Cleanup of attribute parsing errors
Removes the specific `UnknownMetaItem` and `IllFormedAttributeInputLint` errors.
Note that `IllFormedAttributeInputLint` is not a lint, contrary to its name
r? ``````@jdonszelmann``````
Externally implementable items
Supersedes https://github.com/rust-lang/rust/pull/140010
Tracking issue: https://github.com/rust-lang/rust/issues/125418
Getting started:
```rust
#![feature(eii)]
#[eii(eii1)]
pub fn decl1(x: u64)
// body optional (it's the default)
{
println!("default {x}");
}
// in another crate, maybe
#[eii1]
pub fn decl2(x: u64) {
println!("explicit {x}");
}
fn main() {
decl1(4);
}
```
- tiny perf regression, underlying issue makes multiple things in the compiler slow, not just EII, planning to solve those separately.
- No codegen_gcc support, they don't have bindings for weak symbols yet but could
- No windows support yet for weak definitions
This PR merges the implementation of EII for just llvm + not windows, doesn't yet contain like a new panic handler implementation or alloc handler. With this implementation, it would support implementing the panic handler in terms of EII already since it requires no default implementation so no weak symbols
The PR has been open in various forms for about a year now, but I feel that having some implementation merged to build upon
remove duplicated columns from `rustc_error_code::error_codes!`
Possible because of rust-lang/rust#146308 ~~, but currently still blocked on the next stage0 bump~~.
E0793: Clarify that it applies to unions as well
pick up inactive PR: https://github.com/rust-lang/rust/pull/131472
Also:
Adjust the language slightly to be more consistent with other similar messages (was created instead of got created).
Add a short section on union.
Add an example line showing referencing a field in a packed struct is safe if the field's type isn't more strictly aligned than the pack.
r? compiler-errors
Having multiple relaxed bounds like `?Sized + ?Iterator` is actually *fine*.
We actually want to reject *duplicate* relaxed bounds like `?Sized + ?Sized`
because these most certainly represent a user error.
Note that this doesn't mean that we accept more code because a bound like
`?Iterator` is still invalid as it's not relaxing a *default* trait and
the only way to define / use more default bounds is under the experimental
and internal feature `more_maybe_bounds` plus `lang_items` plus unstable
flag `-Zexperimental-default-bounds` (historical context: for the longest
time, bounds like `?Iterator` were actually allowed and lead to a hard
warning).
Ultimately, this simply *reframes* the diagnostic. The scope of
`more_maybe_bounds` / `-Zexperimental-default-bounds` remains unchanged
as well.
The existing code produces `Some(kw::Empty)` for these invalid forms:
- a non-name-value, e.g. `#[rustc_allowed_through_unstable_modules]`
- a non-string arg, e.g. `#[rustc_allowed_through_unstable_modules = 3]`
The new code avoids the `kw::Empty` and is a little shorter. It will
produce `None` in those cases, which means E0789 won't be produced if
the `stable` attribute is missing for these invalid forms. This doesn't
matter, because these invalid forms will trigger an "malformed
`rustc_allowed_through_unstable_modules` attribute" anyway.
This clarifies the explanation of why this is not allowed and also what to do instead.
Fixes 62071
PS There was suggestion of adding a link to the book. I did not yet do that, but if desired that could be added.
