coverage: Various small cleanups
This PR is a collection of small coverage-related changes that I accumulated while working towards other coverage improvements.
Each change should hopefully be fairly straightforward.
Document Poisoning in `LazyCell` and `LazyLock`
Currently, there is no documentation of poisoning behavior in either `LazyCell` or `LazyLock`, even though both of them can be observed as poisoned by users.
`LazyCell` [plagyround example](https://play.rust-lang.org/?version=stable&mode=debug&edition=2024&gist=9cf38b8dc56db100848f54085c2c697d)
`LazyLock` [playground example](https://play.rust-lang.org/?version=stable&mode=debug&edition=2024&gist=f1cd6f9fe16636e347ebb695a0ce30c0)
# Open Questions
- [x] Is it worth making the implementation of `LazyLock` more complicated to ensure that the the panic message is `"LazyLock instance has previously been poisoned"` instead of `"Once instance has previously been poisoned"`? See the `LazyLock` playground link above for more context.
- [x] Does it make sense to move `LazyLock` into the `poison` module? It is certainly a poison-able type, but at the same time it is slightly different from the 4 other types currently in the `poison` module in that it is unrecoverable. I think this is more of a libs-api question.
``@rustbot`` label +T-libs-api
Please let me know if these open questions deserve a separate issue / PR!
Use `as_array` in PartialEq for arrays
Now that `as_array` exists we might as well use it here, since it's a bit more convenient than getting the correct type out of `try_into`.
Add a tidy check to prevent adding UI tests directly under `tests/ui/`
This PR implements https://github.com/rust-lang/compiler-team/issues/902.
Only the last commit (adding the new check) is functional; earlier commits are just small drive-by changes to make the other ui/ui-fulldeps checks more logically contained.
r? ```@Kobzol``` (or compiler)
Implement debugging output of the bootstrap Step graph into a DOT file
There are already a bunch of ways how we can debug bootstrap, so why not add one more =D (ideally I'd like to consolidate these approaches somewhat, ```@Shourya742``` is looking into that, but I think that this specific debugging tool is orthogonal to the rest of them, and is quite useful).
This PR adds the option to render the bootstrap step graph into the DOT format, in order to understand what steps were executed, along with their fields (`Debug` output).
Here you can see an example of the generated DOT files for the `BOOTSTRAP_TRACING=1 ./x build compiler --stage 2 --dry-run` command on x64 Linux. One is with cached deps (what this PR does), the other one without.
[bootstrap-dot.zip](https://github.com/user-attachments/files/21548679/bootstrap-dot.zip)
Visual example:
<img width="1899" height="445" alt="image" src="https://github.com/user-attachments/assets/ae40e6d2-0ea8-48bb-b77e-6b21700b95ee" />
r? ```@jieyouxu```
`Printer` cleanups
The trait `Printer` is implemented by six types, and the sub-trait `PrettyPrinter` is implemented by three of those types. The traits and the impls are complex and a bit of a mess. This PR starts to clean them up.
r? ``@davidtwco``
fix: Error on illegal `[const]`s inside blocks within legal positions
Fixesrust-lang/rust#132067
I initially considered moving `[const]` validations to `rustc_ast_lowering`, but that approach would require adding constness information to `AssocCtxt`, which introduces significant changes - especially within `rustc_expand` - just to support a single use case here:
3fb1b53a9d/compiler/rustc_ast_passes/src/ast_validation.rs (L1596-L1610)
Instead, I believe it's sufficient to simply "reset" `[const]` allowness whenever we enter a new block.
Rehome 21 `tests/ui/issues/` tests to other subdirectories under `tests/ui/`
rust-lang/rust#143902 divided into smaller, easier to review chunks.
Part of rust-lang/rust#133895
Methodology:
1. Refer to the previously written `tests/ui/SUMMARY.md`
2. Find an appropriate category for the test, using the original issue thread and the test contents.
3. Add the issue URL at the bottom (not at the top, as that would mess up stderr line numbers)
4. Rename the tests to make their purpose clearer
Inspired by the methodology that ``@Kivooeo`` was using.
r? ``@jieyouxu``
rustdoc template font links only emit `crossorigin` when needed
The `crossorigin` attribute may cause issues when the href is not actually cross-origin. Specifically, the tag causes the browser to send a preflight OPTIONS request to the server even if it is same-origin. Some temperamental servers may reject all CORS preflight requests even if they're actually same-origin, which causes a CORS error and prevents the fonts from loading, even later on.
This commit fixes that problem by not emitting `crossorigin` if the url appears to be relative to the same origin.
Rollup of 2 pull requests
Successful merges:
- rust-lang/rust#144694 (Distinguish prepending and replacing self ty in predicates)
- rust-lang/rust#144875 (Add some pre-codegen MIR tests for debug mode)
r? `@ghost`
`@rustbot` modify labels: rollup
Add some pre-codegen MIR tests for debug mode
No functional changes; just some tests.
I made these for rust-lang/rust#144483, but that's going in a different direction, so I wanted to propose we just add them to help see the impact of other related changes in the future.
r? mir
Distinguish prepending and replacing self ty in predicates
There are two kinds of functions called `with_self_ty`:
1. Prepends the `Self` type onto an `ExistentialPredicate` which lacks it in its internal representation.
2. Replaces the `Self` type of an existing predicate, either for diagnostics purposes or in the new trait solver when normalizing that self type.
This PR distinguishes these two because I often want to only grep for one of them. Namely, let's call it `with_replaced_self_ty` when all we're doing is replacing the self type.
Rollup of 12 pull requests
Successful merges:
- rust-lang/rust#142205 (Mark `slice::swap_with_slice` unstably const)
- rust-lang/rust#144188 (`available_parallelism`: Add documentation for why we don't look at `ulimit`)
- rust-lang/rust#144322 (Add lint against dangling pointers from local variables)
- rust-lang/rust#144497 (tests: Add test for basic line-by-line stepping in a debugger)
- rust-lang/rust#144559 (Enable extract-insert-dyn.rs test on RISC-V (riscv64))
- rust-lang/rust#144667 (`AlignmentEnum` should just be `repr(usize)` now)
- rust-lang/rust#144706 (Do not give function allocations alignment in consteval and Miri.)
- rust-lang/rust#144746 (resolve: Cleanups and micro-optimizations to extern prelude)
- rust-lang/rust#144785 (Regression test for LLVM error with unsupported expression in static initializer for const pointer in array on macOS.)
- rust-lang/rust#144811 (Stylize `*-lynxos178-*` target maintainer handle to make it easier to copy/paste)
- rust-lang/rust#144848 (For "stage 1" ui-fulldeps, use the stage 1 compiler to query target info)
- rust-lang/rust#144853 (Remove unnecessary `rust_` prefixes)
Failed merges:
- rust-lang/rust#144794 (Port `#[coroutine]` to the new attribute system)
r? `@ghost`
`@rustbot` modify labels: rollup
Remove unnecessary `rust_` prefixes
part of https://github.com/rust-lang/rust/issues/116005
Honestly, not sure if this can affect linking somehow, also I didn't touched things like `__rust_panic_cleanup` and `__rust_start_panic` which very likely will break something, so just small cleanup here
also didn't changed `rust_panic_without_hook` because it was renamed here https://github.com/rust-lang/rust/pull/144852
r? libs
For "stage 1" ui-fulldeps, use the stage 1 compiler to query target info
Testing ui-fulldeps in "stage 1" actually uses the stage 0 compiler, so that test programs can link against stage 1 rustc crates.
Unfortunately, using the stage 0 compiler causes problems when compiletest tries to obtain target information from the compiler, but the output format has changed since the last bootstrap beta bump.
We can work around this by also providing compiletest with a stage 1 compiler, and having it use that compiler to query for target information.
---
This fixes the stage 1 ui-fulldeps failure seen at https://github.com/rust-lang/rust/pull/144443#issuecomment-3146992771.
Stylize `*-lynxos178-*` target maintainer handle to make it easier to copy/paste
Apparently I forgot to submit this branch I had lying around.
Noticed while reviewing Tier 3 target platform support pages. In the same style as rust-lang/rust#139028.
Regression test for LLVM error with unsupported expression in static initializer for const pointer in array on macOS.
Regression test for rust-lang/rust#89225, I have shortened the original example as much as i could, while still generating the error.
here is my output on MacOs:
```
rustup run 1.60 cargo build --release
Compiling rug_int v0.1.0 (/Users/luca/dev/rug_int)
LLVM ERROR: Unsupported expression in static initializer: zext (i64 ptrtoint (<{ [4 x i8] }>* `@anon.fad58de7366495db4650cfefac2fcd61.0` to i64) to i128)
error: could not compile `rug_int`
rustup run 1.61 cargo build --release
Compiling rug_int v0.1.0 (/Users/luca/dev/rug_int)
Finished release [optimized] target(s) in 0.60s
```
resolve: Cleanups and micro-optimizations to extern prelude
This is what can be done without changing the structure of `ExternPreludeEntry`, like in https://github.com/rust-lang/rust/pull/144737.
See individual commits for details.
Do not give function allocations alignment in consteval and Miri.
We do not yet have a (clear and T-lang approved) design for how `#[align(N)]` on functions should affect function pointers' addresses on various platforms, so for now do not give function pointers alignment in consteval and Miri.
----
Old summary:
Not a full solution to <https://github.com/rust-lang/rust/issues/144661>, but fixes the immediate issue by making function allocations all have alignment 1 in consteval, ignoring `#[rustc_align(N)]`, so the compiler doesn't know if any offset other than 0 is non-null.
A more "principlied" solution would probably be to make function pointers to `#[instruction_set(arm::t32)]` functions be at offset 1 of an align-`max(2, align attribute)` allocation instead of at offset 0 of their allocation during consteval, and on wasm to either disallow `#[align(N)]` where N > 1, or to pad the function table such that the function pointer of a `#[align(N)]` function is a multiple of `N` at runtime.
`AlignmentEnum` should just be `repr(usize)` now
These used to use specific sizes because they were compiled on all widths. But now that the types themselves are `#[cfg]`'d, we can save some conversions by having it always be `repr(usize)`.
Enable extract-insert-dyn.rs test on RISC-V (riscv64)
This PR adds support for running the `tests/codegen-llvm/simd/extract-insert-dyn.rs` test on the RISC-V (riscv64) architecture.
Previously, this test would fail on RISC-V targets due to architecture-specific code generation issues. This patch modifies the test to ensure compatibility while preserving its intent.
The change has been tested locally using `./x test` on a riscv64 target, and the test now passes as expected.
### Notes:
- This change is scoped specifically to improve RISC-V compatibility.
- It does not affect behavior or test results on other architectures.
Add lint against dangling pointers from local variables
## `dangling_pointers_from_locals`
*warn-by-default*
The `dangling_pointers_from_locals` lint detects getting a pointer to data of a local that will be dropped at the end of the function.
### Example
```rust
fn f() -> *const u8 {
let x = 0;
&x // returns a dangling ptr to `x`
}
```
```text
warning: a dangling pointer will be produced because the local variable `x` will be dropped
--> $DIR/dangling-pointers-from-locals.rs:10:5
|
LL | fn simple() -> *const u8 {
| --------- return type of the function is `*const u8`
LL | let x = 0;
| - `x` is defined inside the function and will be drop at the end of the function
LL | &x
| ^^
|
= note: pointers do not have a lifetime; after returning, the `u8` will be deallocated at the end of the function because nothing is referencing it as far as the type system is concerned
= note: `#[warn(dangling_pointers_from_locals)]` on by default
```
### Explanation
Returning a pointer from a local value will not prolong its lifetime, which means that the value can be dropped and the allocation freed while the pointer still exists, making the pointer dangling.
If you need stronger guarantees, consider using references instead, as they are statically verified by the borrow-checker to never dangle.
------
This is related to GitHub codeql [CWE-825](https://github.com/github/codeql/blob/main/rust/ql/src/queries/security/CWE-825/AccessAfterLifetimeBad.rs) which shows examples of such simple miss-use.
It should be noted that C compilers warns against such patterns even without `-Wall`, https://godbolt.org/z/P7z98arrc.
------
`@rustbot` labels +I-lang-nominated +T-lang
cc `@traviscross`
r? compiler
