core::slice was originally written to tolerate overflow (notably, with
slices of zero-sized elements), but it was never updated to use wrapping
arithmetic when overflow traps were added.
Also correctly handle the case of calling .nth() on an Iter with a
zero-sized element type. The iterator was assuming that the pointer
value of the returned reference was meaningful, but that's not true for
zero-sized elements.
Fixes#25016.
It is currently broken to use syntax such as `<T as Foo>::U::static_method()` where `<T as Foo>::U` is an associated type. I was able to fix this and simplify the parser a bit at the same time.
This also fixes the corresponding issue with associated types (#22139), but that's somewhat irrelevant because #22519 is still open, so this syntax still causes an error in type checking.
Similarly, although this fix applies to associated consts, #25046 forbids associated constants from using type parameters or `Self`, while #19559 means that associated types have to always have one of those two. Therefore, I think that you can't use an associated const from an associated type anyway.
Rustdoc fixes for associated items
This is related to isssue #22442 and solves it partly.
This solves the search index links of associated types and constants,
so that they link to the trait page.
Also add an Associated Constants section if constants are present.
core::slice::Iter.ptr can be null when iterating a slice of zero-sized
elements, but the pointer value used for the slice itself cannot. Handle
this case by always returning a dummy pointer for slices of zero-sized
elements.
core::slice was originally written to tolerate overflow (notably, with
slices of zero-sized elements), but it was never updated to use wrapping
arithmetic when overflow traps were added.
Also correctly handle the case of calling .nth() on an Iter with a
zero-sized element type. The iterator was assuming that the pointer
value of the returned reference was meaningful, but that's not true for
zero-sized elements.
Fixes#25016.
There were still some mentions of `~[T]` and `~T`, mostly in comments and debugging statements. I tried to do my best to preserve meaning, but I might have gotten some wrong-- I'm happy to fix anything :)
Fixes the problem in #16974 with unhelpful error messages when accidentally using the wrong syntax for the `crate_type="lib"` attribute. The attribute syntax error now shows up instead of "main function not found".
If the user intended to set the crate_type to "lib" but accidentally used
incorrect syntax such as `#![crate_type(lib)]`, the compilation would fail with
"main function not found". This made it hard to locate the source of the
problem, since the failure would cause the warning about the incorrect
attribute not to be shown.
I've found that there are still huge amounts of occurrences of `task`s in the documentation. This PR tries to eliminate all of them in favor of `thread`.
dropck: must assume `Box<Trait + 'a>` has a destructor of interest.
Fix#25199.
This detail was documented in [RFC 769]; the implementation was just missing.
[breaking-change]
The breakage here falls into both obvious and non-obvious cases.
The obvious case: if you were relying on the unsoundness this exposes (namely being able to reference dead storage from a destructor, by doing it via a boxed trait object bounded by the lifetime of the dead storage), then this change disallows that.
The non-obvious cases: The way dropck works, it causes lifetimes to be extended to longer extents than they covered before. I.e. lifetimes that are attached as trait-bounds may become longer than they were previously.
* This includes lifetimes that are only *implicitly* attached as trait-bounds (due to [RFC 599]). So you may have code that was e.g. taking a parameter of type `&'a Box<Trait>` (which expands to `&'a Box<Trait+'a>`), that now may need to be assigned type `&'a Box<Trait+'static>` to ensure that `'a` is not inadvertantly inferred to a region that is actually too long. (See commit ee06263 for an example of this.)
[RFC 769]: https://github.com/rust-lang/rfcs/blob/master/text/0769-sound-generic-drop.md#the-drop-check-rule
[RFC 599]: https://github.com/rust-lang/rfcs/blob/master/text/0599-default-object-bound.md
This syntax was removed in b24a3b8 but references remained in the
grammar, the reference, rustdoc generation, and some auxiliary test
files that don't seem to have been used since 812637e.
An automated script was run against the `.rs` and `.md` files,
subsituting every occurrence of `task` with `thread`. In the `.rs`
files, only the texts in the comment blocks were affected.
This change is worrisome to me, both because:
1. I thought the rules in RFC 599 imply that the `Box<Trait>` without `'static`
in the first case would expand to the second case, but their behaviors
here differ. And,
2. The explicit handling of `'static` should mean `dropck` has no application
here and thus we should have seen no change to the expected error messages.
Nonetheless, the error messages changed.
The error message was misleading, so I adjusted it, and I also added the long diagnostics for this error (resolves one point in #24407).
I was unsure about how to phrase the error message. Is “generic parameter binding” the correct term for this?
The [UnsafeCell documentation says it is undefined behavior](http://doc.rust-lang.org/nightly/std/cell/struct.UnsafeCell.html), so people shouldn't do it.
This happened to catch one case in libstd that was doing this, and I switched that to use an UnsafeCell internally.
Closes#13146
[breaking-change] Technically breaking, since code that had been using
these transmutes before will no longer compile. However, it was
undefined behavior, so really, it's a good thing. Fixing your code would
require some re-working to use an UnsafeCell instead.
Closes#13146
