Use a separate interner type for UniqueTypeId
Using symbol::Interner makes it very easy to mixup UniqueTypeId symbols
with the global interner. In fact the Debug implementation of
UniqueTypeId did exactly this.
Using a separate interner type also avoids prefilling the interner with
unused symbols and allow for optimizing the symbol interner for parallel
access without negatively affecting the single threaded module codegen.
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`
This is a straightforward wrapper that uses the existing helpers for C
string handling and errno handling.
Having this available is convenient for UNIX utility programs written in
Rust, and avoids having to call unsafe functions like `libc::chown`
directly and handle errors manually, in a program that may otherwise be
entirely safe code.
In addition, these functions provide a more Rustic interface by
accepting appropriate traits and using `None` rather than `-1`.
Fixes#88910
When we initially store a `NormalizedTy` in the projection cache,
we discard all obligations that we can (while ensuring that we
don't cause any issues with incremental compilation).
Marking a projection cache entry as 'completed' discards all
obligations associated with it. This can only cause problems,
since any obligations stored in the cache are there for a reason
(e.g. they evaluate to `EvaluatedToOkModuloRegions`).
This commit removes `complete` and `complete_normalized` entirely.
Add linting on non_exhaustive structs and enum variants
Add ui tests for non_exhaustive reachable lint
Rename to non_exhaustive_omitted_patterns and avoid triggering on if let
This encoding allows for random access without an expensive upfront decoding
state which in turn allows simplifying the DefPathIndex lookup logic without
regressing performance.
Enum should prefer discriminant zero for niche
Given an enum with unassigned zero-discriminant, rust should prefer it for niche selection.
Zero as discriminant for `Option<Enum>` makes it possible for LLVM to optimize resulting asm.
- Eliminate branch when expected value coincides.
- Use smaller instruction `test eax, eax` instead of `cmp eax, ?`
- Possible interaction with zeroed memory?
Example:
```rust
pub enum Size {
One = 1,
Two = 2,
Three = 3,
}
pub fn handle(x: Option<Size>) -> u8 {
match x {
None => {0}
Some(size) => {size as u8}
}
}
```
In this case discriminant zero is available as a niche.
Above example on nightly:
```asm
mov eax, edi
cmp al, 4
jne .LBB0_2
xor eax, eax
.LBB0_2:
ret
```
PR:
```asm
mov eax, edi
ret
```
I created this PR because I had a performance regression when I tried to use an enum to represent legal grapheme byte-length for utf8.
Using an enum instead of `NonZeroU8` [here](d683304f5d/src/internal/decoder_incomplete.rs (L90))
resulted in a performance regression of about 5%.
I consider this to be a somewhat realistic benchmark.
Thanks to `@ogoffart` for pointing me in the right direction!
Edit: Updated description
Improve error message for missing trait in trait impl
Fixes#88818. For the following example:
```rust
struct S { }
impl for S { }
```
the current output is:
```
error: missing trait in a trait impl
--> t1.rs:2:5
|
2 | impl for S { }
| ^
```
With my changes, I get:
```
error: missing trait in a trait impl
--> t1.rs:2:5
|
2 | impl for S { }
| ^
|
help: add a trait here
|
2 | impl Trait for S { }
| +++++
help: for an inherent impl, drop this `for`
|
2 - impl for S { }
2 + impl S { }
|
```
Fix duplicate bounds for const_trait_impl
Fixes#88383.
Compare the constness of the candidates before winnowing and removing a `~const` `BoundCandidate`.
Add links for primitives in "jump to definition" feature
Follow-up of #84176.
I created a function `primitive_from_str` which is code that was originally in `collect_intra_doc_links::resolve_primitive` to prevent code duplication.
I also created the `primitive_link_url` function which is somewhat similar to `primitive_link` but too much different to merge both of them.
r? ``@jyn514``
Use smaller spans for some structured suggestions
Use more accurate suggestion spans for
* argument parse error
* fully qualified path
* missing code block type
* numeric casts
