Auto merge of #141116 - RalfJung:miri-sync, r=RalfJung

Miri subtree update

r? `@ghost`

23 files changed, 69 insertions, 111 deletions

diff --git a/src/tools/miri/Cargo.toml b/src/tools/miri/Cargo.toml
index 7b7be97aa51..e4d7abdb0f7 100644
--- a/src/tools/miri/Cargo.toml
+++ b/src/tools/miri/Cargo.toml
@@ -6,7 +6,7 @@ name = "miri"
 repository = "https://github.com/rust-lang/miri"
 version = "0.1.0"
 default-run = "miri"
-edition = "2021"
+edition = "2024"
 
 [lib]
 test = true     # we have unit tests
diff --git a/src/tools/miri/cargo-miri/Cargo.toml b/src/tools/miri/cargo-miri/Cargo.toml
index ed142b0e211..23048914af1 100644
--- a/src/tools/miri/cargo-miri/Cargo.toml
+++ b/src/tools/miri/cargo-miri/Cargo.toml
@@ -5,7 +5,7 @@ license = "MIT OR Apache-2.0"
 name = "cargo-miri"
 repository = "https://github.com/rust-lang/miri"
 version = "0.1.0"
-edition = "2021"
+edition = "2024"
 
 [[bin]]
 name = "cargo-miri"
diff --git a/src/tools/miri/cargo-miri/src/main.rs b/src/tools/miri/cargo-miri/src/main.rs
index 322ef0a6c2a..4c01a81fdfd 100644
--- a/src/tools/miri/cargo-miri/src/main.rs
+++ b/src/tools/miri/cargo-miri/src/main.rs
@@ -63,27 +63,37 @@ fn main() {
         return;
     }
 
+    let Some(first) = args.next() else {
+        show_error!(
+            "`cargo-miri` called without first argument; please only invoke this binary through `cargo miri`"
+        )
+    };
+
     // The way rustdoc invokes rustc is indistinguishable from the way cargo invokes rustdoc by the
     // arguments alone. `phase_cargo_rustdoc` sets this environment variable to let us disambiguate.
     if env::var_os("MIRI_CALLED_FROM_RUSTDOC").is_some() {
         // ...however, we then also see this variable when rustdoc invokes us as the testrunner!
-        // The runner is invoked as `$runtool ($runtool-arg)* output_file`;
-        // since we don't specify any runtool-args, and rustdoc supplies multiple arguments to
-        // the test-builder unconditionally, we can just check the number of remaining arguments:
-        if args.len() == 1 {
-            phase_runner(args, RunnerPhase::Rustdoc);
-        } else {
-            phase_rustc(args, RustcPhase::Rustdoc);
+        // In that case the first argument is `runner` and there are no more arguments.
+        match first.as_str() {
+            "runner" => phase_runner(args, RunnerPhase::Rustdoc),
+            flag if flag.starts_with("--") || flag.starts_with("@") => {
+                // This is probably rustdoc invoking us to build the test. But we need to get `first`
+                // "back onto the iterator", it is some part of the rustc invocation.
+                phase_rustc(iter::once(first).chain(args), RustcPhase::Rustdoc);
+            }
+            _ => {
+                show_error!(
+                    "`cargo-miri` failed to recognize which phase of the build process this is, please report a bug.\n\
+                    We are inside MIRI_CALLED_FROM_RUSTDOC.\n\
+                    The command-line arguments were: {:#?}",
+                    Vec::from_iter(env::args()),
+                );
+            }
         }
 
         return;
     }
 
-    let Some(first) = args.next() else {
-        show_error!(
-            "`cargo-miri` called without first argument; please only invoke this binary through `cargo miri`"
-        )
-    };
     match first.as_str() {
         "miri" => phase_cargo_miri(args),
         "runner" => phase_runner(args, RunnerPhase::Cargo),
diff --git a/src/tools/miri/cargo-miri/src/phases.rs b/src/tools/miri/cargo-miri/src/phases.rs
index cb62e12413c..171e157789d 100644
--- a/src/tools/miri/cargo-miri/src/phases.rs
+++ b/src/tools/miri/cargo-miri/src/phases.rs
@@ -176,6 +176,8 @@ pub fn phase_cargo_miri(mut args: impl Iterator<Item = String>) {
     // Set `--target-dir` to `miri` inside the original target directory.
     let target_dir = get_target_dir(&metadata);
     cmd.arg("--target-dir").arg(target_dir);
+    // Enable cross-target doctests (for consistency between different cargo versions).
+    cmd.arg("-Zdoctest-xcompile");
 
     // *After* we set all the flags that need setting, forward everything else. Make sure to skip
     // `--target-dir` (which would otherwise be set twice).
@@ -666,11 +668,6 @@ pub fn phase_rustdoc(mut args: impl Iterator<Item = String>) {
         if arg == "--extern" {
             // Patch --extern arguments to use *.rmeta files, since phase_cargo_rustc only creates stub *.rlib files.
             forward_patched_extern_arg(&mut args, &mut cmd);
-        } else if arg == "--test-runtool" {
-            // An existing --test-runtool flag indicates cargo is running in cross-target mode, which we don't support.
-            // Note that this is only passed when cargo is run with the unstable -Zdoctest-xcompile flag;
-            // otherwise, we won't be called as rustdoc at all.
-            show_error!("cross-interpreting doctests is not currently supported by Miri.");
         } else {
             cmd.arg(arg);
         }
@@ -702,10 +699,10 @@ pub fn phase_rustdoc(mut args: impl Iterator<Item = String>) {
     // make sure the 'miri' flag is set for rustdoc
     cmd.arg("--cfg").arg("miri");
 
-    // Make rustdoc call us back.
+    // Make rustdoc call us back for the build.
+    // (cargo already sets `--test-runtool` to us since we are the cargo test runner.)
     let cargo_miri_path = env::current_exe().expect("current executable path invalid");
     cmd.arg("--test-builder").arg(&cargo_miri_path); // invoked by forwarding most arguments
-    cmd.arg("--test-runtool").arg(&cargo_miri_path); // invoked with just a single path argument
 
     debug_cmd("[cargo-miri rustdoc]", verbose, &cmd);
     exec(cmd)
diff --git a/src/tools/miri/cargo-miri/src/setup.rs b/src/tools/miri/cargo-miri/src/setup.rs
index 7afc8481009..b9b58c04f9e 100644
--- a/src/tools/miri/cargo-miri/src/setup.rs
+++ b/src/tools/miri/cargo-miri/src/setup.rs
@@ -24,11 +24,9 @@ pub fn setup(
     let ask_user = !only_setup;
     let print_sysroot = only_setup && has_arg_flag("--print-sysroot"); // whether we just print the sysroot path
     let show_setup = only_setup && !print_sysroot;
-    if !only_setup {
-        if let Some(sysroot) = std::env::var_os("MIRI_SYSROOT") {
-            // Skip setup step if MIRI_SYSROOT is explicitly set, *unless* we are `cargo miri setup`.
-            return sysroot.into();
-        }
+    if !only_setup && let Some(sysroot) = std::env::var_os("MIRI_SYSROOT") {
+        // Skip setup step if MIRI_SYSROOT is explicitly set, *unless* we are `cargo miri setup`.
+        return sysroot.into();
     }
 
     // Determine where the rust sources are located.  The env var trumps auto-detection.
diff --git a/src/tools/miri/miri-script/Cargo.toml b/src/tools/miri/miri-script/Cargo.toml
index a04898de6ab..462a9cc62bf 100644
--- a/src/tools/miri/miri-script/Cargo.toml
+++ b/src/tools/miri/miri-script/Cargo.toml
@@ -6,7 +6,7 @@ name = "miri-script"
 repository = "https://github.com/rust-lang/miri"
 version = "0.1.0"
 default-run = "miri-script"
-edition = "2021"
+edition = "2024"
 
 [workspace]
 # We make this a workspace root so that cargo does not go looking in ../Cargo.toml for the workspace root.
diff --git a/src/tools/miri/miri-script/src/commands.rs b/src/tools/miri/miri-script/src/commands.rs
index 1c9750e2cbd..3b7b159aeab 100644
--- a/src/tools/miri/miri-script/src/commands.rs
+++ b/src/tools/miri/miri-script/src/commands.rs
@@ -675,11 +675,9 @@ impl Command {
         let mut early_flags = Vec::<OsString>::new();
 
         // In `dep` mode, the target is already passed via `MIRI_TEST_TARGET`
-        if !dep {
-            if let Some(target) = &target {
-                early_flags.push("--target".into());
-                early_flags.push(target.into());
-            }
+        if !dep && let Some(target) = &target {
+            early_flags.push("--target".into());
+            early_flags.push(target.into());
         }
         early_flags.push("--edition".into());
         early_flags.push(edition.as_deref().unwrap_or("2021").into());
@@ -707,10 +705,8 @@ impl Command {
         // Add Miri flags
         let mut cmd = cmd.args(&miri_flags).args(&early_flags).args(&flags);
         // For `--dep` we also need to set the target in the env var.
-        if dep {
-            if let Some(target) = &target {
-                cmd = cmd.env("MIRI_TEST_TARGET", target);
-            }
+        if dep && let Some(target) = &target {
+            cmd = cmd.env("MIRI_TEST_TARGET", target);
         }
         // Finally, run the thing.
         Ok(cmd.run()?)
diff --git a/src/tools/miri/miri-script/src/util.rs b/src/tools/miri/miri-script/src/util.rs
index c039b4827ee..5c2a055990f 100644
--- a/src/tools/miri/miri-script/src/util.rs
+++ b/src/tools/miri/miri-script/src/util.rs
@@ -213,7 +213,7 @@ impl MiriEnv {
             let toolchain = &self.toolchain;
             let mut cmd = cmd!(
                 self.sh,
-                "rustfmt +{toolchain} --edition=2021 --config-path {config_path} --unstable-features --skip-children {flags...}"
+                "rustfmt +{toolchain} --edition=2024 --config-path {config_path} --unstable-features --skip-children {flags...}"
             );
             if first {
                 // Log an abbreviating command, and only once.
diff --git a/src/tools/miri/rust-version b/src/tools/miri/rust-version
index 97bc826b57a..79abbfaeaf1 100644
--- a/src/tools/miri/rust-version
+++ b/src/tools/miri/rust-version
@@ -1 +1 @@
-2ad5f8607d0e192b60b130e5cc416b477b351c18
+a69bc17fb8026bdc0d24bb1896ff95f0eba1da4e
diff --git a/src/tools/miri/src/bin/miri.rs b/src/tools/miri/src/bin/miri.rs
index f249b58aeb6..469fc264970 100644
--- a/src/tools/miri/src/bin/miri.rs
+++ b/src/tools/miri/src/bin/miri.rs
@@ -459,7 +459,7 @@ fn jemalloc_magic() {
     // linking, so we need to explicitly depend on the function.
     #[cfg(target_os = "macos")]
     {
-        extern "C" {
+        unsafe extern "C" {
             fn _rjem_je_zone_register();
         }
 
diff --git a/src/tools/miri/src/borrow_tracker/tree_borrows/diagnostics.rs b/src/tools/miri/src/borrow_tracker/tree_borrows/diagnostics.rs
index b2fd9b2bf05..f5a0013047a 100644
--- a/src/tools/miri/src/borrow_tracker/tree_borrows/diagnostics.rs
+++ b/src/tools/miri/src/borrow_tracker/tree_borrows/diagnostics.rs
@@ -179,7 +179,7 @@ impl NodeDebugInfo {
     /// Add a name to the tag. If a same tag is associated to several pointers,
     /// it can have several names which will be separated by commas.
     pub fn add_name(&mut self, name: &str) {
-        if let Some(ref mut prev_name) = &mut self.name {
+        if let Some(prev_name) = &mut self.name {
             prev_name.push_str(", ");
             prev_name.push_str(name);
         } else {
diff --git a/src/tools/miri/src/diagnostics.rs b/src/tools/miri/src/diagnostics.rs
index 89768077d87..10570a37e5d 100644
--- a/src/tools/miri/src/diagnostics.rs
+++ b/src/tools/miri/src/diagnostics.rs
@@ -648,8 +648,7 @@ impl<'tcx> MiriMachine<'tcx> {
             AccessedAlloc(AllocId(id), access_kind) =>
                 format!("{access_kind} to allocation with id {id}"),
             FreedAlloc(AllocId(id)) => format!("freed allocation with id {id}"),
-            RejectedIsolatedOp(ref op) =>
-                format!("{op} was made to return an error due to isolation"),
+            RejectedIsolatedOp(op) => format!("{op} was made to return an error due to isolation"),
             ProgressReport { .. } =>
                 format!("progress report: current operation being executed is here"),
             Int2Ptr { .. } => format!("integer-to-pointer cast"),
diff --git a/src/tools/miri/src/lib.rs b/src/tools/miri/src/lib.rs
index 58b93ae82a1..0b7a067058b 100644
--- a/src/tools/miri/src/lib.rs
+++ b/src/tools/miri/src/lib.rs
@@ -9,7 +9,6 @@
 #![feature(variant_count)]
 #![feature(yeet_expr)]
 #![feature(nonzero_ops)]
-#![feature(let_chains)]
 #![feature(strict_overflow_ops)]
 #![feature(pointer_is_aligned_to)]
 #![feature(unqualified_local_imports)]
diff --git a/src/tools/miri/src/shims/panic.rs b/src/tools/miri/src/shims/panic.rs
index 18af8214876..b5ed5ea837b 100644
--- a/src/tools/miri/src/shims/panic.rs
+++ b/src/tools/miri/src/shims/panic.rs
@@ -85,6 +85,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         // Now we make a function call, and pass `data` as first and only argument.
         let f_instance = this.get_ptr_fn(try_fn)?.as_instance()?;
         trace!("try_fn: {:?}", f_instance);
+        #[allow(clippy::cloned_ref_to_slice_refs)] // the code is clearer as-is
         this.call_function(
             f_instance,
             ExternAbi::Rust,
diff --git a/src/tools/miri/test-cargo-miri/run-test.py b/src/tools/miri/test-cargo-miri/run-test.py
index a9d09ac7a9d..40bfe7f845f 100755
--- a/src/tools/miri/test-cargo-miri/run-test.py
+++ b/src/tools/miri/test-cargo-miri/run-test.py
@@ -142,24 +142,19 @@ def test_cargo_miri_run():
     )
 
 def test_cargo_miri_test():
-    # rustdoc is not run on foreign targets
-    is_foreign = ARGS.target is not None
-    default_ref = "test.cross-target.stdout.ref" if is_foreign else "test.default.stdout.ref"
-    filter_ref = "test.filter.cross-target.stdout.ref" if is_foreign else "test.filter.stdout.ref"
-
     test("`cargo miri test`",
         cargo_miri("test"),
-        default_ref, "test.empty.ref",
+        "test.default.stdout.ref", "test.empty.ref",
         env={'MIRIFLAGS': "-Zmiri-seed=4242"},
     )
     test("`cargo miri test` (no isolation, no doctests)",
         cargo_miri("test") + ["--bins", "--tests"], # no `--lib`, we disabled that in `Cargo.toml`
-        "test.cross-target.stdout.ref", "test.empty.ref",
+        "test.no-doc.stdout.ref", "test.empty.ref",
         env={'MIRIFLAGS': "-Zmiri-disable-isolation"},
     )
     test("`cargo miri test` (with filter)",
         cargo_miri("test") + ["--", "--format=pretty", "pl"],
-        filter_ref, "test.empty.ref",
+        "test.filter.stdout.ref", "test.empty.ref",
     )
     test("`cargo miri test` (test target)",
         cargo_miri("test") + ["--test", "test", "--", "--format=pretty"],
@@ -171,7 +166,7 @@ def test_cargo_miri_test():
     )
     test("`cargo miri t` (subcrate, no isolation)",
         cargo_miri("t") + ["-p", "subcrate"],
-        "test.subcrate.cross-target.stdout.ref" if is_foreign else "test.subcrate.stdout.ref",
+        "test.subcrate.stdout.ref",
         "test.empty.ref",
         env={'MIRIFLAGS': "-Zmiri-disable-isolation"},
     )
@@ -181,12 +176,12 @@ def test_cargo_miri_test():
     )
     test("`cargo miri test` (custom target dir)",
         cargo_miri("test") + ["--target-dir=custom-test"],
-        default_ref, "test.empty.ref",
+        "test.default.stdout.ref", "test.empty.ref",
     )
     del os.environ["CARGO_TARGET_DIR"] # this overrides `build.target-dir` passed by `--config`, so unset it
     test("`cargo miri test` (config-cli)",
         cargo_miri("test") + ["--config=build.target-dir=\"config-cli\""],
-        default_ref, "test.empty.ref",
+        "test.default.stdout.ref", "test.empty.ref",
     )
     if ARGS.multi_target:
         test_cargo_miri_multi_target()
diff --git a/src/tools/miri/test-cargo-miri/test.filter.cross-target.stdout.ref b/src/tools/miri/test-cargo-miri/test.filter.cross-target.stdout.ref
deleted file mode 100644
index 59b4deb1ff3..00000000000
--- a/src/tools/miri/test-cargo-miri/test.filter.cross-target.stdout.ref
+++ /dev/null
@@ -1,12 +0,0 @@
-
-running 0 tests
-
-test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 2 filtered out; finished in $TIME
-
-imported main
-
-running 1 test
-test simple ... ok
-
-test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 5 filtered out; finished in $TIME
-
diff --git a/src/tools/miri/test-cargo-miri/test.multiple_targets.stdout.ref b/src/tools/miri/test-cargo-miri/test.multiple_targets.stdout.ref
index 567c5db07d0..a376530a8cf 100644
--- a/src/tools/miri/test-cargo-miri/test.multiple_targets.stdout.ref
+++ b/src/tools/miri/test-cargo-miri/test.multiple_targets.stdout.ref
@@ -20,3 +20,13 @@ running 6 tests
 ...i..
 test result: ok. 5 passed; 0 failed; 1 ignored; 0 measured; 0 filtered out; finished in $TIME
 
+
+running 5 tests
+.....
+test result: ok. 5 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in $TIME
+
+
+running 5 tests
+.....
+test result: ok. 5 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in $TIME
+
diff --git a/src/tools/miri/test-cargo-miri/test.cross-target.stdout.ref b/src/tools/miri/test-cargo-miri/test.no-doc.stdout.ref
index 2ef124e4de8..2ef124e4de8 100644
--- a/src/tools/miri/test-cargo-miri/test.cross-target.stdout.ref
+++ b/src/tools/miri/test-cargo-miri/test.no-doc.stdout.ref
diff --git a/src/tools/miri/test-cargo-miri/test.subcrate.cross-target.stdout.ref b/src/tools/miri/test-cargo-miri/test.subcrate.cross-target.stdout.ref
deleted file mode 100644
index 436e6e4fbbb..00000000000
--- a/src/tools/miri/test-cargo-miri/test.subcrate.cross-target.stdout.ref
+++ /dev/null
@@ -1,11 +0,0 @@
-
-running 0 tests
-
-test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in $TIME
-
-
-running 0 tests
-
-test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in $TIME
-
-subcrate testing
diff --git a/src/tools/miri/tests/fail/weak_memory/racing_mixed_size.stderr b/src/tools/miri/tests/fail/weak_memory/racing_mixed_size.stderr
deleted file mode 100644
index a437ca34258..00000000000
--- a/src/tools/miri/tests/fail/weak_memory/racing_mixed_size.stderr
+++ /dev/null
@@ -1,22 +0,0 @@
-error: Undefined Behavior: Race condition detected between (1) 4-byte atomic store on thread `unnamed-ID` and (2) 2-byte atomic load on thread `unnamed-ID` at ALLOC. (2) just happened here
-  --> tests/fail/weak_memory/racing_mixed_size.rs:LL:CC
-   |
-LL |             std::intrinsics::atomic_load_relaxed(hi);
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Race condition detected between (1) 4-byte atomic store on thread `unnamed-ID` and (2) 2-byte atomic load on thread `unnamed-ID` at ALLOC. (2) just happened here
-   |
-help: and (1) occurred earlier here
-  --> tests/fail/weak_memory/racing_mixed_size.rs:LL:CC
-   |
-LL |         x.store(1, Relaxed);
-   |         ^^^^^^^^^^^^^^^^^^^
-   = help: overlapping unsynchronized atomic accesses must use the same access size
-   = help: see https://doc.rust-lang.org/nightly/std/sync/atomic/index.html#memory-model-for-atomic-accesses for more information about the Rust memory model
-   = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
-   = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
-   = note: BACKTRACE (of the first span) on thread `unnamed-ID`:
-   = note: inside closure at tests/fail/weak_memory/racing_mixed_size.rs:LL:CC
-
-note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
-
-error: aborting due to 1 previous error
-
diff --git a/src/tools/miri/tests/pass/both_borrows/basic_aliasing_model.rs b/src/tools/miri/tests/pass/both_borrows/basic_aliasing_model.rs
index c2b6a7e68be..c76e7f2eebd 100644
--- a/src/tools/miri/tests/pass/both_borrows/basic_aliasing_model.rs
+++ b/src/tools/miri/tests/pass/both_borrows/basic_aliasing_model.rs
@@ -12,7 +12,6 @@ fn main() {
     mut_raw_mut();
     partially_invalidate_mut();
     drop_after_sharing();
-    // direct_mut_to_const_raw();
     two_raw();
     shr_and_raw();
     disjoint_mutable_subborrows();
diff --git a/src/tools/miri/tests/pass/coroutine.rs b/src/tools/miri/tests/pass/coroutine.rs
index 9ec9b1fc5bc..96b60b515cb 100644
--- a/src/tools/miri/tests/pass/coroutine.rs
+++ b/src/tools/miri/tests/pass/coroutine.rs
@@ -183,18 +183,18 @@ fn basic() {
 
 fn smoke_resume_arg() {
     fn drain<G: Coroutine<R, Yield = Y> + Unpin, R, Y>(
-        gen: &mut G,
+        gen_: &mut G,
         inout: Vec<(R, CoroutineState<Y, G::Return>)>,
     ) where
         Y: Debug + PartialEq,
         G::Return: Debug + PartialEq,
     {
-        let mut gen = Pin::new(gen);
+        let mut gen_ = Pin::new(gen_);
 
         for (input, out) in inout {
-            assert_eq!(gen.as_mut().resume(input), out);
+            assert_eq!(gen_.as_mut().resume(input), out);
             // Test if the coroutine is valid (according to type invariants).
-            let _ = unsafe { ManuallyDrop::new(ptr::read(gen.as_mut().get_unchecked_mut())) };
+            let _ = unsafe { ManuallyDrop::new(ptr::read(gen_.as_mut().get_unchecked_mut())) };
         }
     }
 
diff --git a/src/tools/miri/tests/ui.rs b/src/tools/miri/tests/ui.rs
index c37cf15d40a..46472b51f9c 100644
--- a/src/tools/miri/tests/ui.rs
+++ b/src/tools/miri/tests/ui.rs
@@ -44,8 +44,7 @@ pub fn flagsplit(flags: &str) -> Vec<String> {
 fn build_native_lib() -> PathBuf {
     let cc = env::var("CC").unwrap_or_else(|_| "cc".into());
     // Target directory that we can write to.
-    let so_target_dir =
-        Path::new(&env::var_os("CARGO_TARGET_DIR").unwrap()).join("miri-native-lib");
+    let so_target_dir = Path::new(env!("CARGO_TARGET_TMPDIR")).join("miri-native-lib");
     // Create the directory if it does not already exist.
     std::fs::create_dir_all(&so_target_dir)
         .expect("Failed to create directory for shared object file");
@@ -101,7 +100,7 @@ fn miri_config(
     let mut config = Config {
         target: Some(target.to_owned()),
         program,
-        out_dir: PathBuf::from(std::env::var_os("CARGO_TARGET_DIR").unwrap()).join("miri_ui"),
+        out_dir: PathBuf::from(env!("CARGO_TARGET_TMPDIR")).join("miri_ui"),
         threads: std::env::var("MIRI_TEST_THREADS")
             .ok()
             .map(|threads| NonZero::new(threads.parse().unwrap()).unwrap()),
@@ -319,10 +318,10 @@ fn main() -> Result<()> {
     let mut args = std::env::args_os();
 
     // Skip the program name and check whether this is a `./miri run-dep` invocation
-    if let Some(first) = args.nth(1) {
-        if first == "--miri-run-dep-mode" {
-            return run_dep_mode(target, args);
-        }
+    if let Some(first) = args.nth(1)
+        && first == "--miri-run-dep-mode"
+    {
+        return run_dep_mode(target, args);
     }
 
     ui(Mode::Pass, "tests/pass", &target, WithoutDependencies, tmpdir.path())?;