Only compute vtable information during codegen
This PR removes vtable information from the `Object` and `TraitUpcasting` candidate sources in the trait solvers, and defers the computation of relevant information to `Instance::resolve`. This is because vtables really aren't a thing in the trait world -- they're an implementation detail in codegen.
Previously it was just easiest to tangle this information together since we were already doing the work of looking at all the supertraits in the trait solver, and specifically because we use traits to represent when it's possible to call a method via a vtable (`Object` candidate) and do upcasting (`Unsize` candidate). but I am somewhat suspicious we're doing a *lot* of extra work, especially in polymorphic contexts, so let's see what perf says.
smir: merge identical Constant and ConstOperand types
The first commit renames the const operand visitor functions on regular MIR to match the type name, that was forgotten in the original rename.
The second commit changes stable MIR, fixing https://github.com/rust-lang/project-stable-mir/issues/71. Previously there were two different smir types for the MIR type `ConstOperand`, one used in `Operand` and one in `VarDebugInfoContents`.
Maybe we should have done this with https://github.com/rust-lang/rust/pull/125967, so there's only a single breaking change... but I saw that PR too late.
Fixes https://github.com/rust-lang/project-stable-mir/issues/71
Rollup of 9 pull requests
Successful merges:
- #125829 (rustc_span: Add conveniences for working with span formats)
- #126361 (Unify intrinsics body handling in StableMIR)
- #126417 (Add `f16` and `f128` inline ASM support for `x86` and `x86-64`)
- #126424 ( Also sort `crt-static` in `--print target-features` output)
- #126428 (Polish `std::path::absolute` documentation.)
- #126429 (Add `f16` and `f128` const eval for binary and unary operationations)
- #126448 (End support for Python 3.8 in tidy)
- #126488 (Use `std::path::absolute` in bootstrap)
- #126511 (.mailmap: Associate both my work and my private email with me)
r? `@ghost`
`@rustbot` modify labels: rollup
Add `f16` and `f128` const eval for binary and unary operationations
Add const evaluation and Miri support for f16 and f128, including unary and binary operations. Casts are not yet included.
Fixes https://github.com/rust-lang/rust/issues/124583
r? ``@RalfJung``
Use `Variance` glob imported variants everywhere
Fully commit to using the globbed variance. Could be convinced the other way, and change this PR to not use the globbed variants anywhere, but I'd rather we do one or the other.
r? lcnr
change method resolution to constrain hidden types instead of rejecting method candidates
Some of these are in probes and may affect inference. This is therefore a breaking change.
This allows new code to compile on stable:
```rust
trait Trait {}
impl Trait for u32 {}
struct Bar<T>(T);
impl Bar<u32> {
fn foo(self) {}
}
fn foo(x: bool) -> Bar<impl Sized> {
if x {
let x = foo(false);
x.foo();
//^ this used to not find the `foo` method, because while we did equate `x`'s type with possible candidates, we didn't allow opaque type inference while doing so
}
todo!()
}
```
r? ```````@compiler-errors```````
fixes #121404
cc https://github.com/rust-lang/rust/issues/116652
Remove `DebugWithInfcx` machinery
This PR removes `DebugWithInfcx` after having a lot of second thoughts about it due to recent type system uplifting work. We could add it back later if we want, but I don't think the amount of boilerplate in the complier and the existence of (kindof) hacks like `NoInfcx` currently justify the existence of `DebugWithInfcx`, especially since it's not even being used anywhere in the compiler currently.
The motivation for `DebugWithInfcx` is that we want to be able to print infcx-aware information, such as universe information[^1] (though if there are other usages that I'm overlooking, please let me know). I think there are probably more tailored solutions that can specifically be employed in places where this infcx-aware printing is necessary. For example, one way of achieving this is by implementing a custom `FmtPrinter` which overloads `ty_infer_name` (perhaps also extending it to have overrideable stubs for printing placeholders too) to print the `?u.i` name for an infer var. This will necessitate uplifting `Print` from `rustc_middle::ty::print`, but this seems a bit more extensible and reusable than `DebugWithInfcx`.
One of the problems w/ `DebugWithInfcx` is its opt-in-ness. Even if a compiler dev adds a new `debug!(ty)` in a context where there is an `infcx` we can access, they have to *opt-in* to using `DebugWithInfcx` with something like `debug!(infcx.with(ty))`. This feels to me like it risks a lot of boilerplate, and very easy to just forget adding it at all, especially in cases like `#[instrument]`.
A second problem is the `NoInfcx` type itself. It's necessary to have this dummy infcx implementation since we often want to print types outside of the scope of a valid `Infcx`. Right now, `NoInfcx` is only *partially* a valid implementation of `InferCtxtLike`, except for the methods that we specifically need for `DebugWithInfcx`. As I work on uplifting the trait solver, I actually want to add a lot more methods to `InferCtxtLike` and having to add `unreachable!("this should never be called")` stubs for uplifted methods like `next_ty_var` is quite annoying.
In reality, I actually only *really* care about the second problem -- we could, perhaps, instead just try to get rid of `NoInfcx` and just just duplicate `Debug` and `DebugWithInfcx` for most types. If we're okay with duplicating all these implementations (though most of them would just be trivial `#[derive(Debug, DebugWithInfcx)]`), I'd be okay with that too 🤔
r? `@BoxyUwU` `@lcnr` would like to know your thoughts -- happy to discuss this further, mainly trying to bring this problem up
[^1]: Which in my experience is only really necessary when we're debugging things like generalizer bugs.
interpret: ensure we check bool/char for validity when they are used in a cast
In general, `Scalar::to_bits` is a bit dangerous as it bypasses all type information. We should usually prefer matching on the type and acting according to that. So I also refactored `unary_op` handling of integers to do that. The remaining `to_bits` uses are operations that just fundamentally don't care about the sign (and only work on integers).
invalid_char_cast.rs is the key new test, the others already passed before this PR.
r? `@oli-obk`
Only compute `specializes` query if (min)specialization is enabled in the crate of the specializing impl
Fixes (after backport) https://github.com/rust-lang/rust/issues/125197
### What
https://github.com/rust-lang/rust/pull/122791 makes it so that inductive cycles are no longer hard errors. That means that when we are testing, for example, whether these impls overlap:
```rust
impl PartialEq<Self> for AnyId {
fn eq(&self, _: &Self) -> bool {
todo!()
}
}
impl<T: Identifier> PartialEq<T> for AnyId {
fn eq(&self, _: &T) -> bool {
todo!()
}
}
```
...given...
```rust
pub trait Identifier: Display + 'static {}
impl<T> Identifier for T where T: PartialEq + Display + 'static {}
```
Then we try to see if the second impl holds given `T = AnyId`. That requires `AnyId: Identifier`, which requires that `AnyId: PartialEq`, which is satisfied by these two impl candidates... The `PartialEq<T>` impl is a cycle, and we used to winnow it when we used to treat inductive cycles as errors.
However, now that we don't winnow it, this means that we *now* try calling `candidate_should_be_dropped_in_favor_of`, which tries to check whether one of the impls specializes the other: the `specializes` query. In that query, we currently bail early if the impl is local.
However, in a foreign crate, we try to compute if the two impls specialize each other by doing trait solving. This may itself lead to the same situation where we call `specializes`, which will lead to a query cycle.
### How does this fix the problem
We now record whether specialization is enabled in foreign crates, and extend this early-return behavior to foreign impls too. This means that we can only encounter these cycles if we truly have a specializing impl from a crate with specialization enabled.
-----
r? `@oli-obk` or `@lcnr`
offset_of: allow (unstably) taking the offset of slice tail fields
Fields of type `[T]` have a statically known offset, so there is no reason to forbid them in `offset_of!`. This PR adds the `offset_of_slice` feature to allow them.
I created a tracking issue: https://github.com/rust-lang/rust/issues/126151.
Revert: create const block bodies in typeck via query feeding
as per the discussion in https://github.com/rust-lang/rust/pull/125806#discussion_r1622563948
It was a mistake to try to shoehorn const blocks and some specific anon consts into the same box and feed them during typeck. It turned out not simplifying anything (my hope was that we could feed `type_of` to start avoiding the huge HIR matcher, but that didn't work out), but instead making a few things more fragile.
reverts the const-block-specific parts of https://github.com/rust-lang/rust/pull/124650
`@bors` rollup=never had a small perf impact previously
fixes https://github.com/rust-lang/rust/issues/125846
r? `@compiler-errors`
Remove the `ty` field from type system `Const`s
Fixes#125556Fixes#122908
Part of the work on `adt_const_params`/`generic_const_param_types`/`min_generic_const_exprs`/generally making the compiler nicer. cc rust-lang/project-const-generics#44
Please review commit-by-commit otherwise I wasted a lot of time not just squashing this into a giant mess (and also it'll be SO much nicer because theres a lot of fluff changes mixed in with other more careful changes if looking via File Changes
---
Why do this?
- The `ty` field keeps causing ICEs and weird behaviour due to it either being treated as "part of the const" or it being forgotten about leading to ICEs.
- As we move forward with `adt_const_params` and a potential `min_generic_const_exprs` it's going to become more complex to actually lower the correct `Ty<'tcx>`
- It muddles the idea behind how we check `Const` arguments have the correct type. By having the `ty` field it may seem like we ought to be relating it when we relate two types, or that its generally important information about the `Const`.
- Brings the compiler more in line with `a-mir-formality` as that also tracks the type of type system `Const`s via `ConstArgHasType` bounds in the env instead of on the `Const` itself.
- A lot of stuff is a lot nicer when you dont have to pass around the type of a const lol. Everywhere we construct `Const` is now significantly nicer 😅
See #125671's description for some more information about the `ty` field
---
General summary of changes in this PR:
- Add `Ty` to `ConstKind::Value` as otherwise there is no way to implement `ConstArgHasType` to ensure that const arguments are correctly typed for the parameter when we stop creating anon consts for all const args. It's also just incredibly difficult/annoying to thread the correct `Ty` around to a bunch of ctfe functions otherwise.
- Fully implement `ConstArgHasType` in both the old and new solver. Since it now has no reliance on the `ty` field it serves its originally intended purpose of being able to act as a double check that trait vs impls have correctly typed const parameters. It also will now be able to be responsible for checking types of const arguments to parameters under `min_generic_const_exprs`.
- Add `Ty` to `mir::Const::Ty`. I dont have a great understanding of why mir constants are setup like this to be honest. Regardless they need to be able to determine the type of the const and the easiest way to make this happen was to simply store the `Ty` along side the `ty::Const`. Maybe we can do better here in the future but I'd have to spend way more time looking at everywhere we use `mir::Const`.
- rustdoc has its own `Const` which also has a `ty` field. It was relatively easy to remove this.
---
r? `@lcnr` `@compiler-errors`
Don't walk the bodies of free constants for reachability.
follow-up to #122371
cc #119214
This avoids codegening items (e.g. functions) that are only used during const eval, but do not reach their final constant value (e.g. via function pointers).
r? `@tmiasko`
Add intra-doc-links to rustc_middle crate-level docs.
Makes it slightly faster to find these modules, as you don't need to hunt for them in the big list.
Add `size_of` and `size_of_val` and `align_of` and `align_of_val` to the prelude
(Note: need to update the PR to add `align_of` and `align_of_val`, and remove the second commit with the myriad changes to appease the lint.)
Many, many projects use `size_of` to get the size of a type. However,
it's also often equally easy to hardcode a size (e.g. `8` instead of
`size_of::<u64>()`). Minimizing friction in the use of `size_of` helps
ensure that people use it and make code more self-documenting.
The name `size_of` is unambiguous: the name alone, without any prefix or
path, is self-explanatory and unmistakeable for any other functionality.
Adding it to the prelude cannot produce any name conflicts, as any local
definition will silently shadow the one from the prelude. Thus, we don't
need to wait for a new edition prelude to add it.
Store the types of `ty::Expr` arguments in the `ty::Expr`
Part of #125958
In attempting to remove the `ty` field on `Const` it will become necessary to store the `Ty<'tcx>` inside of `Expr<'tcx>`. In order to do this without blowing up the size of `ConstKind`, we start storing the type/const args as `GenericArgs`
r? `@oli-obk`
Align `Term` methods with `GenericArg` methods, add `Term::expect_*`
* `Term::ty` -> `Term::as_type`.
* `Term::ct` -> `Term::as_const`.
* Adds `Term::expect_type` and `Term::expect_const`, and uses them in favor of `.ty().unwrap()`, etc.
I could also shorten these to `as_ty` and then do `GenericArg::as_ty` as well, but I do think the `as_` is important to signal that this is a conversion method, and not a getter, like `Const::ty` is.
r? types
Use parenthetical notation for `Fn` traits
Always use the `Fn(T) -> R` format when printing closure traits instead of `Fn<(T,), Output = R>`.
Address #67100:
```
error[E0277]: expected a `Fn()` closure, found `F`
--> file.rs:6:13
|
6 | call_fn(f)
| ------- ^ expected an `Fn()` closure, found `F`
| |
| required by a bound introduced by this call
|
= note: wrap the `F` in a closure with no arguments: `|| { /* code */ }`
note: required by a bound in `call_fn`
--> file.rs:1:15
|
1 | fn call_fn<F: Fn() -> ()>(f: &F) {
| ^^^^^^^^^^ required by this bound in `call_fn`
help: consider further restricting this bound
|
5 | fn call_any<F: std::any::Any + Fn()>(f: &F) {
| ++++++
```
Uplift `{Closure,Coroutine,CoroutineClosure}Args` and friends to `rustc_type_ir`
Part of converting the new solver's `structural_traits.rs` to be interner-agnostic.
I decided against aliasing `ClosureArgs<TyCtxt<'tcx>>` to `ClosureArgs<'tcx>` because it seemed so rare. I could do so if desired, though.
r? lcnr
Implement `needs_async_drop` in rustc and optimize async drop glue
This PR expands on #121801 and implements `Ty::needs_async_drop` which works almost exactly the same as `Ty::needs_drop`, which is needed for #123948.
Also made compiler's async drop code to look more like compiler's regular drop code, which enabled me to write an optimization where types which do not use `AsyncDrop` can simply forward async drop glue to `drop_in_place`. This made size of the async block from the [async_drop test](67980dd6fb/tests/ui/async-await/async-drop.rs) to decrease by 12%.
Rename HIR `TypeBinding` to `AssocItemConstraint` and related cleanup
Rename `hir::TypeBinding` and `ast::AssocConstraint` to `AssocItemConstraint` and update all items and locals using the old terminology.
Motivation: The terminology *type binding* is extremely outdated. "Type bindings" not only include constraints on associated *types* but also on associated *constants* (feature `associated_const_equality`) and on RPITITs of associated *functions* (feature `return_type_notation`). Hence the word *item* in the new name. Furthermore, the word *binding* commonly refers to a mapping from a binder/identifier to a "value" for some definition of "value". Its use in "type binding" made sense when equality constraints (e.g., `AssocTy = Ty`) were the only kind of associated item constraint. Nowadays however, we also have *associated type bounds* (e.g., `AssocTy: Bound`) for which the term *binding* doesn't make sense.
---
Old terminology (HIR, rustdoc):
```
`TypeBinding`: (associated) type binding
├── `Constraint`: associated type bound
└── `Equality`: (associated) equality constraint (?)
├── `Ty`: (associated) type binding
└── `Const`: associated const equality (constraint)
```
Old terminology (AST, abbrev.):
```
`AssocConstraint`
├── `Bound`
└── `Equality`
├── `Ty`
└── `Const`
```
New terminology (AST, HIR, rustdoc):
```
`AssocItemConstraint`: associated item constraint
├── `Bound`: associated type bound
└── `Equality`: associated item equality constraint OR associated item binding (for short)
├── `Ty`: associated type equality constraint OR associated type binding (for short)
└── `Const`: associated const equality constraint OR associated const binding (for short)
```
r? compiler-errors
coverage: Rename MC/DC `conditions_num` to `num_conditions`
Updated version of #124571, without the other changes that were split out into #125108 and #125700.
This value represents a quantity of conditions, not an ID, so the new spelling is more appropriate.
Some of the code touched by this PR could perhaps use some other changes, but I would prefer to keep this PR as a simple renaming and avoid scope creep.
`@rustbot` label +A-code-coverage
Always use the `Fn(T) -> R` format when printing closure traits instead of `Fn<(T,), Output = R>`.
Fix#67100:
```
error[E0277]: expected a `Fn()` closure, found `F`
--> file.rs:6:13
|
6 | call_fn(f)
| ------- ^ expected an `Fn()` closure, found `F`
| |
| required by a bound introduced by this call
|
= note: wrap the `F` in a closure with no arguments: `|| { /* code */ }`
note: required by a bound in `call_fn`
--> file.rs:1:15
|
1 | fn call_fn<F: Fn() -> ()>(f: &F) {
| ^^^^^^^^^^ required by this bound in `call_fn`
help: consider further restricting this bound
|
5 | fn call_any<F: std::any::Any + Fn()>(f: &F) {
| ++++++
```
Omit non-needs_drop drop_in_place in vtables
This replaces the drop_in_place reference with null in vtables. On librustc_driver.so, this drops about ~17k (11%) dynamic relocations from the output, since many vtables can now be placed in read-only memory, rather than having a relocated pointer included.
This makes a tradeoff by adding a null check at vtable call sites. I'm not sure that's readily avoidable without changing the vtable format (e.g., so that we can use a pc-relative relocation instead of an absolute address, and avoid the dynamic relocation that way). But it seems likely that the check is cheap at runtime.
Accepted MCP: https://github.com/rust-lang/compiler-team/issues/730
This replaces the drop_in_place reference with null in vtables. On
librustc_driver.so, this drops about ~17k dynamic relocations from the
output, since many vtables can now be placed in read-only memory, rather
than having a relocated pointer included.
This makes a tradeoff by adding a null check at vtable call sites.
That's hard to avoid without changing the vtable format (e.g., to use a
pc-relative relocation instead of an absolute address, and avoid the
dynamic relocation that way). But it seems likely that the check is
cheap at runtime.
