diff --git a/src/lib.rs b/src/lib.rs
index e79fc2add39e..e0da83840edd 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -39,18 +39,18 @@ pub use rustc_mir::interpret::*;
 // Resolve ambiguity.
 pub use rustc_mir::interpret::{self, AllocMap, PlaceTy};
 
-pub use crate::shims::dlsym::{Dlsym, EvalContextExt as DlsymEvalContextExt};
-pub use crate::shims::env::{EnvVars, EvalContextExt as EnvEvalContextExt};
-pub use crate::shims::foreign_items::EvalContextExt as ForeignItemsEvalContextExt;
-pub use crate::shims::fs::{DirHandler, EvalContextExt as FileEvalContextExt, FileHandler};
-pub use crate::shims::intrinsics::EvalContextExt as IntrinsicsEvalContextExt;
-pub use crate::shims::os_str::EvalContextExt as OsStrEvalContextExt;
-pub use crate::shims::panic::{CatchUnwindData, EvalContextExt as PanicEvalContextExt};
-pub use crate::shims::sync::{EvalContextExt as SyncShimsEvalContextExt};
-pub use crate::shims::thread::EvalContextExt as ThreadShimsEvalContextExt;
-pub use crate::shims::time::EvalContextExt as TimeEvalContextExt;
-pub use crate::shims::tls::{EvalContextExt as TlsEvalContextExt, TlsData};
-pub use crate::shims::EvalContextExt as ShimsEvalContextExt;
+pub use crate::shims::dlsym::{Dlsym, EvalContextExt as _};
+pub use crate::shims::env::{EnvVars, EvalContextExt as _};
+pub use crate::shims::foreign_items::EvalContextExt as _;
+pub use crate::shims::fs::{DirHandler, EvalContextExt as _, FileHandler};
+pub use crate::shims::intrinsics::EvalContextExt as _;
+pub use crate::shims::os_str::EvalContextExt as _;
+pub use crate::shims::panic::{CatchUnwindData, EvalContextExt as _};
+pub use crate::shims::posix_sync::{EvalContextExt as _};
+pub use crate::shims::thread::EvalContextExt as _;
+pub use crate::shims::time::EvalContextExt as _;
+pub use crate::shims::tls::{EvalContextExt as _, TlsData};
+pub use crate::shims::EvalContextExt as _;
 
 pub use crate::diagnostics::{
     register_diagnostic, report_error, EvalContextExt as DiagnosticsEvalContextExt,
diff --git a/src/shims/sync.rs b/src/shims/posix_sync.rs
similarity index 99%
rename from src/shims/sync.rs
rename to src/shims/posix_sync.rs
index 8986455a14fc..cdc1f8cc763a 100644
--- a/src/shims/sync.rs
+++ b/src/shims/posix_sync.rs
@@ -522,6 +522,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
 
         mutex_set_kind(this, mutex_op, ScalarMaybeUninit::Uninit)?;
         mutex_set_id(this, mutex_op, ScalarMaybeUninit::Uninit)?;
+        // FIXME: delete interpreter state associated with this mutex.
 
         Ok(0)
     }
@@ -640,6 +641,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
         }
 
         rwlock_set_id(this, rwlock_op, ScalarMaybeUninit::Uninit)?;
+        // FIXME: delete interpreter state associated with this rwlock.
 
         Ok(0)
     }
@@ -833,6 +835,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
         }
         cond_set_id(this, cond_op, ScalarMaybeUninit::Uninit)?;
         cond_set_clock_id(this, cond_op, ScalarMaybeUninit::Uninit)?;
+        // FIXME: delete interpreter state associated with this condvar.
 
         Ok(0)
     }
diff --git a/src/thread.rs b/src/thread.rs
index 246a383d178b..896f93ef1a3a 100644
--- a/src/thread.rs
+++ b/src/thread.rs
@@ -91,8 +91,8 @@ pub enum ThreadState {
     /// responsibility of the synchronization primitives to track threads that
     /// are blocked by them.
     BlockedOnSync,
-    /// The thread has terminated its execution (we do not delete terminated
-    /// threads).
+    /// The thread has terminated its execution. We do not delete terminated
+    /// threads (FIXME: why?).
     Terminated,
 }
 
diff --git a/tests/run-pass/sync_singlethread.rs b/tests/run-pass/concurrency/sync_singlethread.rs
similarity index 100%
rename from tests/run-pass/sync_singlethread.rs
rename to tests/run-pass/concurrency/sync_singlethread.rs