ```rust #[target_feature(enable = "avx2")] fn qux() { let my_closure = || avx2(); // this call to `avx2` is safe let f: fn() = my_closure; } ``` This means that in order to call a function with #[target_feature], you must guarantee that the target-feature is available while the function, any closures defined inside it, as well as any safe function pointers obtained from target-feature functions inside it, execute. This is usually ensured because target features are assumed to never disappear, and: - on any unsafe call to a `#[target_feature]` function, presence of the target feature is guaranteed by the programmer through the safety requirements of the unsafe call. - on any safe call, this is guaranteed recursively by the caller. If you work in an environment where target features can be disabled, it is your responsibility to ensure that no code inside a target feature function (including inside a closure) runs after this (until the feature is enabled again). **Note:** this has an effect on existing code, as nowadays closures do not inherit features from the enclosing function, and thus this strengthens a safety requirement. It was originally proposed in #73631 to solve this by adding a new type of UB: “taking a target feature away from your process after having run code that uses that target feature is UB” . This was motivated by userspace code already assuming in a few places that CPU features never disappear from a program during execution (see i.e. https://github.com/rust-lang/stdarch/blob/2e29bdf90832931ea499755bb4ad7a6b0809295a/crates/std_detect/src/detect/arch/x86.rs); however, concerns were raised in the context of the Linux kernel; thus, we propose to relax that requirement to "causing the set of usable features to be reduced is unsafe; when doing so, the programmer is required to ensure that no closures or safe fn pointers that use removed features are still in scope". * [Fix #[inline(always)] on closures with target feature 1.1 #111836](https://github.com/rust-lang/rust/pull/111836) Closures accept `#[inline(always)]`, even within functions marked with `#[target_feature]`. Since these attributes conflict, `#[inline(always)]` wins out to maintain compatibility. ### ABI concerns * [The extern "C" ABI of SIMD vector types depends on target features #116558](https://github.com/rust-lang/rust/issues/116558) The ABI of some types can change when compiling a function with different target features. This could have introduced unsoundness with target_feature_11, but recent fixes (#133102, #132173) either make those situations invalid or make the ABI no longer dependent on features. Thus, those issues should no longer occur. ### Special functions The `#[target_feature]` attribute is forbidden from a variety of special functions, such as main, current and future lang items (e.g. `#[start]`, `#[panic_handler]`), safe default trait implementations and safe trait methods. This was not disallowed at the time of the first stabilization PR for target_features_11, and resulted in the following issues/PRs: * [`#[target_feature]` is allowed on `main` #108645](https://github.com/rust-lang/rust/issues/108645) * [`#[target_feature]` is allowed on default implementations #108646](https://github.com/rust-lang/rust/issues/108646) * [#[target_feature] is allowed on #[panic_handler] with target_feature 1.1 #109411](https://github.com/rust-lang/rust/issues/109411) * [Prevent using `#[target_feature]` on lang item functions #115910](https://github.com/rust-lang/rust/pull/115910) ## Documentation * Reference: [Document the `target_feature_11` feature reference#1181](https://github.com/rust-lang/reference/pull/1181) --- cc tracking issue https://github.com/rust-lang/rust/issues/69098 cc ```@workingjubilee``` cc ```@RalfJung``` r? ```@rust-lang/lang```
2025-02-12Auto merge of #135994 - 1c3t3a:rename-unsafe-ptr, r=oli-obkbors-7/+7
Rename rustc_middle::Ty::is_unsafe_ptr to is_raw_ptr The wording unsafe pointer is less common and not mentioned in a lot of places, instead this is usually called a "raw pointer". For the sake of uniformity, we rename this method. This came up during the review of https://github.com/rust-lang/rust/pull/134424. r? `@Noratrieb`
2025-02-11compiler: replace ExternAbi::name calls with formattersJubilee Young-3/+1
Most of these just format the ABI string, so... just format ExternAbi? This makes it more consistent and less jank when we can do it.
2025-02-11Rollup merge of #136603 - workingjubilee:move-abi-versioning-into-ast, ↵Matthias Krüger-2/+3
r=compiler-errors compiler: gate `extern "{abi}"` in ast_lowering I don't believe low-level crates like `rustc_abi` should have to know or care about higher-level concerns like whether the ABI string is stable for users. These implementation details can be made less open to public inspection. This way the code that governs stability is near the code that enforces stability, and compiled together. It also abstracts away certain error messages instead of constantly repeating them. A few error messages are simply deleted outright, instead of made uniform, because they are either too dated to be useful or redundant with other diagnostic improvements we could make. These can be pursued in followups: my first concern was making sure there wasn't unnecessary diagnostics-related code in `rustc_abi`, which is not well-positioned to understand what kind of errors are going to be generated based on how it is used. r? ``@ghost``
2025-02-10Rollup merge of #136419 - EnzymeAD:autodiff-tests, r=onur-ozkan,jieyouxuMatthias Krüger-2/+0
adding autodiff tests I'd like to get started with upstreaming some tests, even though I'm still waiting for an answer on how to best integrate the enzyme pass. Can we therefore temporarily support the -Z llvm-plugins here without too much effort? And in that case, how would that work? I saw you can do remapping, e.g. `rust-src-base`, but I don't think that will give me the path to libEnzyme.so. Do you have another suggestion? Other than that this test simply checks that the derivative of `x*x` is `2.0 * x`, which in this case is computed as `%0 = fadd fast double %x.0.val, %x.0.val` (I'll add a few more tests and move it to an autodiff folder if we can use the -Z flag) r? ``@jieyouxu`` Locally at least `-Zllvm-plugins=${PWD}/build/x86_64-unknown-linux-gnu/enzyme/build/Enzyme/libEnzyme-19.so` seems to work if I copy the command I get from x.py test and run it manually. However, running x.py test itself fails. Tracking: - https://github.com/rust-lang/rust/issues/124509 Zulip discussion: https://rust-lang.zulipchat.com/#narrow/channel/326414-t-infra.2Fbootstrap/topic/Enzyme.20build.20changes
2025-02-10Rename rustc_middle::Ty::is_unsafe_ptr to is_raw_ptrBastian Kersting-7/+7
The wording unsafe pointer is less common and not mentioned in a lot of places, instead this is usually called a "raw pointer". For the sake of uniformity, we rename this method. This came up during the review of https://github.com/rust-lang/rust/pull/134424.
2025-02-10remove outdated *First autodiff variants for higher-order adManuel Drehwald-2/+0
2025-02-09compiler: remove rustc_target::spec::abi reexportsJubilee Young-2/+3
2025-02-09Auto merge of #136751 - bjorn3:update_rustfmt, r=Mark-Simulacrumbors-92/+128
Update bootstrap compiler and rustfmt The rustfmt version we previously used formats things differently from what the latest nightly rustfmt does. This causes issues for subtrees that get formatted both in-tree and in their own repo. Updating the rustfmt used in-tree solves those issues. Also bumped the bootstrap compiler as the stage0 update command always updates both at the same time.
2025-02-08Rollup merge of #136706 - workingjubilee:finish-up-rustc-abi-updates, ↵Jubilee-6/+6
r=compiler-errors compiler: mostly-finish `rustc_abi` updates This almost-finishes all the updates in the compiler to use `rustc_abi` and removes some of the reexports of `rustc_abi` items in `rustc_target` that were previously available. r? ```@compiler-errors```
2025-02-08Rustfmtbjorn3-92/+128
2025-02-08Rollup merge of #136200 - purplesyringa:wasm-eh-fixes, r=bjorn3Matthias Krüger-6/+23
Generate correct terminate block under Wasm EH This fixes failing LLVM assertions during insnsel. Improves #135665. r? bjorn3 ^ you reviewed the PR bringing Wasm EH in, I assume this is within your area of expertise?
2025-02-07compiler: remove reexports from rustc_target::callconvJubilee Young-5/+5
2025-02-07compiler: remove rustc_target::abi entirelyJubilee Young-1/+1
2025-02-07Remove Linkage::Appendingbjorn3-2/+0
It can only be used for certain LLVM internal variables like llvm.global_ctors which users are not allowed to define.
2025-02-07Remove Linkage::Privatebjorn3-2/+1
This is the same as Linkage::Internal except that it doesn't emit any symbol. Some backends may not support it and it isn't all that useful anyway.
2025-02-06Generate correct terminate block under Wasm EHAlisa Sireneva-6/+23
This fixes failing LLVM assertions during insnsel. Improves #135665.
2025-02-06Auto merge of #136471 - safinaskar:parallel, r=SparrowLiibors-6/+7
tree-wide: parallel: Fully removed all `Lrc`, replaced with `Arc` tree-wide: parallel: Fully removed all `Lrc`, replaced with `Arc` This is continuation of https://github.com/rust-lang/rust/pull/132282 . I'm pretty sure I did everything right. In particular, I searched all occurrences of `Lrc` in submodules and made sure that they don't need replacement. There are other possibilities, through. We can define `enum Lrc<T> { Rc(Rc<T>), Arc(Arc<T>) }`. Or we can make `Lrc` a union and on every clone we can read from special thread-local variable. Or we can add a generic parameter to `Lrc` and, yes, this parameter will be everywhere across all codebase. So, if you think we should take some alternative approach, then don't merge this PR. But if it is decided to stick with `Arc`, then, please, merge. cc "Parallel Rustc Front-end" ( https://github.com/rust-lang/rust/issues/113349 ) r? SparrowLii `@rustbot` label WG-compiler-parallel
2025-02-05Rollup merge of #128045 - pnkfelix:rustc-contracts, r=oli-obkLeón Orell Valerian Liehr-0/+4
#[contracts::requires(...)] + #[contracts::ensures(...)] cc https://github.com/rust-lang/rust/issues/128044 Updated contract support: attribute syntax for preconditions and postconditions, implemented via a series of desugarings that culminates in: 1. a compile-time flag (`-Z contract-checks`) that, similar to `-Z ub-checks`, attempts to ensure that the decision of enabling/disabling contract checks is delayed until the end user program is compiled, 2. invocations of lang-items that handle invoking the precondition, building a checker for the post-condition, and invoking that post-condition checker at the return sites for the function, and 3. intrinsics for the actual evaluation of pre- and post-condition predicates that third-party verification tools can intercept and reinterpret for their own purposes (e.g. creating shims of behavior that abstract away the function body and replace it solely with the pre- and post-conditions). Known issues: * My original intent, as described in the MCP (https://github.com/rust-lang/compiler-team/issues/759) was to have a rustc-prefixed attribute namespace (like rustc_contracts::requires). But I could not get things working when I tried to do rewriting via a rustc-prefixed builtin attribute-macro. So for now it is called `contracts::requires`. * Our attribute macro machinery does not provide direct support for attribute arguments that are parsed like rust expressions. I spent some time trying to add that (e.g. something that would parse the attribute arguments as an AST while treating the remainder of the items as a token-tree), but its too big a lift for me to undertake. So instead I hacked in something approximating that goal, by semi-trivially desugaring the token-tree attribute contents into internal AST constucts. This may be too fragile for the long-term. * (In particular, it *definitely* breaks when you try to add a contract to a function like this: `fn foo1(x: i32) -> S<{ 23 }> { ... }`, because its token-tree based search for where to inject the internal AST constructs cannot immediately see that the `{ 23 }` is within a generics list. I think we can live for this for the short-term, i.e. land the work, and continue working on it while in parallel adding a new attribute variant that takes a token-tree attribute alongside an AST annotation, which would completely resolve the issue here.) * the *intent* of `-Z contract-checks` is that it behaves like `-Z ub-checks`, in that we do not prematurely commit to including or excluding the contract evaluation in upstream crates (most notably, `core` and `std`). But the current test suite does not actually *check* that this is the case. Ideally the test suite would be extended with a multi-crate test that explores the matrix of enabling/disabling contracts on both the upstream lib and final ("leaf") bin crates.
2025-02-04Auto merge of #135760 - scottmcm:disjoint-bitor, r=WaffleLapkinbors-0/+10
Add `unchecked_disjoint_bitor` per ACP373 Following the names from libs-api in https://github.com/rust-lang/libs-team/issues/373#issuecomment-2085686057 Includes a fallback implementation so this doesn't have to update cg_clif or cg_gcc, and overrides it in cg_llvm to use `or disjoint`, which [is available in LLVM 18](https://releases.llvm.org/18.1.0/docs/LangRef.html#or-instruction) so hopefully we don't need any version checks.
2025-02-03Contracts core intrinsics.Felix S. Klock II-0/+4
These are hooks to: 1. control whether contract checks are run 2. allow 3rd party tools to intercept and reintepret the results of running contracts.
2025-02-03Auto merge of #136413 - EnzymeAD:fix-autodiff-comptime-regression, r=oli-obkbors-1/+1
fix autodiff compile time regression Tries to fix the regression from https://github.com/rust-lang/rust/pull/133429 Tracking: - https://github.com/rust-lang/rust/issues/124509
2025-02-03tree-wide: parallel: Fully removed all `Lrc`, replaced with `Arc`Askar Safin-6/+7
2025-02-02Rollup merge of #136279 - Zalathar:ensure-ok, r=oli-obkMatthias Krüger-1/+1
Rename `tcx.ensure()` to `tcx.ensure_ok()`, and improve the associated docs This is all based on my archaeology for https://rust-lang.zulipchat.com/#narrow/channel/182449-t-compiler.2Fhelp/topic/.60TyCtxtEnsure.60. The main renamings are: - `tcx.ensure()` → `tcx.ensure_ok()` - `tcx.ensure_with_value()` → `tcx.ensure_done()` - Query modifier `ensure_forwards_result_if_red` → `return_result_from_ensure_ok` Hopefully these new names are a better fit for the *actual* function and purpose of these query call modes.
2025-02-01test compile time fixesManuel Drehwald-1/+1
2025-02-01Rollup merge of #130514 - compiler-errors:unsafe-binders, r=oli-obkMatthias Krüger-1/+11
Implement MIR lowering for unsafe binders This is the final bit of the unsafe binders puzzle. It implements MIR, CTFE, and codegen for unsafe binders, and enforces that (for now) they are `Copy`. Later on, I'll introduce a new trait that relaxes this requirement to being "is `Copy` or `ManuallyDrop<T>`" which more closely models how we treat union fields. Namely, wrapping unsafe binders is now `Rvalue::WrapUnsafeBinder`, which acts much like an `Rvalue::Aggregate`. Unwrapping unsafe binders are implemented as a MIR projection `ProjectionElem::UnwrapUnsafeBinder`, which acts much like `ProjectionElem::Field`. Tracking: - https://github.com/rust-lang/rust/issues/130516
2025-01-31Override `disjoint_or` in the LLVM backendScott McMurray-0/+10
2025-02-01Rename `tcx.ensure()` to `tcx.ensure_ok()`Zalathar-1/+1
2025-01-31Implement MIR, CTFE, and codegen for unsafe bindersMichael Goulet-1/+11
2025-01-31Auto merge of #134424 - 1c3t3a:null-checks, r=saethlinbors-0/+5
Insert null checks for pointer dereferences when debug assertions are enabled Similar to how the alignment is already checked, this adds a check for null pointer dereferences in debug mode. It is implemented similarly to the alignment check as a `MirPass`. This inserts checks in the same places as the `CheckAlignment` pass and additionally also inserts checks for `Borrows`, so code like ```rust let ptr: *const u32 = std::ptr::null(); let val: &u32 = unsafe { &*ptr }; ``` will have a check inserted on dereference. This is done because null references are UB. The alignment check doesn't cover these places, because in `&(*ptr).field`, the exact requirement is that the final reference must be aligned. This is something to consider further enhancements of the alignment check. For now this is implemented as a separate `MirPass`, to make it easy to disable this check if necessary. This is related to a 2025H1 project goal for better UB checks in debug mode: https://github.com/rust-lang/rust-project-goals/pull/177. r? `@saethlin`
2025-01-31Insert null checks for pointer dereferences when debug assertions are enabledBastian Kersting-0/+5
Similar to how the alignment is already checked, this adds a check for null pointer dereferences in debug mode. It is implemented similarly to the alignment check as a MirPass. This is related to a 2025H1 project goal for better UB checks in debug mode: https://github.com/rust-lang/rust-project-goals/pull/177.
2025-01-31Auto merge of #136332 - jhpratt:rollup-aa69d0e, r=jhprattbors-8/+162
Rollup of 9 pull requests Successful merges: - #132156 (When encountering unexpected closure return type, point at return type/expression) - #133429 (Autodiff Upstreaming - rustc_codegen_ssa, rustc_middle) - #136281 (`rustc_hir_analysis` cleanups) - #136297 (Fix a typo in profile-guided-optimization.md) - #136300 (atomic: extend compare_and_swap migration docs) - #136310 (normalize `*.long-type.txt` paths for compare-mode tests) - #136312 (Disable `overflow_delimited_expr` in edition 2024) - #136313 (Filter out RPITITs when suggesting unconstrained assoc type on too many generics) - #136323 (Fix a typo in conventions.md) r? `@ghost` `@rustbot` modify labels: rollup
2025-01-31Rollup merge of #133429 - EnzymeAD:autodiff-middle, r=oli-obkJacob Pratt-8/+162
Autodiff Upstreaming - rustc_codegen_ssa, rustc_middle This PR should not be merged until the rustc_codegen_llvm part is merged. I will also alter it a little based on what get's shaved off from the cg_llvm PR, and address some of the feedback I received in the other PR (including cleanups). I am putting it already up to 1) Discuss with `@jieyouxu` if there is more work needed to add tests to this and 2) Pray that there is someone reviewing who can tell me why some of my autodiff invocations get lost. Re 1: My test require fat-lto. I also modify the compilation pipeline. So if there are any other llvm-ir tests in the same compilation unit then I will likely break them. Luckily there are two groups who currently have the same fat-lto requirement for their GPU code which I have for my autodiff code and both groups have some plans to enable support for thin-lto. Once either that work pans out, I'll copy it over for this feature. I will also work on not changing the optimization pipeline for functions not differentiated, but that will require some thoughts and engineering, so I think it would be good to be able to run the autodiff tests isolated from the rest for now. Can you guide me here please? For context, here are some of my tests in the samples folder: https://github.com/EnzymeAD/rustbook Re 2: This is a pretty serious issue, since it effectively prevents publishing libraries making use of autodiff: https://github.com/EnzymeAD/rust/issues/173. For some reason my dummy code persists till the end, so the code which calls autodiff, deletes the dummy, and inserts the code to compute the derivative never gets executed. To me it looks like the rustc_autodiff attribute just get's dropped, but I don't know WHY? Any help would be super appreciated, as rustc queries look a bit voodoo to me. Tracking: - https://github.com/rust-lang/rust/issues/124509 r? `@jieyouxu`
2025-01-31Auto merge of #135318 - compiler-errors:vtable-fixes, r=lcnrbors-20/+26
Fix deduplication mismatches in vtables leading to upcasting unsoundness We currently have two cases where subtleties in supertraits can trigger disagreements in the vtable layout, e.g. leading to a different vtable layout being accessed at a callsite compared to what was prepared during unsizing. Namely: ### #135315 In this example, we were not normalizing supertraits when preparing vtables. In the example, ``` trait Supertrait<T> { fn _print_numbers(&self, mem: &[usize; 100]) { println!("{mem:?}"); } } impl<T> Supertrait<T> for () {} trait Identity { type Selff; } impl<Selff> Identity for Selff { type Selff = Selff; } trait Middle<T>: Supertrait<()> + Supertrait<T> { fn say_hello(&self, _: &usize) { println!("Hello!"); } } impl<T> Middle<T> for () {} trait Trait: Middle<<() as Identity>::Selff> {} impl Trait for () {} fn main() { (&() as &dyn Trait as &dyn Middle<()>).say_hello(&0); } ``` When we prepare `dyn Trait`, we see a supertrait of `Middle<<() as Identity>::Selff>`, which itself has two supertraits `Supertrait<()>` and `Supertrait<<() as Identity>::Selff>`. These two supertraits are identical, but they are not duplicated because we were using structural equality and *not* considering normalization. This leads to a vtable layout with two trait pointers. When we upcast to `dyn Middle<()>`, those two supertraits are now the same, leading to a vtable layout with only one trait pointer. This leads to an offset error, and we call the wrong method. ### #135316 This one is a bit more interesting, and is the bulk of the changes in this PR. It's a bit similar, except it uses binder equality instead of normalization to make the compiler get confused about two vtable layouts. In the example, ``` trait Supertrait<T> { fn _print_numbers(&self, mem: &[usize; 100]) { println!("{mem:?}"); } } impl<T> Supertrait<T> for () {} trait Trait<T, U>: Supertrait<T> + Supertrait<U> { fn say_hello(&self, _: &usize) { println!("Hello!"); } } impl<T, U> Trait<T, U> for () {} fn main() { (&() as &'static dyn for<'a> Trait<&'static (), &'a ()> as &'static dyn Trait<&'static (), &'static ()>) .say_hello(&0); } ``` When we prepare the vtable for `dyn for<'a> Trait<&'static (), &'a ()>`, we currently consider the PolyTraitRef of the vtable as the key for a supertrait. This leads two two supertraits -- `Supertrait<&'static ()>` and `for<'a> Supertrait<&'a ()>`. However, we can upcast[^up] without offsetting the vtable from `dyn for<'a> Trait<&'static (), &'a ()>` to `dyn Trait<&'static (), &'static ()>`. This is just instantiating the principal trait ref for a specific `'a = 'static`. However, when considering those supertraits, we now have only one distinct supertrait -- `Supertrait<&'static ()>` (which is deduplicated since there are two supertraits with the same substitutions). This leads to similar offsetting issues, leading to the wrong method being called. [^up]: I say upcast but this is a cast that is allowed on stable, since it's not changing the vtable at all, just instantiating the binder of the principal trait ref for some lifetime. The solution here is to recognize that a vtable isn't really meaningfully higher ranked, and to just treat a vtable as corresponding to a `TraitRef` so we can do this deduplication more faithfully. That is to say, the vtable for `dyn for<'a> Tr<'a>` and `dyn Tr<'x>` are always identical, since they both would correspond to a set of free regions on an impl... Do note that `Tr<for<'a> fn(&'a ())>` and `Tr<fn(&'static ())>` are still distinct. ---- There's a bit more that can be cleaned up. In codegen, we can stop using `PolyExistentialTraitRef` basically everywhere. We can also fix SMIR to stop storing `PolyExistentialTraitRef` in its vtable allocations. As for testing, it's difficult to actually turn this into something that can be tested with `rustc_dump_vtable`, since having multiple supertraits that are identical is a recipe for ambiguity errors. Maybe someone else is more creative with getting that attr to work, since the tests I added being run-pass tests is a bit unsatisfying. Miri also doesn't help here, since it doesn't really generate vtables that are offset by an index in the same way as codegen. r? `@lcnr` for the vibe check? Or reassign, idk. Maybe let's talk about whether this makes sense. <sup>(I guess an alternative would also be to not do any deduplication of vtable supertraits (or only a really conservative subset) rather than trying to normalize and deduplicate more faithfully here. Not sure if that works and is sufficient tho.)</sup> cc `@steffahn` -- ty for the minimizations cc `@WaffleLapkin` -- since you're overseeing the feature stabilization :3 Fixes #135315 Fixes #135316
2025-01-30Auto merge of #136318 - matthiaskrgr:rollup-a159mzo, r=matthiaskrgrbors-11/+7
Rollup of 9 pull requests Successful merges: - #135026 (Cast global variables to default address space) - #135475 (uefi: Implement path) - #135852 (Add `AsyncFn*` to `core` prelude) - #136004 (tests: Skip const OOM tests on aarch64-unknown-linux-gnu) - #136157 (override build profile for bootstrap tests) - #136180 (Introduce a wrapper for "typed valtrees" and properly check the type before extracting the value) - #136256 (Add release notes for 1.84.1) - #136271 (Remove minor future footgun in `impl Debug for MaybeUninit`) - #136288 (Improve documentation for file locking) r? `@ghost` `@rustbot` modify labels: rollup
2025-01-30Auto merge of #135030 - Flakebi:require-cpu, r=workingjubileebors-0/+9
Target option to require explicit cpu Some targets have many different CPUs and no generic CPU that can be used as a default. For these targets, the user needs to explicitly specify a CPU through `-C target-cpu=`. Add an option for targets and an error message if no CPU is set. This affects the proposed amdgpu and avr targets. amdgpu tracking issue: #135024 AVR MCP: https://github.com/rust-lang/compiler-team/issues/800
2025-01-30More assertions, tests, and miri coverageMichael Goulet-0/+2
2025-01-30introduce `ty::Value`Lukas Markeffsky-11/+7
Co-authored-by: FedericoBruzzone <federico.bruzzone.i@gmail.com>
2025-01-30Use ExistentialTraitRef throughout codegenMichael Goulet-28/+28
2025-01-30Do not treat vtable supertraits as distinct when bound with different bound varsMichael Goulet-5/+9