Some promotion cleanup
Based on top of both https://github.com/rust-lang/rust/pull/75502 and https://github.com/rust-lang/rust/pull/75585, this does some cleanup of the promotion code. The last 2 commits are new.
* Remove the remaining cases where `const fn` is treated different from `fn`. This means no longer promoting ptr-to-int casts, raw ptr operations, and union field accesses in `const fn` -- or anywhere, for that matter. These are all unstable in const-context so this should not break any stable code. Fixes https://github.com/rust-lang/rust/issues/75586.
* ~~Promote references to statics even outside statics (i.e., in functions) for consistency.~~
* Promote `&mut []` everywhere, not just in non-`const` functions, for consistency.
* Explain why we do not promote deref's of statics outside statics. ~~(This is the only remaining direct user of `const_kind`.)~~
This can only land once the other two PRs land; I am mostly putting this up already because I couldn't wait ;) and to get some feedback from `@rust-lang/wg-const-eval` .
shim: monomorphic `FnPtrShim`s during construction
Fixes#69925.
This PR adjusts MIR shim construction so that substitutions are applied to function pointer shims during construction, rather than during codegen (as determined by `substs_for_mir_body`).
r? `@eddyb`
Implement a generic Destination Propagation optimization on MIR
This takes the work that was originally started by `@eddyb` in https://github.com/rust-lang/rust/pull/47954, and then explored by me in https://github.com/rust-lang/rust/pull/71003, and implements it in a general (ie. not limited to acyclic CFGs) and dataflow-driven way (so that no additional infrastructure in rustc is needed).
The pass is configured to run at `mir-opt-level=2` and higher only. To enable it by default, some followup work on it is still needed:
* Performance needs to be evaluated. I did some light optimization work and tested against `tuple-stress`, which caused trouble in my last attempt, but didn't go much in depth here.
* We can also enable the pass only at `opt-level=2` and higher, if it is too slow to run in debug mode, but fine when optimizations run anyways.
* Debuginfo needs to be fixed after locals are merged. I did not look into what is required for this.
* Live ranges of locals (aka `StorageLive` and `StorageDead`) are currently deleted. We either need to decide that this is fine, or if not, merge the variable's live ranges (or remove these statements entirely – https://github.com/rust-lang/rust/issues/68622).
Some benchmarks of the pass were done in https://github.com/rust-lang/rust/pull/72635.
BTreeMap: wrap node's raw parent pointer in NonNull
Now that the other `*const` (root) is gone, seemed like a small step forward.
r? `@Mark-Simulacrum`
Split `core/num/mod.rs` to smaller mods
Note for reviewer:
* I split to multiple commits for easier reviewing, but I could git squash them all to one if requested.
* Recommend pulling this change locally and using advanced git diff viewer or this command:
```
git show --reverse --color-moved=dimmed-zebra master..
```
---
I split `core/num/mod.rs` to these modules:
* `error`: For error structs like `ParseIntError`.
* blanket `shells` dir: For dummy number type modules: std::i32, std::f32, and the likes. Why? See below.
* `int_macros` and `uint_macros`: Real implementation of all integer types via `int_impl` and `uint_impl`
* `nonzero`: For `NonZero*` types and their implementations.
* `wrapping`: For `Wrapping<T>` types.
Rollup of 14 pull requests
Successful merges:
- #73963 (deny(unsafe_op_in_unsafe_fn) in libstd/path.rs)
- #75099 (lint/ty: move fns to avoid abstraction violation)
- #75502 (Use implicit (not explicit) rules for promotability by default in `const fn`)
- #75580 (Add test for checking duplicated branch or-patterns)
- #76310 (Add `[T; N]: TryFrom<Vec<T>>` (insta-stable))
- #76400 (Clean up vec benches bench_in_place style)
- #76434 (do not inline black_box when building for Miri)
- #76492 (Add associated constant `BITS` to all integer types)
- #76525 (Add as_str() to string::Drain.)
- #76636 (assert ScalarMaybeUninit size)
- #76749 (give *even better* suggestion when matching a const range)
- #76757 (don't convert types to the same type with try_into (clippy::useless_conversion))
- #76796 (Give a better error message when x.py uses the wrong stage for CI)
- #76798 (Build fixes for RISC-V 32-bit Linux support)
Failed merges:
r? `@ghost`
give *even better* suggestion when matching a const range
notice that the err already has "constant defined here"
so this is now *exceedingly clear*
extension to #76222
r? @estebank
assert ScalarMaybeUninit size
I noticed most low-level Miri types have such an assert but `ScalarMaybeUninit` does not, so let's add that. Good t see that the `Option`-like optimization kicks in and this is no bigger than `Scalar`. :)
r? @oli-obk
Add as_str() to string::Drain.
Vec's Drain recently [had its `.as_slice()` stabilized](https://github.com/rust-lang/rust/pull/72584), but String's Drain was still missing the analogous `.as_str()`. This adds that.
Also improves the Debug implementation, which now shows the remaining data instead of just `"Drain { .. }"`.
Add associated constant `BITS` to all integer types
Recently I've regularly come across this snippet (in a few different crates, including `core` and `std`):
```rust
std::mem::size_of<usize>() * 8
```
I think it's time for a `usize::BITS`.
do not inline black_box when building for Miri
We cannot do the assembly trick in Miri, but let's at least make sure MIR inlining does not circumvent the black_box.
Also use black_box instead of local optimization barriers in a few const tests.
Add test for checking duplicated branch or-patterns
This adds a regression test for checking `or-patterns` in MIR as shown in #75439.
This doesn't introduce a fix as I'm not sure where it would go(I suspect maybe here: src/librustc_mir_build/build/matches/mod.rs), and I'm not particularly able to fix it.
cc: @lzutao
lint/ty: move fns to avoid abstraction violation
This PR moves `transparent_newtype_field` and `is_zst` to `LateContext` where they are used, rather than being on the `VariantDef` and `TyS` types, hopefully addressing @eddyb's concern [from this comment](https://github.com/rust-lang/rust/pull/74340#discussion_r456534910).
deny(unsafe_op_in_unsafe_fn) in libstd/path.rs
The libstd/path.rs part of #73904 . Wraps the two calls to an unsafe fn Initializer::nop() in an unsafe block.
Wrap recursive predicate evaluation with `ensure_sufficient_stack`
I haven't been able to come up with a minimized test case for #76770,
but this fixes a stack overflow in rustc as well.
