See comments in the diff; this is such a hack.
The reason this can't be done properly in `register_res` is because
there's no way to get back the parent type: calling
`tcx.parent(assoc_item)` gets you the _impl_, not the type.
You can call `tcx.impl_trait_ref(impl_).self_ty()`, but there's no way
to go from that to a DefId without unwrapping.
It's currently a `BTreeSet<Symbol>`, which is a strange type. The
`BTreeSet` suggests that element order is important, but `Symbol` is a
type whose ordering isn't useful to humans. The ordering of the
collection only manifests in an obscure error message ("no module named
`...`") that doesn't appear in any tests.
This commit changes the `Symbol` to a `String`, which is more
typical.
Fixes#75096
It's U.B. to use anything other than inline assmebling in a naked
function. Fortunately, the `#break` directive works fine without
anything in the function body.
rustc_metadata: track the simplified Self type for every trait impl.
For the `traits_impls_of` query, we index the impls by `fast_reject::SimplifiedType` (a "shallow type"), which allows some simple cases like `impl Trait<..> for Foo<..>` to be efficiently iterated over, by e.g. `for_each_relevant_impl`.
This PR encodes the `fast_reject::SimplifiedType` cross-crate to avoid needing to deserialize the `Self` type of every `impl` in order to simplify it - the simplification itself should be cheap, but the deserialization is less so.
We could go further from here and make loading the list of impls lazy, for a given simplified `Self` type, but that would have more complicated implications for performance, and this PR doesn't do anything in that regard.
r? @nikomatsakis cc @Mark-Simulacrum
Limit I/O vector count on Unix
Unix systems enforce limits on the vector count when performing vectored I/O via the readv and writev system calls and return EINVAL when these limits are exceeded. This changes the standard library to handle those limits as short reads and writes to avoid forcing its users to query these limits using platform specific mechanisms.
Fixes#68042
Show backtrace numbers in backtrace whenever more than one is involved
Previously, we only displayed 'frame' numbers in a macro backtrace when more
than two frames were involved. This commit should help make backtrace
more readable, since these kinds of messages can quickly get confusing.
Previously, we only displayed 'frame' numbers in a macro backtrace when more
than two frames were involved. This commit should help make backtrace
more readable, since these kinds of messages can quickly get confusing.
All #[cfg(unix)] platforms follow the POSIX standard and define _SC_IOV_MAX so
that we rely purely on POSIX semantics to determine the limits on I/O vector
count.
