Add errors for unknown, stable and duplicate feature attributes
- Adds an error for unknown (lang and lib) features.
- Extends the lint for unnecessary feature attributes for stable features to libs features (this already exists for lang features).
- Adds an error for duplicate (lang and lib) features.
```rust
#![feature(fake_feature)] //~ ERROR unknown feature `fake_feature`
#![feature(i128_type)] //~ WARNING the feature `i128_type` has been stable since 1.26.0
#![feature(non_exhaustive)]
#![feature(non_exhaustive)] //~ ERROR duplicate `non_exhaustive` feature attribute
```
Fixes#52053, fixes#53032 and address some of the problems noted in #44232 (though not unused features).
There are a few outstanding problems, that I haven't narrowed down yet:
- [x] Stability attributes on macros do not seem to be taken into account.
- [x] Stability attributes behind `cfg` attributes are not taken into account.
- [x] There are failing incremental tests.
stabilize lint handling in rustdoc
When https://github.com/rust-lang/rust/pull/51732 added CLI flags to manipulate lints in rustdoc, they were added as unstable flags. This made sense as they were new additions, but since they mirrored the flags that rustc has, it's worth considering them to not need an unstable period.
Stabilizing them also provides the opportunity for a critical fix: allowing Cargo to pass `--cap-lints allow` when documenting dependencies, the same as when it compiles them.
r? @rust-lang/rustdoc
This commit changes the exit status of rustc to 1 in the presence of
compilation errors. In the event of an unexpected panic (ICE) the
standard panic error exit status of 101 remains.
A run-make test is added to ensure that the exit code does not regress,
and compiletest is updated to check for an exit status of 1 or 101,
depending on the mode and suite.
This is a breaking change for custom drivers.
Fixes#51971.
The Great Generics Generalisation: HIR Edition
This is essentially a followup to https://github.com/rust-lang/rust/pull/45930, consolidating the use of separate lifetime and type vectors into single kinds vectors wherever possible. This is intended to provide more of the groundwork for const generics (https://github.com/rust-lang/rust/issues/44580).
r? @eddyb
cc @yodaldevoid
Switch to bootstrapping from 1.27
It's possible the Float trait could be removed from core, but I couldn't tell whether it was intended to be removed or not. @SimonSapin may be able to comment more here; we can presumably also do that in a follow up PR as this one is already quite large.
rustdoc: deprecate `#![doc(passes, plugins, no_default_passes)]`
Closes https://github.com/rust-lang/rust/issues/48164
Blocked on https://github.com/rust-lang/rust/pull/50541 - this includes those changes, which were necessary to create the UI test
cc https://github.com/rust-lang/rust/issues/44136
Turns out, there were special attributes to mess with rustdoc passes and plugins! Who knew! Since we deprecated the CLI flags for this functionality, it makes sense that we do the same for the attributes.
This PR also introduces a `#![doc(document_private_items)]` attribute, to match the `--document-private-items` flag introduced in https://github.com/rust-lang/rust/pull/44138 when the passes/plugins flags were deprecated.
I haven't done a search to see whether these attributes are being used at all, but if the flags were any indication, i don't expect to see any users of these.
rustdoc: replace most (e)println! statements with structured warnings/errors
Turns out, the rustc diagnostic handler doesn't need a whole lot of setup that we weren't already doing. For errors that occur outside a "dealing with source code" context, we can just use the format/color config we were already parsing and make up a `Handler` that we can emit structured warnings/errors from. So i did that. This will make it way easier to test things with `rustdoc-ui` tests, since those require the JSON error output. (In fact, this PR is a yak shave for a different one where i was trying to do just that. `>_>`)
Prevent broken pipes causing ICEs
As the private `std::io::print_to` panics if there is an I/O error, which is used by `println!`, the compiler would ICE if one attempted to use a broken pipe (e.g. `rustc --help | false`). This introduces a new (private) macro `try_println!` which allows us to avoid this.
As a side note, it seems this macro might be useful publicly (and actually there seems to be [a crate specifically for this purpose](https://crates.io/crates/try_print/)), though that can probably be left for a future discussion.
One slight alternative approach would be to simply early exit without an error (i.e. exit code `0`), which [this comment](https://github.com/rust-lang/rust/issues/34376#issuecomment-377822526) suggests is the usual approach. I've opted not to take that approach initially, because I think it's more helpful to know when there is a broken pipe.
Fixes#34376.
