Remove `DropArena`.
Most arena-allocate types that impl `Drop` get their own `TypedArena`, but a
few infrequently used ones share a `DropArena`. This sharing adds complexity
but doesn't help performance or memory usage. Perhaps it was more effective in
the past prior to some other improvements to arenas.
This commit removes `DropArena` and the sharing of arenas via the `few`
attribute of the `arena_types` macro. This change removes over 100 lines of
code and nine uses of `unsafe` (one of which affects the parallel compiler) and
makes the remaining code easier to read.
Most arena-allocate types that impl `Drop` get their own `TypedArena`, but a
few infrequently used ones share a `DropArena`. This sharing adds complexity
but doesn't help performance or memory usage. Perhaps it was more effective in
the past prior to some other improvements to arenas.
This commit removes `DropArena` and the sharing of arenas via the `few`
attribute of the `arena_types` macro. This change removes over 100 lines of
code and nine uses of `unsafe` (one of which affects the parallel compiler) and
makes the remaining code easier to read.
Collect `panic/panic_bounds_check` during monomorphization
This would prevent link time errors if these functions are `#[inline]` (e.g. when `panic_immediate_abort` is used).
Fix#90405Fixrust-lang/cargo#10019
`@rustbot` label: T-compiler A-codegen
Remove hir::map::blocks and use FnKind instead
The principal tool is `FnLikeNode`, which is not often used and can be easily implemented using `rustc_hir::intravisit::FnKind`.
Index and hash HIR as part of lowering
Part of https://github.com/rust-lang/rust/pull/88186
~Based on https://github.com/rust-lang/rust/pull/88880 (see merge commit).~
Once HIR is lowered, it is later indexed by the `index_hir` query and hashed for `crate_hash`. This PR moves those post-processing steps to lowering itself. As a side objective, the HIR crate data structure is refactored as an `IndexVec<LocalDefId, Option<OwnerInfo<'hir>>>` where `OwnerInfo` stores all the relevant information for an HIR owner.
r? `@michaelwoerister`
cc `@petrochenkov`
Add `const_eval_select` intrinsic
Adds an intrinsic that calls a given function when evaluated at compiler time, but generates a call to another function when called at runtime.
See https://github.com/rust-lang/const-eval/issues/7 for previous discussion.
r? `@oli-obk.`
Rework HIR API to make invocations of the hir_crate query harder.
`hir_crate` forces the recomputation of queries that depend on it.
This PR aims at avoiding useless invocations of `hir_crate` by making dependent code go through `tcx.hir()`.
Fix ICE when `start` lang item has wrong generics
In my previous pr #87875 I missed the requirements on the `start` lang item due to its relative difficulty to test and opting for more conservative estimates. This fixes that by updating the requirement to be exactly one generic type.
The `start` lang item should have exactly one generic type for the return type of the `main` fn ptr passed to it. I believe having zero would previously *sometimes* compile (often with the use of `fn() -> ()` as the fn ptr but it was likely UB to call if the return type of `main` was not `()` as far as I know) however it also sometimes would not for various errors including ICEs and LLVM errors depending on exact situations. Having more than 1 generic has always failed with an ICE because only the one generic type is expected and provided.
Fixes#79559, fixes#73584, fixes#83117 (all duplicates)
Relevant to #9307
r? ````@cjgillot````
As shown in the two test requirements that got updated, if there's other problems,
then those other problems are probably the root cause of the incorrect generics count.
Migrate in-tree crates to 2021
This replaces #89075 (cherry picking some of the commits from there), and closes#88637 and fixes#89074.
It excludes a migration of the library crates for now (see tidy diff) because we have some pending bugs around macro spans to fix there.
I instrumented bootstrap during the migration to make sure all crates moved from 2018 to 2021 had the compatibility warnings applied first.
Originally, the intent was to support cargo fix --edition within bootstrap, but this proved fairly difficult to pull off. We'd need to architect the check functionality to support running cargo check and cargo fix within the same x.py invocation, and only resetting sysroots on check. Further, it was found that cargo fix doesn't behave too well with "not quite workspaces", such as Clippy which has several crates. Bootstrap runs with --manifest-path ... for all the tools, and this makes cargo fix only attempt migration for that crate. We can't use e.g. --workspace due to needing to maintain sysroots for different phases of compilation appropriately.
It is recommended to skip the mass migration of Cargo.toml's to 2021 for review purposes; you can also use `git diff d6cd2c6c87 -I'^edition = .20...$'` to ignore the edition = 2018/21 lines in the diff.
Lower only one HIR owner at a time
Based on https://github.com/rust-lang/rust/pull/83723
Additional diff is here: https://github.com/cjgillot/rust/compare/ownernode...lower-mono
Lowering is very tangled and has a tendency to intertwine the transformation of different items. This PR aims at simplifying the logic by:
- moving global analyses to the resolver (item_generics_num_lifetimes, proc_macros, trait_impls);
- removing a few special cases (non-exported macros and use statements);
- restricting the amount of available information at any one time;
- avoiding back-and-forth between different owners: an item must now be lowered all at once, and its parent cannot refer to its nodes.
I also removed the sorting of bodies by span. The diagnostic ordering changes marginally, since definitions are pretty much sorted already according to the AST. This uncovered a subtlety in thir-unsafeck.
(While these items could logically be in different PRs, the dependency between commits and the amount of conflicts force a monolithic PR.)
Gather module items after lowering.
This avoids having a non-local analysis inside lowering.
By implementing `hir_module_items` using a visitor, we make sure that iterations and visitors are consistent.
Simplify lazy DefPathHash decoding by using an on-disk hash table.
This PR simplifies the logic around mapping `DefPathHash` values encountered during incremental compilation to valid `DefId`s in the current session. It is able to do so by using an on-disk hash table encoding that allows for looking up values directly, i.e. without deserializing the entire table.
The main simplification comes from not having to keep track of `DefPathHashes` being used during the compilation session.
Allow `panic!("{}", computed_str)` in const fn.
Special-case `panic!("{}", arg)` and translate it to `panic_display(&arg)`. `panic_display` will behave like `panic_any` in cosnt eval and behave like `panic!(format_args!("{}", arg))` in runtime.
This should bring Rust 2015 and 2021 to feature parity in terms of `const_panic`; and hopefully would unblock the stabilisation of #51999.
`@rustbot` modify labels: +T-compiler +T-libs +A-const-eval +A-const-fn
r? `@oli-obk`
Const drop
The changes are pretty primitive at this point. But at least it works. ^-^
Problems with the current change that I can think of now:
- [x] `~const Drop` shouldn't change anything in the non-const world.
- [x] types that do not have drop glues shouldn't fail to satisfy `~const Drop` in const contexts. `struct S { a: u8, b: u16 }` This might not fail for `needs_non_const_drop`, but it will fail in `rustc_trait_selection`.
- [x] The current change accepts types that have `const Drop` impls but have non-const `Drop` glue.
Fixes#88424.
Significant Changes:
- `~const Drop` is no longer treated as a normal trait bound. In non-const contexts, this bound has no effect, but in const contexts, this restricts the input type and all of its transitive fields to either a) have a `const Drop` impl or b) can be trivially dropped (i.e. no drop glue)
- `T: ~const Drop` will not be linted like `T: Drop`.
- Instead of recursing and iterating through the type in `rustc_mir::transform::check_consts`, we use the trait system to special case `~const Drop`. See [`rustc_trait_selection::...::candidate_assembly#assemble_const_drop_candidates`](https://github.com/fee1-dead/rust/blob/const-drop/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs#L817) and others.
Changes not related to `const Drop`ping and/or changes that are insignificant:
- `Node.constness_for_typeck` no longer returns `hir::Constness::Const` for type aliases in traits. This was previously used to hack how we determine default bound constness for items. But because we now use an explicit opt-in, it is no longer needed.
- Removed `is_const_impl_raw` query. We have `impl_constness`, and the only existing use of that query uses `HirId`, which means we can just operate it with hir.
- `ty::Destructor` now has a field `constness`, which represents the constness of the destructor.
r? `@oli-obk`
