Auto merge of #1322 - RalfJung:noref, r=RalfJung

avoid ref in matches

Inspired by https://internals.rust-lang.org/t/is-ref-more-powerful-than-match-ergonomics/12111

Author: bors

src/bin/cargo-miri.rs

@@ -115,7 +115,7 @@ fn list_targets() -> impl Iterator<Item = cargo_metadata::Target> {
         get_arg_flag_value("--manifest-path").map(|m| Path::new(&m).canonicalize().unwrap());
 
     let mut cmd = cargo_metadata::MetadataCommand::new();
-    if let Some(ref manifest_path) = manifest_path {
+    if let Some(manifest_path) = manifest_path.as_ref() {
         cmd.manifest_path(manifest_path);
     }
     let mut metadata = if let Ok(metadata) = cmd.exec() {
@@ -131,7 +131,7 @@ fn list_targets() -> impl Iterator<Item = cargo_metadata::Target> {
         .iter()
         .position(|package| {
             let package_manifest_path = Path::new(&package.manifest_path);
-            if let Some(ref manifest_path) = manifest_path {
+            if let Some(manifest_path) = manifest_path.as_ref() {
                 package_manifest_path == manifest_path
             } else {
                 let current_dir = current_dir.as_ref().expect("could not read current directory");
@@ -368,7 +368,7 @@ path = "lib.rs"
     command.env("XARGO_HOME", &dir);
     command.env("XARGO_RUST_SRC", &rust_src);
     // Handle target flag.
-    if let Some(ref target) = target {
+    if let Some(target) = target.as_ref() {
         command.arg("--target").arg(&target);
     }
     // Finally run it!
@@ -379,9 +379,9 @@ path = "lib.rs"
     // That should be it! But we need to figure out where xargo built stuff.
     // Unfortunately, it puts things into a different directory when the
     // architecture matches the host.
-    let is_host = match target {
+    let is_host = match target.as_ref() {
         None => true,
-        Some(target) => target == rustc_version::version_meta().unwrap().host,
+        Some(target) => target == &rustc_version::version_meta().unwrap().host,
     };
     let sysroot = if is_host { dir.join("HOST") } else { PathBuf::from(dir) };
     std::env::set_var("MIRI_SYSROOT", &sysroot); // pass the env var to the processes we spawn, which will turn it into "--sysroot" flags
@@ -583,6 +583,6 @@ fn inside_cargo_rustc() {
             if !exit.success() {
                 std::process::exit(exit.code().unwrap_or(42));
             },
-        Err(ref e) => panic!("error running {:?}:\n{:?}", command, e),
+        Err(e) => panic!("error running {:?}:\n{:?}", command, e),
     }
 }

src/diagnostics.rs

@@ -51,8 +51,8 @@ pub fn report_error<'tcx, 'mir>(
 ) -> Option<i64> {
     use InterpError::*;
 
-    let (title, helps) = match e.kind {
-        MachineStop(ref info) => {
+    let (title, helps) = match &e.kind {
+        MachineStop(info) => {
             let info = info.downcast_ref::<TerminationInfo>().expect("invalid MachineStop payload");
             use TerminationInfo::*;
             let title = match info {

src/machine.rs

@@ -518,7 +518,7 @@ impl AllocationExtra<Tag> for AllocExtra {
         ptr: Pointer<Tag>,
         size: Size,
     ) -> InterpResult<'tcx> {
-        if let Some(ref stacked_borrows) = alloc.extra.stacked_borrows {
+        if let Some(stacked_borrows) = alloc.extra.stacked_borrows.as_ref() {
             stacked_borrows.memory_read(ptr, size)
         } else {
             Ok(())
@@ -531,7 +531,7 @@ impl AllocationExtra<Tag> for AllocExtra {
         ptr: Pointer<Tag>,
         size: Size,
     ) -> InterpResult<'tcx> {
-        if let Some(ref mut stacked_borrows) = alloc.extra.stacked_borrows {
+        if let Some(stacked_borrows) = alloc.extra.stacked_borrows.as_mut() {
             stacked_borrows.memory_written(ptr, size)
         } else {
             Ok(())
@@ -544,7 +544,7 @@ impl AllocationExtra<Tag> for AllocExtra {
         ptr: Pointer<Tag>,
         size: Size,
     ) -> InterpResult<'tcx> {
-        if let Some(ref mut stacked_borrows) = alloc.extra.stacked_borrows {
+        if let Some(stacked_borrows) = alloc.extra.stacked_borrows.as_mut() {
             stacked_borrows.memory_deallocated(ptr, size)
         } else {
             Ok(())

src/mono_hash_map.rs

@@ -64,7 +64,7 @@ impl<K: Hash + Eq, V> AllocMap<K, V> for MonoHashMap<K, V> {
         self.0.borrow().iter().filter_map(move |(k, v)| f(k, &*v)).collect()
     }
 
-    /// The most interesting method: Providing a shared ref without
+    /// The most interesting method: Providing a shared reference without
     /// holding the `RefCell` open, and inserting new data if the key
     /// is not used yet.
     /// `vacant` is called if the key is not found in the map;

src/shims/panic.rs

@@ -191,7 +191,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
         let this = self.eval_context_mut();
 
         match msg {
-            BoundsCheck { ref index, ref len } => {
+            BoundsCheck { index, len } => {
                 // Forward to `panic_bounds_check` lang item.
 
                 // First arg: index.

src/shims/tls.rs

@@ -87,7 +87,7 @@ impl<'tcx> TlsData<'tcx> {
 
     pub fn store_tls(&mut self, key: TlsKey, new_data: Option<Scalar<Tag>>) -> InterpResult<'tcx> {
         match self.keys.get_mut(&key) {
-            Some(&mut TlsEntry { ref mut data, .. }) => {
+            Some(TlsEntry { data, .. }) => {
                 trace!("TLS key {} stored: {:?}", key, new_data);
                 *data = new_data;
                 Ok(())
@@ -139,12 +139,12 @@ impl<'tcx> TlsData<'tcx> {
             Some(key) => Excluded(key),
             None => Unbounded,
         };
-        for (&key, &mut TlsEntry { ref mut data, dtor }) in
+        for (&key, TlsEntry { data, dtor }) in
             thread_local.range_mut((start, Unbounded))
         {
             if let Some(data_scalar) = *data {
                 if let Some(dtor) = dtor {
-                    let ret = Some((dtor, data_scalar, key));
+                    let ret = Some((*dtor, data_scalar, key));
                     *data = None;
                     return ret;
                 }