comment tweaks

Author: RalfJung

src/tools/miri/src/concurrency/sync.rs

@@ -70,7 +70,7 @@ struct Mutex {
     lock_count: usize,
     /// The queue of threads waiting for this mutex.
     queue: VecDeque<ThreadId>,
-    /// Data race handle, this tracks the happens-before
+    /// Data race handle. This tracks the happens-before
     /// relationship between each mutex access. It is
     /// released to during unlock and acquired from during
     /// locking, and therefore stores the clock of the last
@@ -92,7 +92,7 @@ struct RwLock {
     writer_queue: VecDeque<ThreadId>,
     /// The queue of reader threads waiting for this lock.
     reader_queue: VecDeque<ThreadId>,
-    /// Data race handle for writers, tracks the happens-before
+    /// Data race handle for writers. Tracks the happens-before
     /// ordering between each write access to a rwlock and is updated
     /// after a sequence of concurrent readers to track the happens-
     /// before ordering between the set of previous readers and
@@ -101,7 +101,7 @@ struct RwLock {
     /// lock or the joined clock of the set of last threads to release
     /// shared reader locks.
     data_race: VClock,
-    /// Data race handle for readers, this is temporary storage
+    /// Data race handle for readers. This is temporary storage
     /// for the combined happens-before ordering for between all
     /// concurrent readers and the next writer, and the value
     /// is stored to the main data_race variable once all

src/tools/miri/tests/fail/enum-set-discriminant-niche-variant-wrong.rs

@@ -4,11 +4,11 @@
 use std::intrinsics::mir::*;
 use std::num::NonZeroI32;
 
-// We define our own option type so that we can control the varian indices.
+// We define our own option type so that we can control the variant indices.
 #[allow(unused)]
 enum Option<T> {
-    None,
-    Some(T),
+    None,    // variant 0
+    Some(T), // variant 1
 }
 use Option::*;
 

src/tools/miri/tests/pass-dep/concurrency/libc_pthread_cond.rs

@@ -22,7 +22,7 @@ fn test_timed_wait_timeout(clock_id: i32) {
         let mut now_mu: MaybeUninit<libc::timespec> = MaybeUninit::uninit();
         assert_eq!(libc::clock_gettime(clock_id, now_mu.as_mut_ptr()), 0);
         let now = now_mu.assume_init();
-        // Waiting for a second... mostly because waiting less requires mich more tricky arithmetic.
+        // Waiting for a second... mostly because waiting less requires much more tricky arithmetic.
         // FIXME: wait less.
         let timeout = libc::timespec { tv_sec: now.tv_sec + 1, tv_nsec: now.tv_nsec };
 

src/tools/miri/tests/pass-dep/concurrency/libc_pthread_cond_isolated.rs

@@ -21,7 +21,7 @@ fn test_timed_wait_timeout(clock_id: i32) {
         let mut now_mu: MaybeUninit<libc::timespec> = MaybeUninit::uninit();
         assert_eq!(libc::clock_gettime(clock_id, now_mu.as_mut_ptr()), 0);
         let now = now_mu.assume_init();
-        // Waiting for a second... mostly because waiting less requires mich more tricky arithmetic.
+        // Waiting for a second... mostly because waiting less requires much more tricky arithmetic.
         // FIXME: wait less.
         let timeout = libc::timespec { tv_sec: now.tv_sec + 1, tv_nsec: now.tv_nsec };
 

src/tools/miri/tests/pass-dep/shims/pthread-sync.rs

@@ -98,9 +98,8 @@ fn test_mutex_libc_static_initializer_recursive() {
     }
 }
 
-// Testing the behavior of std::sync::RwLock does not fully exercise the pthread rwlock shims, we
-// need to go a layer deeper and test the behavior of the libc functions, because
-// std::sys::unix::rwlock::RWLock itself keeps track of write_locked and num_readers.
+// std::sync::RwLock does not even used pthread_rwlock any more.
+// Do some smoke testing of the API surface.
 fn test_rwlock_libc_static_initializer() {
     let rw = std::cell::UnsafeCell::new(libc::PTHREAD_RWLOCK_INITIALIZER);
     unsafe {