This gets rid of the 'experimental' level, removes the non-staged_api
case (i.e. stability levels for out-of-tree crates), and lets the
staged_api attributes use 'unstable' and 'deprecated' lints.
This makes the transition period to the full feature staging design
a bit nicer.
This removes the needlessly constricting bound on `intrinsics::type_Id` and `TypeId::of`. Also fixes an ICE where using bounds on type parameters in extern blocks fails to resolve the used traits.
This bound is probably unintentional and is unnecessarily
constricting.
To facilitate this change, it was also necessary to modify
resolve to recurse on and resolve type parameters in extern { }
blocks. This fixes an ICE when using bounds on type parameters
during the declaration of intrinsics.
This also adds tests for TypeId on both Sized and Unsized
tests as well as a test for using type parameters and bounds
in extern { } blocks.
This partially implements the feature staging described in the
[release channel RFC][rc]. It does not yet fully conform to the RFC as
written, but does accomplish its goals sufficiently for the 1.0 alpha
release.
It has three primary user-visible effects:
* On the nightly channel, use of unstable APIs generates a warning.
* On the beta channel, use of unstable APIs generates a warning.
* On the beta channel, use of feature gates generates a warning.
Code that does not trigger these warnings is considered 'stable',
modulo pre-1.0 bugs.
Disabling the warnings for unstable APIs continues to be done in the
existing (i.e. old) style, via `#[allow(...)]`, not that specified in
the RFC. I deem this marginally acceptable since any code that must do
this is not using the stable dialect of Rust.
Use of feature gates is itself gated with the new 'unstable_features'
lint, on nightly set to 'allow', and on beta 'warn'.
The attribute scheme used here corresponds to an older version of the
RFC, with the `#[staged_api]` crate attribute toggling the staging
behavior of the stability attributes, but the user impact is only
in-tree so I'm not concerned about having to make design changes later
(and I may ultimately prefer the scheme here after all, with the
`#[staged_api]` crate attribute).
Since the Rust codebase itself makes use of unstable features the
compiler and build system to a midly elaborate dance to allow it to
bootstrap while disobeying these lints (which would otherwise be
errors because Rust builds with `-D warnings`).
This patch includes one significant hack that causes a
regression. Because the `format_args!` macro emits calls to unstable
APIs it would trigger the lint. I added a hack to the lint to make it
not trigger, but this in turn causes arguments to `println!` not to be
checked for feature gates. I don't presently understand macro
expansion well enough to fix. This is bug #20661.
Closes#16678
[rc]: https://github.com/rust-lang/rfcs/blob/master/text/0507-release-channels.md
This commit performs a pass over the implementations of the new `String` trait
in the formatting module. Some implementations were removed as a conservative
move pending an upcoming convention about `String` implementations, and some
were added in order to retain consistency across the libraries. Specifically:
* All "smart pointers" implement `String` now, adding missing implementations
for `Arc` and `Rc`.
* The `Vec<T>` and `[T]` types no longer implement `String`.
* The `*const T` and `*mut T` type no longer implement `String`.
* The `()` type no longer implements `String`.
* The `Path` type's `Show` implementation does not surround itself with `Path
{}` (a minor tweak).
All implementations of `String` in this PR were also marked `#[stable]` to
indicate that the types will continue to implement the `String` trait regardless
of what it looks like.
Opt-in built-in traits allowed one to explicitly implement both `Drop`
and `Copy` for a type. This can theoretically make some sense, but the
current implementation means it is codegened totally incorrectly which
can lead to memory unsafety, so this feature is disabled for now.
Fixes#20126.
