expand on using rustup custom toolchains in CONTRIBUTING.md
fixes#42484
Should i include more notes about how to use a local build *without* rustup? It can kinda feel like a cop-out otherwise. Other means that come to mind are setting `$RUSTC` directly and fully installing it.
cc @rust-lang/docs
Although types that don't implement Drop can't be Copyable, this can
still be useful when ManuallyDrop is used inside a generic type. This
doesn't derive from Copy as that would require T: Copy + Clone, instead
it provides an impl of Clone for T: Clone.
rustc: Flag {i,u}128 as unsafe for FFI
These don't appear to have a stable ABI as noted in #41799 and the work in
compiler-builtins definitely seems to be confirming it!
More general `on_unimplemented`, with uses in `Try`
Allow `on_unimplemented` directives to specify both the label and the primary message of the trait error, and allow them to be controlled by flags - currently only to be desugaring-sensitive.
e.g.
```Rust
#[rustc_on_unimplemented(
on(all(direct, from_desugaring="?"),
message="the `?` operator can only be used in a \
function that returns `Result` \
(or another type that implements `{Try}`)",
label="cannot use the `?` operator in a function that returns `{Self}`"),
)]
```
r? @nikomatsakis
Implement downcast the like it exists for Box.
The implementation avoids using into_raw/from_raw, because the pointer
arithmetic which should cancel does not seem to optimize out at the
moment.
Since Rc<T> is never Send, only Rc<Any> and not Rc<Any + Send>
implements downcast.
Better StorageLive / StorageDead placement for constants.
Fixes problems in miri (see https://github.com/solson/miri/pull/324#issuecomment-326555552) caused by the new scope rules in #43932.
What I've tried to do here is always have a `StorageLive` but no `StorageDead` for `'static` slots.
It might not work perfectly in all cases, but it should unblock miri.
r? @nikomatsakis cc @oli-obk
rustc: Remove the `used_unsafe` field on TyCtxt
Now that lint levels are available for the entire compilation, this can be an
entirely local lint in `effect.rs`
cc #44137
Update rls
And expose the `CFG_VERSION` env var to tools so they can determine the version of Rust.
This gets the RLS back on master and so completes the PR dance for the generators PR.
r? @alexcrichton
powerpc64: improve extern struct ABI
These fixes all have to do with the 64-bit PowerPC ELF ABI for big-endian
targets. The ELF v2 ABI for powerpc64le already worked well.
- Return after marking return aggregates indirect. Fixes#42757.
- Pass one-member float aggregates as direct argument values.
- Aggregate arguments less than 64-bit must be written in the least-
significant bits of the parameter space.
- Larger aggregates are instead padded at the tail.
(i.e. filling MSBs, padding the remaining LSBs.)
New tests were also added for the single-float aggregate, and a 3-byte
aggregate to check that it's filled into LSBs. Overall, at least these
formerly-failing tests now pass on powerpc64:
- run-make/extern-fn-struct-passing-abi
- run-make/extern-fn-with-packed-struct
- run-pass/extern-pass-TwoU16s.rs
- run-pass/extern-pass-TwoU8s.rs
- run-pass/struct-return.rs
Add clippy as a submodule
~~This builds clippy as part of `./x.py build` (locally and in CI).~~
This allows building clippy with `./x.py build src/tools/clippy`
~~Needs https://github.com/nrc/dev-tools-team/issues/18#issuecomment-322456461 to be resolved before it can be merged.~~ Contributers can simply open a PR to clippy and point the submodule at the `pull/$pr_number/head` branch.
This does **not** build clippy or test the clippy test suite at all as per https://github.com/nrc/dev-tools-team/issues/18#issuecomment-321411418
r? @nrc
cc @Manishearth @llogiq @mcarton @alexcrichton
Keep **all** the obligations for every projection is wasteful of
memory and compilation time. We only really care about those
subobligations that may inform the result of the projection (i.e., may
help to resolve any inference variables that appear within).
Therefore, we can clear the subobligations from the cache that don't
potentially affect the result of the projection. On every cache hit,
we also take the opportunity to check if the type variables have been
resolved *yet* and, if so, clear out the pending obligations.
Fixes#43613
