This PR is a rebase of the original PR by @eddyb https://github.com/rust-lang/rust/pull/21836 with some unrebasable parts manually reapplied, feature gate added + type equality restriction added as described below.
This implementation is partial because the type equality restriction is applied to all type ascription expressions and not only those in lvalue contexts. Thus, all difficulties with detection of these contexts and translation of coercions having effect in runtime are avoided.
So, you can't write things with coercions like `let slice = &[1, 2, 3]: &[u8];`. It obviously makes type ascription less useful than it should be, but it's still much more useful than not having type ascription at all.
In particular, things like `let v = something.iter().collect(): Vec<_>;` and `let u = t.into(): U;` work as expected and I'm pretty happy with these improvements alone.
Part of https://github.com/rust-lang/rust/issues/23416
Still will not translate references to items like `X` or `Y::V` where
```
struct X;
enum Y { V }
```
but I must go work on university things so I’m PRing what I have.
r? @nikomatsakis
This fixes a bug in which unused imports can get wrongly marked as used when checking for unused qualifications in `resolve_path` (issue #30078), and it removes unused imports that were previously undetected because of the bug.
We can now handle name resolution errors and get past type checking (if we're a bit lucky). This is the first step towards doing code completion for partial programs (we need error recovery in the parser and early access to save-analysis).
This PR reverts #29543 and instead implements proper support for "=*m" and "+*m" indirect output operands. This provides a framework on top of which support for plain memory operands ("m", "=m" and "+m") can be implemented.
This also fixes the liveness analysis pass not handling read/write operands correctly.
r? @nagisa
I'm going to need the `ConstVal` -> `ValueRef` translation to start removing trans/consts piece by piece. If you need anything implemented in the translation, feel free to assign an issue to me.
Fixes#26403
This adjusts the pointer, if needed, to the correct alignment by using the alignment information in the vtable.
Handling zero might not be necessary, as it shouldn't actually occur. I've left it as it's own commit so it can be removed fairly easily if people don't think it's worth doing. The way it's handled though means that there shouldn't be much impact on performance.
Instead of `ast::Ident`, bindings, paths and labels in HIR now keep a new structure called `hir::Ident` containing mtwt-renamed `name` and the original not-renamed `unhygienic_name`. `name` is supposed to be used by default, `unhygienic_name` is rarely used.
This is not ideal, but better than the status quo for two reasons:
- MTWT tables can be cleared immediately after lowering to HIR
- This is less bug-prone, because it is impossible now to forget applying `mtwt::resolve` to a name. It is still possible to use `name` instead of `unhygienic_name` by mistake, but `unhygienic_name`s are used only in few very special circumstances, so it shouldn't be a problem.
Besides name resolution `unhygienic_name` is used in some lints and debuginfo. `unhygienic_name` can be very well approximated by "reverse renaming" `token::intern(name.as_str())` or even plain string `name.as_str()`, except that it would break gensyms like `iter` in desugared `for` loops. This approximation is likely good enough for lints and debuginfo, but not for name resolution, unfortunately (see https://github.com/rust-lang/rust/issues/27639), so `unhygienic_name` has to be kept.
cc https://github.com/rust-lang/rust/issues/29782
r? @nrc
The presence of the drop flag caused the offset calculation to be
incorrect, leading to the pointer being incorrect. This has been fixed
by calculating the offset based on the field index (and not assuming
that the field is always the last one).
However, I've also stopped the drop flag from being added to the end of
unsized structs to begin with. Since it's not actually accessed for
unsized structs, and isn't actually where we would say it is, this made
more sense.
I've measured the time/memory consumption before and after - the difference is lost in statistical noise, so it's mostly a code simplification.
Sizes of `enum`s are not affected.
r? @nrc
I wonder if AST/HIR visitors could run faster if `P`s are systematically removed (except for cases where they control `enum` sizes). Theoretically they should.
Remaining unnecessary `P`s can't be easily removed because many folders accept `P<X>`s as arguments, but these folders can be converted to accept `X`s instead without loss of efficiency.
When I have a mood for some mindless refactoring again, I'll probably try to convert the folders, remove remaining `P`s and measure again.
DST fields, being of an unknown type, are not automatically aligned
properly, so a pointer to the field needs to be aligned using the
information in the vtable.
Fixes#26403 and a number of other DST-related bugs discovered while
implementing this.
This commit is the standard API stabilization commit for the 1.6 release cycle.
The list of issues and APIs below have all been through their cycle-long FCP and
the libs team decisions are listed below
Stabilized APIs
* `Read::read_exact`
* `ErrorKind::UnexpectedEof` (renamed from `UnexpectedEOF`)
* libcore -- this was a bit of a nuanced stabilization, the crate itself is now
marked as `#[stable]` and the methods appearing via traits for primitives like
`char` and `str` are now also marked as stable. Note that the extension traits
themeselves are marked as unstable as they're imported via the prelude. The
`try!` macro was also moved from the standard library into libcore to have the
same interface. Otherwise the functions all have copied stability from the
standard library now.
* The `#![no_std]` attribute
* `fs::DirBuilder`
* `fs::DirBuilder::new`
* `fs::DirBuilder::recursive`
* `fs::DirBuilder::create`
* `os::unix::fs::DirBuilderExt`
* `os::unix::fs::DirBuilderExt::mode`
* `vec::Drain`
* `vec::Vec::drain`
* `string::Drain`
* `string::String::drain`
* `vec_deque::Drain`
* `vec_deque::VecDeque::drain`
* `collections::hash_map::Drain`
* `collections::hash_map::HashMap::drain`
* `collections::hash_set::Drain`
* `collections::hash_set::HashSet::drain`
* `collections::binary_heap::Drain`
* `collections::binary_heap::BinaryHeap::drain`
* `Vec::extend_from_slice` (renamed from `push_all`)
* `Mutex::get_mut`
* `Mutex::into_inner`
* `RwLock::get_mut`
* `RwLock::into_inner`
* `Iterator::min_by_key` (renamed from `min_by`)
* `Iterator::max_by_key` (renamed from `max_by`)
Deprecated APIs
* `ErrorKind::UnexpectedEOF` (renamed to `UnexpectedEof`)
* `OsString::from_bytes`
* `OsStr::to_cstring`
* `OsStr::to_bytes`
* `fs::walk_dir` and `fs::WalkDir`
* `path::Components::peek`
* `slice::bytes::MutableByteVector`
* `slice::bytes::copy_memory`
* `Vec::push_all` (renamed to `extend_from_slice`)
* `Duration::span`
* `IpAddr`
* `SocketAddr::ip`
* `Read::tee`
* `io::Tee`
* `Write::broadcast`
* `io::Broadcast`
* `Iterator::min_by` (renamed to `min_by_key`)
* `Iterator::max_by` (renamed to `max_by_key`)
* `net::lookup_addr`
New APIs (still unstable)
* `<[T]>::sort_by_key` (added to mirror `min_by_key`)
Closes#27585Closes#27704Closes#27707Closes#27710Closes#27711Closes#27727Closes#27740Closes#27744Closes#27799Closes#27801
cc #27801 (doesn't close as `Chars` is still unstable)
Closes#28968
