Auto merge of rust-lang#2568 - oli-obk:josh, r=RalfJung

Merge rustc changes back into the miri repo

This uses https://github.com/josh-project/josh (RIIR ftw)

The first time it looks a bit odd with the merges and so, all future syncs will work just like the instructions say. I'll add instructions for the sync from miri to rustc, too, starting to do that right now.

Initial cache building now takes 5 mins 🥳

CONTRIBUTING.md

@@ -275,3 +275,28 @@ see <https://rustc-dev-guide.rust-lang.org/building/how-to-build-and-run.html>.
 
 With this, you should now have a working development setup! See
 [above](#building-and-testing-miri) for how to proceed working on Miri.
+
+
+### Fetching the latest changes from the rustc repo
+
+Run the josh proxy locally
+
+```
+docker run -p 8000:8000 -e JOSH_REMOTE=https://github.com -v josh-vol:/data/git joshproject/josh-proxy:latest
+```
+
+Register the josh proxy as a remote
+
+```
+git remote add josh http://localhost:8000/rust-lang/rust.git:/src/tools/miri.git
+```
+
+Fetch (takes ca 5-10 min the first time)
+
+```
+git fetch josh
+git checkout josh/master
+git switch -c josh_sync
+```
+
+Now push `josh_sync` to your own miri fork and open a PR with it.

cargo-miri/src/main.rs

@@ -1,3 +1,4 @@
+#![cfg_attr(bootstrap, feature(let_else))]
 #![allow(clippy::useless_format, clippy::derive_partial_eq_without_eq, rustc::internal)]
 
 #[macro_use]

rust-version

@@ -1 +1 @@
-acb8934fd57b3c2740c4abac0a5728c2c9b1423b
+21265dd0d209e7b682f249a3a45034f02d32650b

src/lib.rs

@@ -10,6 +10,7 @@
 #![feature(is_some_with)]
 #![feature(nonzero_ops)]
 #![feature(local_key_cell_methods)]
+#![cfg_attr(bootstrap, feature(let_else))]
 // Configure clippy and other lints
 #![allow(
     clippy::collapsible_else_if,

tests/fail/concurrency/windows_join_detached.stderr

@@ -8,7 +8,7 @@ LL |         let rc = unsafe { c::WaitForSingleObject(self.handle.as_raw_handle(
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
    = note: BACKTRACE:
    = note: inside `std::sys::PLATFORM::thread::Thread::join` at RUSTLIB/std/src/sys/PLATFORM/thread.rs:LL:CC
-   = note: inside `std::thread::JoinInner::<()>::join` at RUSTLIB/std/src/thread/mod.rs:LL:CC
+   = note: inside `std::thread::JoinInner::<'_, ()>::join` at RUSTLIB/std/src/thread/mod.rs:LL:CC
    = note: inside `std::thread::JoinHandle::<()>::join` at RUSTLIB/std/src/thread/mod.rs:LL:CC
 note: inside `main` at $DIR/windows_join_detached.rs:LL:CC
   --> $DIR/windows_join_detached.rs:LL:CC

tests/pass/issues/issue-miri-2433.rs

@@ -0,0 +1,24 @@
+#![feature(type_alias_impl_trait)]
+
+trait T {
+    type Item;
+}
+
+type Alias<'a> = impl T<Item = &'a ()>;
+
+struct S;
+impl<'a> T for &'a S {
+    type Item = &'a ();
+}
+
+fn filter_positive<'a>() -> Alias<'a> {
+    &S
+}
+
+fn with_positive(fun: impl Fn(Alias<'_>)) {
+    fun(filter_positive());
+}
+
+fn main() {
+    with_positive(|_| ());
+}