No longer lint against `#[must_use] async fn foo()`.
When encountering a statement that awaits on a `Future`, check if the
`Future`'s parent item is annotated with `#[must_use]` and emit a lint
if so. This effectively makes `must_use` an annotation on the
`Future::Output` instead of only the `Future` itself.
Fix#78149.
spastorino noticed some silly expressions like `item_id.def_id.def_id`.
This commit renames several `def_id: OwnerId` fields as `owner_id`, so
those expressions become `item_id.owner_id.def_id`.
`item_id.owner_id.local_def_id` would be even clearer, but the use of
`def_id` for values of type `LocalDefId` is *very* widespread, so I left
that alone.
Add missing checks for `doc(cfg_hide(...))`
Part of #43781.
The `doc(cfg_hide(...))` attribute can only be used at the crate level and takes a list of attributes as argument.
r? ```@Manishearth```
Migrate rustc_passes diagnostics
Picks up abandoned work from https://github.com/rust-lang/rust/pull/100870
I would like to do this collaboratively, as there is a lot of work! Here's the process:
- Comment below that you are willing to help and I will add you as a collaborator to my `rust` fork (that gives you write access)
- Indicate which file/task you would like to work on (so we don't duplicate work) from the list below
- Do the work, push up a commit, comment that you're done with that file/task
- Repeat until done 😄
### Files to Migrate (in `compiler/rustc_passes/src/`)
- [x] check_attr.rs ``@CleanCut``
- [x] check_const.rs ``@CleanCut``
- [x] dead.rs ``@CleanCut``
- [x] debugger_visualizer.rs ``@CleanCut``
- [x] diagnostic_items.rs ``@CleanCut``
- [x] entry.rs ``@CleanCut``
- [x] lang_items.rs ``@CleanCut``
- [x] layout_test.rs ``@CleanCut``
- [x] lib_features.rs ``@CleanCut``
- [x] ~liveness.rs~ ``@CleanCut`` Nothing to do
- [x] loops.rs ``@CleanCut``
- [x] naked_functions.rs ``@CleanCut``
- [x] stability.rs ``@CleanCut``
- [x] weak_lang_items.rs ``@CleanCut``
### Tasks
- [x] Rebase on current `master` ``@CleanCut``
- [x] Review work from [the earlier PR](https://github.com/rust-lang/rust/pull/100870) and make sure it all looks good
- [x] compiler/rustc_error_messages/locales/en-US/passes.ftl ``@CleanCut``
- [x] compiler/rustc_passes/src/check_attr.rs ``@CleanCut``
- [x] compiler/rustc_passes/src/errors.rs ``@CleanCut``
- [x] compiler/rustc_passes/src/lang_items.rs ``@CleanCut``
- [x] compiler/rustc_passes/src/lib.rs ``@CleanCut``
- [x] compiler/rustc_passes/src/weak_lang_items.rs ``@CleanCut``
fix a ui test
use `into`
fix clippy ui test
fix a run-make-fulldeps test
implement `IntoQueryParam<DefId>` for `OwnerId`
use `OwnerId` for more queries
change the type of `ParentOwnerIterator::Item` to `(OwnerId, OwnerNode)`
ssa: implement `#[collapse_debuginfo]`
cc #39153rust-lang/compiler-team#386
Debuginfo line information for macro invocations are collapsed by default - line information are replaced by the line of the outermost expansion site. Using `-Zdebug-macros` disables this behaviour.
When the `collapse_debuginfo` feature is enabled, the default behaviour is reversed so that debuginfo is not collapsed by default. In addition, the `#[collapse_debuginfo]` attribute is available and can be applied to macro definitions which will then have their line information collapsed.
r? rust-lang/wg-debugging
Debuginfo line information for macro invocations are collapsed by
default - line information are replaced by the line of the outermost
expansion site. Using `-Zdebug-macros` disables this behaviour.
When the `collapse_debuginfo` feature is enabled, the default behaviour
is reversed so that debuginfo is not collapsed by default. In addition,
the `#[collapse_debuginfo]` attribute is available and can be applied to
macro definitions which will then have their line information collapsed.
Signed-off-by: David Wood <david.wood@huawei.com>
Support `#[unix_sigpipe = "inherit|sig_dfl"]` on `fn main()` to prevent ignoring `SIGPIPE`
When enabled, programs don't have to explicitly handle `ErrorKind::BrokenPipe` any longer. Currently, the program
```rust
fn main() { loop { println!("hello world"); } }
```
will print an error if used with a short-lived pipe, e.g.
% ./main | head -n 1
hello world
thread 'main' panicked at 'failed printing to stdout: Broken pipe (os error 32)', library/std/src/io/stdio.rs:1016:9
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
by enabling `#[unix_sigpipe = "sig_dfl"]` like this
```rust
#![feature(unix_sigpipe)]
#[unix_sigpipe = "sig_dfl"]
fn main() { loop { println!("hello world"); } }
```
there is no error, because `SIGPIPE` will not be ignored and thus the program will be killed appropriately:
% ./main | head -n 1
hello world
The current libstd behaviour of ignoring `SIGPIPE` before `fn main()` can be explicitly requested by using `#[unix_sigpipe = "sig_ign"]`.
With `#[unix_sigpipe = "inherit"]`, no change at all is made to `SIGPIPE`, which typically means the behaviour will be the same as `#[unix_sigpipe = "sig_dfl"]`.
See https://github.com/rust-lang/rust/issues/62569 and referenced issues for discussions regarding the `SIGPIPE` problem itself
See the [this](https://rust-lang.zulipchat.com/#narrow/stream/219381-t-libs/topic/Proposal.3A.20First.20step.20towards.20solving.20the.20SIGPIPE.20problem) Zulip topic for more discussions, including about this PR.
Tracking issue: https://github.com/rust-lang/rust/issues/97889
Remove separate indexing of early-bound regions
~Based on https://github.com/rust-lang/rust/pull/99728.~
This PR copies some modifications from https://github.com/rust-lang/rust/pull/97839 around object lifetime defaults.
These modifications allow to stop counting generic parameters during lifetime resolution, and rely on the indexing given by `rustc_typeck::collect`.
This makes it possible to instruct libstd to never touch the signal
handler for `SIGPIPE`, which makes programs pipeable by default (e.g.
with `./your-program | head -n 1`) without `ErrorKind::BrokenPipe`
errors.
This helps simplify the code. It also fixes it to use the correct parent
when lowering. One consequence is the `non_snake_case` lint needed
to change the way it looked for parent nodes in a struct pattern.
This also includes a small fix to use the correct `Target` for
expression field attribute validation.
Attributes on struct expression fields were not being checked for
validity. This adds the fields as HIR nodes so that `CheckAttrVisitor`
can visit those nodes to check their attributes.
Attributes on pattern struct fields were not being checked for validity.
This adds the fields as HIR nodes so that the `CheckAttrVisitor` can
visit those nodes to check their attributes.
Check link ordinal to make sure it is targetted for foreign function
Fix#100009, when link ordinal is not target for foreign functions, emit an error.
cc `@dpaoliello`
Add test for raw-dylib with an external variable
All existing tests of link kind `raw-dylib` only validate the ability to link against functions, but it is also possible to link against variables.
This adds tests for linking against a variable using `raw-dylib` both by-name and by-ordinal.
Warn about dead tuple struct fields
Continuation of #92972. Fixes#92790.
The language team has already commented on this in https://github.com/rust-lang/rust/pull/92972#issuecomment-1021511970; I have incorporated their requests here. Specifically, there is now a new allow-by-default `unused_tuple_struct_fields` lint (name bikesheddable), and fields of unit type are ignored (https://github.com/rust-lang/rust/pull/92972#issuecomment-1021815408), so error messages look like this:
```
error: field is never read: `1`
--> $DIR/tuple-struct-field.rs:6:21
|
LL | struct Wrapper(i32, [u8; LEN], String);
| ^^^^^^^^^
|
help: change the field to unit type to suppress this warning while preserving the field numbering
|
LL | struct Wrapper(i32, (), String);
| ~~
```
r? `@joshtriplett`
Some command-line options accessible through `sess.opts` are best
accessed through wrapper functions on `Session`, `TyCtxt` or otherwise,
rather than through field access on the option struct in the `Session`.
Adds a new lint which triggers on those options that should be accessed
through a wrapper function so that this is prohibited. Options are
annotated with a new attribute `rustc_lint_opt_deny_field_access` which
can specify the error message (i.e. "use this other function instead")
to be emitted.
A simpler alternative would be to simply rename the options in the
option type so that it is clear they should not be used, however this
doesn't prevent uses, just discourages them. Another alternative would
be to make the option fields private, and adding accessor functions on
the option types, however the wrapper functions sometimes rely on
additional state from `Session` or `TyCtxt` which wouldn't be available
in an function on the option type, so the accessor would simply make the
field available and its use would be discouraged too.
Signed-off-by: David Wood <david.wood@huawei.com>
Accept `DiagnosticMessage` in `LintDiagnosticBuilder::build` so that
lints can be built with translatable diagnostic messages.
Signed-off-by: David Wood <david.wood@huawei.com>
Remove `rustc_deprecated` diagnostics
Follow-up on #95960. The diagnostics will remain until the next bootstrap, at which point people will have had six weeks to adjust.
``@rustbot`` label +A-diagnostics
r? ``@compiler-errors``
Make `ExprKind::Closure` a struct variant.
Simple refactor since we both need it to introduce additional fields in `ExprKind::Closure`.
r? ``@Aaron1011``
lint: add diagnostic translation migration lints
Introduce allow-by-default lints for checking whether diagnostics are written in
`SessionDiagnostic` or `AddSubdiagnostic` impls and whether diagnostics are translatable. These lints can be denied for modules once they are fully migrated to impls and translation.
These lints are intended to be temporary - once all diagnostics have been changed then we can just change the APIs we have and that will enforce these constraints thereafter.
r? `````@oli-obk`````
Introduce allow-by-default lints for checking whether diagnostics are
written in `SessionDiagnostic`/`AddSubdiagnostic` impls and whether
diagnostics are translatable. These lints can be denied for modules once
they are fully migrated to impls and translation.
Signed-off-by: David Wood <david.wood@huawei.com>
This commit adds a new unstable attribute, `#[doc(tuple_varadic)]`, that
shows a 1-tuple as `(T, ...)` instead of just `(T,)`, and links to a section
in the tuple primitive docs that talks about these.
Add E0788 for improper #[no_coverage] usage
Essentially, this adds proper checking for the attribute (tracking issue #84605) and throws errors when it's put in obviously-wrong places, like on struct or const definitions. Most of the code is taken directly from the checks for the `#[inline]` attribute, since it's very similar.
Right now, the code only checks at the function level, but it seems reasonable to allow adding `#[no_coverage]` to individual blocks or expressions, so, for now those just throw `unused_attributes` warnings. Similarly, since there was a lot of desire to eventually allow recursive definitions as well on modules and impl blocks, these also throw `unused_attributes` instead of an error.
I'm not sure if anything has to be done since this error is technically for an unstable feature, but since an error for using unstable features will show up anyway, I think it's okay.
This is the first big piece needed for stabilising this attribute, although I personally would like to explore renaming it to `#[coverage(never)]` on a separate PR, which I will offer soon. There's a lot of discussion still to be had about that, which is why it will be kept separate.
I don't think much is needed besides adding this simple check and a UI test, but let me know if there's something else that should be added to make this happen.
Replace `#[default_method_body_is_const]` with `#[const_trait]`
pulled out of #96077
related issues: #67792 and #92158
cc `@fee1-dead`
This is groundwork to only allowing `impl const Trait` for traits that are marked with `#[const_trait]`. This is necessary to prevent adding a new default method from becoming a breaking change (as it could be a non-const fn).
Ensure all error checking for `#[debugger_visualizer]` is done up front and not when the `debugger_visualizer` query is run.
Clean up potential ODR violations when embedding pretty printers into the `__rustc_debug_gdb_scripts_section__` section.
Respond to PR comments and update documentation.
Cleanup `DebuggerVisualizerFile` type and other minor cleanup of queries.
Merge the queries for debugger visualizers into a single query.
Revert move of `resolve_path` to `rustc_builtin_macros`. Update dependencies in Cargo.toml for `rustc_passes`.
Respond to PR comments. Load visualizer files into opaque bytes `Vec<u8>`. Debugger visualizers for dynamically linked crates should not be embedded in the current crate.
Update the unstable book with the new feature. Add the tracking issue for the debugger_visualizer feature.
Respond to PR comments and minor cleanups.
check_doc_alias_value: get argument as Symbol to prevent needless string convertions
check_doc_attrs: don't alloc vec, iterate over slice. Vec introduced in #83149, but no perf run posted on merge
replace as_str() check with symbol check
get_single_str_from_tts: don't prealloc string
trivial string to str replace
LifetimeScopeForPath::NonElided use Vec<Symbol> instead of Vec<String>
AssertModuleSource use BTreeSet<Symbol> instead of BTreeSet<String>
CrateInfo.crate_name replace FxHashMap<CrateNum, String> with FxHashMap<CrateNum, Symbol>
`MultiSpan` contains labels, which are more complicated with the
introduction of diagnostic translation and will use types from
`rustc_errors` - however, `rustc_errors` depends on `rustc_span` so
`rustc_span` cannot use types like `DiagnosticMessage` without
dependency cycles. Introduce a new `rustc_error_messages` crate that can
contain `DiagnosticMessage` and `MultiSpan`.
Signed-off-by: David Wood <david.wood@huawei.com>
There are a few places were we have to construct it, though, and a few
places that are more invasive to change. To do this, we create a
constructor with a long obvious name.
Lint against more useless `#[must_use]` attributes
This expands the existing `#[must_use]` check in `unused_attributes` to lint against pretty much everything `#[must_use]` doesn't support.
Fixes#93906.
This expands the existing `#[must_use]` check in `unused_attributes`
to lint against pretty much everything `#[must_use]` doesn't support.
Fixes#93906.
rustc_errors: let `DiagnosticBuilder::emit` return a "guarantee of emission".
That is, `DiagnosticBuilder` is now generic over the return type of `.emit()`, so we'll now have:
* `DiagnosticBuilder<ErrorReported>` for error (incl. fatal/bug) diagnostics
* can only be created via a `const L: Level`-generic constructor, that limits allowed variants via a `where` clause, so not even `rustc_errors` can accidentally bypass this limitation
* asserts `diagnostic.is_error()` on emission, just in case the construction restriction was bypassed (e.g. by replacing the whole `Diagnostic` inside `DiagnosticBuilder`)
* `.emit()` returns `ErrorReported`, as a "proof" token that `.emit()` was called
(though note that this isn't a real guarantee until after completing the work on
#69426)
* `DiagnosticBuilder<()>` for everything else (warnings, notes, etc.)
* can also be obtained from other `DiagnosticBuilder`s by calling `.forget_guarantee()`
This PR is a companion to other ongoing work, namely:
* #69426
and it's ongoing implementation:
#93222
the API changes in this PR are needed to get statically-checked "only errors produce `ErrorReported` from `.emit()`", but doesn't itself provide any really strong guarantees without those other `ErrorReported` changes
* #93244
would make the choices of API changes (esp. naming) in this PR fit better overall
In order to be able to let `.emit()` return anything trustable, several changes had to be made:
* `Diagnostic`'s `level` field is now private to `rustc_errors`, to disallow arbitrary "downgrade"s from "some kind of error" to "warning" (or anything else that doesn't cause compilation to fail)
* it's still possible to replace the whole `Diagnostic` inside the `DiagnosticBuilder`, sadly, that's harder to fix, but it's unlikely enough that we can paper over it with asserts on `.emit()`
* `.cancel()` now consumes `DiagnosticBuilder`, preventing `.emit()` calls on a cancelled diagnostic
* it's also now done internally, through `DiagnosticBuilder`-private state, instead of having a `Level::Cancelled` variant that can be read (or worse, written) by the user
* this removes a hazard of calling `.cancel()` on an error then continuing to attach details to it, and even expect to be able to `.emit()` it
* warnings were switched to *only* `can_emit_warnings` on emission (instead of pre-cancelling early)
* `struct_dummy` was removed (as it relied on a pre-`Cancelled` `Diagnostic`)
* since `.emit()` doesn't consume the `DiagnosticBuilder` <sub>(I tried and gave up, it's much more work than this PR)</sub>,
we have to make `.emit()` idempotent wrt the guarantees it returns
* thankfully, `err.emit(); err.emit();` can return `ErrorReported` both times, as the second `.emit()` call has no side-effects *only* because the first one did do the appropriate emission
* `&mut Diagnostic` is now used in a lot of function signatures, which used to take `&mut DiagnosticBuilder` (in the interest of not having to make those functions generic)
* the APIs were already mostly identical, allowing for low-effort porting to this new setup
* only some of the suggestion methods needed some rework, to have the extra `DiagnosticBuilder` functionality on the `Diagnostic` methods themselves (that change is also present in #93259)
* `.emit()`/`.cancel()` aren't available, but IMO calling them from an "error decorator/annotator" function isn't a good practice, and can lead to strange behavior (from the caller's perspective)
* `.downgrade_to_delayed_bug()` was added, letting you convert any `.is_error()` diagnostic into a `delay_span_bug` one (which works because in both cases the guarantees available are the same)
This PR should ideally be reviewed commit-by-commit, since there is a lot of fallout in each.
r? `@estebank` cc `@Manishearth` `@nikomatsakis` `@mark-i-m`
Add some more attribute validation
This adds some more validation for the position of attributes:
* `link` is only valid on an `extern` block
* `windows_subsystem` and `no_builtins` are only valid at the crate level
Replace `NestedVisitorMap` with generic `NestedFilter`
This is an attempt to make the `intravisit::Visitor` API simpler and "more const" with regard to nested visiting.
With this change, `intravisit::Visitor` does not visit nested things by default, unless you specify `type NestedFilter = nested_filter::OnlyBodies` (or `All`). `nested_visit_map` returns `Self::Map` instead of `NestedVisitorMap<Self::Map>`. It panics by default (unreachable if `type NestedFilter` is omitted).
One somewhat trixty thing here is that `nested_filter::{OnlyBodies, All}` live in `rustc_middle` so that they may have `type Map = map::Map` and so that `impl Visitor`s never need to specify `type Map` - it has a default of `Self::NestedFilter::Map`.
expand: Pick `cfg`s and `cfg_attrs` one by one, like other attributes
This is a rebase of https://github.com/rust-lang/rust/pull/83354, but without any language-changing parts ~(except for https://github.com/rust-lang/rust/pull/84110)~, i.e. the attribute expansion order is the same.
This is a pre-requisite for any other changes making cfg attributes closer to regular macro attributes
- Possibly changing their expansion order (https://github.com/rust-lang/rust/issues/83331)
- Keeping macro backtraces for cfg attributes, or otherwise making them visible after expansion without keeping them in place literally (https://github.com/rust-lang/rust/pull/84110).
Two exceptions to the "one by one" behavior are:
- cfgs eagerly expanded by `derive` and `cfg_eval`, they are still expanded in a batch, that's by design.
- cfgs at the crate root, they are currently expanded not during the main expansion pass, but before that, during `#![feature]` collection. I'll try to disentangle that logic later in a separate PR.
r? `@Aaron1011`
Remove `SymbolStr`
This was originally proposed in https://github.com/rust-lang/rust/pull/74554#discussion_r466203544. As well as removing the icky `SymbolStr` type, it allows the removal of a lot of `&` and `*` occurrences.
Best reviewed one commit at a time.
r? `@oli-obk`
tidy run
update invalid crate attributes, improve error
update test outputs
de-capitalise error
update tests
Update invalid crate attributes, add help message
Update - generate span without using BytePos
Add correct dependancies
Update - generate suggestion without BytePos
Tidy run
update tests
Generate Suggestion without BytePos
Add all builtin attributes
add err builtin inner attr at top of crate
fix tests
add err builtin inner attr at top of crate
tidy fix
add err builtin inner attr at top of crate
warn on must_use use on async fn's
As referenced in #78149
This only works on `async` fn's for now, I can also look into if I can get `Box<dyn Future>` and `impl Future` working at this level (hir)
Unify titles in rustdoc book doc attributes chapter
As discussed in https://github.com/rust-lang/rust/pull/90339.
I wasn't able to find out where the link to the titles was used so let's see if the CI fails. :)
r? ``@camelid``
Make cfg imply doc(cfg)
This is a reopening of #79341, rebased and modified a bit (we made a lot of refactoring in rustdoc's types so they needed to be reflected in this PR as well):
* `hidden_cfg` is now in the `Cache` instead of `DocContext` because `cfg` information isn't stored anymore on `clean::Attributes` type but instead computed on-demand, so we need this information in later parts of rustdoc.
* I removed the `bool_to_options` feature (which makes the code a bit simpler to read for `SingleExt` trait implementation.
* I updated the version for the feature.
There is only one thing I couldn't figure out: [this comment](https://github.com/rust-lang/rust/pull/79341#discussion_r561855624)
> I think I'll likely scrap the whole `SingleExt` extension trait as the diagnostics for 0 and >1 items should be different.
How/why should they differ?
EDIT: this part has been solved, the current code was fine, just needed a little simplification.
cc `@Nemo157`
r? `@jyn514`
Original PR description:
This is only active when the `doc_cfg` feature is active.
The implicit cfg can be overridden via `#[doc(cfg(...))]`, so e.g. to hide a `#[cfg]` you can use something like:
```rust
#[cfg(unix)]
#[doc(cfg(all()))]
pub struct Unix;
```
By adding `#![doc(cfg_hide(foobar))]` to the crate attributes the cfg `#[cfg(foobar)]` (and _only_ that _exact_ cfg) will not be implicitly treated as a `doc(cfg)` to render a message in the documentation.
Instead of updating global state to mark attributes as used,
we now explicitly emit a warning when an attribute is used in
an unsupported position. As a side effect, we are to emit more
detailed warning messages (instead of just a generic "unused" message).
`Session.check_name` is removed, since its only purpose was to mark
the attribute as used. All of the callers are modified to use
`Attribute.has_name`
Additionally, `AttributeType::AssumedUsed` is removed - an 'assumed
used' attribute is implemented by simply not performing any checks
in `CheckAttrVisitor` for a particular attribute.
We no longer emit unused attribute warnings for the `#[rustc_dummy]`
attribute - it's an internal attribute used for tests, so it doesn't
mark sense to treat it as 'unused'.
With this commit, a large source of global untracked state is removed.
Match against attribute name when validating attributes
Extract attribute name once and match it against symbols that are being
validated, instead of using `Session::check_name` for each symbol
individually.
Assume that all validated attributes are used, instead of marking them
as such, since the attribute check should be exhaustive.
Extract attribute name once and match it against symbols that are being
validated, instead of using `Session::check_name` for each symbol
individually.
Assume that all validated attributes are used, instead of marking them
as such, since the attribute check should be exhaustive.
Rename `#[doc(spotlight)]` to `#[doc(notable_trait)]`
Fixes#80936.
"spotlight" is not a very specific or self-explaining name.
Additionally, the dialog that it triggers is called "Notable traits".
So, "notable trait" is a better name.
* Rename `#[doc(spotlight)]` to `#[doc(notable_trait)]`
* Rename `#![feature(doc_spotlight)]` to `#![feature(doc_notable_trait)]`
* Update documentation
* Improve documentation
r? `@Manishearth`
rustdoc: allow list syntax for #[doc(alias)] attributes
Fixes https://github.com/rust-lang/rust/issues/81205.
It now allows to have:
```rust
#[doc(alias = "x")]
// and:
#[doc(alias("y", "z"))]
```
cc ``@jplatte``
r? ``@jyn514``
StructField -> FieldDef ("field definition")
Field -> ExprField ("expression field", not "field expression")
FieldPat -> PatField ("pattern field", not "field pattern")
Also rename visiting and other methods working on them.
"spotlight" is not a very specific or self-explaining name.
Additionally, the dialog that it triggers is called "Notable traits".
So, "notable trait" is a better name.
* Rename `#[doc(spotlight)]` to `#[doc(notable_trait)]`
* Rename `#![feature(doc_spotlight)]` to `#![feature(doc_notable_trait)]`
* Update documentation
* Improve documentation
Find more invalid doc attributes
- Lint on `#[doc(123)]`, `#[doc("hello")]`, etc.
- Lint every attribute; e.g., will now report two warnings for `#[doc(foo, bar)]`
- Add hyphen to "crate level"
- Display paths like `#[doc(foo::bar)]` correctly instead of as an empty string
This change makes it easier to follow the control flow.
I also moved the end-of-line comments attached to some symbols to before
the symbol listing. This allows rustfmt to format the code; otherwise no
formatting occurs (see rust-lang/rustfmt#4750).
Cleanup rustdoc warnings
## Clean up error reporting for deprecated passes
Using `error!` here goes all the way back to the original commit, https://github.com/rust-lang/rust/pull/8540. I don't see any reason to use logging; rustdoc should use diagnostics wherever possible. See https://github.com/rust-lang/rust/pull/81932#issuecomment-785291244 for further context.
- Use spans for deprecated attributes
- Use a proper diagnostic for unknown passes, instead of error logging
- Add tests for unknown passes
- Improve some wording in diagnostics
## Report that `doc(plugins)` doesn't work using diagnostics instead of `eprintln!`
This also adds a test for the output.
This was added in https://github.com/rust-lang/rust/pull/52194. I don't see any particular reason not to use diagnostics here, I think it was just missed in https://github.com/rust-lang/rust/pull/50541.
