Rustup#16153
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…elmann" This reverts commit 5dc3c19417d0fbfd979c5a1ecd8bebe2d8d9110e, reversing changes made to 11339a0ef5ed586bb7ea4f85a9b7287880caac3a.
This is a preparation for introducing a unnormalized source length field
Clippy subtree update r? `@Manishearth`
Inherent const impl Some constifications are annoying because we need to repeat `T: Trait` bounds from an impl block on the individual constified `const fn`s as `T: [const] Trait`. We've brainstormed solutions before, and one would be to have separate `const impl` blocks or sth. However the final syntax will look, I decided to just impl this syntax and either have sth nice on nightly to work with or at least move the discussion along. Also interacts with the discussion around `impl const Trait for Type` vs `const impl Trait for Type`, as we may want to use the latter to keep inherent and trait impls in sync (unless we come up with even another scheme). * [ ] rustdoc + tests * [ ] macro stability /regression tests r? `@fee1-dead` cc `@traviscross` `@rust-lang/project-const-traits`
…thanBrouwer
Warn against calls which mutate an interior mutable `const`-item
## `const_item_interior_mutations`
~~`interior_mutable_const_item_mutations`~~
~~`suspicious_mutation_of_interior_mutable_consts`~~
*warn-by-default*
The `const_item_interior_mutations` lint checks for calls which mutates an interior mutable const-item.
### Example
```rust
use std::sync::Once;
const INIT: Once = Once::new(); // using `INIT` will always create a temporary and
// never modify it-self on use, should be a `static`
// instead for shared use
fn init() {
INIT.call_once(|| {
println!("Once::call_once first call");
});
}
```
```text
warning: mutation of an interior mutable `const` item with call to `call_once`
--> a.rs:11:5
|
11 | INIT.call_once(|| {
| ^---
| |
| _____`INIT` is a interior mutable `const` item of type `std::sync::Once`
| |
12 | | println!("Once::call_once first call");
13 | | });
| |______^
|
= note: each usage of a `const` item creates a new temporary
= note: only the temporaries and never the original `const INIT` will be modified
= help: for more details on interior mutability see <https://doc.rust-lang.org/reference/interior-mutability.html>
= note: `#[warn(const_item_interior_mutations)]` on by default
help: for a shared instance of `INIT`, consider making it a `static` item instead
|
6 - const INIT: Once = Once::new(); // using `INIT` will always create a temporary and
6 + static INIT: Once = Once::new(); // using `INIT` will always create a temporary and
|
```
### Explanation
Calling a method which mutates an interior mutable type has no effect as const-item are essentially inlined wherever they are used, meaning that they are copied directly into the relevant context when used rendering modification through interior mutability ineffective across usage of that const-item.
The current implementation of this lint only warns on significant `std` and `core` interior mutable types, like `Once`, `AtomicI32`, ... this is done out of prudence and may be extended in the future.
----
This PR is an targeted alternative to rust-lang/rust#132146. It avoids false-positives by adding an internal-only attribute `#[rustc_should_not_be_called_on_const_items]` on methods and functions that mutates an interior mutale type through a shared reference (mutable refrences are already linted by the `const_item_mutation` lint).
It should also be noted that this is NOT an uplift of the more general [`clippy::borrow_interior_mutable_const`](https://rust-lang.github.io/rust-clippy/master/index.html#/borrow_interior_mutable_const) lint, which is a much more general lint regarding borrow of interior mutable types, but has false-positives that are completly avoided by this lint.
A simple [GitHub Search](https://github.com/search?q=lang%3Arust+%2F%28%3F-i%29const+%5Ba-zA-Z0-9_%5D*%3A+Once%2F&type=code) reveals many instance where the user probably wanted to use a `static`-item instead.
----
````@rustbot```` labels +I-lang-nominated +T-lang
cc ````@traviscross````
r? compiler
Fixes [IRLO - Forbidding creation of constant mutexes, etc](https://internals.rust-lang.org/t/forbidding-creation-of-constant-mutexes-etc/19005)
Fixes rust-lang/rust#132028
Fixes rust-lang/rust#40543
Using the new `override_allocator_on_supported_platforms` feature in `tikv-jemalloc-sys v0.6.1` we can avoid the manual statics.
remove support for `typeof` see rust-lang/compiler-team#940 closes rust-lang/rust#148700 This also enables checks for invariants previously broken by `typeof` again. r? types
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Lintcheck changes for aa988c8
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r? @ghost
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