diff --git a/compiler/rustc_const_eval/src/const_eval/eval_queries.rs b/compiler/rustc_const_eval/src/const_eval/eval_queries.rs
index c8cbd955acc5e..6ad79541bdbea 100644
--- a/compiler/rustc_const_eval/src/const_eval/eval_queries.rs
+++ b/compiler/rustc_const_eval/src/const_eval/eval_queries.rs
@@ -109,6 +109,19 @@ fn eval_body_using_ecx<'tcx, R: InterpretationResult<'tcx>>(
         cid.promoted.map_or_else(String::new, |p| format!("::{p:?}"))
     );
 
+    // We are about to initialize a frame without any arguments,
+    // and without `#[track_caller]` support.
+    // Make sure that the body expects this.
+    // Note: Promoteds don't require a caller location,
+    // even when inside an `Instance` with `#[track_caller]`
+    assert_eq!(body.arg_count, 0);
+    if cid.promoted.is_none() && cid.instance.def.requires_caller_location(tcx) {
+        // FIXME: Once #131787 is fixed, turn this delayed bug into an assertion.
+        throw_inval!(AlreadyReported(ReportedErrorInfo::non_const_eval_error(
+            tcx.dcx().span_delayed_bug(body.span, "can't evaluate body with `#[track_caller]`")
+        )));
+    }
+
     // This can't use `init_stack_frame` since `body` is not a function,
     // so computing its ABI would fail. It's also not worth it since there are no arguments to pass.
     ecx.push_stack_frame_raw(
diff --git a/compiler/rustc_const_eval/src/const_eval/machine.rs b/compiler/rustc_const_eval/src/const_eval/machine.rs
index 876759b9ab41e..cb9432f9832e5 100644
--- a/compiler/rustc_const_eval/src/const_eval/machine.rs
+++ b/compiler/rustc_const_eval/src/const_eval/machine.rs
@@ -252,7 +252,7 @@ impl<'tcx> CompileTimeInterpCx<'tcx> {
             }
 
             let msg = Symbol::intern(self.read_str(&msg_place)?);
-            let span = self.find_closest_untracked_caller_location();
+            let span = self.caller_location();
             let (file, line, col) = self.location_triple_for_span(span);
             return Err(ConstEvalErrKind::Panic { msg, file, line, col }).into();
         } else if self.tcx.is_lang_item(def_id, LangItem::PanicFmt) {
@@ -469,7 +469,7 @@ impl<'tcx> interpret::Machine<'tcx> for CompileTimeMachine<'tcx> {
 
     fn panic_nounwind(ecx: &mut InterpCx<'tcx, Self>, msg: &str) -> InterpResult<'tcx> {
         let msg = Symbol::intern(msg);
-        let span = ecx.find_closest_untracked_caller_location();
+        let span = ecx.caller_location();
         let (file, line, col) = ecx.location_triple_for_span(span);
         Err(ConstEvalErrKind::Panic { msg, file, line, col }).into()
     }
diff --git a/compiler/rustc_const_eval/src/interpret/call.rs b/compiler/rustc_const_eval/src/interpret/call.rs
index 3658982002e60..b5c3eceab9b4b 100644
--- a/compiler/rustc_const_eval/src/interpret/call.rs
+++ b/compiler/rustc_const_eval/src/interpret/call.rs
@@ -462,6 +462,21 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
         let _trace = enter_trace_span!(M, step::init_stack_frame, %instance, tracing_separate_thread = Empty);
         let def_id = instance.def_id();
 
+        match (instance.def.requires_caller_location(*self.tcx), with_caller_location) {
+            (false, true) => {
+                throw_ub_format!(
+                    "calling a non-`#[track_caller]` function from a `#[track_caller]` declaration"
+                )
+            }
+            (true, false) => {
+                throw_ub_format!(
+                    "calling a `#[track_caller]` function from a non-`#[track_caller]` declaration"
+                )
+            }
+            _ => {}
+        }
+        let caller_location = with_caller_location.then(|| self.caller_location());
+
         // The first order of business is to figure out the callee signature.
         // However, that requires the list of variadic arguments.
         // We use the *caller* information to determine where to split the list of arguments,
@@ -542,6 +557,9 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                 .collect::<Vec<_>>()
         );
 
+        // Initialize special caller_location "local", if this function has it.
+        self.frame_mut().track_caller_arg = caller_location;
+
         // Determine whether there is a special VaList argument. This is always the
         // last argument, and since arguments start at index 1 that's `arg_count`.
         let va_list_arg = callee_fn_abi.c_variadic.then(|| mir::Local::from_usize(body.arg_count));
@@ -563,7 +581,8 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
         // The "where they come from" part is easy, we expect the caller to do any special handling
         // that might be required here (e.g. for untupling).
         // If `with_caller_location` is set we pretend there is an extra argument (that
-        // we will not pass; our `caller_location` intrinsic implementation walks the stack instead).
+        // we will not pass normally; our `caller_location` intrinsic implementation handles
+        // that separately).
         assert_eq!(
             args.len() + if with_caller_location { 1 } else { 0 },
             caller_fn_abi.args.len(),
@@ -760,6 +779,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
         match instance.def {
             ty::InstanceKind::Intrinsic(def_id) => {
                 assert!(self.tcx.intrinsic(def_id).is_some());
+                assert!(!with_caller_location);
                 // FIXME: Should `InPlace` arguments be reset to uninit?
                 if let Some(fallback) = M::call_intrinsic(
                     self,
@@ -771,11 +791,16 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                 )? {
                     assert!(!self.tcx.intrinsic(fallback.def_id()).unwrap().must_be_overridden);
                     assert_matches!(fallback.def, ty::InstanceKind::Item(_));
+                    // For `#[rustc_intrinsic] fn`, two `Instance`s are involved:
+                    // the original `InstanceKind::Intrinsic` (no caller location arg), and
+                    // the fallback `InstanceKind::Item` (has caller location arg if
+                    // it's `#[track_caller]`).
+                    // We replace the former with the latter.
                     return self.init_fn_call(
                         FnVal::Instance(fallback),
                         (caller_abi, caller_fn_abi),
                         args,
-                        with_caller_location,
+                        fallback.def.requires_caller_location(*self.tcx),
                         destination,
                         target,
                         unwind,
diff --git a/compiler/rustc_const_eval/src/interpret/eval_context.rs b/compiler/rustc_const_eval/src/interpret/eval_context.rs
index 94b73a830503e..4307019c6cf27 100644
--- a/compiler/rustc_const_eval/src/interpret/eval_context.rs
+++ b/compiler/rustc_const_eval/src/interpret/eval_context.rs
@@ -1,5 +1,6 @@
 use std::cell::RefCell;
 use std::collections::hash_map::Entry;
+use std::convert::identity;
 
 use either::{Left, Right};
 use rustc_abi::{Align, HasDataLayout, Size, TargetDataLayout};
@@ -18,7 +19,7 @@ use rustc_middle::ty::{
 use rustc_span::{Span, span_bug};
 use rustc_structures::Limit;
 use rustc_target::callconv::FnAbi;
-use tracing::{debug, trace};
+use tracing::trace;
 
 use super::{
     Frame, FrameInfo, GlobalId, InterpErrorKind, InterpResult, MPlaceTy, Machine, MemPlaceMeta,
@@ -376,49 +377,41 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
         }
     }
 
-    /// Walks up the callstack from the intrinsic's callsite, searching for the first callsite in a
-    /// frame which is not `#[track_caller]`. This matches the `caller_location` intrinsic,
+    /// Grabs the implicit caller location argument, if there is one,
+    /// or falls back to the "current" span. This matches the `caller_location` intrinsic,
     /// and is primarily intended for the panic machinery.
-    pub(crate) fn find_closest_untracked_caller_location(&self) -> Span {
-        for frame in self.stack().iter().rev() {
-            debug!("find_closest_untracked_caller_location: checking frame {:?}", frame.instance);
-
-            // Assert that the frame we look at is actually executing code currently
-            // (`loc` is `Right` when we are unwinding and the frame does not require cleanup).
-            let loc = frame.loc.left().unwrap();
-
-            // This could be a non-`Call` terminator (such as `Drop`), or not a terminator at all
-            // (such as `box`). Use the normal span by default.
-            let mut source_info = *frame.body.source_info(loc);
-
-            // If this is a `Call` terminator, use the `fn_span` instead.
-            let block = &frame.body.basic_blocks[loc.block];
-            if loc.statement_index == block.statements.len() {
-                debug!(
-                    "find_closest_untracked_caller_location: got terminator {:?} ({:?})",
-                    block.terminator(),
-                    block.terminator().kind,
-                );
-                if let mir::TerminatorKind::Call { fn_span, .. } = block.terminator().kind {
-                    source_info.span = fn_span;
-                }
-            }
-
-            let caller_location = if frame.instance.def.requires_caller_location(*self.tcx) {
-                // We use `Err(())` as indication that we should continue up the call stack since
-                // this is a `#[track_caller]` function.
-                Some(Err(()))
-            } else {
-                None
-            };
-            if let Ok(span) =
-                frame.body.caller_location_span(source_info, caller_location, *self.tcx, Ok)
-            {
-                return span;
-            }
+    pub(crate) fn caller_location(&self) -> Span {
+        let frame = self.frame();
+
+        // Assert that the frame we look at is actually executing code currently
+        // (`loc` is `Right` when we are unwinding and the frame does not require cleanup).
+        let loc = frame.loc.left().unwrap();
+
+        // FIXME: It would be nice to have the following redundant sanity check.
+        // However, `requires_caller_location` would return true on a promoted that's
+        // inside a `#[track_caller]` function, and we currently don't keep track of
+        // enough information to identify such cases happening.
+        // assert_eq!(
+        //     frame.track_caller_arg.is_some(),
+        //     frame.instance.def.requires_caller_location(*self.tcx)
+        // );
+
+        // This could be a non-`Call` terminator (such as `Drop`), or not a terminator at all
+        // (such as `box`). Use the normal span by default.
+        let mut source_info = *frame.body.source_info(loc);
+
+        // If this is a `Call` terminator, use the `fn_span` instead.
+        let block = &frame.body.basic_blocks[loc.block];
+        if loc.statement_index == block.statements.len()
+            && let mir::TerminatorKind::Call { fn_span, .. } = block.terminator().kind
+        {
+            source_info.span = fn_span;
         }
 
-        span_bug!(self.cur_span(), "no non-`#[track_caller]` frame found")
+        // Directly returning `frame.track_caller_arg` would be wrong if we are
+        // in code that got inlined from another function. `caller_location_span`
+        // handles that for us.
+        frame.body.caller_location_span(source_info, frame.track_caller_arg, *self.tcx, identity)
     }
 
     /// Returns the actual dynamic size and alignment of the place at the given type.
diff --git a/compiler/rustc_const_eval/src/interpret/intrinsics.rs b/compiler/rustc_const_eval/src/interpret/intrinsics.rs
index b8b372ad1dab1..d66f4cf900eca 100644
--- a/compiler/rustc_const_eval/src/interpret/intrinsics.rs
+++ b/compiler/rustc_const_eval/src/interpret/intrinsics.rs
@@ -293,7 +293,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
             }
 
             sym::caller_location => {
-                let span = self.find_closest_untracked_caller_location();
+                let span = self.caller_location();
                 let val = self.tcx.span_as_caller_location(span);
                 let val =
                     self.const_val_to_op(val, self.tcx.caller_location_ty(), Some(dest.layout))?;
diff --git a/compiler/rustc_const_eval/src/interpret/stack.rs b/compiler/rustc_const_eval/src/interpret/stack.rs
index 61cc31479b652..1bc6d43aa6dfb 100644
--- a/compiler/rustc_const_eval/src/interpret/stack.rs
+++ b/compiler/rustc_const_eval/src/interpret/stack.rs
@@ -66,6 +66,8 @@ pub struct Frame<'tcx, Prov: Provenance = CtfeProvenance, Extra = ()> {
     pub(super) body: &'tcx mir::Body<'tcx>,
 
     /// The def_id and args of the current function.
+    /// Note that if this is the body of a promoted, the `instance` points
+    /// to the surrounding body!
     pub(super) instance: ty::Instance<'tcx>,
 
     /// Extra data for the machine.
@@ -96,6 +98,10 @@ pub struct Frame<'tcx, Prov: Provenance = CtfeProvenance, Extra = ()> {
     /// frame is popped.
     pub(super) va_list: Vec<MPlaceTy<'tcx, Prov>>,
 
+    /// The implicit caller location argument that is passed by this function's caller, if any.
+    /// This is `Some` if and only if `instance.def.requires_caller_location` returns `true`.
+    pub(super) track_caller_arg: Option<Span>,
+
     /// The span of the `tracing` crate is stored here.
     /// When the guard is dropped, the span is exited. This gives us
     /// a full stack trace on all tracing statements.
@@ -258,13 +264,14 @@ impl<'tcx, Prov: Provenance> Frame<'tcx, Prov> {
         Frame {
             body: self.body,
             instance: self.instance,
+            extra,
             return_cont: self.return_cont,
             return_place: self.return_place,
             locals: self.locals,
             va_list: self.va_list,
-            loc: self.loc,
-            extra,
+            track_caller_arg: self.track_caller_arg,
             tracing_span: self.tracing_span,
+            loc: self.loc,
         }
     }
 }
@@ -400,6 +407,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
             return_place: return_place.clone(),
             locals,
             va_list: vec![],
+            track_caller_arg: None,
             instance,
             tracing_span: SpanGuard::new(),
             extra: (),
diff --git a/compiler/rustc_const_eval/src/interpret/step.rs b/compiler/rustc_const_eval/src/interpret/step.rs
index b647cc624bc04..a3e972f3b1ac1 100644
--- a/compiler/rustc_const_eval/src/interpret/step.rs
+++ b/compiler/rustc_const_eval/src/interpret/step.rs
@@ -496,15 +496,33 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
             }
             ty::FnDef(def_id, args) => {
                 let instance = self.resolve(def_id, args.no_bound_vars().unwrap())?;
-                // Don't compute FnAbi for LLVM intrinsics. Trying to do that would panic.
-                // Rust intrinsics however *do* need a FnAbi as we may invoke the
-                // fallback body like a regular function.
-                let has_fn_abi = !matches!(instance.def, ty::InstanceKind::LlvmIntrinsic(_));
+                let fn_abi =
+                    match instance.def {
+                        // Don't compute FnAbi for LLVM intrinsics. Trying to do that would panic.
+                        ty::InstanceKind::LlvmIntrinsic(_) => None,
+                        // Rust intrinsics don't really have a normal ABI, except for the case
+                        // where we call the fallback body like a regular function.
+                        // So, we compute the ABI based on the fallback body.
+                        // We can't compute the ABI based on the `instance` directly,
+                        // because `#[track_caller]` affects the ABI of the fallback body,
+                        // but not affect the "ABI" of the intrinsic itself.
+                        // Even if there is no fallback body, this computes a valid ABI
+                        // (that we then mostly ignore).
+                        ty::InstanceKind::Intrinsic(def_id) => {
+                            let fallback_instance = ty::Instance {
+                                def: ty::InstanceKind::Item(def_id),
+                                args: instance.args,
+                            };
+                            Some(self.fn_abi_of_instance_no_deduced_attrs(
+                                fallback_instance,
+                                extra_args,
+                            )?)
+                        }
+                        _ => Some(self.fn_abi_of_instance_no_deduced_attrs(instance, extra_args)?),
+                    };
                 (
                     FnVal::Instance(instance),
-                    has_fn_abi
-                        .then(|| self.fn_abi_of_instance_no_deduced_attrs(instance, extra_args))
-                        .transpose()?,
+                    fn_abi,
                     instance.def.requires_caller_location(*self.tcx),
                 )
             }
diff --git a/compiler/rustc_const_eval/src/interpret/util.rs b/compiler/rustc_const_eval/src/interpret/util.rs
index 4efef90581080..416207371e51c 100644
--- a/compiler/rustc_const_eval/src/interpret/util.rs
+++ b/compiler/rustc_const_eval/src/interpret/util.rs
@@ -25,7 +25,7 @@ pub(crate) fn type_implements_dyn_trait<'tcx, M: Machine<'tcx>>(
 
     let ty::Dynamic(preds, _) = trait_ty.kind() else {
         span_bug!(
-            ecx.find_closest_untracked_caller_location(),
+            ecx.cur_span(),
             "Invalid type provided to type_implements_predicates. U must be dyn Trait, got {trait_ty}."
         );
     };
diff --git a/compiler/rustc_type_ir/src/binder.rs b/compiler/rustc_type_ir/src/binder.rs
index 7f67435428b6c..d9b5ec7356e3e 100644
--- a/compiler/rustc_type_ir/src/binder.rs
+++ b/compiler/rustc_type_ir/src/binder.rs
@@ -136,6 +136,7 @@ impl<I: Interner, T> Binder<I, T> {
         self.as_ref().map_bound(f)
     }
 
+    #[inline]
     pub fn map_bound<F, U: TypeVisitable<I>>(self, f: F) -> Binder<I, U>
     where
         F: FnOnce(T) -> U,
@@ -152,6 +153,7 @@ impl<I: Interner, T> Binder<I, T> {
     /// There are some uses of `map_bound` which are incredibly hot and trivially
     /// correct. Only use this if this significantly improves the performance of
     /// builds with debug assertions.
+    #[inline]
     pub fn map_bound_no_validate_bound_vars<F, U: TypeVisitable<I>>(self, f: F) -> Binder<I, U>
     where
         F: FnOnce(T) -> U,
diff --git a/library/alloc/src/bstr.rs b/library/alloc/src/byte_str.rs
similarity index 81%
rename from library/alloc/src/bstr.rs
rename to library/alloc/src/byte_str.rs
index 59909ed1db9b2..55caf4012b21c 100644
--- a/library/alloc/src/bstr.rs
+++ b/library/alloc/src/byte_str.rs
@@ -4,9 +4,9 @@
 #![cfg(not(no_global_oom_handling))]
 
 use core::borrow::{Borrow, BorrowMut};
-#[unstable(feature = "bstr", issue = "134915")]
-pub use core::bstr::ByteStr;
-use core::bstr::{impl_partial_eq, impl_partial_eq_n, impl_partial_eq_ord};
+#[unstable(feature = "byte_str", issue = "134915")]
+pub use core::byte_str::ByteStr;
+use core::byte_str::{impl_partial_eq, impl_partial_eq_n, impl_partial_eq_ord};
 use core::cmp::Ordering;
 use core::ops::{
     Deref, DerefMut, DerefPure, Index, IndexMut, Range, RangeFrom, RangeFull, RangeInclusive,
@@ -33,7 +33,7 @@ use crate::vec::Vec;
 /// need to round-trip whatever data the user provides.
 ///
 /// A `ByteString` owns its contents and can grow and shrink, like a `Vec` or `String`. For a
-/// borrowed byte string, see [`ByteStr`](../../std/bstr/struct.ByteStr.html).
+/// borrowed byte string, see [`ByteStr`](../../std/byte_str/struct.ByteStr.html).
 ///
 /// `ByteString` implements `Deref` to `&Vec<u8>`, so all methods available on `&Vec<u8>` are
 /// available on `ByteString`. Similarly, `ByteString` implements `DerefMut` to `&mut Vec<u8>`,
@@ -41,7 +41,7 @@ use crate::vec::Vec;
 ///
 /// The `Debug` and `Display` implementations for `ByteString` are the same as those for `ByteStr`,
 /// showing invalid UTF-8 as hex escapes or the Unicode replacement character, respectively.
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 #[repr(transparent)]
 #[derive(Clone, Default)]
 #[doc(alias = "BString")]
@@ -70,7 +70,7 @@ impl ByteString {
     /// implementation for types that implement `Display`, and the trait version
     /// will use the Unicode replacement character rather than returning a
     /// `Result` and allowing for the possibility of the content not being UTF-8.
-    #[unstable(feature = "bstr_to_string", issue = "134915")]
+    #[unstable(feature = "byte_str_to_string", issue = "134915")]
     #[rustc_allow_incoherent_impl]
     pub fn to_string(&self) -> Result<String, Utf8Error> {
         // Avoid allocating a copy of the contents for invalid UTF-8
@@ -82,7 +82,7 @@ impl ByteString {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl Deref for ByteString {
     type Target = Vec<u8>;
 
@@ -92,7 +92,7 @@ impl Deref for ByteString {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl DerefMut for ByteString {
     #[inline]
     fn deref_mut(&mut self) -> &mut Self::Target {
@@ -103,7 +103,7 @@ impl DerefMut for ByteString {
 #[unstable(feature = "deref_pure_trait", issue = "87121")]
 unsafe impl DerefPure for ByteString {}
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl fmt::Debug for ByteString {
     #[inline]
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
@@ -111,7 +111,7 @@ impl fmt::Debug for ByteString {
     }
 }
 
-#[unstable(feature = "bstr_to_string", issue = "134915")]
+#[unstable(feature = "byte_str_to_string", issue = "134915")]
 impl fmt::Display for ByteString {
     #[inline]
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
@@ -119,7 +119,7 @@ impl fmt::Display for ByteString {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl AsRef<[u8]> for ByteString {
     #[inline]
     fn as_ref(&self) -> &[u8] {
@@ -127,7 +127,7 @@ impl AsRef<[u8]> for ByteString {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl AsRef<ByteStr> for ByteString {
     #[inline]
     fn as_ref(&self) -> &ByteStr {
@@ -135,7 +135,7 @@ impl AsRef<ByteStr> for ByteString {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl AsMut<[u8]> for ByteString {
     #[inline]
     fn as_mut(&mut self) -> &mut [u8] {
@@ -143,7 +143,7 @@ impl AsMut<[u8]> for ByteString {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl AsMut<ByteStr> for ByteString {
     #[inline]
     fn as_mut(&mut self) -> &mut ByteStr {
@@ -151,7 +151,7 @@ impl AsMut<ByteStr> for ByteString {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl Borrow<[u8]> for ByteString {
     #[inline]
     fn borrow(&self) -> &[u8] {
@@ -159,7 +159,7 @@ impl Borrow<[u8]> for ByteString {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl Borrow<ByteStr> for ByteString {
     #[inline]
     fn borrow(&self) -> &ByteStr {
@@ -170,7 +170,7 @@ impl Borrow<ByteStr> for ByteString {
 // `impl Borrow<ByteStr> for Vec<u8>` omitted to avoid inference failures
 // `impl Borrow<ByteStr> for String` omitted to avoid inference failures
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl BorrowMut<[u8]> for ByteString {
     #[inline]
     fn borrow_mut(&mut self) -> &mut [u8] {
@@ -178,7 +178,7 @@ impl BorrowMut<[u8]> for ByteString {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl BorrowMut<ByteStr> for ByteString {
     #[inline]
     fn borrow_mut(&mut self) -> &mut ByteStr {
@@ -190,7 +190,7 @@ impl BorrowMut<ByteStr> for ByteString {
 
 // Omitted due to inference failures
 //
-// #[unstable(feature = "bstr", issue = "134915")]
+// #[unstable(feature = "byte_str", issue = "134915")]
 // impl<'a, const N: usize> From<&'a [u8; N]> for ByteString {
 //     #[inline]
 //     fn from(s: &'a [u8; N]) -> Self {
@@ -198,7 +198,7 @@ impl BorrowMut<ByteStr> for ByteString {
 //     }
 // }
 //
-// #[unstable(feature = "bstr", issue = "134915")]
+// #[unstable(feature = "byte_str", issue = "134915")]
 // impl<const N: usize> From<[u8; N]> for ByteString {
 //     #[inline]
 //     fn from(s: [u8; N]) -> Self {
@@ -206,7 +206,7 @@ impl BorrowMut<ByteStr> for ByteString {
 //     }
 // }
 //
-// #[unstable(feature = "bstr", issue = "134915")]
+// #[unstable(feature = "byte_str", issue = "134915")]
 // impl<'a> From<&'a [u8]> for ByteString {
 //     #[inline]
 //     fn from(s: &'a [u8]) -> Self {
@@ -214,7 +214,7 @@ impl BorrowMut<ByteStr> for ByteString {
 //     }
 // }
 //
-// #[unstable(feature = "bstr", issue = "134915")]
+// #[unstable(feature = "byte_str", issue = "134915")]
 // impl From<Vec<u8>> for ByteString {
 //     #[inline]
 //     fn from(s: Vec<u8>) -> Self {
@@ -222,7 +222,7 @@ impl BorrowMut<ByteStr> for ByteString {
 //     }
 // }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl From<ByteString> for Vec<u8> {
     #[inline]
     fn from(s: ByteString) -> Self {
@@ -232,7 +232,7 @@ impl From<ByteString> for Vec<u8> {
 
 // Omitted due to inference failures
 //
-// #[unstable(feature = "bstr", issue = "134915")]
+// #[unstable(feature = "byte_str", issue = "134915")]
 // impl<'a> From<&'a str> for ByteString {
 //     #[inline]
 //     fn from(s: &'a str) -> Self {
@@ -240,7 +240,7 @@ impl From<ByteString> for Vec<u8> {
 //     }
 // }
 //
-// #[unstable(feature = "bstr", issue = "134915")]
+// #[unstable(feature = "byte_str", issue = "134915")]
 // impl From<String> for ByteString {
 //     #[inline]
 //     fn from(s: String) -> Self {
@@ -248,7 +248,7 @@ impl From<ByteString> for Vec<u8> {
 //     }
 // }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl<'a> From<&'a ByteStr> for ByteString {
     #[inline]
     fn from(s: &'a ByteStr) -> Self {
@@ -256,7 +256,7 @@ impl<'a> From<&'a ByteStr> for ByteString {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl<'a> From<ByteString> for Cow<'a, ByteStr> {
     #[inline]
     fn from(s: ByteString) -> Self {
@@ -264,7 +264,7 @@ impl<'a> From<ByteString> for Cow<'a, ByteStr> {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl<'a> From<&'a ByteString> for Cow<'a, ByteStr> {
     #[inline]
     fn from(s: &'a ByteString) -> Self {
@@ -272,7 +272,7 @@ impl<'a> From<&'a ByteString> for Cow<'a, ByteStr> {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl FromIterator<char> for ByteString {
     #[inline]
     fn from_iter<I: IntoIterator<Item = char>>(iter: I) -> Self {
@@ -280,7 +280,7 @@ impl FromIterator<char> for ByteString {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl FromIterator<u8> for ByteString {
     #[inline]
     fn from_iter<I: IntoIterator<Item = u8>>(iter: I) -> Self {
@@ -288,7 +288,7 @@ impl FromIterator<u8> for ByteString {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl<'a> FromIterator<&'a str> for ByteString {
     #[inline]
     fn from_iter<I: IntoIterator<Item = &'a str>>(iter: I) -> Self {
@@ -296,7 +296,7 @@ impl<'a> FromIterator<&'a str> for ByteString {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl<'a> FromIterator<&'a [u8]> for ByteString {
     #[inline]
     fn from_iter<I: IntoIterator<Item = &'a [u8]>>(iter: I) -> Self {
@@ -308,7 +308,7 @@ impl<'a> FromIterator<&'a [u8]> for ByteString {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl<'a> FromIterator<&'a ByteStr> for ByteString {
     #[inline]
     fn from_iter<I: IntoIterator<Item = &'a ByteStr>>(iter: I) -> Self {
@@ -320,7 +320,7 @@ impl<'a> FromIterator<&'a ByteStr> for ByteString {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl FromIterator<ByteString> for ByteString {
     #[inline]
     fn from_iter<I: IntoIterator<Item = ByteString>>(iter: I) -> Self {
@@ -332,7 +332,7 @@ impl FromIterator<ByteString> for ByteString {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl FromStr for ByteString {
     type Err = !;
 
@@ -342,7 +342,7 @@ impl FromStr for ByteString {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl Index<usize> for ByteString {
     type Output = u8;
 
@@ -352,7 +352,7 @@ impl Index<usize> for ByteString {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl Index<RangeFull> for ByteString {
     type Output = ByteStr;
 
@@ -362,7 +362,7 @@ impl Index<RangeFull> for ByteString {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl Index<Range<usize>> for ByteString {
     type Output = ByteStr;
 
@@ -372,7 +372,7 @@ impl Index<Range<usize>> for ByteString {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl Index<RangeInclusive<usize>> for ByteString {
     type Output = ByteStr;
 
@@ -382,7 +382,7 @@ impl Index<RangeInclusive<usize>> for ByteString {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl Index<RangeFrom<usize>> for ByteString {
     type Output = ByteStr;
 
@@ -392,7 +392,7 @@ impl Index<RangeFrom<usize>> for ByteString {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl Index<RangeTo<usize>> for ByteString {
     type Output = ByteStr;
 
@@ -402,7 +402,7 @@ impl Index<RangeTo<usize>> for ByteString {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl Index<RangeToInclusive<usize>> for ByteString {
     type Output = ByteStr;
 
@@ -412,7 +412,7 @@ impl Index<RangeToInclusive<usize>> for ByteString {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl IndexMut<usize> for ByteString {
     #[inline]
     fn index_mut(&mut self, idx: usize) -> &mut u8 {
@@ -420,7 +420,7 @@ impl IndexMut<usize> for ByteString {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl IndexMut<RangeFull> for ByteString {
     #[inline]
     fn index_mut(&mut self, _: RangeFull) -> &mut ByteStr {
@@ -428,7 +428,7 @@ impl IndexMut<RangeFull> for ByteString {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl IndexMut<Range<usize>> for ByteString {
     #[inline]
     fn index_mut(&mut self, r: Range<usize>) -> &mut ByteStr {
@@ -436,7 +436,7 @@ impl IndexMut<Range<usize>> for ByteString {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl IndexMut<RangeInclusive<usize>> for ByteString {
     #[inline]
     fn index_mut(&mut self, r: RangeInclusive<usize>) -> &mut ByteStr {
@@ -444,7 +444,7 @@ impl IndexMut<RangeInclusive<usize>> for ByteString {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl IndexMut<RangeFrom<usize>> for ByteString {
     #[inline]
     fn index_mut(&mut self, r: RangeFrom<usize>) -> &mut ByteStr {
@@ -452,7 +452,7 @@ impl IndexMut<RangeFrom<usize>> for ByteString {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl IndexMut<RangeTo<usize>> for ByteString {
     #[inline]
     fn index_mut(&mut self, r: RangeTo<usize>) -> &mut ByteStr {
@@ -460,7 +460,7 @@ impl IndexMut<RangeTo<usize>> for ByteString {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl IndexMut<RangeToInclusive<usize>> for ByteString {
     #[inline]
     fn index_mut(&mut self, r: RangeToInclusive<usize>) -> &mut ByteStr {
@@ -468,7 +468,7 @@ impl IndexMut<RangeToInclusive<usize>> for ByteString {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl hash::Hash for ByteString {
     #[inline]
     fn hash<H: hash::Hasher>(&self, state: &mut H) {
@@ -476,10 +476,10 @@ impl hash::Hash for ByteString {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl Eq for ByteString {}
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl PartialEq for ByteString {
     #[inline]
     fn eq(&self, other: &ByteString) -> bool {
@@ -489,7 +489,7 @@ impl PartialEq for ByteString {
 
 macro_rules! impl_partial_eq_ord_cow {
     ($lhs:ty, $rhs:ty) => {
-        #[unstable(feature = "bstr", issue = "134915")]
+        #[unstable(feature = "byte_str", issue = "134915")]
         impl PartialEq<$rhs> for $lhs {
             #[inline]
             fn eq(&self, other: &$rhs) -> bool {
@@ -498,7 +498,7 @@ macro_rules! impl_partial_eq_ord_cow {
             }
         }
 
-        #[unstable(feature = "bstr", issue = "134915")]
+        #[unstable(feature = "byte_str", issue = "134915")]
         impl PartialEq<$lhs> for $rhs {
             #[inline]
             fn eq(&self, other: &$lhs) -> bool {
@@ -507,7 +507,7 @@ macro_rules! impl_partial_eq_ord_cow {
             }
         }
 
-        #[unstable(feature = "bstr", issue = "134915")]
+        #[unstable(feature = "byte_str", issue = "134915")]
         impl PartialOrd<$rhs> for $lhs {
             #[inline]
             fn partial_cmp(&self, other: &$rhs) -> Option<Ordering> {
@@ -516,7 +516,7 @@ macro_rules! impl_partial_eq_ord_cow {
             }
         }
 
-        #[unstable(feature = "bstr", issue = "134915")]
+        #[unstable(feature = "byte_str", issue = "134915")]
         impl PartialOrd<$lhs> for $rhs {
             #[inline]
             fn partial_cmp(&self, other: &$lhs) -> Option<Ordering> {
@@ -549,7 +549,7 @@ impl_partial_eq_ord_cow!(ByteString, Cow<'_, ByteStr>);
 impl_partial_eq_ord_cow!(ByteString, Cow<'_, str>);
 impl_partial_eq_ord_cow!(ByteString, Cow<'_, [u8]>);
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl Ord for ByteString {
     #[inline]
     fn cmp(&self, other: &ByteString) -> Ordering {
@@ -557,7 +557,7 @@ impl Ord for ByteString {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl PartialOrd for ByteString {
     #[inline]
     fn partial_cmp(&self, other: &ByteString) -> Option<Ordering> {
@@ -565,7 +565,7 @@ impl PartialOrd for ByteString {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl ToOwned for ByteStr {
     type Owned = ByteString;
 
@@ -575,7 +575,7 @@ impl ToOwned for ByteStr {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl TryFrom<ByteString> for String {
     type Error = crate::string::FromUtf8Error;
 
@@ -585,7 +585,7 @@ impl TryFrom<ByteString> for String {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl<'a> TryFrom<&'a ByteString> for &'a str {
     type Error = crate::str::Utf8Error;
 
@@ -597,7 +597,7 @@ impl<'a> TryFrom<&'a ByteString> for &'a str {
 
 // Additional impls for `ByteStr` that require types from `alloc`:
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl<A: Allocator + Clone> Clone for Box<ByteStr, A> {
     #[inline]
     fn clone(&self) -> Self {
@@ -605,7 +605,7 @@ impl<A: Allocator + Clone> Clone for Box<ByteStr, A> {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl<'a> From<&'a ByteStr> for Cow<'a, ByteStr> {
     #[inline]
     fn from(s: &'a ByteStr) -> Self {
@@ -613,7 +613,7 @@ impl<'a> From<&'a ByteStr> for Cow<'a, ByteStr> {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl From<Box<[u8]>> for Box<ByteStr> {
     #[inline]
     fn from(s: Box<[u8]>) -> Box<ByteStr> {
@@ -622,7 +622,7 @@ impl From<Box<[u8]>> for Box<ByteStr> {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl From<Box<ByteStr>> for Box<[u8]> {
     #[inline]
     fn from(s: Box<ByteStr>) -> Box<[u8]> {
@@ -631,7 +631,7 @@ impl From<Box<ByteStr>> for Box<[u8]> {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 #[cfg(not(no_rc))]
 impl From<Rc<[u8]>> for Rc<ByteStr> {
     #[inline]
@@ -641,7 +641,7 @@ impl From<Rc<[u8]>> for Rc<ByteStr> {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 #[cfg(not(no_rc))]
 impl From<Rc<ByteStr>> for Rc<[u8]> {
     #[inline]
@@ -651,7 +651,7 @@ impl From<Rc<ByteStr>> for Rc<[u8]> {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 #[cfg(all(not(no_rc), not(no_sync), target_has_atomic = "ptr"))]
 impl From<Arc<[u8]>> for Arc<ByteStr> {
     #[inline]
@@ -661,7 +661,7 @@ impl From<Arc<[u8]>> for Arc<ByteStr> {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 #[cfg(all(not(no_rc), not(no_sync), target_has_atomic = "ptr"))]
 impl From<Arc<ByteStr>> for Arc<[u8]> {
     #[inline]
@@ -679,7 +679,7 @@ impl_partial_eq_ord_cow!(&ByteStr, Cow<'_, ByteStr>);
 impl_partial_eq_ord_cow!(&ByteStr, Cow<'_, str>);
 impl_partial_eq_ord_cow!(&ByteStr, Cow<'_, [u8]>);
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl<'a> TryFrom<&'a ByteStr> for String {
     type Error = core::str::Utf8Error;
 
@@ -698,7 +698,7 @@ impl ByteStr {
     /// implementation for types that implement `Display`, and the trait version
     /// will use the Unicode replacement character rather than returning a
     /// `Result` and allowing for the possibility of the content not being UTF-8.
-    #[unstable(feature = "bstr_to_string", issue = "134915")]
+    #[unstable(feature = "byte_str_to_string", issue = "134915")]
     #[rustc_allow_incoherent_impl]
     pub fn to_string(&self) -> Result<String, Utf8Error> {
         // Avoid allocating a copy of the contents for invalid UTF-8
diff --git a/library/alloc/src/lib.rs b/library/alloc/src/lib.rs
index f95cb5c58eaeb..3c24cf7a6c102 100644
--- a/library/alloc/src/lib.rs
+++ b/library/alloc/src/lib.rs
@@ -95,8 +95,8 @@
 #![feature(async_fn_traits)]
 #![feature(async_iterator)]
 #![feature(borrowed_buf_init)]
-#![feature(bstr)]
-#![feature(bstr_internals)]
+#![feature(byte_str)]
+#![feature(byte_str_internals)]
 #![feature(can_vector)]
 #![feature(case_ignorable)]
 #![feature(cast_maybe_uninit)]
@@ -256,8 +256,8 @@ pub mod alloc;
 // to allow code to have `use boxed::Box;` declarations.
 pub mod borrow;
 pub mod boxed;
-#[unstable(feature = "bstr", issue = "134915")]
-pub mod bstr;
+#[unstable(feature = "byte_str", issue = "134915")]
+pub mod byte_str;
 pub mod collections;
 #[cfg(all(not(no_rc), not(no_sync), not(no_global_oom_handling)))]
 pub mod ffi;
diff --git a/library/alloctests/tests/bstr.rs b/library/alloctests/tests/byte_str.rs
similarity index 99%
rename from library/alloctests/tests/bstr.rs
rename to library/alloctests/tests/byte_str.rs
index 64a1b901f1300..f8484985d84fe 100644
--- a/library/alloctests/tests/bstr.rs
+++ b/library/alloctests/tests/byte_str.rs
@@ -1,4 +1,4 @@
-use alloc::bstr::ByteString;
+use alloc::byte_str::ByteString;
 use core::assert_matches;
 
 #[test]
diff --git a/library/alloctests/tests/lib.rs b/library/alloctests/tests/lib.rs
index 5c8ee92388dd0..291ee9ddff3ff 100644
--- a/library/alloctests/tests/lib.rs
+++ b/library/alloctests/tests/lib.rs
@@ -8,9 +8,9 @@
 #![feature(binary_heap_into_iter_sorted)]
 #![feature(binary_heap_pop_if)]
 #![feature(borrowed_buf_init)]
-#![feature(bstr)]
-#![feature(bstr_to_string)]
 #![feature(buf_read_has_data_left)]
+#![feature(byte_str)]
+#![feature(byte_str_to_string)]
 #![feature(can_vector)]
 #![feature(casefold)]
 #![feature(const_btree_len)]
@@ -72,8 +72,8 @@ mod arc;
 mod autotraits;
 mod borrow;
 mod boxed;
-mod bstr;
 mod btree_set_hash;
+mod byte_str;
 mod c_str;
 mod c_str2;
 mod collections;
diff --git a/library/core/src/arch.rs b/library/core/src/arch.rs
index 92ff55ecc75c0..570427f508554 100644
--- a/library/core/src/arch.rs
+++ b/library/core/src/arch.rs
@@ -80,6 +80,8 @@ pub macro global_asm("assembly template", $(operands,)* $(options($(option),*))?
 /// - On aarch64 targets, this produces a `brk #0xf000` instruction.
 // When adding more items above, also add cases to the test in `tests/assembly-llvm/breakpoint.rs`.
 // When stabilizing this, update the comment on `core::intrinsics::breakpoint`.
+// NOTE: there is an alternative in `process::resumable_breakpoint`. We may or may not
+// actually want to stabilize both of them.
 #[unstable(feature = "breakpoint", issue = "133724")]
 #[inline(always)]
 pub fn breakpoint() {
diff --git a/library/core/src/bstr/mod.rs b/library/core/src/byte_str/mod.rs
similarity index 85%
rename from library/core/src/bstr/mod.rs
rename to library/core/src/byte_str/mod.rs
index 0530ddc292a99..9ce00b813b6d8 100644
--- a/library/core/src/bstr/mod.rs
+++ b/library/core/src/byte_str/mod.rs
@@ -2,7 +2,7 @@
 
 mod traits;
 
-#[unstable(feature = "bstr_internals", issue = "none")]
+#[unstable(feature = "byte_str_internals", issue = "none")]
 pub use traits::{impl_partial_eq, impl_partial_eq_n, impl_partial_eq_ord};
 
 use crate::borrow::{Borrow, BorrowMut};
@@ -17,7 +17,7 @@ use crate::ops::{Deref, DerefMut, DerefPure};
 /// need to round-trip whatever data the user provides.
 ///
 /// For an owned, growable byte string buffer, use
-/// [`ByteString`](../../std/bstr/struct.ByteString.html).
+/// [`ByteString`](../../std/byte_str/struct.ByteString.html).
 ///
 /// `ByteStr` implements `Deref` to `[u8]`, so all methods available on `[u8]` are available on
 /// `ByteStr`.
@@ -37,7 +37,7 @@ use crate::ops::{Deref, DerefMut, DerefPure};
 ///
 /// The `Display` implementation behaves as if the `ByteStr` were first lossily converted to a
 /// `str`, with invalid UTF-8 presented as the Unicode replacement character (�).
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 #[rustc_has_incoherent_inherent_impls]
 #[repr(transparent)]
 #[doc(alias = "BStr")]
@@ -53,8 +53,8 @@ impl ByteStr {
     /// You can create a `ByteStr` from a byte array, a byte slice or a string slice:
     ///
     /// ```
-    /// # #![feature(bstr)]
-    /// # use std::bstr::ByteStr;
+    /// # #![feature(byte_str)]
+    /// # use std::byte_str::ByteStr;
     /// let a = ByteStr::new(b"abc");
     /// let b = ByteStr::new(&b"abc"[..]);
     /// let c = ByteStr::new("abc");
@@ -63,7 +63,7 @@ impl ByteStr {
     /// assert_eq!(a, c);
     /// ```
     #[inline]
-    #[unstable(feature = "bstr", issue = "134915")]
+    #[unstable(feature = "byte_str", issue = "134915")]
     #[rustc_const_unstable(feature = "const_convert", issue = "143773")]
     pub const fn new<B: ?Sized + [const] AsRef<[u8]>>(bytes: &B) -> &Self {
         ByteStr::from_bytes(bytes.as_ref())
@@ -76,7 +76,7 @@ impl ByteStr {
     /// for example `Box<ByteStr>` or `Arc<ByteStr>`.
     #[inline]
     // #[unstable(feature = "str_as_str", issue = "130366")]
-    #[unstable(feature = "bstr", issue = "134915")]
+    #[unstable(feature = "byte_str", issue = "134915")]
     pub const fn as_byte_str(&self) -> &ByteStr {
         self
     }
@@ -88,15 +88,15 @@ impl ByteStr {
     /// for example `Box<ByteStr>` or `MutexGuard<ByteStr>`.
     #[inline]
     // #[unstable(feature = "str_as_str", issue = "130366")]
-    #[unstable(feature = "bstr", issue = "134915")]
+    #[unstable(feature = "byte_str", issue = "134915")]
     pub const fn as_mut_byte_str(&mut self) -> &mut ByteStr {
         self
     }
 
     #[doc(hidden)]
-    #[unstable(feature = "bstr_internals", issue = "none")]
+    #[unstable(feature = "byte_str_internals", issue = "none")]
     #[inline]
-    #[rustc_const_unstable(feature = "bstr_internals", issue = "none")]
+    #[rustc_const_unstable(feature = "byte_str_internals", issue = "none")]
     pub const fn from_bytes(slice: &[u8]) -> &Self {
         // SAFETY: `ByteStr` is a transparent wrapper around `[u8]`, so we can turn a reference to
         // the wrapped type into a reference to the wrapper type.
@@ -104,9 +104,9 @@ impl ByteStr {
     }
 
     #[doc(hidden)]
-    #[unstable(feature = "bstr_internals", issue = "none")]
+    #[unstable(feature = "byte_str_internals", issue = "none")]
     #[inline]
-    #[rustc_const_unstable(feature = "bstr_internals", issue = "none")]
+    #[rustc_const_unstable(feature = "byte_str_internals", issue = "none")]
     pub const fn from_bytes_mut(slice: &mut [u8]) -> &mut Self {
         // SAFETY: `ByteStr` is a transparent wrapper around `[u8]`, so we can turn a reference to
         // the wrapped type into a reference to the wrapper type.
@@ -114,23 +114,23 @@ impl ByteStr {
     }
 
     #[doc(hidden)]
-    #[unstable(feature = "bstr_internals", issue = "none")]
+    #[unstable(feature = "byte_str_internals", issue = "none")]
     #[inline]
-    #[rustc_const_unstable(feature = "bstr_internals", issue = "none")]
+    #[rustc_const_unstable(feature = "byte_str_internals", issue = "none")]
     pub const fn as_bytes(&self) -> &[u8] {
         &self.0
     }
 
     #[doc(hidden)]
-    #[unstable(feature = "bstr_internals", issue = "none")]
+    #[unstable(feature = "byte_str_internals", issue = "none")]
     #[inline]
-    #[rustc_const_unstable(feature = "bstr_internals", issue = "none")]
+    #[rustc_const_unstable(feature = "byte_str_internals", issue = "none")]
     pub const fn as_bytes_mut(&mut self) -> &mut [u8] {
         &mut self.0
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 #[rustc_const_unstable(feature = "const_convert", issue = "143773")]
 const impl Deref for ByteStr {
     type Target = [u8];
@@ -141,7 +141,7 @@ const impl Deref for ByteStr {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 #[rustc_const_unstable(feature = "const_convert", issue = "143773")]
 const impl DerefMut for ByteStr {
     #[inline]
@@ -153,7 +153,7 @@ const impl DerefMut for ByteStr {
 #[unstable(feature = "deref_pure_trait", issue = "87121")]
 unsafe impl DerefPure for ByteStr {}
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl fmt::Debug for ByteStr {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(f, "\"")?;
@@ -172,7 +172,7 @@ impl fmt::Debug for ByteStr {
     }
 }
 
-#[unstable(feature = "bstr_to_string", issue = "134915")]
+#[unstable(feature = "byte_str_to_string", issue = "134915")]
 impl fmt::Display for ByteStr {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         fn emit(byte_str: &ByteStr, f: &mut fmt::Formatter<'_>) -> fmt::Result {
@@ -257,7 +257,7 @@ impl fmt::Display for ByteStr {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 #[rustc_const_unstable(feature = "const_convert", issue = "143773")]
 const impl AsRef<[u8]> for ByteStr {
     #[inline]
@@ -266,7 +266,7 @@ const impl AsRef<[u8]> for ByteStr {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 #[rustc_const_unstable(feature = "const_convert", issue = "143773")]
 const impl AsRef<ByteStr> for ByteStr {
     #[inline]
@@ -277,7 +277,7 @@ const impl AsRef<ByteStr> for ByteStr {
 
 // `impl AsRef<ByteStr> for [u8]` omitted to avoid widespread inference failures
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 #[rustc_const_unstable(feature = "const_convert", issue = "143773")]
 const impl AsRef<ByteStr> for str {
     #[inline]
@@ -286,7 +286,7 @@ const impl AsRef<ByteStr> for str {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 #[rustc_const_unstable(feature = "const_convert", issue = "143773")]
 const impl AsMut<[u8]> for ByteStr {
     #[inline]
@@ -301,7 +301,7 @@ const impl AsMut<[u8]> for ByteStr {
 
 // `impl Borrow<ByteStr> for str` omitted to avoid widespread inference failures
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 #[rustc_const_unstable(feature = "const_convert", issue = "143773")]
 const impl Borrow<[u8]> for ByteStr {
     #[inline]
@@ -312,7 +312,7 @@ const impl Borrow<[u8]> for ByteStr {
 
 // `impl BorrowMut<ByteStr> for [u8]` omitted to avoid widespread inference failures
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 #[rustc_const_unstable(feature = "const_convert", issue = "143773")]
 const impl BorrowMut<[u8]> for ByteStr {
     #[inline]
@@ -321,14 +321,14 @@ const impl BorrowMut<[u8]> for ByteStr {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl<'a> Default for &'a ByteStr {
     fn default() -> Self {
         ByteStr::from_bytes(b"")
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl<'a> Default for &'a mut ByteStr {
     fn default() -> Self {
         ByteStr::from_bytes_mut(&mut [])
@@ -337,7 +337,7 @@ impl<'a> Default for &'a mut ByteStr {
 
 // Omitted due to inference failures
 //
-// #[unstable(feature = "bstr", issue = "134915")]
+// #[unstable(feature = "byte_str", issue = "134915")]
 // impl<'a, const N: usize> From<&'a [u8; N]> for &'a ByteStr {
 //     #[inline]
 //     fn from(s: &'a [u8; N]) -> Self {
@@ -345,7 +345,7 @@ impl<'a> Default for &'a mut ByteStr {
 //     }
 // }
 //
-// #[unstable(feature = "bstr", issue = "134915")]
+// #[unstable(feature = "byte_str", issue = "134915")]
 // impl<'a> From<&'a [u8]> for &'a ByteStr {
 //     #[inline]
 //     fn from(s: &'a [u8]) -> Self {
@@ -355,7 +355,7 @@ impl<'a> Default for &'a mut ByteStr {
 
 // Omitted due to slice-from-array-issue-113238:
 //
-// #[unstable(feature = "bstr", issue = "134915")]
+// #[unstable(feature = "byte_str", issue = "134915")]
 // impl<'a> From<&'a ByteStr> for &'a [u8] {
 //     #[inline]
 //     fn from(s: &'a ByteStr) -> Self {
@@ -363,7 +363,7 @@ impl<'a> Default for &'a mut ByteStr {
 //     }
 // }
 //
-// #[unstable(feature = "bstr", issue = "134915")]
+// #[unstable(feature = "byte_str", issue = "134915")]
 // impl<'a> From<&'a mut ByteStr> for &'a mut [u8] {
 //     #[inline]
 //     fn from(s: &'a mut ByteStr) -> Self {
@@ -373,7 +373,7 @@ impl<'a> Default for &'a mut ByteStr {
 
 // Omitted due to inference failures
 //
-// #[unstable(feature = "bstr", issue = "134915")]
+// #[unstable(feature = "byte_str", issue = "134915")]
 // impl<'a> From<&'a str> for &'a ByteStr {
 //     #[inline]
 //     fn from(s: &'a str) -> Self {
@@ -381,7 +381,7 @@ impl<'a> Default for &'a mut ByteStr {
 //     }
 // }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 #[rustc_const_unstable(feature = "const_convert", issue = "143773")]
 const impl<'a> TryFrom<&'a ByteStr> for &'a str {
     type Error = crate::str::Utf8Error;
@@ -392,7 +392,7 @@ const impl<'a> TryFrom<&'a ByteStr> for &'a str {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 #[rustc_const_unstable(feature = "const_convert", issue = "143773")]
 const impl<'a> TryFrom<&'a mut ByteStr> for &'a mut str {
     type Error = crate::str::Utf8Error;
diff --git a/library/core/src/bstr/traits.rs b/library/core/src/byte_str/traits.rs
similarity index 86%
rename from library/core/src/bstr/traits.rs
rename to library/core/src/byte_str/traits.rs
index 6e9d836f1a1ff..93370ed7b0346 100644
--- a/library/core/src/bstr/traits.rs
+++ b/library/core/src/byte_str/traits.rs
@@ -1,11 +1,11 @@
 //! Trait implementations for `ByteStr`.
 
-use crate::bstr::ByteStr;
+use crate::byte_str::ByteStr;
 use crate::cmp::Ordering;
 use crate::slice::SliceIndex;
 use crate::{hash, ops, range};
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 #[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
 const impl Ord for ByteStr {
     #[inline]
@@ -14,7 +14,7 @@ const impl Ord for ByteStr {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 #[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
 const impl PartialOrd for ByteStr {
     #[inline]
@@ -23,7 +23,7 @@ const impl PartialOrd for ByteStr {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 #[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
 const impl PartialEq<ByteStr> for ByteStr {
     #[inline]
@@ -32,11 +32,11 @@ const impl PartialEq<ByteStr> for ByteStr {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 #[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
 const impl Eq for ByteStr {}
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl hash::Hash for ByteStr {
     #[inline]
     fn hash<H: hash::Hasher>(&self, state: &mut H) {
@@ -46,7 +46,7 @@ impl hash::Hash for ByteStr {
 
 #[doc(hidden)]
 #[macro_export]
-#[unstable(feature = "bstr_internals", issue = "none")]
+#[unstable(feature = "byte_str_internals", issue = "none")]
 macro_rules! impl_partial_eq {
     ($lhs:ty, $rhs:ty) => {
         impl PartialEq<$rhs> for $lhs {
@@ -68,17 +68,17 @@ macro_rules! impl_partial_eq {
 }
 
 #[doc(hidden)]
-#[unstable(feature = "bstr_internals", issue = "none")]
+#[unstable(feature = "byte_str_internals", issue = "none")]
 pub use impl_partial_eq;
 
 #[doc(hidden)]
 #[macro_export]
-#[unstable(feature = "bstr_internals", issue = "none")]
+#[unstable(feature = "byte_str_internals", issue = "none")]
 macro_rules! impl_partial_eq_ord {
     ($lhs:ty, $rhs:ty) => {
-        $crate::bstr::impl_partial_eq!($lhs, $rhs);
+        $crate::byte_str::impl_partial_eq!($lhs, $rhs);
 
-        #[unstable(feature = "bstr", issue = "134915")]
+        #[unstable(feature = "byte_str", issue = "134915")]
         impl PartialOrd<$rhs> for $lhs {
             #[inline]
             fn partial_cmp(&self, other: &$rhs) -> Option<Ordering> {
@@ -87,7 +87,7 @@ macro_rules! impl_partial_eq_ord {
             }
         }
 
-        #[unstable(feature = "bstr", issue = "134915")]
+        #[unstable(feature = "byte_str", issue = "134915")]
         impl PartialOrd<$lhs> for $rhs {
             #[inline]
             fn partial_cmp(&self, other: &$lhs) -> Option<Ordering> {
@@ -99,15 +99,15 @@ macro_rules! impl_partial_eq_ord {
 }
 
 #[doc(hidden)]
-#[unstable(feature = "bstr_internals", issue = "none")]
+#[unstable(feature = "byte_str_internals", issue = "none")]
 pub use impl_partial_eq_ord;
 
 #[doc(hidden)]
 #[macro_export]
-#[unstable(feature = "bstr_internals", issue = "none")]
+#[unstable(feature = "byte_str_internals", issue = "none")]
 macro_rules! impl_partial_eq_n {
     ($lhs:ty, $rhs:ty) => {
-        #[unstable(feature = "bstr", issue = "134915")]
+        #[unstable(feature = "byte_str", issue = "134915")]
         impl<const N: usize> PartialEq<$rhs> for $lhs {
             #[inline]
             fn eq(&self, other: &$rhs) -> bool {
@@ -116,7 +116,7 @@ macro_rules! impl_partial_eq_n {
             }
         }
 
-        #[unstable(feature = "bstr", issue = "134915")]
+        #[unstable(feature = "byte_str", issue = "134915")]
         impl<const N: usize> PartialEq<$lhs> for $rhs {
             #[inline]
             fn eq(&self, other: &$lhs) -> bool {
@@ -128,7 +128,7 @@ macro_rules! impl_partial_eq_n {
 }
 
 #[doc(hidden)]
-#[unstable(feature = "bstr_internals", issue = "none")]
+#[unstable(feature = "byte_str_internals", issue = "none")]
 pub use impl_partial_eq_n;
 
 // PartialOrd with `[u8]` omitted to avoid inference failures
@@ -144,7 +144,7 @@ impl_partial_eq_n!(ByteStr, [u8; N]);
 // PartialOrd with `[u8; N]` omitted to avoid inference failures
 impl_partial_eq_n!(ByteStr, &[u8; N]);
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl<I> ops::Index<I> for ByteStr
 where
     I: SliceIndex<ByteStr>,
@@ -157,7 +157,7 @@ where
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 impl<I> ops::IndexMut<I> for ByteStr
 where
     I: SliceIndex<ByteStr>,
@@ -168,7 +168,7 @@ where
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 unsafe impl SliceIndex<ByteStr> for ops::RangeFull {
     type Output = ByteStr;
     #[inline]
@@ -197,7 +197,7 @@ unsafe impl SliceIndex<ByteStr> for ops::RangeFull {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
+#[unstable(feature = "byte_str", issue = "134915")]
 unsafe impl SliceIndex<ByteStr> for usize {
     type Output = u8;
     #[inline]
@@ -230,7 +230,7 @@ unsafe impl SliceIndex<ByteStr> for usize {
 
 macro_rules! impl_slice_index {
     ($index:ty) => {
-        #[unstable(feature = "bstr", issue = "134915")]
+        #[unstable(feature = "byte_str", issue = "134915")]
         unsafe impl SliceIndex<ByteStr> for $index {
             type Output = ByteStr;
             #[inline]
diff --git a/library/core/src/clone.rs b/library/core/src/clone.rs
index bd6d929c6d2b0..61528873a38c7 100644
--- a/library/core/src/clone.rs
+++ b/library/core/src/clone.rs
@@ -686,8 +686,8 @@ unsafe impl CloneToUninit for crate::ffi::CStr {
     }
 }
 
-#[unstable(feature = "bstr", issue = "134915")]
-unsafe impl CloneToUninit for crate::bstr::ByteStr {
+#[unstable(feature = "byte_str", issue = "134915")]
+unsafe impl CloneToUninit for crate::byte_str::ByteStr {
     #[inline]
     #[cfg_attr(debug_assertions, track_caller)]
     unsafe fn clone_to_uninit(&self, dst: *mut u8) {
diff --git a/library/core/src/ffi/c_str.rs b/library/core/src/ffi/c_str.rs
index daa68e885d893..8dcabacd2c7fd 100644
--- a/library/core/src/ffi/c_str.rs
+++ b/library/core/src/ffi/c_str.rs
@@ -173,7 +173,7 @@ impl fmt::Display for FromBytesUntilNulError {
 #[stable(feature = "cstr_debug", since = "1.3.0")]
 impl fmt::Debug for CStr {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        fmt::Debug::fmt(crate::bstr::ByteStr::from_bytes(self.to_bytes()), f)
+        fmt::Debug::fmt(crate::byte_str::ByteStr::from_bytes(self.to_bytes()), f)
     }
 }
 
@@ -889,6 +889,6 @@ impl fmt::Debug for Display<'_> {
 #[stable(feature = "cstr_display", since = "CURRENT_RUSTC_VERSION")]
 impl fmt::Display for Display<'_> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        fmt::Display::fmt(crate::bstr::ByteStr::from_bytes(self.c_str.to_bytes()), f)
+        fmt::Display::fmt(crate::byte_str::ByteStr::from_bytes(self.c_str.to_bytes()), f)
     }
 }
diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
index ff63e10a67d58..4974f62f15bcd 100644
--- a/library/core/src/lib.rs
+++ b/library/core/src/lib.rs
@@ -86,7 +86,7 @@
 // Library features:
 // tidy-alphabetical-start
 #![feature(asm_experimental_arch)]
-#![feature(bstr_internals)]
+#![feature(byte_str_internals)]
 #![feature(cfg_target_has_reliable_f16_f128)]
 #![feature(const_carrying_mul_add)]
 #![feature(const_cmp)]
@@ -295,8 +295,8 @@ pub mod ascii;
 pub mod asserting;
 #[unstable(feature = "async_iterator", issue = "79024")]
 pub mod async_iter;
-#[unstable(feature = "bstr", issue = "134915")]
-pub mod bstr;
+#[unstable(feature = "byte_str", issue = "134915")]
+pub mod byte_str;
 pub mod cell;
 pub mod char;
 pub mod ffi;
diff --git a/library/core/src/process.rs b/library/core/src/process.rs
index 1c2769f07895b..e92339f34d68e 100644
--- a/library/core/src/process.rs
+++ b/library/core/src/process.rs
@@ -42,3 +42,22 @@
 pub const fn abort_immediate() -> ! {
     crate::intrinsics::abort_immediate()
 }
+
+/// Triggers a debugger breakpoint, pausing execution if possible.
+///
+/// This signals the environment to pause execution if a debugger is attached, and pass control to
+/// the debugger. Execution may then be aborted or continued by the user controlling the debugger.
+///
+/// If possible, this will produce an instruction sequence that allows a debugger to resume *after*
+/// the breakpoint, rather than resuming *at* the breakpoint; however, the exact behavior is
+/// target-specific and debugger-specific, and not guaranteed.
+///
+/// If no debugger is attached, this will typically abort the process but may also continue
+/// execution.
+// NOTE: this is meant to discuss alternatives to `arch::breakpoint`. We may or may not
+// actually want to stabilize both of them.
+#[unstable(feature = "breakpoint", issue = "133724")]
+#[inline(always)]
+pub fn resumable_breakpoint() {
+    crate::intrinsics::breakpoint();
+}
diff --git a/library/coretests/tests/bstr.rs b/library/coretests/tests/byte_str.rs
similarity index 99%
rename from library/coretests/tests/bstr.rs
rename to library/coretests/tests/byte_str.rs
index dffc7e3f03494..bc90b348446bf 100644
--- a/library/coretests/tests/bstr.rs
+++ b/library/coretests/tests/byte_str.rs
@@ -1,4 +1,4 @@
-use core::bstr::ByteStr;
+use core::byte_str::ByteStr;
 
 #[test]
 fn test_debug() {
diff --git a/library/coretests/tests/lib.rs b/library/coretests/tests/lib.rs
index 1fdb0c820d662..9054f9331f7bf 100644
--- a/library/coretests/tests/lib.rs
+++ b/library/coretests/tests/lib.rs
@@ -10,7 +10,7 @@
 #![feature(async_iterator)]
 #![feature(atomic_volatile)]
 #![feature(borrowed_buf_init)]
-#![feature(bstr)]
+#![feature(byte_str)]
 #![feature(casefold)]
 #![feature(cfg_overflow_checks)]
 #![feature(cfg_target_has_reliable_f16_f128)]
@@ -179,7 +179,7 @@ mod asserting;
 mod async_iter;
 mod atomic;
 mod bool;
-mod bstr;
+mod byte_str;
 mod cell;
 mod char;
 mod clone;
diff --git a/library/std/src/bstr.rs b/library/std/src/bstr.rs
deleted file mode 100644
index dd49177162833..0000000000000
--- a/library/std/src/bstr.rs
+++ /dev/null
@@ -1,4 +0,0 @@
-//! The `ByteStr` and `ByteString` types and trait implementations.
-
-#[unstable(feature = "bstr", issue = "134915")]
-pub use alloc::bstr::{ByteStr, ByteString};
diff --git a/library/std/src/byte_str.rs b/library/std/src/byte_str.rs
new file mode 100644
index 0000000000000..48703b52ece21
--- /dev/null
+++ b/library/std/src/byte_str.rs
@@ -0,0 +1,4 @@
+//! The `ByteStr` and `ByteString` types and trait implementations.
+
+#[unstable(feature = "byte_str", issue = "134915")]
+pub use alloc::byte_str::{ByteStr, ByteString};
diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs
index 773049d0ff6c4..0d0d9e0759d82 100644
--- a/library/std/src/lib.rs
+++ b/library/std/src/lib.rs
@@ -317,8 +317,8 @@
 // Library features (core):
 // tidy-alphabetical-start
 #![feature(borrowed_buf_init)]
-#![feature(bstr)]
-#![feature(bstr_internals)]
+#![feature(byte_str)]
+#![feature(byte_str_internals)]
 #![feature(c_size_t)]
 #![feature(can_vector)]
 #![feature(cast_maybe_uninit)]
@@ -625,8 +625,8 @@ pub mod f64;
 pub mod thread;
 pub mod ascii;
 pub mod backtrace;
-#[unstable(feature = "bstr", issue = "134915")]
-pub mod bstr;
+#[unstable(feature = "byte_str", issue = "134915")]
+pub mod byte_str;
 pub mod collections;
 pub mod env;
 pub mod error;
diff --git a/library/std/src/os/unix/net/addr.rs b/library/std/src/os/unix/net/addr.rs
index 0520da62ffae9..b03b359cdea91 100644
--- a/library/std/src/os/unix/net/addr.rs
+++ b/library/std/src/os/unix/net/addr.rs
@@ -1,4 +1,4 @@
-use crate::bstr::ByteStr;
+use crate::byte_str::ByteStr;
 use crate::ffi::OsStr;
 #[cfg(any(doc, target_os = "android", target_os = "linux", target_os = "cygwin"))]
 use crate::os::net::linux_ext;
diff --git a/library/std/src/os/windows/net/addr.rs b/library/std/src/os/windows/net/addr.rs
index c330432039a8f..5f6b93e56e723 100644
--- a/library/std/src/os/windows/net/addr.rs
+++ b/library/std/src/os/windows/net/addr.rs
@@ -1,5 +1,5 @@
 #![unstable(feature = "windows_unix_domain_sockets", issue = "150487")]
-use crate::bstr::ByteStr;
+use crate::byte_str::ByteStr;
 use crate::ffi::OsStr;
 use crate::path::Path;
 #[cfg(not(doc))]
diff --git a/library/std/src/sys/os_str/bytes.rs b/library/std/src/sys/os_str/bytes.rs
index 048e5def1369b..040a9568ca1f6 100644
--- a/library/std/src/sys/os_str/bytes.rs
+++ b/library/std/src/sys/os_str/bytes.rs
@@ -4,7 +4,7 @@
 use core::clone::CloneToUninit;
 
 use crate::borrow::Cow;
-use crate::bstr::ByteStr;
+use crate::byte_str::ByteStr;
 use crate::collections::TryReserveError;
 use crate::rc::Rc;
 use crate::sync::Arc;
diff --git a/library/std/src/sys/platform_version/darwin/mod.rs b/library/std/src/sys/platform_version/darwin/mod.rs
index 4756716452c88..7e82c04fce76c 100644
--- a/library/std/src/sys/platform_version/darwin/mod.rs
+++ b/library/std/src/sys/platform_version/darwin/mod.rs
@@ -3,7 +3,7 @@ use self::core_foundation::{
     kCFPropertyListImmutable, kCFStringEncodingUTF8,
 };
 use crate::borrow::Cow;
-use crate::bstr::ByteStr;
+use crate::byte_str::ByteStr;
 use crate::ffi::{CStr, c_char};
 use crate::num::{NonZero, ParseIntError};
 use crate::path::{Path, PathBuf};
diff --git a/src/tools/linkchecker/main.rs b/src/tools/linkchecker/main.rs
index 0d3870f456a07..e5187f7655940 100644
--- a/src/tools/linkchecker/main.rs
+++ b/src/tools/linkchecker/main.rs
@@ -51,7 +51,7 @@ const LINKCHECK_EXCEPTIONS: &[(&str, &[&str])] = &[
     ("alloc/slice/trait.Concat.html", &["#method.concat"]),
     ("alloc/slice/index.html", &["#method.concat", "#method.join"]),
     ("alloc/vec/struct.Vec.html", &["#method.sort_by_key", "#method.sort_by_cached_key"]),
-    ("alloc/bstr/struct.ByteStr.html", &[
+    ("alloc/byte_str/struct.ByteStr.html", &[
         "#method.to_ascii_uppercase",
         "#method.to_ascii_lowercase",
         "core/slice::sort_by_key",
@@ -59,7 +59,7 @@ const LINKCHECK_EXCEPTIONS: &[(&str, &[&str])] = &[
         "#method.sort_by_cached_key",
         "#method.sort_by_key"
     ]),
-    ("alloc/bstr/struct.ByteString.html", &[
+    ("alloc/byte_str/struct.ByteString.html", &[
         "#method.to_ascii_uppercase",
         "#method.to_ascii_lowercase",
         "core/slice::sort_by_key",
@@ -67,11 +67,11 @@ const LINKCHECK_EXCEPTIONS: &[(&str, &[&str])] = &[
         "#method.sort_by_cached_key",
         "#method.sort_by_key"
     ]),
-    ("core/bstr/struct.ByteStr.html", &[
+    ("core/byte_str/struct.ByteStr.html", &[
         "#method.to_ascii_uppercase",
         "#method.to_ascii_lowercase",
-        "core/bstr/slice::sort_by_key",
-        "core\\bstr\\slice::sort_by_key",
+        "core/byte_str/slice::sort_by_key",
+        "core\\byte_str\\slice::sort_by_key",
         "#method.sort_by_cached_key"
     ]),
     ("core/primitive.str.html", &["#method.to_ascii_uppercase", "#method.to_ascii_lowercase"]),
diff --git a/src/tools/miri/src/helpers.rs b/src/tools/miri/src/helpers.rs
index f923d5529c6b9..26f2a8a459f79 100644
--- a/src/tools/miri/src/helpers.rs
+++ b/src/tools/miri/src/helpers.rs
@@ -421,9 +421,13 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
             None => MPlaceTy::fake_alloc_zst(this.machine.layouts.unit),
         };
 
+        let with_caller_location = f.def.requires_caller_location(*this.tcx);
+
         // Construct a function pointer type representing the caller perspective.
         let sig = this.tcx.mk_fn_sig(
-            args.iter().map(|a| a.layout.ty),
+            args.iter()
+                .map(|a| a.layout.ty)
+                .chain(with_caller_location.then(|| this.tcx.caller_location_ty())),
             dest.layout.ty,
             // FIXME(splat): Do we need to set splatted here?
             // (Currently this also ignores c_variadic)
@@ -437,7 +441,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
             mir,
             caller_fn_abi,
             &args.iter().map(|a| FnArg::Copy(a.clone().into())).collect::<Vec<_>>(),
-            /*with_caller_location*/ false,
+            with_caller_location,
             &dest.into(),
             cont,
         )
diff --git a/src/tools/miri/tests/fail/extern-extra-track-caller.rs b/src/tools/miri/tests/fail/extern-extra-track-caller.rs
new file mode 100644
index 0000000000000..0396399f9d825
--- /dev/null
+++ b/src/tools/miri/tests/fail/extern-extra-track-caller.rs
@@ -0,0 +1,15 @@
+unsafe extern "Rust" {
+    #[track_caller]
+    safe fn foo();
+}
+
+fn main() {
+    foo(); //~ERROR: calling a non-`#[track_caller]` function from a `#[track_caller]` declaration
+}
+
+mod module {
+    #[unsafe(no_mangle)]
+    fn foo() {
+        panic!();
+    }
+}
diff --git a/src/tools/miri/tests/fail/extern-extra-track-caller.stderr b/src/tools/miri/tests/fail/extern-extra-track-caller.stderr
new file mode 100644
index 0000000000000..c5c45a2ddca58
--- /dev/null
+++ b/src/tools/miri/tests/fail/extern-extra-track-caller.stderr
@@ -0,0 +1,13 @@
+error: Undefined Behavior: calling a non-`#[track_caller]` function from a `#[track_caller]` declaration
+  --> tests/fail/extern-extra-track-caller.rs:LL:CC
+   |
+LL |     foo();
+   |     ^^^^^ Undefined Behavior occurred here
+   |
+   = 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: 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/fail/extern-missing-track-caller.rs b/src/tools/miri/tests/fail/extern-missing-track-caller.rs
new file mode 100644
index 0000000000000..a10bb03670ec1
--- /dev/null
+++ b/src/tools/miri/tests/fail/extern-missing-track-caller.rs
@@ -0,0 +1,15 @@
+unsafe extern "Rust" {
+    safe fn foo();
+}
+
+fn main() {
+    foo(); //~ERROR: calling a `#[track_caller]` function from a non-`#[track_caller]` declaration
+}
+
+mod module {
+    #[unsafe(no_mangle)]
+    #[track_caller]
+    fn foo() {
+        panic!();
+    }
+}
diff --git a/src/tools/miri/tests/fail/extern-missing-track-caller.stderr b/src/tools/miri/tests/fail/extern-missing-track-caller.stderr
new file mode 100644
index 0000000000000..40d0c8165728f
--- /dev/null
+++ b/src/tools/miri/tests/fail/extern-missing-track-caller.stderr
@@ -0,0 +1,13 @@
+error: Undefined Behavior: calling a `#[track_caller]` function from a non-`#[track_caller]` declaration
+  --> tests/fail/extern-missing-track-caller.rs:LL:CC
+   |
+LL |     foo();
+   |     ^^^^^ Undefined Behavior occurred here
+   |
+   = 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: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
+
+error: aborting due to 1 previous error
+
diff --git a/tests/crashes/131787.rs b/tests/crashes/131787.rs
deleted file mode 100644
index 5c24ff8c14303..0000000000000
--- a/tests/crashes/131787.rs
+++ /dev/null
@@ -1,5 +0,0 @@
-//@ known-bug: #131787
-#[track_caller]
-static no_mangle: u32 = {
-    unimplemented!();
-};
diff --git a/tests/ui/attributes/issue-105594-invalid-attr-validation.rs b/tests/ui/attributes/issue-105594-invalid-attr-validation.rs
index f9e01cd1507ec..4f3f4993648cb 100644
--- a/tests/ui/attributes/issue-105594-invalid-attr-validation.rs
+++ b/tests/ui/attributes/issue-105594-invalid-attr-validation.rs
@@ -4,4 +4,4 @@
 fn main() {}
 
 #[track_caller] //~ ERROR attribute cannot be used on
-static _A: () = ();
+static _A: () = panic!();
diff --git a/tests/ui/indexing/index-help.stderr b/tests/ui/indexing/index-help.stderr
index 65faaec41258e..d40d511ab5a2f 100644
--- a/tests/ui/indexing/index-help.stderr
+++ b/tests/ui/indexing/index-help.stderr
@@ -9,7 +9,7 @@ help: `usize` implements trait `SliceIndex<T>`
   --> $SRC_DIR/core/src/slice/index.rs:LL:COL
    |
    = note: `SliceIndex<[T]>`
-  --> $SRC_DIR/core/src/bstr/traits.rs:LL:COL
+  --> $SRC_DIR/core/src/byte_str/traits.rs:LL:COL
    |
    = note: `SliceIndex<ByteStr>`
    = note: required for `Vec<{integer}>` to implement `Index<i32>`
diff --git a/tests/ui/indexing/indexing-integral-types.stderr b/tests/ui/indexing/indexing-integral-types.stderr
index 604161325afcb..9577444703f83 100644
--- a/tests/ui/indexing/indexing-integral-types.stderr
+++ b/tests/ui/indexing/indexing-integral-types.stderr
@@ -9,7 +9,7 @@ help: `usize` implements trait `SliceIndex<T>`
   --> $SRC_DIR/core/src/slice/index.rs:LL:COL
    |
    = note: `SliceIndex<[T]>`
-  --> $SRC_DIR/core/src/bstr/traits.rs:LL:COL
+  --> $SRC_DIR/core/src/byte_str/traits.rs:LL:COL
    |
    = note: `SliceIndex<ByteStr>`
    = note: required for `Vec<isize>` to implement `Index<u8>`
@@ -25,7 +25,7 @@ help: `usize` implements trait `SliceIndex<T>`
   --> $SRC_DIR/core/src/slice/index.rs:LL:COL
    |
    = note: `SliceIndex<[T]>`
-  --> $SRC_DIR/core/src/bstr/traits.rs:LL:COL
+  --> $SRC_DIR/core/src/byte_str/traits.rs:LL:COL
    |
    = note: `SliceIndex<ByteStr>`
    = note: required for `Vec<isize>` to implement `Index<i8>`
@@ -41,7 +41,7 @@ help: `usize` implements trait `SliceIndex<T>`
   --> $SRC_DIR/core/src/slice/index.rs:LL:COL
    |
    = note: `SliceIndex<[T]>`
-  --> $SRC_DIR/core/src/bstr/traits.rs:LL:COL
+  --> $SRC_DIR/core/src/byte_str/traits.rs:LL:COL
    |
    = note: `SliceIndex<ByteStr>`
    = note: required for `Vec<isize>` to implement `Index<u32>`
@@ -57,7 +57,7 @@ help: `usize` implements trait `SliceIndex<T>`
   --> $SRC_DIR/core/src/slice/index.rs:LL:COL
    |
    = note: `SliceIndex<[T]>`
-  --> $SRC_DIR/core/src/bstr/traits.rs:LL:COL
+  --> $SRC_DIR/core/src/byte_str/traits.rs:LL:COL
    |
    = note: `SliceIndex<ByteStr>`
    = note: required for `Vec<isize>` to implement `Index<i32>`
@@ -73,7 +73,7 @@ help: `usize` implements trait `SliceIndex<T>`
   --> $SRC_DIR/core/src/slice/index.rs:LL:COL
    |
    = note: `SliceIndex<[T]>`
-  --> $SRC_DIR/core/src/bstr/traits.rs:LL:COL
+  --> $SRC_DIR/core/src/byte_str/traits.rs:LL:COL
    |
    = note: `SliceIndex<ByteStr>`
    = note: required for `[u8]` to implement `Index<u8>`
@@ -89,7 +89,7 @@ help: `usize` implements trait `SliceIndex<T>`
   --> $SRC_DIR/core/src/slice/index.rs:LL:COL
    |
    = note: `SliceIndex<[T]>`
-  --> $SRC_DIR/core/src/bstr/traits.rs:LL:COL
+  --> $SRC_DIR/core/src/byte_str/traits.rs:LL:COL
    |
    = note: `SliceIndex<ByteStr>`
    = note: required for `[u8]` to implement `Index<i8>`
@@ -105,7 +105,7 @@ help: `usize` implements trait `SliceIndex<T>`
   --> $SRC_DIR/core/src/slice/index.rs:LL:COL
    |
    = note: `SliceIndex<[T]>`
-  --> $SRC_DIR/core/src/bstr/traits.rs:LL:COL
+  --> $SRC_DIR/core/src/byte_str/traits.rs:LL:COL
    |
    = note: `SliceIndex<ByteStr>`
    = note: required for `[u8]` to implement `Index<u32>`
@@ -121,7 +121,7 @@ help: `usize` implements trait `SliceIndex<T>`
   --> $SRC_DIR/core/src/slice/index.rs:LL:COL
    |
    = note: `SliceIndex<[T]>`
-  --> $SRC_DIR/core/src/bstr/traits.rs:LL:COL
+  --> $SRC_DIR/core/src/byte_str/traits.rs:LL:COL
    |
    = note: `SliceIndex<ByteStr>`
    = note: required for `[u8]` to implement `Index<i32>`
diff --git a/tests/ui/indexing/indexing-requires-a-uint.stderr b/tests/ui/indexing/indexing-requires-a-uint.stderr
index 9e974c8c9bbcc..5c93fcd948a24 100644
--- a/tests/ui/indexing/indexing-requires-a-uint.stderr
+++ b/tests/ui/indexing/indexing-requires-a-uint.stderr
@@ -9,7 +9,7 @@ help: `usize` implements trait `SliceIndex<T>`
   --> $SRC_DIR/core/src/slice/index.rs:LL:COL
    |
    = note: `SliceIndex<[T]>`
-  --> $SRC_DIR/core/src/bstr/traits.rs:LL:COL
+  --> $SRC_DIR/core/src/byte_str/traits.rs:LL:COL
    |
    = note: `SliceIndex<ByteStr>`
    = note: required for `[{integer}]` to implement `Index<u8>`
diff --git a/tests/ui/on-unimplemented/slice-index.stderr b/tests/ui/on-unimplemented/slice-index.stderr
index 61d4866f5618b..a5a3d8c000e76 100644
--- a/tests/ui/on-unimplemented/slice-index.stderr
+++ b/tests/ui/on-unimplemented/slice-index.stderr
@@ -9,7 +9,7 @@ help: `usize` implements trait `SliceIndex<T>`
   --> $SRC_DIR/core/src/slice/index.rs:LL:COL
    |
    = note: `SliceIndex<[T]>`
-  --> $SRC_DIR/core/src/bstr/traits.rs:LL:COL
+  --> $SRC_DIR/core/src/byte_str/traits.rs:LL:COL
    |
    = note: `SliceIndex<ByteStr>`
    = note: required for `[i32]` to implement `Index<i32>`
@@ -25,10 +25,10 @@ help: `RangeTo<usize>` implements trait `SliceIndex<T>`
   --> $SRC_DIR/core/src/slice/index.rs:LL:COL
    |
    = note: `SliceIndex<[T]>`
-  --> $SRC_DIR/core/src/bstr/traits.rs:LL:COL
+  --> $SRC_DIR/core/src/byte_str/traits.rs:LL:COL
    |
    = note: `SliceIndex<ByteStr>`
-  ::: $SRC_DIR/core/src/bstr/traits.rs:LL:COL
+  ::: $SRC_DIR/core/src/byte_str/traits.rs:LL:COL
    |
    = note: in this macro invocation
   --> $SRC_DIR/core/src/str/traits.rs:LL:COL
diff --git a/tests/ui/str/str-idx.stderr b/tests/ui/str/str-idx.stderr
index 84f698a6e6625..b515a2e9dfb76 100644
--- a/tests/ui/str/str-idx.stderr
+++ b/tests/ui/str/str-idx.stderr
@@ -11,7 +11,7 @@ help: `usize` implements trait `SliceIndex<T>`
   --> $SRC_DIR/core/src/slice/index.rs:LL:COL
    |
    = note: `SliceIndex<[T]>`
-  --> $SRC_DIR/core/src/bstr/traits.rs:LL:COL
+  --> $SRC_DIR/core/src/byte_str/traits.rs:LL:COL
    |
    = note: `SliceIndex<ByteStr>`
    = note: required for `str` to implement `Index<{integer}>`
@@ -31,7 +31,7 @@ help: `usize` implements trait `SliceIndex<T>`
   --> $SRC_DIR/core/src/slice/index.rs:LL:COL
    |
    = note: `SliceIndex<[T]>`
-  --> $SRC_DIR/core/src/bstr/traits.rs:LL:COL
+  --> $SRC_DIR/core/src/byte_str/traits.rs:LL:COL
    |
    = note: `SliceIndex<ByteStr>`
 note: required by a bound in `core::str::<impl str>::get`
@@ -52,7 +52,7 @@ help: `usize` implements trait `SliceIndex<T>`
   --> $SRC_DIR/core/src/slice/index.rs:LL:COL
    |
    = note: `SliceIndex<[T]>`
-  --> $SRC_DIR/core/src/bstr/traits.rs:LL:COL
+  --> $SRC_DIR/core/src/byte_str/traits.rs:LL:COL
    |
    = note: `SliceIndex<ByteStr>`
 note: required by a bound in `core::str::<impl str>::get_unchecked`
diff --git a/tests/ui/str/str-mut-idx.stderr b/tests/ui/str/str-mut-idx.stderr
index 87b78915075d2..89582c437c917 100644
--- a/tests/ui/str/str-mut-idx.stderr
+++ b/tests/ui/str/str-mut-idx.stderr
@@ -35,7 +35,7 @@ help: `usize` implements trait `SliceIndex<T>`
   --> $SRC_DIR/core/src/slice/index.rs:LL:COL
    |
    = note: `SliceIndex<[T]>`
-  --> $SRC_DIR/core/src/bstr/traits.rs:LL:COL
+  --> $SRC_DIR/core/src/byte_str/traits.rs:LL:COL
    |
    = note: `SliceIndex<ByteStr>`
    = note: required for `str` to implement `Index<usize>`
@@ -55,7 +55,7 @@ help: `usize` implements trait `SliceIndex<T>`
   --> $SRC_DIR/core/src/slice/index.rs:LL:COL
    |
    = note: `SliceIndex<[T]>`
-  --> $SRC_DIR/core/src/bstr/traits.rs:LL:COL
+  --> $SRC_DIR/core/src/byte_str/traits.rs:LL:COL
    |
    = note: `SliceIndex<ByteStr>`
 note: required by a bound in `core::str::<impl str>::get_mut`
@@ -76,7 +76,7 @@ help: `usize` implements trait `SliceIndex<T>`
   --> $SRC_DIR/core/src/slice/index.rs:LL:COL
    |
    = note: `SliceIndex<[T]>`
-  --> $SRC_DIR/core/src/bstr/traits.rs:LL:COL
+  --> $SRC_DIR/core/src/byte_str/traits.rs:LL:COL
    |
    = note: `SliceIndex<ByteStr>`
 note: required by a bound in `core::str::<impl str>::get_unchecked_mut`
diff --git a/tests/ui/suggestions/suggest-dereferencing-index.stderr b/tests/ui/suggestions/suggest-dereferencing-index.stderr
index cee5ffcb2ae8c..7bf3b4ffaf275 100644
--- a/tests/ui/suggestions/suggest-dereferencing-index.stderr
+++ b/tests/ui/suggestions/suggest-dereferencing-index.stderr
@@ -9,7 +9,7 @@ help: `usize` implements trait `SliceIndex<T>`
   --> $SRC_DIR/core/src/slice/index.rs:LL:COL
    |
    = note: `SliceIndex<[T]>`
-  --> $SRC_DIR/core/src/bstr/traits.rs:LL:COL
+  --> $SRC_DIR/core/src/byte_str/traits.rs:LL:COL
    |
    = note: `SliceIndex<ByteStr>`
    = note: required for `[{integer}]` to implement `Index<&usize>`
diff --git a/tests/ui/suggestions/suggest-remove-reference-index.stderr b/tests/ui/suggestions/suggest-remove-reference-index.stderr
index 4f396fe529508..f435dfa54db06 100644
--- a/tests/ui/suggestions/suggest-remove-reference-index.stderr
+++ b/tests/ui/suggestions/suggest-remove-reference-index.stderr
@@ -9,7 +9,7 @@ help: `usize` implements trait `SliceIndex<T>`
   --> $SRC_DIR/core/src/slice/index.rs:LL:COL
    |
    = note: `SliceIndex<[T]>`
-  --> $SRC_DIR/core/src/bstr/traits.rs:LL:COL
+  --> $SRC_DIR/core/src/byte_str/traits.rs:LL:COL
    |
    = note: `SliceIndex<ByteStr>`
    = note: required for `[bool]` to implement `Index<&usize>`
@@ -30,7 +30,7 @@ help: `usize` implements trait `SliceIndex<T>`
   --> $SRC_DIR/core/src/slice/index.rs:LL:COL
    |
    = note: `SliceIndex<[T]>`
-  --> $SRC_DIR/core/src/bstr/traits.rs:LL:COL
+  --> $SRC_DIR/core/src/byte_str/traits.rs:LL:COL
    |
    = note: `SliceIndex<ByteStr>`
    = note: required for `[bool]` to implement `Index<&usize>`
@@ -51,7 +51,7 @@ help: `usize` implements trait `SliceIndex<T>`
   --> $SRC_DIR/core/src/slice/index.rs:LL:COL
    |
    = note: `SliceIndex<[T]>`
-  --> $SRC_DIR/core/src/bstr/traits.rs:LL:COL
+  --> $SRC_DIR/core/src/byte_str/traits.rs:LL:COL
    |
    = note: `SliceIndex<ByteStr>`
    = note: required for `[bool]` to implement `Index<&usize>`