avoid using the word 'initialized' to talk about that non-reentrant-capable state of the mutex

3 files changed, 5 insertions, 3 deletions

diff --git a/src/libstd/sys_common/at_exit_imp.rs b/src/libstd/sys_common/at_exit_imp.rs
index 85679837312..76e5df2c865 100644
--- a/src/libstd/sys_common/at_exit_imp.rs
+++ b/src/libstd/sys_common/at_exit_imp.rs
@@ -23,7 +23,7 @@ type Queue = Vec<Box<dyn FnBox()>>;
 // on poisoning and this module needs to operate at a lower level than requiring
 // the thread infrastructure to be in place (useful on the borders of
 // initialization/destruction).
-// `LOCK` is never initialized fully, so it is UB to attempt to
+// We never call `LOCK.init()`, so it is UB to attempt to
 // acquire this mutex reentrantly!
 static LOCK: Mutex = Mutex::new();
 static mut QUEUE: *mut Queue = ptr::null_mut();
diff --git a/src/libstd/sys_common/mutex.rs b/src/libstd/sys_common/mutex.rs
index 74e1defd9f4..c6d531c7a1a 100644
--- a/src/libstd/sys_common/mutex.rs
+++ b/src/libstd/sys_common/mutex.rs
@@ -32,7 +32,9 @@ impl Mutex {
     /// Prepare the mutex for use.
     ///
     /// This should be called once the mutex is at a stable memory address.
-    /// Behavior is undefined unless this is called before any other operation.
+    /// If called, this must be the very first thing that happens to the mutex.
+    /// Calling it in parallel with or after any operation (including another
+    /// `init()`) is undefined behavior.
     #[inline]
     pub unsafe fn init(&mut self) { self.0.init() }
 
diff --git a/src/libstd/sys_common/thread_local.rs b/src/libstd/sys_common/thread_local.rs
index 9db7d732698..bb72cb0930a 100644
--- a/src/libstd/sys_common/thread_local.rs
+++ b/src/libstd/sys_common/thread_local.rs
@@ -161,7 +161,7 @@ impl StaticKey {
         // Additionally a 0-index of a tls key hasn't been seen on windows, so
         // we just simplify the whole branch.
         if imp::requires_synchronized_create() {
-            // `INIT_LOCK` is never initialized fully, so it is UB to attempt to
+            // We never call `INIT_LOCK.init()`, so it is UB to attempt to
             // acquire this mutex reentrantly!
             static INIT_LOCK: Mutex = Mutex::new();
             let _guard = INIT_LOCK.lock();