Shrink `TyKind::FnPtr`.
By splitting the `FnSig` within `TyKind::FnPtr` into `FnSigTys` and `FnHeader`, which can be packed more efficiently. This reduces the size of the hot `TyKind` type from 32 bytes to 24 bytes on 64-bit platforms. This reduces peak memory usage by a few percent on some benchmarks. It also reduces cache misses and page faults similarly, though this doesn't translate to clear cycles or wall-time improvements on CI.
r? `@compiler-errors`
Use more slice patterns inside the compiler
Nothing super noteworthy. Just replacing the common 'fragile' pattern of "length check followed by indexing or unwrap" with slice patterns for legibility and 'robustness'.
r? ghost
By splitting the `FnSig` within `TyKind::FnPtr` into `FnSigTys` and
`FnHeader`, which can be packed more efficiently. This reduces the size
of the hot `TyKind` type from 32 bytes to 24 bytes on 64-bit platforms.
This reduces peak memory usage by a few percent on some benchmarks. It
also reduces cache misses and page faults similarly, though this doesn't
translate to clear cycles or wall-time improvements on CI.
Emit an error for invalid use of the `#[no_sanitize]` attribute
fixes#128487.
Currently, the use of the `#[no_sanitize]` attribute for Mod, Impl,... is incorrectly permitted. This PR will correct this issue by generating errors, and I've also added some UI test cases for it.
Referenced #128458. As far as I know, the `#[no_sanitize]` attribute can only be used with functions, so I changed that part to `Fn` and `Method` using `check_applied_to_fn_or_method`. However, I couldn't find explicit documentation on this, so I could be mistaken...
PR #128581 introduced an assertion that all builtin attributes are
actually checked via `CheckAttrVisitor` and aren't accidentally usable
on completely unrelated HIR nodes. Unfortunately, the check had
correctness problems.
The match on attribute path segments looked like
```rust,ignore
[sym::should_panic] => /* check is implemented */
match BUILTIN_ATTRIBUTE_MAP.get(name) {
// checked below
Some(BuiltinAttribute { type_: AttributeType::CrateLevel, .. }) => {}
Some(_) => {
if !name.as_str().starts_with("rustc_") {
span_bug!(
attr.span,
"builtin attribute {name:?} not handled by `CheckAttrVisitor`"
)
}
}
None => (),
}
```
However, it failed to account for edge cases such as an attribute whose:
1. path segments *starts* with a builtin attribute such as
`should_panic`
2. which does not start with `rustc_`, and
3. is also an `AttributeType::Normal` attribute upon registration with
the builtin attribute map
These conditions when all satisfied cause the span bug to be issued for e.g.
`#[should_panic::skip]` because the `[sym::should_panic]` arm is not matched (since it's
`[sym::should_panic, sym::skip]`).
See <https://github.com/rust-lang/rust/issues/128622>.
Assert that all attributes are actually checked via `CheckAttrVisitor` and aren't accidentally usable on completely unrelated HIR nodes
``@oli-obk's`` #128444 with unreachable case removed to avoid that PR bitrotting away.
Based on #128402.
This PR will make adding a new attribute ICE on any use of that attribute unless it gets a handler added in `rustc_passes::CheckAttrVisitor`.
r? ``@nnethercote`` (since you were the reviewer of the original PR)
Attribute checking simplifications
remove an unused boolean and then merge two big matches into one
I was reviewing some attributes and realized we don't really check this list against the list of builtin attributes, so we "may" totally be missing some attributes that we should be checking (like the `coroutine` attribute, which you can just apply to random stuff)
```rust
#![feature(coroutines)]
#[coroutine]
struct Foo;
```
just compiles for example. Unless we check that the fallthrough match arm is never reached for builtin attributes, we're just going to keep forgetting to add them here, too. I can do that without the changes in this PR, but it seemed like a nice cleanup
`#[naked]`: report incompatible attributes
tracking issue: https://github.com/rust-lang/rust/issues/90957
this is a re-implementation of https://github.com/rust-lang/rust/pull/93809 by ``@bstrie`` which was closed 2 years ago due to inactivity.
This PR takes some of the final comments into account, specifically providing a little more context in error messages, and using an allow list to determine which attributes are compatible with `#[naked]`.
Notable attributes that are incompatible with `#[naked]` are:
* `#[inline]`
* `#[track_caller]`
* ~~`#[target_feature]`~~ (this is now allowed, see PR discussion)
* `#[test]`, `#[ignore]`, `#[should_panic]`
These attributes just directly conflict with what `#[naked]` should do.
Naked functions are still important for systems programming, embedded, and operating systems, so I'd like to move them forward.
improve error message when `global_asm!` uses `asm!` options
specifically, what was
error: expected one of `)`, `att_syntax`, or `raw`, found `preserves_flags`
--> $DIR/bad-options.rs:45:25
|
LL | global_asm!("", options(preserves_flags));
| ^^^^^^^^^^^^^^^ expected one of `)`, `att_syntax`, or `raw`
is now
error: the `preserves_flags` option cannot be used with `global_asm!`
--> $DIR/bad-options.rs:45:25
|
LL | global_asm!("", options(preserves_flags));
| ^^^^^^^^^^^^^^^ the `preserves_flags` option is not meaningful for global-scoped inline assembly
mirroring the phrasing of the [reference](https://doc.rust-lang.org/reference/inline-assembly.html#options).
This is also a bit of a refactor for a future `naked_asm!` macro (for use in `#[naked]` functions). Currently this sort of error can come up when switching from inline to global asm, or when a user just isn't that experienced with assembly. With `naked_asm!` added to the mix hitting this error is more likely.
- merge error codes
- use attribute name that is incompatible in error message
- add test for conditional incompatible attribute
- add `linkage` to the allowlist
Extend rules of dead code analysis for impls for adts to impls for types refer to adts
The rules of dead code analysis for impl blocks can be extended to self types which refer to adts.
So that we can lint the following unused struct and trait:
```rust
struct Foo; //~ ERROR struct `Foo` is never constructed
trait Trait { //~ ERROR trait `Trait` is never used
fn foo(&self) {}
}
impl Trait for &Foo {}
```
r? `@pnkfelix`
`#[naked]`: use an allowlist for allowed options on `asm!` in naked functions
tracking issue: https://github.com/rust-lang/rust/issues/90957
this is mostly just a refactor, but using an allowlist (rather than a denylist) for which asm options are allowed in naked functions is a little safer.
These options are disallowed because naked functions are effectively global asm, but defined using inline asm.
Improve dead code analysis
Fixes#120770
1. check impl items later if self ty is private although the trait method is public, cause we must use the ty firstly if it's private
2. mark the adt live if it appears in pattern, like generic argument, this implies the use of the adt
3. based on the above, we can handle the case that private adts impl Default, so that we don't need adding rustc_trivial_field_reads on Default, and the logic in should_ignore_item
r? ``@pnkfelix``
Miri function identity hack: account for possible inlining
Having a non-lifetime generic is not the only reason a function can be duplicated. Another possibility is that the function may be eligible for cross-crate inlining. So also take into account the inlining attribute in this Miri hack for function pointer identity.
That said, `cross_crate_inlinable` will still sometimes return true even for `inline(never)` functions:
- when they are `DefKind::Ctor(..) | DefKind::Closure` -- I assume those cannot be `InlineAttr::Never` anyway?
- when `cross_crate_inline_threshold == InliningThreshold::Always`
so maybe this is still not quite the right criterion to use for function pointer identity.
Re-implement a type-size based limit
r? lcnr
This PR reintroduces the type length limit added in #37789, which was accidentally made practically useless by the caching changes to `Ty::walk` in #72412, which caused the `walk` function to no longer walk over identical elements.
Hitting this length limit is not fatal unless we are in codegen -- so it shouldn't affect passes like the mir inliner which creates potentially very large types (which we observed, for example, when the new trait solver compiles `itertools` in `--release` mode).
This also increases the type length limit from `1048576 == 2 ** 20` to `2 ** 24`, which covers all of the code that can be reached with craterbot-check. Individual crates can increase the length limit further if desired.
Perf regression is mild and I think we should accept it -- reinstating this limit is important for the new trait solver and to make sure we don't accidentally hit more type-size related regressions in the future.
Fixes#125460
Show `used attribute`'s kind for user when find it isn't applied to a `static` variable.
For example :
```rust
extern "C" {
#[used] //~ ERROR attribute must be applied to a `static` variable
static FOO: i32; // show the kind of this item to help user understand why the error is reported.
}
```
fixes#126789
