Auto merge of #2583 - RalfJung:rustup, r=oli-obk

initial josh subtree sync

This demonstrates what a josh-based rustup would look like with my patched josh. To create it I did
```
git fetch http://localhost:8000/rust-lang/rust.git:start=75dd959a3a40eb5b4574f8d2e23aa6efbeb33573[:prefix=src/tools/miri]:/src/tools/miri.git master
git merge FETCH_HEAD
./rustup-toolchain HEAD && ./miri fmt
git commit -am rustup
```
Unlike the [previous attempt](rust-lang/miri#2554), this does not add a new root commit to the repo.

Once we merge this, we committed to using josh for subtree syncing, and in particular a version of josh that includes josh-project/josh#961 (or something compatible).

Author: bors

src/tools/miri/README.md

@@ -435,11 +435,10 @@ Moreover, Miri recognizes some environment variables:
   purpose.
 * `MIRI_NO_STD` (recognized by `cargo miri` and the test suite) makes sure that the target's
   sysroot is built without libstd. This allows testing and running no_std programs.
-* `MIRI_BLESS` (recognized by the test suite) overwrite all `stderr` and `stdout` files
-  instead of checking whether the output matches.
-* `MIRI_SKIP_UI_CHECKS` (recognized by the test suite) don't check whether the
-  `stderr` or `stdout` files match the actual output. Useful for the rustc test suite
-  which has subtle differences that we don't care about.
+* `MIRI_BLESS` (recognized by the test suite and `cargo-miri-test/run-test.py`): overwrite all
+  `stderr` and `stdout` files instead of checking whether the output matches.
+* `MIRI_SKIP_UI_CHECKS` (recognized by the test suite): don't check whether the
+  `stderr` or `stdout` files match the actual output.
 
 The following environment variables are *internal* and must not be used by
 anyone but Miri itself. They are used to communicate between different Miri

src/tools/miri/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]

src/tools/miri/rust-version

@@ -1 +1 @@
-acb8934fd57b3c2740c4abac0a5728c2c9b1423b
+e42c4d7218b2596276152c5eb1e69335621f3086

src/tools/miri/src/lib.rs

@@ -7,9 +7,10 @@
 #![feature(int_log)]
 #![feature(variant_count)]
 #![feature(yeet_expr)]
-#![feature(is_some_with)]
+#![feature(is_some_and)]
 #![feature(nonzero_ops)]
 #![feature(local_key_cell_methods)]
+#![cfg_attr(bootstrap, feature(let_else))]
 // Configure clippy and other lints
 #![allow(
     clippy::collapsible_else_if,
@@ -27,6 +28,7 @@
     clippy::type_complexity,
     clippy::single_element_loop,
     clippy::needless_return,
+    clippy::bool_to_int_with_if,
     // We are not implementing queries here so it's fine
     rustc::potential_query_instability
 )]

src/tools/miri/src/shims/unix/android/dlsym.rs

@@ -42,7 +42,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
                     );
                 }
 
-                let &[ref _sig, ref _func] = check_arg_count(args)?;
+                let [_sig, _func] = check_arg_count(args)?;
                 this.write_null(dest)?;
             }
         }

src/tools/miri/src/shims/unix/fs.rs

@@ -1073,23 +1073,23 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
                 mask |= this.eval_libc("STATX_ATIME")?.to_u32()?;
                 InterpResult::Ok(tup)
             })
-            .unwrap_or(Ok((0, 0)))?;
+            .unwrap_or_else(|| Ok((0, 0)))?;
 
         let (created_sec, created_nsec) = metadata
             .created
             .map(|tup| {
                 mask |= this.eval_libc("STATX_BTIME")?.to_u32()?;
                 InterpResult::Ok(tup)
             })
-            .unwrap_or(Ok((0, 0)))?;
+            .unwrap_or_else(|| Ok((0, 0)))?;
 
         let (modified_sec, modified_nsec) = metadata
             .modified
             .map(|tup| {
                 mask |= this.eval_libc("STATX_MTIME")?.to_u32()?;
                 InterpResult::Ok(tup)
             })
-            .unwrap_or(Ok((0, 0)))?;
+            .unwrap_or_else(|| Ok((0, 0)))?;
 
         // Now we write everything to `statxbuf`. We write a zero for the unavailable fields.
         this.write_int_fields_named(

src/tools/miri/src/stacked_borrows/mod.rs

@@ -45,6 +45,7 @@ impl SbTag {
     }
 
     // The default to be used when SB is disabled
+    #[allow(clippy::should_implement_trait)]
     pub fn default() -> Self {
         Self::new(1).unwrap()
     }

src/tools/miri/src/stacked_borrows/stack.rs

@@ -214,7 +214,7 @@ impl<'tcx> Stack {
         }
 
         // Couldn't find it in the stack; but if there is an unknown bottom it might be there.
-        let found = self.unknown_bottom.is_some_and(|&unknown_limit| {
+        let found = self.unknown_bottom.is_some_and(|unknown_limit| {
             tag.0 < unknown_limit.0 // unknown_limit is an upper bound for what can be in the unknown bottom.
         });
         if found { Ok(None) } else { Err(()) }

src/tools/miri/test-cargo-miri/run-test.py

@@ -33,10 +33,13 @@ def normalize_stderr(str):
     return str
 
 def check_output(actual, path, name):
+    if 'MIRI_BLESS' in os.environ:
+        open(path, mode='w').write(actual)
+        return True
     expected = open(path).read()
     if expected == actual:
         return True
-    print(f"{path} did not match reference!")
+    print(f"{name} output did not match reference in {path}!")
     print(f"--- BEGIN diff {name} ---")
     for text in difflib.unified_diff(expected.split("\n"), actual.split("\n")):
         print(text)

src/tools/miri/test-cargo-miri/test.filter.cross-target.stdout.ref

@@ -1,4 +1,9 @@
 
+running 0 tests
+
+test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out
+
+
 running 0 tests
 
 test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 2 filtered out