This change has two consequences:
1. It makes `Arc<T>` and `Rc<T>` covariant in `T`.
2. It causes the compiler to reject code that was unsound with respect
to dropck. See compile-fail/issue-29106.rs for an example of code that
no longer compiles. Because of this, this is a [breaking-change].
Fixes#29037.
Fixes#29106.
Stricter checking of stability attributes + enforcement of their invariants at compile time
(+ removed dead file librustc_front/attr.rs)
I intended to enforce use of `reason` for unstable items as well (it normally presents for new items), but it turned out too intrusive, many older unstable items don't have `reason`s.
r? @aturon
I'm studying how stability works and do some refactoring along the way, so it's probably not the last PR.
Previously, `/**/` was incorrectly regarded as a doc comment because it starts with `/**` and ends with `*/`. However, this caused an ICE because some code assumed that the length of a doc comment is at least 5. This commit adds an additional check to `is_block_doc_comment` that tests the length of the input.
Fixes#28844.
Previously, `/**/` was incorrectly regarded as a doc comment because it
starts with `/**` and ends with `*/`. However, this caused an ICE
because some code assumed that the length of a doc comment is at least
5. This commit adds an additional check to `is_block_doc_comment` that
tests the length of the input.
Fixes#28844.
This turned up as part of #3170. When constructing an `undef` value to
return in the error case, we were trying to get the element type of the
Rust-level value being indexed instead of the underlying array; when
indexing a slice, that's not an array and the LLVM assertion failure
reflects this.
The regression test is a lightly altered copy of `const-array-oob.rs`.
(It is not *exactly* the text from the RFC, but the only thing it adds
is a call to a no-op function that is just an attempt to make it clear
where the potential for impl specialization comes from.)
One just checks that we are feature-gating the UGEH attribute (as
usual for attributes associated with unstable features).
The other is adapted from the RFC 1238 text, except that it has been
extended somewhat to actually *illustrate* the scenario that we are
trying to prevent, namely observing the state of data, from safe code,
after the destructor for that data has been executed.
This lint warning was originally intended to help against misuse of the old Rust
`int` and `uint` types in FFI bindings where the Rust `int` was not equal to the
C `int`. This confusion no longer exists (as Rust's types are now `isize` and
`usize`), and as a result the need for this lint has become much less over time.
Additionally, starting with [the RFC for libc][rfc] it's likely that `isize` and
`usize` will be quite common in FFI bindings (e.g. they're the definition of
`size_t` and `ssize_t` on many platforms).
[rfc]: https://github.com/rust-lang/rfcs/pull/1291
This commit disables these lints to instead consider `isize` and `usize` valid
types to have in FFI signatures.
This turned up as part of #3170. When constructing an `undef` value to
return in the error case, we were trying to get the element type of the
Rust-level value being indexed instead of the underlying array; when
indexing a slice, that's not an array and the LLVM assertion failure
reflects this.
The regression test is a lightly altered copy of `const-array-oob.rs`.
By RFC1214:
> Before calling a fn, we check that its argument and return types are WF.
The previous code only checked the trait-ref, which was not enough
in several cases.
As this is a soundness fix, it is a [breaking-change]. Some new annotations are needed, which I think are because of #18653 and the imperfection of `projection_must_outlive` (that can probably be worked around by moving the wf obligation later).
Fixes#28609
r? @nikomatsakis
By RFC1214:
Before calling a fn, we check that its argument and return types are WF. This check takes place after all higher-ranked lifetimes have been instantiated. Checking the argument types ensures that the implied bounds due to argument types are correct. Checking the return type ensures that the resulting type of the call is WF.
The previous code only checked the trait-ref, which was not enough
in several cases.
As this is a soundness fix, it is a [breaking-change].
Fixes#28609
The behavior here isn't really ideal, but we can't really do much better
given the current state of constant evaluation.
The changes to ExprUseVisitor are to avoid a compile error; apparently
that bit of code is extremely sensitive to changes in other areas of the
compiler.
Fixes#28670, and probably a bunch of duplicates.
