Make `IntoIterator` lifetime bounds of `&BTreeMap` match with `&HashMap`
This is a pretty small change on the lifetime bounds of `IntoIterator` implementations of both `&BTreeMap` and `&mut BTreeMap`. This is loosening the lifetime bounds, so more code should be accepted with this PR. This is lifetime bounds will still be implicit since we have `type Item = (&'a K, &'a V);` in the implementation. This change will make the HashMap and BTreeMap share the same signature, so we can share the same function/trait with both HashMap and BTreeMap in the code.
Fixes#74034.
r? @dtolnay hey, I was touching this file on my previous PR and wanted to fix this on the way. Would you mind taking a look at this, or redirecting it if you are busy?
adds [*mut|*const] ptr::set_ptr_value
I propose the addition of these two functions to `*mut T` and `*const T`, respectively. The motivation for this is primarily byte-wise pointer arithmetic on (potentially) fat pointers, i.e. for types with a `T: ?Sized` bound. A concrete use-case has been discussed in [this](https://internals.rust-lang.org/t/byte-wise-fat-pointer-arithmetic/12739) thread.
TL;DR: Currently, byte-wise pointer arithmetic with potentially fat pointers in not possible in either stable or nightly Rust without making assumptions about the layout of fat pointers, which is currently still an implementation detail and not formally stabilized. This PR adds one function to `*mut T` and `*const T` each, allowing to circumvent this restriction without exposing any internal implementation details.
One possible alternative would be to add specific byte-wise pointer arithmetic functions to the two pointer types in addition to the already existing count-wise functions. However, I feel this fairly niche use case does not warrant adding a whole set of new functions like `add_bytes`, `offset_bytes`, `wrapping_offset_bytes`, etc. (times two, one for each pointer type) to `libcore`.
Change the type of `AssertModuleSource::available_cgus`.
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.
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
