adjust how backtraces get rendered; always show thread name when there are multiple threads

src/tools/miri/src/diagnostics.rs

@@ -250,7 +250,7 @@ pub fn report_result<'tcx>(
             StackedBorrowsUb { .. } | TreeBorrowsUb { .. } | DataRace { .. } =>
                 Some("Undefined Behavior"),
             LocalDeadlock => {
-                labels.push(format!("this thread got stuck here"));
+                labels.push(format!("thread got stuck here"));
                 None
             }
             GlobalDeadlock => {
@@ -264,10 +264,7 @@ pub fn report_result<'tcx>(
                     report_msg(
                         DiagLevel::Error,
                         format!("the evaluated program deadlocked"),
-                        vec![format!(
-                            "thread `{}` got stuck here",
-                            ecx.machine.threads.get_thread_display_name(thread)
-                        )],
+                        vec![format!("thread got stuck here")],
                         vec![],
                         vec![],
                         &stacktrace,
@@ -563,6 +560,7 @@ fn report_msg<'tcx>(
         None =>
             match thread {
                 Some(thread_id) => machine.threads.thread_ref(thread_id).origin_span,
+                // This fallback is super rare, but can happen e.g. when `main` has the wrong ABI
                 None => DUMMY_SP,
             },
     };
@@ -608,36 +606,53 @@ fn report_msg<'tcx>(
     }
 
     // Add backtrace
-    if stacktrace.len() > 1 {
-        let mut backtrace_title = String::from("BACKTRACE");
-        if extra_span {
-            write!(backtrace_title, " (of the first span)").unwrap();
+    if let Some((first, rest)) = stacktrace.split_first() {
+        // Start with the function and thread that contain the first span.
+        let mut fn_and_thread = String::new();
+        // Only print thread name if there are multiple threads.
+        if let Some(thread) = thread
+            && machine.threads.get_total_thread_count() > 1
+        {
+            write!(
+                fn_and_thread,
+                "on thread `{}`",
+                machine.threads.get_thread_display_name(thread)
+            )
+            .unwrap();
         }
-        if let Some(thread) = thread {
-            let thread_name = machine.threads.get_thread_display_name(thread);
-            if thread_name != "main" {
-                // Only print thread name if it is not `main`.
-                write!(backtrace_title, " on thread `{thread_name}`").unwrap();
-            };
+        // Only print function name if we show a backtrace
+        if rest.len() > 0 {
+            if !fn_and_thread.is_empty() {
+                fn_and_thread.push_str(", ");
+            }
+            write!(fn_and_thread, "{first}").unwrap();
         }
-        write!(backtrace_title, ":").unwrap();
-        err.note(backtrace_title);
-        for (idx, frame_info) in stacktrace.iter().enumerate() {
+        if !fn_and_thread.is_empty() {
+            if extra_span && rest.len() > 0 {
+                // Print a `span_note` as otherwise the backtrace looks attached to the last
+                // `span_help`. We somewhat arbitrarily use the span of the surrounding function.
+                err.span_note(
+                    machine.tcx.def_span(first.instance.def_id()),
+                    format!("{level} occurred {fn_and_thread}"),
+                );
+            } else {
+                err.note(format!("this is {fn_and_thread}"));
+            }
+        }
+        // Continue with where that function got called.
+        for frame_info in rest.iter() {
             let is_local = machine.is_local(frame_info.instance);
             // No span for non-local frames and the first frame (which is the error site).
-            if is_local && idx > 0 {
-                err.subdiagnostic(frame_info.as_note(machine.tcx));
+            if is_local {
+                err.span_note(frame_info.span, format!("which got called {frame_info}"));
             } else {
                 let sm = sess.source_map();
                 let span = sm.span_to_diagnostic_string(frame_info.span);
-                err.note(format!("{frame_info} at {span}"));
+                err.note(format!("which got called {frame_info} (at {span})"));
             }
         }
-    } else if stacktrace.len() == 0 && !span.is_dummy() {
-        err.note(format!(
-            "this {} occurred while pushing a call frame onto an empty stack",
-            level.to_str()
-        ));
+    } else if !span.is_dummy() {
+        err.note(format!("this {level} occurred while pushing a call frame onto an empty stack"));
         err.note("the span indicates which code caused the function to be called, but may not be the literal call site");
     }
 

src/tools/miri/tests/fail-dep/concurrency/apple_os_unfair_lock_move_with_queue.stderr

@@ -6,6 +6,7 @@ LL |             let _val = atomic_ref.load(Ordering::Relaxed);
    |
    = 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: this is on thread `unnamed-ID`
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

src/tools/miri/tests/fail-dep/concurrency/libc_pthread_cond_move.init.stderr

@@ -6,9 +6,8 @@ LL |         libc::pthread_cond_destroy(cond2.as_mut_ptr());
    |
    = 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: BACKTRACE:
-   = note: inside `check` at tests/fail-dep/concurrency/libc_pthread_cond_move.rs:LL:CC
-note: inside `main`
+   = note: this is inside `check`
+note: which got called inside `main`
   --> tests/fail-dep/concurrency/libc_pthread_cond_move.rs:LL:CC
    |
 LL |     check()

src/tools/miri/tests/fail-dep/concurrency/libc_pthread_cond_move.static_initializer.stderr

@@ -6,9 +6,8 @@ LL |         libc::pthread_cond_destroy(&mut cond2 as *mut _);
    |
    = 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: BACKTRACE:
-   = note: inside `check` at tests/fail-dep/concurrency/libc_pthread_cond_move.rs:LL:CC
-note: inside `main`
+   = note: this is inside `check`
+note: which got called inside `main`
   --> tests/fail-dep/concurrency/libc_pthread_cond_move.rs:LL:CC
    |
 LL |     check()

src/tools/miri/tests/fail-dep/concurrency/libc_pthread_join_detached.stderr

@@ -6,6 +6,7 @@ LL |         assert_eq!(libc::pthread_join(native, ptr::null_mut()), 0);
    |
    = 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: this is on thread `main`
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

src/tools/miri/tests/fail-dep/concurrency/libc_pthread_join_joined.stderr

@@ -6,6 +6,7 @@ LL | ...   assert_eq!(libc::pthread_join(native, ptr::null_mut()), 0);
    |
    = 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: this is on thread `main`
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

src/tools/miri/tests/fail-dep/concurrency/libc_pthread_join_main.stderr

@@ -6,6 +6,7 @@ LL | ...   assert_eq!(libc::pthread_join(thread_id, ptr::null_mut()), 0);
    |
    = 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: this is on thread `unnamed-ID`
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

src/tools/miri/tests/fail-dep/concurrency/libc_pthread_join_multiple.stderr

@@ -6,6 +6,7 @@ LL | ...   assert_eq!(libc::pthread_join(native_copy, ptr::null_mut()), 0);
    |
    = 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: this is on thread `unnamed-ID`
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

src/tools/miri/tests/fail-dep/concurrency/libc_pthread_join_self.stderr

@@ -6,6 +6,7 @@ LL |             assert_eq!(libc::pthread_join(native, ptr::null_mut()), 0);
    |
    = 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: this is on thread `unnamed-ID`
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

src/tools/miri/tests/fail-dep/concurrency/libc_pthread_mutex_deadlock.stderr

@@ -2,13 +2,12 @@ error: the evaluated program deadlocked
   --> RUSTLIB/std/src/sys/thread/PLATFORM.rs:LL:CC
    |
 LL |         let ret = unsafe { libc::pthread_join(id, ptr::null_mut()) };
-   |                                                                  ^ thread `main` got stuck here
+   |                                                                  ^ thread got stuck here
    |
-   = note: BACKTRACE:
-   = note: inside `std::sys::thread::PLATFORM::Thread::join` at RUSTLIB/std/src/sys/thread/PLATFORM.rs:LL:CC
-   = note: inside `std::thread::lifecycle::JoinInner::<'_, ()>::join` at RUSTLIB/std/src/thread/lifecycle.rs:LL:CC
-   = note: inside `std::thread::JoinHandle::<()>::join` at RUSTLIB/std/src/thread/join_handle.rs:LL:CC
-note: inside `main`
+   = note: this is on thread `main`, inside `std::sys::thread::PLATFORM::Thread::join`
+   = note: which got called inside `std::thread::lifecycle::JoinInner::<'_, ()>::join` (at RUSTLIB/std/src/thread/lifecycle.rs:LL:CC)
+   = note: which got called inside `std::thread::JoinHandle::<()>::join` (at RUSTLIB/std/src/thread/join_handle.rs:LL:CC)
+note: which got called inside `main`
   --> tests/fail-dep/concurrency/libc_pthread_mutex_deadlock.rs:LL:CC
    |
 LL | /         thread::spawn(move || {
@@ -21,7 +20,9 @@ error: the evaluated program deadlocked
   --> tests/fail-dep/concurrency/libc_pthread_mutex_deadlock.rs:LL:CC
    |
 LL |             assert_eq!(libc::pthread_mutex_lock(lock_copy.0.get() as *mut _), 0);
-   |                                                                            ^ thread `unnamed-ID` got stuck here
+   |                                                                            ^ thread got stuck here
+   |
+   = note: this is on thread `unnamed-ID`
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

src/tools/miri/tests/fail-dep/concurrency/libc_pthread_mutex_free_while_queued.stderr

@@ -6,11 +6,10 @@ LL |                 self.1.deallocate(From::from(ptr.cast()), layout);
    |
    = 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: BACKTRACE on thread `unnamed-ID`:
-   = note: inside `<std::boxed::Box<Mutex> as std::ops::Drop>::drop` at RUSTLIB/alloc/src/boxed.rs:LL:CC
-   = note: inside `std::ptr::drop_in_place::<std::boxed::Box<Mutex>> - shim(Some(std::boxed::Box<Mutex>))` at RUSTLIB/core/src/ptr/mod.rs:LL:CC
-   = note: inside `std::mem::drop::<std::boxed::Box<Mutex>>` at RUSTLIB/core/src/mem/mod.rs:LL:CC
-note: inside closure
+   = note: this is on thread `unnamed-ID`, inside `<std::boxed::Box<Mutex> as std::ops::Drop>::drop`
+   = note: which got called inside `std::ptr::drop_in_place::<std::boxed::Box<Mutex>> - shim(Some(std::boxed::Box<Mutex>))` (at RUSTLIB/core/src/ptr/mod.rs:LL:CC)
+   = note: which got called inside `std::mem::drop::<std::boxed::Box<Mutex>>` (at RUSTLIB/core/src/mem/mod.rs:LL:CC)
+note: which got called inside closure
   --> tests/fail-dep/concurrency/libc_pthread_mutex_free_while_queued.rs:LL:CC
    |
 LL |             drop(unsafe { Box::from_raw(m.get().cast::<Mutex>()) });

src/tools/miri/tests/fail-dep/concurrency/libc_pthread_mutex_move.init.stderr

@@ -6,9 +6,8 @@ LL |         libc::pthread_mutex_lock(&mut m2 as *mut _);
    |
    = 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: BACKTRACE:
-   = note: inside `check` at tests/fail-dep/concurrency/libc_pthread_mutex_move.rs:LL:CC
-note: inside `main`
+   = note: this is inside `check`
+note: which got called inside `main`
   --> tests/fail-dep/concurrency/libc_pthread_mutex_move.rs:LL:CC
    |
 LL |     check();

src/tools/miri/tests/fail-dep/concurrency/libc_pthread_mutex_move.static_initializer.stderr

@@ -6,9 +6,8 @@ LL |         libc::pthread_mutex_unlock(&mut m2 as *mut _);
    |
    = 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: BACKTRACE:
-   = note: inside `check` at tests/fail-dep/concurrency/libc_pthread_mutex_move.rs:LL:CC
-note: inside `main`
+   = note: this is inside `check`
+note: which got called inside `main`
   --> tests/fail-dep/concurrency/libc_pthread_mutex_move.rs:LL:CC
    |
 LL |     check();

src/tools/miri/tests/fail-dep/concurrency/libc_pthread_mutex_normal_reentrant.stderr

@@ -2,7 +2,7 @@ error: a thread deadlocked
   --> tests/fail-dep/concurrency/libc_pthread_mutex_normal_reentrant.rs:LL:CC
    |
 LL |         libc::pthread_mutex_lock(&mut mutex as *mut _);
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ this thread got stuck here
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ thread got stuck here
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

src/tools/miri/tests/fail-dep/concurrency/libc_pthread_mutex_read_while_queued.stderr

@@ -6,6 +6,7 @@ LL | ...   let _val = atomic_ref.load(Ordering::Relaxed);
    |
    = 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: this is on thread `unnamed-ID`
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

src/tools/miri/tests/fail-dep/concurrency/libc_pthread_mutex_write_while_queued.stderr

@@ -6,6 +6,7 @@ LL |             atomic_ref.store(0, Ordering::Relaxed);
    |
    = 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: this is on thread `unnamed-ID`
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

src/tools/miri/tests/fail-dep/concurrency/libc_pthread_mutex_wrong_owner.stderr

@@ -6,6 +6,7 @@ LL | ...   assert_eq!(libc::pthread_mutex_unlock(lock_copy.0.get() as *mut _), 0
    |
    = 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: this is on thread `unnamed-ID`
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

src/tools/miri/tests/fail-dep/concurrency/libc_pthread_rwlock_read_write_deadlock_single_thread.stderr

@@ -2,7 +2,7 @@ error: the evaluated program deadlocked
   --> tests/fail-dep/concurrency/libc_pthread_rwlock_read_write_deadlock_single_thread.rs:LL:CC
    |
 LL |         libc::pthread_rwlock_wrlock(rw.get());
-   |                                             ^ thread `main` got stuck here
+   |                                             ^ thread got stuck here
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

src/tools/miri/tests/fail-dep/concurrency/libc_pthread_rwlock_read_wrong_owner.stderr

@@ -6,6 +6,7 @@ LL | ...   assert_eq!(libc::pthread_rwlock_unlock(lock_copy.0.get() as *mut _),
    |
    = 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: this is on thread `unnamed-ID`
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

src/tools/miri/tests/fail-dep/concurrency/libc_pthread_rwlock_write_read_deadlock.stderr

@@ -2,13 +2,12 @@ error: the evaluated program deadlocked
   --> RUSTLIB/std/src/sys/thread/PLATFORM.rs:LL:CC
    |
 LL |         let ret = unsafe { libc::pthread_join(id, ptr::null_mut()) };
-   |                                                                  ^ thread `main` got stuck here
+   |                                                                  ^ thread got stuck here
    |
-   = note: BACKTRACE:
-   = note: inside `std::sys::thread::PLATFORM::Thread::join` at RUSTLIB/std/src/sys/thread/PLATFORM.rs:LL:CC
-   = note: inside `std::thread::lifecycle::JoinInner::<'_, ()>::join` at RUSTLIB/std/src/thread/lifecycle.rs:LL:CC
-   = note: inside `std::thread::JoinHandle::<()>::join` at RUSTLIB/std/src/thread/join_handle.rs:LL:CC
-note: inside `main`
+   = note: this is on thread `main`, inside `std::sys::thread::PLATFORM::Thread::join`
+   = note: which got called inside `std::thread::lifecycle::JoinInner::<'_, ()>::join` (at RUSTLIB/std/src/thread/lifecycle.rs:LL:CC)
+   = note: which got called inside `std::thread::JoinHandle::<()>::join` (at RUSTLIB/std/src/thread/join_handle.rs:LL:CC)
+note: which got called inside `main`
   --> tests/fail-dep/concurrency/libc_pthread_rwlock_write_read_deadlock.rs:LL:CC
    |
 LL | /         thread::spawn(move || {
@@ -21,7 +20,9 @@ error: the evaluated program deadlocked
   --> tests/fail-dep/concurrency/libc_pthread_rwlock_write_read_deadlock.rs:LL:CC
    |
 LL |             assert_eq!(libc::pthread_rwlock_wrlock(lock_copy.0.get() as *mut _), 0);
-   |                                                                               ^ thread `unnamed-ID` got stuck here
+   |                                                                               ^ thread got stuck here
+   |
+   = note: this is on thread `unnamed-ID`
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

src/tools/miri/tests/fail-dep/concurrency/libc_pthread_rwlock_write_read_deadlock_single_thread.stderr

@@ -2,7 +2,7 @@ error: the evaluated program deadlocked
   --> tests/fail-dep/concurrency/libc_pthread_rwlock_write_read_deadlock_single_thread.rs:LL:CC
    |
 LL |         libc::pthread_rwlock_rdlock(rw.get());
-   |                                             ^ thread `main` got stuck here
+   |                                             ^ thread got stuck here
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

src/tools/miri/tests/fail-dep/concurrency/libc_pthread_rwlock_write_write_deadlock.stderr

@@ -2,13 +2,12 @@ error: the evaluated program deadlocked
   --> RUSTLIB/std/src/sys/thread/PLATFORM.rs:LL:CC
    |
 LL |         let ret = unsafe { libc::pthread_join(id, ptr::null_mut()) };
-   |                                                                  ^ thread `main` got stuck here
+   |                                                                  ^ thread got stuck here
    |
-   = note: BACKTRACE:
-   = note: inside `std::sys::thread::PLATFORM::Thread::join` at RUSTLIB/std/src/sys/thread/PLATFORM.rs:LL:CC
-   = note: inside `std::thread::lifecycle::JoinInner::<'_, ()>::join` at RUSTLIB/std/src/thread/lifecycle.rs:LL:CC
-   = note: inside `std::thread::JoinHandle::<()>::join` at RUSTLIB/std/src/thread/join_handle.rs:LL:CC
-note: inside `main`
+   = note: this is on thread `main`, inside `std::sys::thread::PLATFORM::Thread::join`
+   = note: which got called inside `std::thread::lifecycle::JoinInner::<'_, ()>::join` (at RUSTLIB/std/src/thread/lifecycle.rs:LL:CC)
+   = note: which got called inside `std::thread::JoinHandle::<()>::join` (at RUSTLIB/std/src/thread/join_handle.rs:LL:CC)
+note: which got called inside `main`
   --> tests/fail-dep/concurrency/libc_pthread_rwlock_write_write_deadlock.rs:LL:CC
    |
 LL | /         thread::spawn(move || {
@@ -21,7 +20,9 @@ error: the evaluated program deadlocked
   --> tests/fail-dep/concurrency/libc_pthread_rwlock_write_write_deadlock.rs:LL:CC
    |
 LL |             assert_eq!(libc::pthread_rwlock_wrlock(lock_copy.0.get() as *mut _), 0);
-   |                                                                               ^ thread `unnamed-ID` got stuck here
+   |                                                                               ^ thread got stuck here
+   |
+   = note: this is on thread `unnamed-ID`
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

src/tools/miri/tests/fail-dep/concurrency/libc_pthread_rwlock_write_write_deadlock_single_thread.stderr

@@ -2,7 +2,7 @@ error: the evaluated program deadlocked
   --> tests/fail-dep/concurrency/libc_pthread_rwlock_write_write_deadlock_single_thread.rs:LL:CC
    |
 LL |         libc::pthread_rwlock_wrlock(rw.get());
-   |                                             ^ thread `main` got stuck here
+   |                                             ^ thread got stuck here
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

src/tools/miri/tests/fail-dep/concurrency/libc_pthread_rwlock_write_wrong_owner.stderr

@@ -6,6 +6,7 @@ LL | ...   assert_eq!(libc::pthread_rwlock_unlock(lock_copy.0.get() as *mut _),
    |
    = 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: this is on thread `unnamed-ID`
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

src/tools/miri/tests/fail-dep/concurrency/windows_join_detached.stderr

@@ -6,11 +6,10 @@ LL |         let rc = unsafe { c::WaitForSingleObject(self.handle.as_raw_handle(
    |
    = 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: BACKTRACE:
-   = note: inside `std::sys::thread::PLATFORM::Thread::join` at RUSTLIB/std/src/sys/thread/PLATFORM.rs:LL:CC
-   = note: inside `std::thread::lifecycle::JoinInner::<'_, ()>::join` at RUSTLIB/std/src/thread/lifecycle.rs:LL:CC
-   = note: inside `std::thread::JoinHandle::<()>::join` at RUSTLIB/std/src/thread/join_handle.rs:LL:CC
-note: inside `main`
+   = note: this is on thread `main`, inside `std::sys::thread::PLATFORM::Thread::join`
+   = note: which got called inside `std::thread::lifecycle::JoinInner::<'_, ()>::join` (at RUSTLIB/std/src/thread/lifecycle.rs:LL:CC)
+   = note: which got called inside `std::thread::JoinHandle::<()>::join` (at RUSTLIB/std/src/thread/join_handle.rs:LL:CC)
+note: which got called inside `main`
   --> tests/fail-dep/concurrency/windows_join_detached.rs:LL:CC
    |
 LL |     thread.join().unwrap();

src/tools/miri/tests/fail-dep/concurrency/windows_join_main.stderr

@@ -2,13 +2,12 @@ error: the evaluated program deadlocked
   --> RUSTLIB/std/src/sys/thread/PLATFORM.rs:LL:CC
    |
 LL |         let rc = unsafe { c::WaitForSingleObject(self.handle.as_raw_handle(), c::INFINITE) };
-   |                                                                                          ^ thread `main` got stuck here
+   |                                                                                          ^ thread got stuck here
    |
-   = note: BACKTRACE:
-   = note: inside `std::sys::thread::PLATFORM::Thread::join` at RUSTLIB/std/src/sys/thread/PLATFORM.rs:LL:CC
-   = note: inside `std::thread::lifecycle::JoinInner::<'_, ()>::join` at RUSTLIB/std/src/thread/lifecycle.rs:LL:CC
-   = note: inside `std::thread::JoinHandle::<()>::join` at RUSTLIB/std/src/thread/join_handle.rs:LL:CC
-note: inside `main`
+   = note: this is on thread `main`, inside `std::sys::thread::PLATFORM::Thread::join`
+   = note: which got called inside `std::thread::lifecycle::JoinInner::<'_, ()>::join` (at RUSTLIB/std/src/thread/lifecycle.rs:LL:CC)
+   = note: which got called inside `std::thread::JoinHandle::<()>::join` (at RUSTLIB/std/src/thread/join_handle.rs:LL:CC)
+note: which got called inside `main`
   --> tests/fail-dep/concurrency/windows_join_main.rs:LL:CC
    |
 LL | /     thread::spawn(|| {
@@ -22,8 +21,9 @@ error: the evaluated program deadlocked
   --> tests/fail-dep/concurrency/windows_join_main.rs:LL:CC
    |
 LL |             assert_eq!(WaitForSingleObject(MAIN_THREAD, INFINITE), WAIT_OBJECT_0);
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ thread `unnamed-ID` got stuck here
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ thread got stuck here
    |
+   = note: this is on thread `unnamed-ID`
    = note: this error originates in the macro `assert_eq` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace

src/tools/miri/tests/fail-dep/concurrency/windows_join_self.stderr

@@ -2,13 +2,12 @@ error: the evaluated program deadlocked
   --> RUSTLIB/std/src/sys/thread/PLATFORM.rs:LL:CC
    |
 LL |         let rc = unsafe { c::WaitForSingleObject(self.handle.as_raw_handle(), c::INFINITE) };
-   |                                                                                          ^ thread `main` got stuck here
+   |                                                                                          ^ thread got stuck here
    |
-   = note: BACKTRACE:
-   = note: inside `std::sys::thread::PLATFORM::Thread::join` at RUSTLIB/std/src/sys/thread/PLATFORM.rs:LL:CC
-   = note: inside `std::thread::lifecycle::JoinInner::<'_, ()>::join` at RUSTLIB/std/src/thread/lifecycle.rs:LL:CC
-   = note: inside `std::thread::JoinHandle::<()>::join` at RUSTLIB/std/src/thread/join_handle.rs:LL:CC
-note: inside `main`
+   = note: this is on thread `main`, inside `std::sys::thread::PLATFORM::Thread::join`
+   = note: which got called inside `std::thread::lifecycle::JoinInner::<'_, ()>::join` (at RUSTLIB/std/src/thread/lifecycle.rs:LL:CC)
+   = note: which got called inside `std::thread::JoinHandle::<()>::join` (at RUSTLIB/std/src/thread/join_handle.rs:LL:CC)
+note: which got called inside `main`
   --> tests/fail-dep/concurrency/windows_join_self.rs:LL:CC
    |
 LL | /     thread::spawn(|| {
@@ -24,7 +23,9 @@ error: the evaluated program deadlocked
   --> tests/fail-dep/concurrency/windows_join_self.rs:LL:CC
    |
 LL |             assert_eq!(WaitForSingleObject(native, INFINITE), WAIT_OBJECT_0);
-   |                                                            ^ thread `unnamed-ID` got stuck here
+   |                                                            ^ thread got stuck here
+   |
+   = note: this is on thread `unnamed-ID`
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

src/tools/miri/tests/fail-dep/libc/env-set_var-data-race.stderr

@@ -11,6 +11,7 @@ LL |     env::set_var("MY_RUST_VAR", "Ferris");
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    = 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: this is on thread `unnamed-ID`
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

src/tools/miri/tests/fail-dep/libc/eventfd_block_read_twice.stderr

@@ -2,13 +2,12 @@ error: the evaluated program deadlocked
   --> RUSTLIB/std/src/sys/thread/PLATFORM.rs:LL:CC
    |
 LL |         let ret = unsafe { libc::pthread_join(id, ptr::null_mut()) };
-   |                                                                  ^ thread `main` got stuck here
+   |                                                                  ^ thread got stuck here
    |
-   = note: BACKTRACE:
-   = note: inside `std::sys::thread::PLATFORM::Thread::join` at RUSTLIB/std/src/sys/thread/PLATFORM.rs:LL:CC
-   = note: inside `std::thread::lifecycle::JoinInner::<'_, ()>::join` at RUSTLIB/std/src/thread/lifecycle.rs:LL:CC
-   = note: inside `std::thread::JoinHandle::<()>::join` at RUSTLIB/std/src/thread/join_handle.rs:LL:CC
-note: inside `main`
+   = note: this is on thread `main`, inside `std::sys::thread::PLATFORM::Thread::join`
+   = note: which got called inside `std::thread::lifecycle::JoinInner::<'_, ()>::join` (at RUSTLIB/std/src/thread/lifecycle.rs:LL:CC)
+   = note: which got called inside `std::thread::JoinHandle::<()>::join` (at RUSTLIB/std/src/thread/join_handle.rs:LL:CC)
+note: which got called inside `main`
   --> tests/fail-dep/libc/eventfd_block_read_twice.rs:LL:CC
    |
 LL |     thread2.join().unwrap();
@@ -18,7 +17,9 @@ error: the evaluated program deadlocked
   --> tests/fail-dep/libc/eventfd_block_read_twice.rs:LL:CC
    |
 LL |         let res: i64 = unsafe { libc::read(fd, buf.as_mut_ptr().cast(), 8).try_into().unwrap() };
-   |                                                                          ^ thread `unnamed-ID` got stuck here
+   |                                                                          ^ thread got stuck here
+   |
+   = note: this is on thread `unnamed-ID`
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

src/tools/miri/tests/fail-dep/libc/eventfd_block_write_twice.stderr

@@ -2,13 +2,12 @@ error: the evaluated program deadlocked
   --> RUSTLIB/std/src/sys/thread/PLATFORM.rs:LL:CC
    |
 LL |         let ret = unsafe { libc::pthread_join(id, ptr::null_mut()) };
-   |                                                                  ^ thread `main` got stuck here
+   |                                                                  ^ thread got stuck here
    |
-   = note: BACKTRACE:
-   = note: inside `std::sys::thread::PLATFORM::Thread::join` at RUSTLIB/std/src/sys/thread/PLATFORM.rs:LL:CC
-   = note: inside `std::thread::lifecycle::JoinInner::<'_, ()>::join` at RUSTLIB/std/src/thread/lifecycle.rs:LL:CC
-   = note: inside `std::thread::JoinHandle::<()>::join` at RUSTLIB/std/src/thread/join_handle.rs:LL:CC
-note: inside `main`
+   = note: this is on thread `main`, inside `std::sys::thread::PLATFORM::Thread::join`
+   = note: which got called inside `std::thread::lifecycle::JoinInner::<'_, ()>::join` (at RUSTLIB/std/src/thread/lifecycle.rs:LL:CC)
+   = note: which got called inside `std::thread::JoinHandle::<()>::join` (at RUSTLIB/std/src/thread/join_handle.rs:LL:CC)
+note: which got called inside `main`
   --> tests/fail-dep/libc/eventfd_block_write_twice.rs:LL:CC
    |
 LL |     thread2.join().unwrap();
@@ -18,7 +17,9 @@ error: the evaluated program deadlocked
   --> tests/fail-dep/libc/eventfd_block_write_twice.rs:LL:CC
    |
 LL |             libc::write(fd, sized_8_data.as_ptr() as *const libc::c_void, 8).try_into().unwrap()
-   |                                                                            ^ thread `unnamed-ID` got stuck here
+   |                                                                            ^ thread got stuck here
+   |
+   = note: this is on thread `unnamed-ID`
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

src/tools/miri/tests/fail-dep/libc/fcntl_fsetfl_while_blocking.stderr

@@ -2,7 +2,9 @@ error: the evaluated program deadlocked
   --> tests/fail-dep/libc/fcntl_fsetfl_while_blocking.rs:LL:CC
    |
 LL |     let _res = unsafe { libc::read(fds[0], buf.as_mut_ptr().cast(), buf.len() as libc::size_t) };
-   |                                                                                              ^ thread `main` got stuck here
+   |                                                                                              ^ thread got stuck here
+   |
+   = note: this is on thread `main`
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

src/tools/miri/tests/fail-dep/libc/fs/mkstemp_immutable_arg.stderr

@@ -6,9 +6,8 @@ LL |     let _fd = unsafe { libc::mkstemp(s) };
    |
    = 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: BACKTRACE:
-   = note: inside `test_mkstemp_immutable_arg` at tests/fail-dep/libc/fs/mkstemp_immutable_arg.rs:LL:CC
-note: inside `main`
+   = note: this is inside `test_mkstemp_immutable_arg`
+note: which got called inside `main`
   --> tests/fail-dep/libc/fs/mkstemp_immutable_arg.rs:LL:CC
    |
 LL |     test_mkstemp_immutable_arg();

src/tools/miri/tests/fail-dep/libc/fs/unix_open_missing_required_mode.stderr

@@ -6,9 +6,8 @@ LL |     let _fd = unsafe { libc::open(name_ptr, libc::O_CREAT) };
    |
    = 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: BACKTRACE:
-   = note: inside `test_file_open_missing_needed_mode` at tests/fail-dep/libc/fs/unix_open_missing_required_mode.rs:LL:CC
-note: inside `main`
+   = note: this is inside `test_file_open_missing_needed_mode`
+note: which got called inside `main`
   --> tests/fail-dep/libc/fs/unix_open_missing_required_mode.rs:LL:CC
    |
 LL |     test_file_open_missing_needed_mode();

src/tools/miri/tests/fail-dep/libc/libc-epoll-data-race.stderr

@@ -11,6 +11,7 @@ LL |         unsafe { VAL_TWO = 51 };
    |                  ^^^^^^^^^^^^
    = 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: this is on thread `main`
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

src/tools/miri/tests/fail-dep/libc/libc_epoll_block_two_thread.stderr

@@ -2,13 +2,12 @@ error: the evaluated program deadlocked
   --> RUSTLIB/std/src/sys/thread/PLATFORM.rs:LL:CC
    |
 LL |         let ret = unsafe { libc::pthread_join(id, ptr::null_mut()) };
-   |                                                                  ^ thread `main` got stuck here
+   |                                                                  ^ thread got stuck here
    |
-   = note: BACKTRACE:
-   = note: inside `std::sys::thread::PLATFORM::Thread::join` at RUSTLIB/std/src/sys/thread/PLATFORM.rs:LL:CC
-   = note: inside `std::thread::lifecycle::JoinInner::<'_, ()>::join` at RUSTLIB/std/src/thread/lifecycle.rs:LL:CC
-   = note: inside `std::thread::JoinHandle::<()>::join` at RUSTLIB/std/src/thread/join_handle.rs:LL:CC
-note: inside `main`
+   = note: this is on thread `main`, inside `std::sys::thread::PLATFORM::Thread::join`
+   = note: which got called inside `std::thread::lifecycle::JoinInner::<'_, ()>::join` (at RUSTLIB/std/src/thread/lifecycle.rs:LL:CC)
+   = note: which got called inside `std::thread::JoinHandle::<()>::join` (at RUSTLIB/std/src/thread/join_handle.rs:LL:CC)
+note: which got called inside `main`
   --> tests/fail-dep/libc/libc_epoll_block_two_thread.rs:LL:CC
    |
 LL |     thread2.join().unwrap();
@@ -18,7 +17,9 @@ error: the evaluated program deadlocked
   --> tests/fail-dep/libc/libc_epoll_block_two_thread.rs:LL:CC
    |
 LL |         check_epoll_wait::<TAG>(epfd, &expected, -1);
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ thread `unnamed-ID` got stuck here
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ thread got stuck here
+   |
+   = note: this is on thread `unnamed-ID`
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

src/tools/miri/tests/fail-dep/libc/socketpair-close-while-blocked.stderr

@@ -2,13 +2,12 @@ error: the evaluated program deadlocked
   --> RUSTLIB/std/src/sys/thread/PLATFORM.rs:LL:CC
    |
 LL |         let ret = unsafe { libc::pthread_join(id, ptr::null_mut()) };
-   |                                                                  ^ thread `main` got stuck here
+   |                                                                  ^ thread got stuck here
    |
-   = note: BACKTRACE:
-   = note: inside `std::sys::thread::PLATFORM::Thread::join` at RUSTLIB/std/src/sys/thread/PLATFORM.rs:LL:CC
-   = note: inside `std::thread::lifecycle::JoinInner::<'_, ()>::join` at RUSTLIB/std/src/thread/lifecycle.rs:LL:CC
-   = note: inside `std::thread::JoinHandle::<()>::join` at RUSTLIB/std/src/thread/join_handle.rs:LL:CC
-note: inside `main`
+   = note: this is on thread `main`, inside `std::sys::thread::PLATFORM::Thread::join`
+   = note: which got called inside `std::thread::lifecycle::JoinInner::<'_, ()>::join` (at RUSTLIB/std/src/thread/lifecycle.rs:LL:CC)
+   = note: which got called inside `std::thread::JoinHandle::<()>::join` (at RUSTLIB/std/src/thread/join_handle.rs:LL:CC)
+note: which got called inside `main`
   --> tests/fail-dep/libc/socketpair-close-while-blocked.rs:LL:CC
    |
 LL |     thread1.join().unwrap();
@@ -18,7 +17,9 @@ error: the evaluated program deadlocked
   --> tests/fail-dep/libc/socketpair-close-while-blocked.rs:LL:CC
    |
 LL |             libc::read(fds[1], buf.as_mut_ptr().cast(), buf.len() as libc::size_t)
-   |                                                                                  ^ thread `unnamed-ID` got stuck here
+   |                                                                                  ^ thread got stuck here
+   |
+   = note: this is on thread `unnamed-ID`
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

src/tools/miri/tests/fail-dep/libc/socketpair-data-race.stderr

@@ -11,6 +11,7 @@ LL |         unsafe { VAL = 1 };
    |                  ^^^^^^^
    = 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: this is on thread `main`
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

src/tools/miri/tests/fail-dep/libc/socketpair_block_read_twice.stderr

@@ -2,13 +2,12 @@ error: the evaluated program deadlocked
   --> RUSTLIB/std/src/sys/thread/PLATFORM.rs:LL:CC
    |
 LL |         let ret = unsafe { libc::pthread_join(id, ptr::null_mut()) };
-   |                                                                  ^ thread `main` got stuck here
+   |                                                                  ^ thread got stuck here
    |
-   = note: BACKTRACE:
-   = note: inside `std::sys::thread::PLATFORM::Thread::join` at RUSTLIB/std/src/sys/thread/PLATFORM.rs:LL:CC
-   = note: inside `std::thread::lifecycle::JoinInner::<'_, ()>::join` at RUSTLIB/std/src/thread/lifecycle.rs:LL:CC
-   = note: inside `std::thread::JoinHandle::<()>::join` at RUSTLIB/std/src/thread/join_handle.rs:LL:CC
-note: inside `main`
+   = note: this is on thread `main`, inside `std::sys::thread::PLATFORM::Thread::join`
+   = note: which got called inside `std::thread::lifecycle::JoinInner::<'_, ()>::join` (at RUSTLIB/std/src/thread/lifecycle.rs:LL:CC)
+   = note: which got called inside `std::thread::JoinHandle::<()>::join` (at RUSTLIB/std/src/thread/join_handle.rs:LL:CC)
+note: which got called inside `main`
   --> tests/fail-dep/libc/socketpair_block_read_twice.rs:LL:CC
    |
 LL |     thread2.join().unwrap();
@@ -18,7 +17,9 @@ error: the evaluated program deadlocked
   --> tests/fail-dep/libc/socketpair_block_read_twice.rs:LL:CC
    |
 LL |             libc::read(fds[1], buf.as_mut_ptr().cast(), buf.len() as libc::size_t)
-   |                                                                                  ^ thread `unnamed-ID` got stuck here
+   |                                                                                  ^ thread got stuck here
+   |
+   = note: this is on thread `unnamed-ID`
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

src/tools/miri/tests/fail-dep/libc/socketpair_block_write_twice.stderr

@@ -2,13 +2,12 @@ error: the evaluated program deadlocked
   --> RUSTLIB/std/src/sys/thread/PLATFORM.rs:LL:CC
    |
 LL |         let ret = unsafe { libc::pthread_join(id, ptr::null_mut()) };
-   |                                                                  ^ thread `main` got stuck here
+   |                                                                  ^ thread got stuck here
    |
-   = note: BACKTRACE:
-   = note: inside `std::sys::thread::PLATFORM::Thread::join` at RUSTLIB/std/src/sys/thread/PLATFORM.rs:LL:CC
-   = note: inside `std::thread::lifecycle::JoinInner::<'_, ()>::join` at RUSTLIB/std/src/thread/lifecycle.rs:LL:CC
-   = note: inside `std::thread::JoinHandle::<()>::join` at RUSTLIB/std/src/thread/join_handle.rs:LL:CC
-note: inside `main`
+   = note: this is on thread `main`, inside `std::sys::thread::PLATFORM::Thread::join`
+   = note: which got called inside `std::thread::lifecycle::JoinInner::<'_, ()>::join` (at RUSTLIB/std/src/thread/lifecycle.rs:LL:CC)
+   = note: which got called inside `std::thread::JoinHandle::<()>::join` (at RUSTLIB/std/src/thread/join_handle.rs:LL:CC)
+note: which got called inside `main`
   --> tests/fail-dep/libc/socketpair_block_write_twice.rs:LL:CC
    |
 LL |     thread2.join().unwrap();
@@ -18,7 +17,9 @@ error: the evaluated program deadlocked
   --> tests/fail-dep/libc/socketpair_block_write_twice.rs:LL:CC
    |
 LL |         let res = unsafe { libc::write(fds[0], data.as_ptr() as *const libc::c_void, data.len()) };
-   |                                                                                                ^ thread `unnamed-ID` got stuck here
+   |                                                                                                ^ thread got stuck here
+   |
+   = note: this is on thread `unnamed-ID`
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

src/tools/miri/tests/fail/alloc/alloc_error_handler.stderr

@@ -7,14 +7,13 @@ error: abnormal termination: the program aborted execution
 LL |         crate::process::abort()
    |         ^^^^^^^^^^^^^^^^^^^^^^^ abnormal termination occurred here
    |
-   = note: BACKTRACE:
-   = note: inside closure at RUSTLIB/std/src/alloc.rs:LL:CC
-   = note: inside `std::sys::backtrace::__rust_end_short_backtrace::<{closure@std::alloc::rust_oom::{closure#0}}, !>` at RUSTLIB/std/src/sys/backtrace.rs:LL:CC
-   = note: inside `std::alloc::rust_oom` at RUSTLIB/std/src/alloc.rs:LL:CC
-   = note: inside `std::alloc::_::__rust_alloc_error_handler` at RUSTLIB/std/src/alloc.rs:LL:CC
-   = note: inside `std::alloc::handle_alloc_error::rt_error` at RUSTLIB/alloc/src/alloc.rs:LL:CC
-   = note: inside `std::alloc::handle_alloc_error` at RUSTLIB/alloc/src/alloc.rs:LL:CC
-note: inside `main`
+   = note: this is inside closure
+   = note: which got called inside `std::sys::backtrace::__rust_end_short_backtrace::<{closure@std::alloc::rust_oom::{closure#0}}, !>` (at RUSTLIB/std/src/sys/backtrace.rs:LL:CC)
+   = note: which got called inside `std::alloc::rust_oom` (at RUSTLIB/std/src/alloc.rs:LL:CC)
+   = note: which got called inside `std::alloc::_::__rust_alloc_error_handler` (at RUSTLIB/std/src/alloc.rs:LL:CC)
+   = note: which got called inside `std::alloc::handle_alloc_error::rt_error` (at RUSTLIB/alloc/src/alloc.rs:LL:CC)
+   = note: which got called inside `std::alloc::handle_alloc_error` (at RUSTLIB/alloc/src/alloc.rs:LL:CC)
+note: which got called inside `main`
   --> tests/fail/alloc/alloc_error_handler.rs:LL:CC
    |
 LL |     handle_alloc_error(Layout::for_value(&0));

src/tools/miri/tests/fail/alloc/alloc_error_handler_custom.stderr

@@ -5,18 +5,17 @@ error: abnormal termination: the program aborted execution
 LL |     core::intrinsics::abort();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^ abnormal termination occurred here
    |
-   = note: BACKTRACE:
-   = note: inside `alloc_error_handler` at tests/fail/alloc/alloc_error_handler_custom.rs:LL:CC
-note: inside `_::__rust_alloc_error_handler`
+   = note: this is inside `alloc_error_handler`
+note: which got called inside `_::__rust_alloc_error_handler`
   --> tests/fail/alloc/alloc_error_handler_custom.rs:LL:CC
    |
 LL | #[alloc_error_handler]
    | ---------------------- in this attribute macro expansion
 LL | fn alloc_error_handler(layout: Layout) -> ! {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   = note: inside `alloc::alloc::handle_alloc_error::rt_error` at RUSTLIB/alloc/src/alloc.rs:LL:CC
-   = note: inside `alloc::alloc::handle_alloc_error` at RUSTLIB/alloc/src/alloc.rs:LL:CC
-note: inside `miri_start`
+   = note: which got called inside `alloc::alloc::handle_alloc_error::rt_error` (at RUSTLIB/alloc/src/alloc.rs:LL:CC)
+   = note: which got called inside `alloc::alloc::handle_alloc_error` (at RUSTLIB/alloc/src/alloc.rs:LL:CC)
+note: which got called inside `miri_start`
   --> tests/fail/alloc/alloc_error_handler_custom.rs:LL:CC
    |
 LL |     handle_alloc_error(Layout::for_value(&0));

src/tools/miri/tests/fail/alloc/alloc_error_handler_no_std.stderr

@@ -7,12 +7,11 @@ error: abnormal termination: the program aborted execution
 LL |     core::intrinsics::abort();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^ abnormal termination occurred here
    |
-   = note: BACKTRACE:
-   = note: inside `panic_handler` at tests/fail/alloc/alloc_error_handler_no_std.rs:LL:CC
-   = note: inside `alloc::alloc::__alloc_error_handler::__rdl_alloc_error_handler` at RUSTLIB/alloc/src/alloc.rs:LL:CC
-   = note: inside `alloc::alloc::handle_alloc_error::rt_error` at RUSTLIB/alloc/src/alloc.rs:LL:CC
-   = note: inside `alloc::alloc::handle_alloc_error` at RUSTLIB/alloc/src/alloc.rs:LL:CC
-note: inside `miri_start`
+   = note: this is inside `panic_handler`
+   = note: which got called inside `alloc::alloc::__alloc_error_handler::__rdl_alloc_error_handler` (at RUSTLIB/alloc/src/alloc.rs:LL:CC)
+   = note: which got called inside `alloc::alloc::handle_alloc_error::rt_error` (at RUSTLIB/alloc/src/alloc.rs:LL:CC)
+   = note: which got called inside `alloc::alloc::handle_alloc_error` (at RUSTLIB/alloc/src/alloc.rs:LL:CC)
+note: which got called inside `miri_start`
   --> tests/fail/alloc/alloc_error_handler_no_std.rs:LL:CC
    |
 LL |     handle_alloc_error(Layout::for_value(&0));

src/tools/miri/tests/fail/alloc/global_system_mixup.stderr

@@ -6,10 +6,9 @@ LL |         FREE();
    |
    = 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: BACKTRACE:
-   = note: inside `std::sys::alloc::PLATFORM::<impl std::alloc::GlobalAlloc for std::alloc::System>::dealloc` at RUSTLIB/std/src/sys/alloc/PLATFORM.rs:LL:CC
-   = note: inside `<std::alloc::System as std::alloc::Allocator>::deallocate` at RUSTLIB/std/src/alloc.rs:LL:CC
-note: inside `main`
+   = note: this is inside `std::sys::alloc::PLATFORM::<impl std::alloc::GlobalAlloc for std::alloc::System>::dealloc`
+   = note: which got called inside `<std::alloc::System as std::alloc::Allocator>::deallocate` (at RUSTLIB/std/src/alloc.rs:LL:CC)
+note: which got called inside `main`
   --> tests/fail/alloc/global_system_mixup.rs:LL:CC
    |
 LL |     unsafe { System.deallocate(ptr, l) };

src/tools/miri/tests/fail/alloc/stack_free.stderr

@@ -6,11 +6,10 @@ LL |                 self.1.deallocate(From::from(ptr.cast()), layout);
    |
    = 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: BACKTRACE:
-   = note: inside `<std::boxed::Box<i32> as std::ops::Drop>::drop` at RUSTLIB/alloc/src/boxed.rs:LL:CC
-   = note: inside `std::ptr::drop_in_place::<std::boxed::Box<i32>> - shim(Some(std::boxed::Box<i32>))` at RUSTLIB/core/src/ptr/mod.rs:LL:CC
-   = note: inside `std::mem::drop::<std::boxed::Box<i32>>` at RUSTLIB/core/src/mem/mod.rs:LL:CC
-note: inside `main`
+   = note: this is inside `<std::boxed::Box<i32> as std::ops::Drop>::drop`
+   = note: which got called inside `std::ptr::drop_in_place::<std::boxed::Box<i32>> - shim(Some(std::boxed::Box<i32>))` (at RUSTLIB/core/src/ptr/mod.rs:LL:CC)
+   = note: which got called inside `std::mem::drop::<std::boxed::Box<i32>>` (at RUSTLIB/core/src/mem/mod.rs:LL:CC)
+note: which got called inside `main`
   --> tests/fail/alloc/stack_free.rs:LL:CC
    |
 LL |     drop(bad_box);

src/tools/miri/tests/fail/async-shared-mutable.stack.stderr

@@ -20,15 +20,18 @@ help: <TAG> was later invalidated at offsets [OFFSET] by a SharedReadOnly retag
    |
 LL |     let _: Pin<&_> = f.as_ref(); // Or: `f.as_mut().into_ref()`.
    |                      ^^^^^^^^^^
-   = note: BACKTRACE (of the first span):
-   = note: inside closure at tests/fail/async-shared-mutable.rs:LL:CC
-   = note: inside `<std::future::PollFn<{closure@tests/fail/async-shared-mutable.rs:LL:CC}> as std::future::Future>::poll` at RUSTLIB/core/src/future/poll_fn.rs:LL:CC
-note: inside closure
+note: error occurred inside closure
+  --> tests/fail/async-shared-mutable.rs:LL:CC
+   |
+LL |         core::future::poll_fn(move |_| {
+   |                               ^^^^^^^^
+   = note: which got called inside `<std::future::PollFn<{closure@tests/fail/async-shared-mutable.rs:LL:CC}> as std::future::Future>::poll` (at RUSTLIB/core/src/future/poll_fn.rs:LL:CC)
+note: which got called inside closure
   --> tests/fail/async-shared-mutable.rs:LL:CC
    |
 LL |         .await
    |          ^^^^^
-note: inside `main`
+note: which got called inside `main`
   --> tests/fail/async-shared-mutable.rs:LL:CC
    |
 LL |     assert_eq!(f.as_mut().poll(&mut cx), Poll::Pending);

src/tools/miri/tests/fail/async-shared-mutable.tree.stderr

@@ -28,15 +28,18 @@ help: the accessed tag <TAG> later transitioned to Frozen due to a reborrow (act
 LL |     let _: Pin<&_> = f.as_ref(); // Or: `f.as_mut().into_ref()`.
    |                      ^^^^^^^^^^
    = help: this transition corresponds to a loss of write permissions
-   = note: BACKTRACE (of the first span):
-   = note: inside closure at tests/fail/async-shared-mutable.rs:LL:CC
-   = note: inside `<std::future::PollFn<{closure@tests/fail/async-shared-mutable.rs:LL:CC}> as std::future::Future>::poll` at RUSTLIB/core/src/future/poll_fn.rs:LL:CC
-note: inside closure
+note: error occurred inside closure
+  --> tests/fail/async-shared-mutable.rs:LL:CC
+   |
+LL |         core::future::poll_fn(move |_| {
+   |                               ^^^^^^^^
+   = note: which got called inside `<std::future::PollFn<{closure@tests/fail/async-shared-mutable.rs:LL:CC}> as std::future::Future>::poll` (at RUSTLIB/core/src/future/poll_fn.rs:LL:CC)
+note: which got called inside closure
   --> tests/fail/async-shared-mutable.rs:LL:CC
    |
 LL |         .await
    |          ^^^^^
-note: inside `main`
+note: which got called inside `main`
   --> tests/fail/async-shared-mutable.rs:LL:CC
    |
 LL |     assert_eq!(f.as_mut().poll(&mut cx), Poll::Pending);

src/tools/miri/tests/fail/both_borrows/aliasing_mut1.stack.stderr

@@ -16,9 +16,12 @@ help: <TAG> is this argument
    |
 LL | fn safe(x: &mut i32, y: &mut i32) {
    |         ^
-   = note: BACKTRACE (of the first span):
-   = note: inside `safe` at tests/fail/both_borrows/aliasing_mut1.rs:LL:CC
-note: inside `main`
+note: error occurred inside `safe`
+  --> tests/fail/both_borrows/aliasing_mut1.rs:LL:CC
+   |
+LL | fn safe(x: &mut i32, y: &mut i32) {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+note: which got called inside `main`
   --> tests/fail/both_borrows/aliasing_mut1.rs:LL:CC
    |
 LL |     safe_raw(xraw, xraw);

src/tools/miri/tests/fail/both_borrows/aliasing_mut1.tree.stderr

@@ -18,9 +18,12 @@ help: the accessed tag <TAG> later transitioned to Reserved (conflicted) due to
 LL | fn safe(x: &mut i32, y: &mut i32) {
    |                      ^
    = help: this transition corresponds to a temporary loss of write permissions until function exit
-   = note: BACKTRACE (of the first span):
-   = note: inside `safe` at tests/fail/both_borrows/aliasing_mut1.rs:LL:CC
-note: inside `main`
+note: error occurred inside `safe`
+  --> tests/fail/both_borrows/aliasing_mut1.rs:LL:CC
+   |
+LL | fn safe(x: &mut i32, y: &mut i32) {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+note: which got called inside `main`
   --> tests/fail/both_borrows/aliasing_mut1.rs:LL:CC
    |
 LL |     safe_raw(xraw, xraw);

src/tools/miri/tests/fail/both_borrows/aliasing_mut2.stack.stderr

@@ -16,9 +16,12 @@ help: <TAG> is this argument
    |
 LL | fn safe(x: &i32, y: &mut i32) {
    |         ^
-   = note: BACKTRACE (of the first span):
-   = note: inside `safe` at tests/fail/both_borrows/aliasing_mut2.rs:LL:CC
-note: inside `main`
+note: error occurred inside `safe`
+  --> tests/fail/both_borrows/aliasing_mut2.rs:LL:CC
+   |
+LL | fn safe(x: &i32, y: &mut i32) {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+note: which got called inside `main`
   --> tests/fail/both_borrows/aliasing_mut2.rs:LL:CC
    |
 LL |     safe_raw(xshr, xraw);

src/tools/miri/tests/fail/both_borrows/aliasing_mut2.tree.stderr

@@ -18,9 +18,12 @@ help: the accessed tag <TAG> later transitioned to Reserved (conflicted) due to
 LL |     let _v = *x;
    |              ^^
    = help: this transition corresponds to a temporary loss of write permissions until function exit
-   = note: BACKTRACE (of the first span):
-   = note: inside `safe` at tests/fail/both_borrows/aliasing_mut2.rs:LL:CC
-note: inside `main`
+note: error occurred inside `safe`
+  --> tests/fail/both_borrows/aliasing_mut2.rs:LL:CC
+   |
+LL | fn safe(x: &i32, y: &mut i32) {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+note: which got called inside `main`
   --> tests/fail/both_borrows/aliasing_mut2.rs:LL:CC
    |
 LL |     safe_raw(xshr, xraw);

src/tools/miri/tests/fail/both_borrows/aliasing_mut3.stack.stderr

@@ -16,9 +16,12 @@ help: <TAG> was later invalidated at offsets [0x0..0x4] by a Unique function-ent
    |
 LL |     safe_raw(xraw, xshr);
    |     ^^^^^^^^^^^^^^^^^^^^
-   = note: BACKTRACE (of the first span):
-   = note: inside `safe` at tests/fail/both_borrows/aliasing_mut3.rs:LL:CC
-note: inside `main`
+note: error occurred inside `safe`
+  --> tests/fail/both_borrows/aliasing_mut3.rs:LL:CC
+   |
+LL | fn safe(x: &mut i32, y: &i32) {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+note: which got called inside `main`
   --> tests/fail/both_borrows/aliasing_mut3.rs:LL:CC
    |
 LL |     safe_raw(xraw, xshr);

src/tools/miri/tests/fail/both_borrows/aliasing_mut3.tree.stderr

@@ -18,9 +18,12 @@ help: the accessed tag <TAG> later transitioned to Reserved (conflicted) due to
 LL | fn safe(x: &mut i32, y: &i32) {
    |                      ^
    = help: this transition corresponds to a temporary loss of write permissions until function exit
-   = note: BACKTRACE (of the first span):
-   = note: inside `safe` at tests/fail/both_borrows/aliasing_mut3.rs:LL:CC
-note: inside `main`
+note: error occurred inside `safe`
+  --> tests/fail/both_borrows/aliasing_mut3.rs:LL:CC
+   |
+LL | fn safe(x: &mut i32, y: &i32) {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+note: which got called inside `main`
   --> tests/fail/both_borrows/aliasing_mut3.rs:LL:CC
    |
 LL |     safe_raw(xraw, xshr);

src/tools/miri/tests/fail/both_borrows/aliasing_mut4.stack.stderr

@@ -16,9 +16,12 @@ help: <TAG> is this argument
    |
 LL | fn safe(x: &i32, y: &mut Cell<i32>) {
    |         ^
-   = note: BACKTRACE (of the first span):
-   = note: inside `safe` at tests/fail/both_borrows/aliasing_mut4.rs:LL:CC
-note: inside `main`
+note: error occurred inside `safe`
+  --> tests/fail/both_borrows/aliasing_mut4.rs:LL:CC
+   |
+LL | fn safe(x: &i32, y: &mut Cell<i32>) {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+note: which got called inside `main`
   --> tests/fail/both_borrows/aliasing_mut4.rs:LL:CC
    |
 LL |     safe_raw(xshr, xraw as *mut _);

src/tools/miri/tests/fail/both_borrows/aliasing_mut4.tree.stderr

@@ -19,16 +19,19 @@ help: the protected tag <TAG> was created here, in the initial state Frozen
    |
 LL | fn safe(x: &i32, y: &mut Cell<i32>) {
    |         ^
-   = note: BACKTRACE (of the first span):
-   = note: inside `std::mem::replace::<i32>` at RUSTLIB/core/src/mem/mod.rs:LL:CC
-   = note: inside `std::cell::Cell::<i32>::replace` at RUSTLIB/core/src/cell.rs:LL:CC
-   = note: inside `std::cell::Cell::<i32>::set` at RUSTLIB/core/src/cell.rs:LL:CC
-note: inside `safe`
+note: error occurred inside `std::mem::replace::<i32>`
+  --> RUSTLIB/core/src/mem/mod.rs:LL:CC
+   |
+LL | pub const fn replace<T>(dest: &mut T, src: T) -> T {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   = note: which got called inside `std::cell::Cell::<i32>::replace` (at RUSTLIB/core/src/cell.rs:LL:CC)
+   = note: which got called inside `std::cell::Cell::<i32>::set` (at RUSTLIB/core/src/cell.rs:LL:CC)
+note: which got called inside `safe`
   --> tests/fail/both_borrows/aliasing_mut4.rs:LL:CC
    |
 LL |     y.set(1);
    |     ^^^^^^^^
-note: inside `main`
+note: which got called inside `main`
   --> tests/fail/both_borrows/aliasing_mut4.rs:LL:CC
    |
 LL |     safe_raw(xshr, xraw as *mut _);

src/tools/miri/tests/fail/both_borrows/box_exclusive_violation1.stack.stderr

@@ -16,14 +16,17 @@ help: <TAG> was later invalidated at offsets [0x0..0x4] by a write access
    |
 LL |     *our = 5;
    |     ^^^^^^^^
-   = note: BACKTRACE (of the first span):
-   = note: inside `unknown_code_2` at tests/fail/both_borrows/box_exclusive_violation1.rs:LL:CC
-note: inside `demo_box_advanced_unique`
+note: error occurred inside `unknown_code_2`
+  --> tests/fail/both_borrows/box_exclusive_violation1.rs:LL:CC
+   |
+LL | fn unknown_code_2() {
+   | ^^^^^^^^^^^^^^^^^^^
+note: which got called inside `demo_box_advanced_unique`
   --> tests/fail/both_borrows/box_exclusive_violation1.rs:LL:CC
    |
 LL |     unknown_code_2();
    |     ^^^^^^^^^^^^^^^^
-note: inside `main`
+note: which got called inside `main`
   --> tests/fail/both_borrows/box_exclusive_violation1.rs:LL:CC
    |
 LL |     demo_box_advanced_unique(Box::new(0));

src/tools/miri/tests/fail/both_borrows/box_exclusive_violation1.tree.stderr

@@ -18,14 +18,17 @@ help: the accessed tag <TAG> later transitioned to Disabled due to a foreign wri
 LL |     *our = 5;
    |     ^^^^^^^^
    = help: this transition corresponds to a loss of read permissions
-   = note: BACKTRACE (of the first span):
-   = note: inside `unknown_code_2` at tests/fail/both_borrows/box_exclusive_violation1.rs:LL:CC
-note: inside `demo_box_advanced_unique`
+note: error occurred inside `unknown_code_2`
+  --> tests/fail/both_borrows/box_exclusive_violation1.rs:LL:CC
+   |
+LL | fn unknown_code_2() {
+   | ^^^^^^^^^^^^^^^^^^^
+note: which got called inside `demo_box_advanced_unique`
   --> tests/fail/both_borrows/box_exclusive_violation1.rs:LL:CC
    |
 LL |     unknown_code_2();
    |     ^^^^^^^^^^^^^^^^
-note: inside `main`
+note: which got called inside `main`
   --> tests/fail/both_borrows/box_exclusive_violation1.rs:LL:CC
    |
 LL |     demo_box_advanced_unique(Box::new(0));

src/tools/miri/tests/fail/both_borrows/box_noalias_violation.stack.stderr

@@ -16,9 +16,12 @@ help: <TAG> is this argument
    |
 LL | unsafe fn test(mut x: Box<i32>, y: *const i32) -> i32 {
    |                ^^^^^
-   = note: BACKTRACE (of the first span):
-   = note: inside `test` at tests/fail/both_borrows/box_noalias_violation.rs:LL:CC
-note: inside `main`
+note: error occurred inside `test`
+  --> tests/fail/both_borrows/box_noalias_violation.rs:LL:CC
+   |
+LL | unsafe fn test(mut x: Box<i32>, y: *const i32) -> i32 {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+note: which got called inside `main`
   --> tests/fail/both_borrows/box_noalias_violation.rs:LL:CC
    |
 LL |         test(Box::from_raw(ptr), ptr);

src/tools/miri/tests/fail/both_borrows/box_noalias_violation.tree.stderr

@@ -25,9 +25,12 @@ help: the protected tag <TAG> later transitioned to Unique due to a child write
 LL |     *x = 5;
    |     ^^^^^^
    = help: this transition corresponds to the first write to a 2-phase borrowed mutable reference
-   = note: BACKTRACE (of the first span):
-   = note: inside `test` at tests/fail/both_borrows/box_noalias_violation.rs:LL:CC
-note: inside `main`
+note: error occurred inside `test`
+  --> tests/fail/both_borrows/box_noalias_violation.rs:LL:CC
+   |
+LL | unsafe fn test(mut x: Box<i32>, y: *const i32) -> i32 {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+note: which got called inside `main`
   --> tests/fail/both_borrows/box_noalias_violation.rs:LL:CC
    |
 LL |         test(Box::from_raw(ptr), ptr);

src/tools/miri/tests/fail/both_borrows/buggy_split_at_mut.stack.stderr

@@ -22,9 +22,12 @@ help: <TAG> was later invalidated at offsets [0x0..0x10] by a Unique retag
    |
 LL |                 from_raw_parts_mut(ptr.offset(mid as isize), len - mid),
    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   = note: BACKTRACE (of the first span):
-   = note: inside `safe::split_at_mut::<i32>` at tests/fail/both_borrows/buggy_split_at_mut.rs:LL:CC
-note: inside `main`
+note: error occurred inside `safe::split_at_mut::<i32>`
+  --> tests/fail/both_borrows/buggy_split_at_mut.rs:LL:CC
+   |
+LL |     pub fn split_at_mut<T>(self_: &mut [T], mid: usize) -> (&mut [T], &mut [T]) {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+note: which got called inside `main`
   --> tests/fail/both_borrows/buggy_split_at_mut.rs:LL:CC
    |
 LL |     let (a, b) = safe::split_at_mut(&mut array, 0);

src/tools/miri/tests/fail/both_borrows/illegal_write6.stack.stderr

@@ -16,9 +16,12 @@ help: <TAG> is this argument
    |
 LL | fn foo(a: &mut u32, y: *mut u32) -> u32 {
    |        ^
-   = note: BACKTRACE (of the first span):
-   = note: inside `foo` at tests/fail/both_borrows/illegal_write6.rs:LL:CC
-note: inside `main`
+note: error occurred inside `foo`
+  --> tests/fail/both_borrows/illegal_write6.rs:LL:CC
+   |
+LL | fn foo(a: &mut u32, y: *mut u32) -> u32 {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+note: which got called inside `main`
   --> tests/fail/both_borrows/illegal_write6.rs:LL:CC
    |
 LL |     foo(x, p);

src/tools/miri/tests/fail/both_borrows/illegal_write6.tree.stderr

@@ -25,9 +25,12 @@ help: the protected tag <TAG> later transitioned to Unique due to a child write
 LL |     *a = 1;
    |     ^^^^^^
    = help: this transition corresponds to the first write to a 2-phase borrowed mutable reference
-   = note: BACKTRACE (of the first span):
-   = note: inside `foo` at tests/fail/both_borrows/illegal_write6.rs:LL:CC
-note: inside `main`
+note: error occurred inside `foo`
+  --> tests/fail/both_borrows/illegal_write6.rs:LL:CC
+   |
+LL | fn foo(a: &mut u32, y: *mut u32) -> u32 {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+note: which got called inside `main`
   --> tests/fail/both_borrows/illegal_write6.rs:LL:CC
    |
 LL |     foo(x, p);

src/tools/miri/tests/fail/both_borrows/invalidate_against_protector2.stack.stderr

@@ -16,9 +16,12 @@ help: <TAG> is this argument
    |
 LL | fn inner(x: *mut i32, _y: &i32) {
    |                       ^^
-   = note: BACKTRACE (of the first span):
-   = note: inside `inner` at tests/fail/both_borrows/invalidate_against_protector2.rs:LL:CC
-note: inside `main`
+note: error occurred inside `inner`
+  --> tests/fail/both_borrows/invalidate_against_protector2.rs:LL:CC
+   |
+LL | fn inner(x: *mut i32, _y: &i32) {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+note: which got called inside `main`
   --> tests/fail/both_borrows/invalidate_against_protector2.rs:LL:CC
    |
 LL |     inner(xraw, xref);

src/tools/miri/tests/fail/both_borrows/invalidate_against_protector2.tree.stderr

@@ -19,9 +19,12 @@ help: the protected tag <TAG> was created here, in the initial state Frozen
    |
 LL | fn inner(x: *mut i32, _y: &i32) {
    |                       ^^
-   = note: BACKTRACE (of the first span):
-   = note: inside `inner` at tests/fail/both_borrows/invalidate_against_protector2.rs:LL:CC
-note: inside `main`
+note: error occurred inside `inner`
+  --> tests/fail/both_borrows/invalidate_against_protector2.rs:LL:CC
+   |
+LL | fn inner(x: *mut i32, _y: &i32) {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+note: which got called inside `main`
   --> tests/fail/both_borrows/invalidate_against_protector2.rs:LL:CC
    |
 LL |     inner(xraw, xref);

src/tools/miri/tests/fail/both_borrows/invalidate_against_protector3.stack.stderr

@@ -16,9 +16,12 @@ help: <TAG> is this argument
    |
 LL | fn inner(x: *mut i32, _y: &i32) {
    |                       ^^
-   = note: BACKTRACE (of the first span):
-   = note: inside `inner` at tests/fail/both_borrows/invalidate_against_protector3.rs:LL:CC
-note: inside `main`
+note: error occurred inside `inner`
+  --> tests/fail/both_borrows/invalidate_against_protector3.rs:LL:CC
+   |
+LL | fn inner(x: *mut i32, _y: &i32) {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+note: which got called inside `main`
   --> tests/fail/both_borrows/invalidate_against_protector3.rs:LL:CC
    |
 LL |         inner(ptr, &*ptr);

src/tools/miri/tests/fail/both_borrows/invalidate_against_protector3.tree.stderr

@@ -19,9 +19,12 @@ help: the protected tag <TAG> was created here, in the initial state Frozen
    |
 LL | fn inner(x: *mut i32, _y: &i32) {
    |                       ^^
-   = note: BACKTRACE (of the first span):
-   = note: inside `inner` at tests/fail/both_borrows/invalidate_against_protector3.rs:LL:CC
-note: inside `main`
+note: error occurred inside `inner`
+  --> tests/fail/both_borrows/invalidate_against_protector3.rs:LL:CC
+   |
+LL | fn inner(x: *mut i32, _y: &i32) {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+note: which got called inside `main`
   --> tests/fail/both_borrows/invalidate_against_protector3.rs:LL:CC
    |
 LL |         inner(ptr, &*ptr);

src/tools/miri/tests/fail/both_borrows/issue-miri-1050-1.stack.stderr

@@ -11,10 +11,13 @@ help: ALLOC was allocated here:
    |
 LL |         let ptr = Box::into_raw(Box::new(0u16));
    |                                 ^^^^^^^^^^^^^^
-   = note: BACKTRACE (of the first span):
-   = note: inside `std::boxed::Box::<u32>::from_raw_in` at RUSTLIB/alloc/src/boxed.rs:LL:CC
-   = note: inside `std::boxed::Box::<u32>::from_raw` at RUSTLIB/alloc/src/boxed.rs:LL:CC
-note: inside `main`
+note: error occurred inside `std::boxed::Box::<u32>::from_raw_in`
+  --> RUSTLIB/alloc/src/boxed.rs:LL:CC
+   |
+LL |     pub unsafe fn from_raw_in(raw: *mut T, alloc: A) -> Self {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   = note: which got called inside `std::boxed::Box::<u32>::from_raw` (at RUSTLIB/alloc/src/boxed.rs:LL:CC)
+note: which got called inside `main`
   --> tests/fail/both_borrows/issue-miri-1050-1.rs:LL:CC
    |
 LL |         drop(Box::from_raw(ptr as *mut u32));

src/tools/miri/tests/fail/both_borrows/issue-miri-1050-1.tree.stderr

@@ -11,10 +11,13 @@ help: ALLOC was allocated here:
    |
 LL |         let ptr = Box::into_raw(Box::new(0u16));
    |                                 ^^^^^^^^^^^^^^
-   = note: BACKTRACE (of the first span):
-   = note: inside `std::boxed::Box::<u32>::from_raw_in` at RUSTLIB/alloc/src/boxed.rs:LL:CC
-   = note: inside `std::boxed::Box::<u32>::from_raw` at RUSTLIB/alloc/src/boxed.rs:LL:CC
-note: inside `main`
+note: error occurred inside `std::boxed::Box::<u32>::from_raw_in`
+  --> RUSTLIB/alloc/src/boxed.rs:LL:CC
+   |
+LL |     pub unsafe fn from_raw_in(raw: *mut T, alloc: A) -> Self {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   = note: which got called inside `std::boxed::Box::<u32>::from_raw` (at RUSTLIB/alloc/src/boxed.rs:LL:CC)
+note: which got called inside `main`
   --> tests/fail/both_borrows/issue-miri-1050-1.rs:LL:CC
    |
 LL |         drop(Box::from_raw(ptr as *mut u32));

src/tools/miri/tests/fail/both_borrows/issue-miri-1050-2.stack.stderr

@@ -6,10 +6,9 @@ LL |         Box(unsafe { Unique::new_unchecked(raw) }, alloc)
    |
    = 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: BACKTRACE:
-   = note: inside `std::boxed::Box::<i32>::from_raw_in` at RUSTLIB/alloc/src/boxed.rs:LL:CC
-   = note: inside `std::boxed::Box::<i32>::from_raw` at RUSTLIB/alloc/src/boxed.rs:LL:CC
-note: inside `main`
+   = note: this is inside `std::boxed::Box::<i32>::from_raw_in`
+   = note: which got called inside `std::boxed::Box::<i32>::from_raw` (at RUSTLIB/alloc/src/boxed.rs:LL:CC)
+note: which got called inside `main`
   --> tests/fail/both_borrows/issue-miri-1050-2.rs:LL:CC
    |
 LL |         drop(Box::from_raw(ptr.as_ptr()));

src/tools/miri/tests/fail/both_borrows/issue-miri-1050-2.tree.stderr

@@ -6,10 +6,9 @@ LL |         Box(unsafe { Unique::new_unchecked(raw) }, alloc)
    |
    = 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: BACKTRACE:
-   = note: inside `std::boxed::Box::<i32>::from_raw_in` at RUSTLIB/alloc/src/boxed.rs:LL:CC
-   = note: inside `std::boxed::Box::<i32>::from_raw` at RUSTLIB/alloc/src/boxed.rs:LL:CC
-note: inside `main`
+   = note: this is inside `std::boxed::Box::<i32>::from_raw_in`
+   = note: which got called inside `std::boxed::Box::<i32>::from_raw` (at RUSTLIB/alloc/src/boxed.rs:LL:CC)
+note: which got called inside `main`
   --> tests/fail/both_borrows/issue-miri-1050-2.rs:LL:CC
    |
 LL |         drop(Box::from_raw(ptr.as_ptr()));

src/tools/miri/tests/fail/both_borrows/mut_exclusive_violation1.stack.stderr

@@ -16,14 +16,17 @@ help: <TAG> was later invalidated at offsets [0x0..0x4] by a write access
    |
 LL |     *our = 5;
    |     ^^^^^^^^
-   = note: BACKTRACE (of the first span):
-   = note: inside `unknown_code_2` at tests/fail/both_borrows/mut_exclusive_violation1.rs:LL:CC
-note: inside `demo_mut_advanced_unique`
+note: error occurred inside `unknown_code_2`
+  --> tests/fail/both_borrows/mut_exclusive_violation1.rs:LL:CC
+   |
+LL | fn unknown_code_2() {
+   | ^^^^^^^^^^^^^^^^^^^
+note: which got called inside `demo_mut_advanced_unique`
   --> tests/fail/both_borrows/mut_exclusive_violation1.rs:LL:CC
    |
 LL |     unknown_code_2();
    |     ^^^^^^^^^^^^^^^^
-note: inside `main`
+note: which got called inside `main`
   --> tests/fail/both_borrows/mut_exclusive_violation1.rs:LL:CC
    |
 LL |     demo_mut_advanced_unique(&mut 0);

src/tools/miri/tests/fail/both_borrows/mut_exclusive_violation1.tree.stderr

@@ -18,14 +18,17 @@ help: the accessed tag <TAG> later transitioned to Disabled due to a foreign wri
 LL |     *our = 5;
    |     ^^^^^^^^
    = help: this transition corresponds to a loss of read permissions
-   = note: BACKTRACE (of the first span):
-   = note: inside `unknown_code_2` at tests/fail/both_borrows/mut_exclusive_violation1.rs:LL:CC
-note: inside `demo_mut_advanced_unique`
+note: error occurred inside `unknown_code_2`
+  --> tests/fail/both_borrows/mut_exclusive_violation1.rs:LL:CC
+   |
+LL | fn unknown_code_2() {
+   | ^^^^^^^^^^^^^^^^^^^
+note: which got called inside `demo_mut_advanced_unique`
   --> tests/fail/both_borrows/mut_exclusive_violation1.rs:LL:CC
    |
 LL |     unknown_code_2();
    |     ^^^^^^^^^^^^^^^^
-note: inside `main`
+note: which got called inside `main`
   --> tests/fail/both_borrows/mut_exclusive_violation1.rs:LL:CC
    |
 LL |     demo_mut_advanced_unique(&mut 0);

src/tools/miri/tests/fail/both_borrows/newtype_pair_retagging.stack.stderr

@@ -16,20 +16,23 @@ help: <TAG> is this argument
    |
 LL | fn dealloc_while_running(_n: Newtype<'_>, dealloc: impl FnOnce()) {
    |                          ^^
-   = note: BACKTRACE (of the first span):
-   = note: inside `std::boxed::Box::<i32>::from_raw_in` at RUSTLIB/alloc/src/boxed.rs:LL:CC
-   = note: inside `std::boxed::Box::<i32>::from_raw` at RUSTLIB/alloc/src/boxed.rs:LL:CC
-note: inside closure
+note: error occurred inside `std::boxed::Box::<i32>::from_raw_in`
+  --> RUSTLIB/alloc/src/boxed.rs:LL:CC
+   |
+LL |     pub unsafe fn from_raw_in(raw: *mut T, alloc: A) -> Self {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   = note: which got called inside `std::boxed::Box::<i32>::from_raw` (at RUSTLIB/alloc/src/boxed.rs:LL:CC)
+note: which got called inside closure
   --> tests/fail/both_borrows/newtype_pair_retagging.rs:LL:CC
    |
 LL |             || drop(Box::from_raw(ptr)),
    |                     ^^^^^^^^^^^^^^^^^^
-note: inside `dealloc_while_running::<{closure@tests/fail/both_borrows/newtype_pair_retagging.rs:LL:CC}>`
+note: which got called inside `dealloc_while_running::<{closure@tests/fail/both_borrows/newtype_pair_retagging.rs:LL:CC}>`
   --> tests/fail/both_borrows/newtype_pair_retagging.rs:LL:CC
    |
 LL |     dealloc();
    |     ^^^^^^^^^
-note: inside `main`
+note: which got called inside `main`
   --> tests/fail/both_borrows/newtype_pair_retagging.rs:LL:CC
    |
 LL | /         dealloc_while_running(

src/tools/miri/tests/fail/both_borrows/newtype_pair_retagging.tree.stderr

@@ -25,21 +25,24 @@ help: the protected tag <TAG> later transitioned to Reserved (conflicted) due to
 LL |             || drop(Box::from_raw(ptr)),
    |                     ^^^^^^^^^^^^^^^^^^
    = help: this transition corresponds to a temporary loss of write permissions until function exit
-   = note: BACKTRACE (of the first span):
-   = note: inside `<std::boxed::Box<i32> as std::ops::Drop>::drop` at RUSTLIB/alloc/src/boxed.rs:LL:CC
-   = note: inside `std::ptr::drop_in_place::<std::boxed::Box<i32>> - shim(Some(std::boxed::Box<i32>))` at RUSTLIB/core/src/ptr/mod.rs:LL:CC
-   = note: inside `std::mem::drop::<std::boxed::Box<i32>>` at RUSTLIB/core/src/mem/mod.rs:LL:CC
-note: inside closure
+note: error occurred inside `<std::boxed::Box<i32> as std::ops::Drop>::drop`
+  --> RUSTLIB/alloc/src/boxed.rs:LL:CC
+   |
+LL |     fn drop(&mut self) {
+   |     ^^^^^^^^^^^^^^^^^^
+   = note: which got called inside `std::ptr::drop_in_place::<std::boxed::Box<i32>> - shim(Some(std::boxed::Box<i32>))` (at RUSTLIB/core/src/ptr/mod.rs:LL:CC)
+   = note: which got called inside `std::mem::drop::<std::boxed::Box<i32>>` (at RUSTLIB/core/src/mem/mod.rs:LL:CC)
+note: which got called inside closure
   --> tests/fail/both_borrows/newtype_pair_retagging.rs:LL:CC
    |
 LL |             || drop(Box::from_raw(ptr)),
    |                ^^^^^^^^^^^^^^^^^^^^^^^^
-note: inside `dealloc_while_running::<{closure@tests/fail/both_borrows/newtype_pair_retagging.rs:LL:CC}>`
+note: which got called inside `dealloc_while_running::<{closure@tests/fail/both_borrows/newtype_pair_retagging.rs:LL:CC}>`
   --> tests/fail/both_borrows/newtype_pair_retagging.rs:LL:CC
    |
 LL |     dealloc();
    |     ^^^^^^^^^
-note: inside `main`
+note: which got called inside `main`
   --> tests/fail/both_borrows/newtype_pair_retagging.rs:LL:CC
    |
 LL | /         dealloc_while_running(

src/tools/miri/tests/fail/both_borrows/newtype_retagging.stack.stderr

@@ -16,20 +16,23 @@ help: <TAG> is this argument
    |
 LL | fn dealloc_while_running(_n: Newtype<'_>, dealloc: impl FnOnce()) {
    |                          ^^
-   = note: BACKTRACE (of the first span):
-   = note: inside `std::boxed::Box::<i32>::from_raw_in` at RUSTLIB/alloc/src/boxed.rs:LL:CC
-   = note: inside `std::boxed::Box::<i32>::from_raw` at RUSTLIB/alloc/src/boxed.rs:LL:CC
-note: inside closure
+note: error occurred inside `std::boxed::Box::<i32>::from_raw_in`
+  --> RUSTLIB/alloc/src/boxed.rs:LL:CC
+   |
+LL |     pub unsafe fn from_raw_in(raw: *mut T, alloc: A) -> Self {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   = note: which got called inside `std::boxed::Box::<i32>::from_raw` (at RUSTLIB/alloc/src/boxed.rs:LL:CC)
+note: which got called inside closure
   --> tests/fail/both_borrows/newtype_retagging.rs:LL:CC
    |
 LL |             || drop(Box::from_raw(ptr)),
    |                     ^^^^^^^^^^^^^^^^^^
-note: inside `dealloc_while_running::<{closure@tests/fail/both_borrows/newtype_retagging.rs:LL:CC}>`
+note: which got called inside `dealloc_while_running::<{closure@tests/fail/both_borrows/newtype_retagging.rs:LL:CC}>`
   --> tests/fail/both_borrows/newtype_retagging.rs:LL:CC
    |
 LL |     dealloc();
    |     ^^^^^^^^^
-note: inside `main`
+note: which got called inside `main`
   --> tests/fail/both_borrows/newtype_retagging.rs:LL:CC
    |
 LL | /         dealloc_while_running(

src/tools/miri/tests/fail/both_borrows/newtype_retagging.tree.stderr

@@ -25,21 +25,24 @@ help: the protected tag <TAG> later transitioned to Reserved (conflicted) due to
 LL |             || drop(Box::from_raw(ptr)),
    |                     ^^^^^^^^^^^^^^^^^^
    = help: this transition corresponds to a temporary loss of write permissions until function exit
-   = note: BACKTRACE (of the first span):
-   = note: inside `<std::boxed::Box<i32> as std::ops::Drop>::drop` at RUSTLIB/alloc/src/boxed.rs:LL:CC
-   = note: inside `std::ptr::drop_in_place::<std::boxed::Box<i32>> - shim(Some(std::boxed::Box<i32>))` at RUSTLIB/core/src/ptr/mod.rs:LL:CC
-   = note: inside `std::mem::drop::<std::boxed::Box<i32>>` at RUSTLIB/core/src/mem/mod.rs:LL:CC
-note: inside closure
+note: error occurred inside `<std::boxed::Box<i32> as std::ops::Drop>::drop`
+  --> RUSTLIB/alloc/src/boxed.rs:LL:CC
+   |
+LL |     fn drop(&mut self) {
+   |     ^^^^^^^^^^^^^^^^^^
+   = note: which got called inside `std::ptr::drop_in_place::<std::boxed::Box<i32>> - shim(Some(std::boxed::Box<i32>))` (at RUSTLIB/core/src/ptr/mod.rs:LL:CC)
+   = note: which got called inside `std::mem::drop::<std::boxed::Box<i32>>` (at RUSTLIB/core/src/mem/mod.rs:LL:CC)
+note: which got called inside closure
   --> tests/fail/both_borrows/newtype_retagging.rs:LL:CC
    |
 LL |             || drop(Box::from_raw(ptr)),
    |                ^^^^^^^^^^^^^^^^^^^^^^^^
-note: inside `dealloc_while_running::<{closure@tests/fail/both_borrows/newtype_retagging.rs:LL:CC}>`
+note: which got called inside `dealloc_while_running::<{closure@tests/fail/both_borrows/newtype_retagging.rs:LL:CC}>`
   --> tests/fail/both_borrows/newtype_retagging.rs:LL:CC
    |
 LL |     dealloc();
    |     ^^^^^^^^^
-note: inside `main`
+note: which got called inside `main`
   --> tests/fail/both_borrows/newtype_retagging.rs:LL:CC
    |
 LL | /         dealloc_while_running(

src/tools/miri/tests/fail/both_borrows/retag_data_race_write.stack.stderr

@@ -14,9 +14,12 @@ LL |         let _r = &mut *p;
    = help: therefore from the perspective of data races, a retag has the same implications as a read or write
    = 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: BACKTRACE (of the first span) on thread `unnamed-ID`:
-   = note: inside `thread_2` at tests/fail/both_borrows/retag_data_race_write.rs:LL:CC
-note: inside closure
+note: error occurred on thread `unnamed-ID`, inside `thread_2`
+  --> tests/fail/both_borrows/retag_data_race_write.rs:LL:CC
+   |
+LL | fn thread_2(p: SendPtr) {
+   | ^^^^^^^^^^^^^^^^^^^^^^^
+note: which got called inside closure
   --> tests/fail/both_borrows/retag_data_race_write.rs:LL:CC
    |
 LL |     let t2 = std::thread::spawn(move || thread_2(p));

src/tools/miri/tests/fail/both_borrows/retag_data_race_write.tree.stderr

@@ -14,9 +14,12 @@ LL |         let _r = &mut *p;
    = help: therefore from the perspective of data races, a retag has the same implications as a read or write
    = 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: BACKTRACE (of the first span) on thread `unnamed-ID`:
-   = note: inside `thread_2` at tests/fail/both_borrows/retag_data_race_write.rs:LL:CC
-note: inside closure
+note: error occurred on thread `unnamed-ID`, inside `thread_2`
+  --> tests/fail/both_borrows/retag_data_race_write.rs:LL:CC
+   |
+LL | fn thread_2(p: SendPtr) {
+   | ^^^^^^^^^^^^^^^^^^^^^^^
+note: which got called inside closure
   --> tests/fail/both_borrows/retag_data_race_write.rs:LL:CC
    |
 LL |     let t2 = std::thread::spawn(move || thread_2(p));

src/tools/miri/tests/fail/both_borrows/return_invalid_shr.stack.stderr

@@ -16,9 +16,12 @@ help: <TAG> was later invalidated at offsets [0x4..0x8] by a write access
    |
 LL |     unsafe { *xraw = (42, 23) }; // unfreeze
    |              ^^^^^^^^^^^^^^^^
-   = note: BACKTRACE (of the first span):
-   = note: inside `foo` at tests/fail/both_borrows/return_invalid_shr.rs:LL:CC
-note: inside `main`
+note: error occurred inside `foo`
+  --> tests/fail/both_borrows/return_invalid_shr.rs:LL:CC
+   |
+LL | fn foo(x: &mut (i32, i32)) -> &i32 {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+note: which got called inside `main`
   --> tests/fail/both_borrows/return_invalid_shr.rs:LL:CC
    |
 LL |     foo(&mut (1, 2));

src/tools/miri/tests/fail/both_borrows/return_invalid_shr.tree.stderr

@@ -18,9 +18,12 @@ help: the accessed tag <TAG> later transitioned to Disabled due to a foreign wri
 LL |     unsafe { *xraw = (42, 23) }; // unfreeze
    |              ^^^^^^^^^^^^^^^^
    = help: this transition corresponds to a loss of read permissions
-   = note: BACKTRACE (of the first span):
-   = note: inside `foo` at tests/fail/both_borrows/return_invalid_shr.rs:LL:CC
-note: inside `main`
+note: error occurred inside `foo`
+  --> tests/fail/both_borrows/return_invalid_shr.rs:LL:CC
+   |
+LL | fn foo(x: &mut (i32, i32)) -> &i32 {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+note: which got called inside `main`
   --> tests/fail/both_borrows/return_invalid_shr.rs:LL:CC
    |
 LL |     foo(&mut (1, 2));

src/tools/miri/tests/fail/both_borrows/return_invalid_shr_option.stack.stderr

@@ -19,9 +19,12 @@ help: <TAG> was later invalidated at offsets [0x4..0x8] by a write access
    |
 LL |     unsafe { *xraw = (42, 23) }; // unfreeze
    |              ^^^^^^^^^^^^^^^^
-   = note: BACKTRACE (of the first span):
-   = note: inside `foo` at tests/fail/both_borrows/return_invalid_shr_option.rs:LL:CC
-note: inside `main`
+note: error occurred inside `foo`
+  --> tests/fail/both_borrows/return_invalid_shr_option.rs:LL:CC
+   |
+LL | fn foo(x: &mut (i32, i32)) -> Option<&i32> {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+note: which got called inside `main`
   --> tests/fail/both_borrows/return_invalid_shr_option.rs:LL:CC
    |
 LL |     match foo(&mut (1, 2)) {

src/tools/miri/tests/fail/both_borrows/return_invalid_shr_option.tree.stderr

@@ -18,9 +18,12 @@ help: the accessed tag <TAG> later transitioned to Disabled due to a foreign wri
 LL |     unsafe { *xraw = (42, 23) }; // unfreeze
    |              ^^^^^^^^^^^^^^^^
    = help: this transition corresponds to a loss of read permissions
-   = note: BACKTRACE (of the first span):
-   = note: inside `foo` at tests/fail/both_borrows/return_invalid_shr_option.rs:LL:CC
-note: inside `main`
+note: error occurred inside `foo`
+  --> tests/fail/both_borrows/return_invalid_shr_option.rs:LL:CC
+   |
+LL | fn foo(x: &mut (i32, i32)) -> Option<&i32> {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+note: which got called inside `main`
   --> tests/fail/both_borrows/return_invalid_shr_option.rs:LL:CC
    |
 LL |     match foo(&mut (1, 2)) {

src/tools/miri/tests/fail/both_borrows/return_invalid_shr_tuple.stack.stderr

@@ -19,9 +19,12 @@ help: <TAG> was later invalidated at offsets [0x4..0x8] by a write access
    |
 LL |     unsafe { *xraw = (42, 23) }; // unfreeze
    |              ^^^^^^^^^^^^^^^^
-   = note: BACKTRACE (of the first span):
-   = note: inside `foo` at tests/fail/both_borrows/return_invalid_shr_tuple.rs:LL:CC
-note: inside `main`
+note: error occurred inside `foo`
+  --> tests/fail/both_borrows/return_invalid_shr_tuple.rs:LL:CC
+   |
+LL | fn foo(x: &mut (i32, i32)) -> (&i32,) {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+note: which got called inside `main`
   --> tests/fail/both_borrows/return_invalid_shr_tuple.rs:LL:CC
    |
 LL |     foo(&mut (1, 2)).0;

src/tools/miri/tests/fail/both_borrows/return_invalid_shr_tuple.tree.stderr

@@ -18,9 +18,12 @@ help: the accessed tag <TAG> later transitioned to Disabled due to a foreign wri
 LL |     unsafe { *xraw = (42, 23) }; // unfreeze
    |              ^^^^^^^^^^^^^^^^
    = help: this transition corresponds to a loss of read permissions
-   = note: BACKTRACE (of the first span):
-   = note: inside `foo` at tests/fail/both_borrows/return_invalid_shr_tuple.rs:LL:CC
-note: inside `main`
+note: error occurred inside `foo`
+  --> tests/fail/both_borrows/return_invalid_shr_tuple.rs:LL:CC
+   |
+LL | fn foo(x: &mut (i32, i32)) -> (&i32,) {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+note: which got called inside `main`
   --> tests/fail/both_borrows/return_invalid_shr_tuple.rs:LL:CC
    |
 LL |     foo(&mut (1, 2)).0;

src/tools/miri/tests/fail/both_borrows/shr_frozen_violation1.stack.stderr

@@ -11,14 +11,17 @@ help: <TAG> was created by a SharedReadOnly retag at offsets [0x0..0x4]
    |
 LL |         *(x as *const i32 as *mut i32) = 7;
    |           ^
-   = note: BACKTRACE (of the first span):
-   = note: inside `unknown_code` at tests/fail/both_borrows/shr_frozen_violation1.rs:LL:CC
-note: inside `foo`
+note: error occurred inside `unknown_code`
+  --> tests/fail/both_borrows/shr_frozen_violation1.rs:LL:CC
+   |
+LL | fn unknown_code(x: &i32) {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^
+note: which got called inside `foo`
   --> tests/fail/both_borrows/shr_frozen_violation1.rs:LL:CC
    |
 LL |     unknown_code(&*x);
    |     ^^^^^^^^^^^^^^^^^
-note: inside `main`
+note: which got called inside `main`
   --> tests/fail/both_borrows/shr_frozen_violation1.rs:LL:CC
    |
 LL |     println!("{}", foo(&mut 0));

src/tools/miri/tests/fail/both_borrows/shr_frozen_violation1.tree.stderr

@@ -12,14 +12,17 @@ help: the accessed tag <TAG> was created here, in the initial state Frozen
    |
 LL | fn unknown_code(x: &i32) {
    |                 ^
-   = note: BACKTRACE (of the first span):
-   = note: inside `unknown_code` at tests/fail/both_borrows/shr_frozen_violation1.rs:LL:CC
-note: inside `foo`
+note: error occurred inside `unknown_code`
+  --> tests/fail/both_borrows/shr_frozen_violation1.rs:LL:CC
+   |
+LL | fn unknown_code(x: &i32) {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^
+note: which got called inside `foo`
   --> tests/fail/both_borrows/shr_frozen_violation1.rs:LL:CC
    |
 LL |     unknown_code(&*x);
    |     ^^^^^^^^^^^^^^^^^
-note: inside `main`
+note: which got called inside `main`
   --> tests/fail/both_borrows/shr_frozen_violation1.rs:LL:CC
    |
 LL |     println!("{}", foo(&mut 0));

src/tools/miri/tests/fail/box-cell-alias.stderr

@@ -16,9 +16,12 @@ help: <TAG> was later invalidated at offsets [0x0..0x1] by a Unique retag
    |
 LL |     let res = helper(val, ptr);
    |                      ^^^
-   = note: BACKTRACE (of the first span):
-   = note: inside `helper` at tests/fail/box-cell-alias.rs:LL:CC
-note: inside `main`
+note: error occurred inside `helper`
+  --> tests/fail/box-cell-alias.rs:LL:CC
+   |
+LL | fn helper(val: Box<Cell<u8>>, ptr: *const Cell<u8>) -> u8 {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+note: which got called inside `main`
   --> tests/fail/box-cell-alias.rs:LL:CC
    |
 LL |     let res = helper(val, ptr);

src/tools/miri/tests/fail/closures/uninhabited-variant.stderr

@@ -6,9 +6,8 @@ LL |         match r {
    |
    = 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: BACKTRACE:
-   = note: inside closure at tests/fail/closures/uninhabited-variant.rs:LL:CC
-note: inside `main`
+   = note: this is inside closure
+note: which got called inside `main`
   --> tests/fail/closures/uninhabited-variant.rs:LL:CC
    |
 LL |     f();

src/tools/miri/tests/fail/concurrency/mutex-leak-move-deadlock.rs

@@ -4,7 +4,7 @@
 //@normalize-stderr-test: "\| +\^+" -> "| ^"
 //@normalize-stderr-test: "\n *= note:.*" -> ""
 // On macOS we use chekced pthread mutexes which changes the error
-//@normalize-stderr-test: "this thread got stuck here" -> "thread `main` got stuck here"
+//@normalize-stderr-test: "a thread got stuck here" -> "thread `main` got stuck here"
 //@normalize-stderr-test: "a thread deadlocked" -> "the evaluated program deadlocked"
 use std::mem;
 use std::sync::Mutex;

src/tools/miri/tests/fail/concurrency/mutex-leak-move-deadlock.stderr

@@ -2,9 +2,9 @@ error: the evaluated program deadlocked
   --> RUSTLIB/std/$FILE:LL:CC
    |
 LL | $CODE
-   | ^ thread `main` got stuck here
+   | ^ thread got stuck here
    |
-note: inside `main`
+note: which got called inside `main`
   --> tests/fail/concurrency/mutex-leak-move-deadlock.rs:LL:CC
    |
 LL | $CODE

src/tools/miri/tests/fail/coroutine-pinned-moved.stderr

@@ -16,15 +16,18 @@ help: ALLOC was deallocated here:
    |
 LL |     }; // *deallocate* coroutine_iterator
    |     ^
-   = note: BACKTRACE (of the first span):
-   = note: inside closure at tests/fail/coroutine-pinned-moved.rs:LL:CC
-note: inside `<CoroutineIteratorAdapter<{static coroutine@tests/fail/coroutine-pinned-moved.rs:LL:CC}> as std::iter::Iterator>::next`
+note: error occurred inside closure
+  --> tests/fail/coroutine-pinned-moved.rs:LL:CC
+   |
+LL |     static move || {
+   |     ^^^^^^^^^^^^^^
+note: which got called inside `<CoroutineIteratorAdapter<{static coroutine@tests/fail/coroutine-pinned-moved.rs:LL:CC}> as std::iter::Iterator>::next`
   --> tests/fail/coroutine-pinned-moved.rs:LL:CC
    |
 LL |         match me.resume(()) {
    |               ^^^^^^^^^^^^^
-   = note: inside `std::boxed::iter::<impl std::iter::Iterator for std::boxed::Box<CoroutineIteratorAdapter<{static coroutine@tests/fail/coroutine-pinned-moved.rs:LL:CC}>>>::next` at RUSTLIB/alloc/src/boxed/iter.rs:LL:CC
-note: inside `main`
+   = note: which got called inside `std::boxed::iter::<impl std::iter::Iterator for std::boxed::Box<CoroutineIteratorAdapter<{static coroutine@tests/fail/coroutine-pinned-moved.rs:LL:CC}>>>::next` (at RUSTLIB/alloc/src/boxed/iter.rs:LL:CC)
+note: which got called inside `main`
   --> tests/fail/coroutine-pinned-moved.rs:LL:CC
    |
 LL |     coroutine_iterator_2.next(); // and use moved value

src/tools/miri/tests/fail/dangling_pointers/dangling_pointer_to_raw_pointer.stderr

@@ -6,9 +6,8 @@ LL |     unsafe { &(*x).0 as *const i32 }
    |
    = 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: BACKTRACE:
-   = note: inside `via_ref` at tests/fail/dangling_pointers/dangling_pointer_to_raw_pointer.rs:LL:CC
-note: inside `main`
+   = note: this is inside `via_ref`
+note: which got called inside `main`
   --> tests/fail/dangling_pointers/dangling_pointer_to_raw_pointer.rs:LL:CC
    |
 LL |     via_ref(ptr); // this is not

src/tools/miri/tests/fail/dangling_pointers/storage_dead_dangling.stderr

@@ -6,9 +6,8 @@ LL |     let _ref = unsafe { &mut *(LEAK as *mut i32) };
    |
    = 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: BACKTRACE:
-   = note: inside `evil` at tests/fail/dangling_pointers/storage_dead_dangling.rs:LL:CC
-note: inside `main`
+   = note: this is inside `evil`
+note: which got called inside `main`
   --> tests/fail/dangling_pointers/storage_dead_dangling.rs:LL:CC
    |
 LL |     evil();

src/tools/miri/tests/fail/data_race/alloc_read_race.stderr

@@ -11,6 +11,7 @@ LL |             pointer.store(Box::into_raw(Box::new_uninit()), Ordering::Relax
    |                                         ^^^^^^^^^^^^^^^^^
    = 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: this is on thread `unnamed-ID`
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

src/tools/miri/tests/fail/data_race/alloc_write_race.stderr

@@ -11,6 +11,7 @@ LL |                 .store(Box::into_raw(Box::<usize>::new_uninit()) as *mut us
    |                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^
    = 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: this is on thread `unnamed-ID`
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

src/tools/miri/tests/fail/data_race/atomic_read_na_write_race1.stderr

@@ -11,6 +11,7 @@ LL |             *(c.0 as *mut usize) = 32;
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^
    = 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: this is on thread `unnamed-ID`
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

src/tools/miri/tests/fail/data_race/atomic_read_na_write_race2.stderr

@@ -11,6 +11,7 @@ LL |             atomic_ref.load(Ordering::SeqCst)
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    = 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: this is on thread `unnamed-ID`
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

src/tools/miri/tests/fail/data_race/atomic_write_na_read_race1.stderr

@@ -11,6 +11,7 @@ LL |             atomic_ref.store(32, Ordering::SeqCst)
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    = 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: this is on thread `unnamed-ID`
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

src/tools/miri/tests/fail/data_race/atomic_write_na_read_race2.stderr

@@ -11,6 +11,7 @@ LL |             let _val = *(c.0 as *mut usize);
    |                        ^^^^^^^^^^^^^^^^^^^^
    = 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: this is on thread `unnamed-ID`
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

src/tools/miri/tests/fail/data_race/atomic_write_na_write_race1.stderr

@@ -11,6 +11,7 @@ LL |             *(c.0 as *mut usize) = 32;
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^
    = 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: this is on thread `unnamed-ID`
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

src/tools/miri/tests/fail/data_race/atomic_write_na_write_race2.stderr

@@ -11,6 +11,7 @@ LL |             atomic_ref.store(64, Ordering::SeqCst);
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    = 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: this is on thread `unnamed-ID`
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace