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
coverage: Make `#[coverage(..)]` apply recursively to nested functions
This PR makes the (currently-unstable) `#[coverage(off)]` and `#[coverage(on)]` attributes apply recursively to all nested functions/closures, instead of just the function they are directly attached to.
Those attributes can now also be applied to modules and to impl/impl-trait blocks, where they have no direct effect, but will be inherited by all enclosed functions/closures/methods that don't override the inherited value.
---
Fixes#126625.
miri: make sure we can find link_section statics even for the local crate
Miri needs some way to iterate all the exported functions and "used" statics of all crates. For dependency crates, this already works fine since we can overwrite the query resonsible for computing `exported_symbols`, but it turns out for local binary crates this does not work: for binaries, `reachable_set` skips a lot of its logic and only checks `contains_extern_indicator()` and `RUSTC_STD_INTERNAL_SYMBOL`. Other flags like `CodegenFnAttrFlags::USED` are entirely ignored.
This PR proposes to use the same check, `has_custom_linkage`, in binaries that we already use to drive the main workqueue of the reachability recursive traversal. I have no idea why binaries used a slightly different check that ignores `USED` -- was that deliberate or does it just not matter most of the time?
Rollup of 7 pull requests
Successful merges:
- #126618 (Mark assoc tys live only if the corresponding trait is live)
- #126746 (Deny `use<>` for RPITITs)
- #126868 (not use offset when there is not ends with brace)
- #126884 (Do not ICE when suggesting dereferencing closure arg)
- #126893 (Eliminate the distinction between PREC_POSTFIX and PREC_PAREN precedence level)
- #126915 (Don't suggest awaiting in closure patterns)
- #126943 (De-duplicate all consecutive native libs regardless of their options)
r? `@ghost`
`@rustbot` modify labels: rollup
Detect unused structs which derived Default
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Fixes#98871
coverage: Overhaul validation of the `#[coverage(..)]` attribute
This PR makes sweeping changes to how the (currently-unstable) coverage attribute is validated:
- Multiple coverage attributes on the same item/expression are now treated as an error.
- The attribute must always be `#[coverage(off)]` or `#[coverage(on)]`, and the error messages for this are more consistent.
- A trailing comma is still allowed after off/on, since that's part of the normal attribute syntax.
- Some places that silently ignored a coverage attribute now produce an error instead.
- These cases were all clearly bugs.
- Some places that ignored a coverage attribute (with a warning) now produce an error instead.
- These were originally added as lints, but I don't think it makes much sense to knowingly allow new attributes to be used in meaningless places.
- Some of these errors might soon disappear, if it's easy to extend recursive coverage attributes to things like modules and impl blocks.
---
One of the goals of this PR is to lay a more solid foundation for making the coverage attribute recursive, so that it applies to all nested functions/closures instead of just the one it is directly attached to.
Fixes#126658.
This PR incorporates #126659, which adds more tests for validation of the coverage attribute.
`@rustbot` label +A-code-coverage
Show notice about "never used" of Debug for enum
Close#123068
If an ADT implements `Debug` trait and it is not used, the compiler says a note that indicates intentionally ignored during dead code analysis as [this note](2207179a59/tests/ui/lint/dead-code/unused-variant.stderr (L9)).
However this node is not shown for variants that have fields in enum. This PR fixes to show the note.
Suggest removing unused tuple fields if they are the last fields
Fixes#124556
We now check if dead/unused fields are the last fields of the tuple and suggest their removal instead of suggesting them to be changed to `()`.
