From 3e633981ef0827bf699559036f1437bca071f804 Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Thu, 18 Apr 2024 11:14:37 +0200
Subject: [PATCH] when suggesting RUST_BACKTRACE=1, add a special note for
 Miri's env var isolation

---
 library/std/src/panicking.rs                               | 7 +++++++
 .../fail/function_calls/exported_symbol_bad_unwind1.stderr | 1 +
 .../function_calls/exported_symbol_bad_unwind2.both.stderr | 1 +
 .../exported_symbol_bad_unwind2.definition.stderr          | 1 +
 .../exported_symbol_bad_unwind2.extern_block.stderr        | 1 +
 .../fail/function_calls/return_pointer_on_unwind.stderr    | 1 +
 .../tests/fail/intrinsics/uninit_uninhabited_type.stderr   | 1 +
 src/tools/miri/tests/fail/intrinsics/zero_fn_ptr.stderr    | 1 +
 src/tools/miri/tests/fail/panic/bad_unwind.stderr          | 1 +
 src/tools/miri/tests/fail/panic/double_panic.stderr        | 1 +
 src/tools/miri/tests/fail/panic/panic_abort1.stderr        | 1 +
 src/tools/miri/tests/fail/panic/panic_abort2.stderr        | 1 +
 src/tools/miri/tests/fail/panic/panic_abort3.stderr        | 1 +
 src/tools/miri/tests/fail/panic/panic_abort4.stderr        | 1 +
 src/tools/miri/tests/fail/terminate-terminator.stderr      | 1 +
 src/tools/miri/tests/fail/unwind-action-terminate.stderr   | 1 +
 src/tools/miri/tests/panic/div-by-zero-2.stderr            | 1 +
 .../function_calls/exported_symbol_good_unwind.stderr      | 1 +
 src/tools/miri/tests/panic/oob_subslice.stderr             | 1 +
 src/tools/miri/tests/panic/overflowing-lsh-neg.stderr      | 1 +
 src/tools/miri/tests/panic/overflowing-rsh-1.stderr        | 1 +
 src/tools/miri/tests/panic/overflowing-rsh-2.stderr        | 1 +
 src/tools/miri/tests/panic/panic2.stderr                   | 1 +
 src/tools/miri/tests/panic/panic3.stderr                   | 1 +
 src/tools/miri/tests/panic/panic4.stderr                   | 1 +
 src/tools/miri/tests/panic/transmute_fat2.stderr           | 1 +
 .../miri/tests/panic/unsupported_foreign_function.stderr   | 1 +
 src/tools/miri/tests/panic/unsupported_syscall.stderr      | 1 +
 src/tools/miri/tests/pass/panic/catch_panic.stderr         | 1 +
 src/tools/miri/tests/pass/panic/concurrent-panic.stderr    | 1 +
 src/tools/miri/tests/pass/panic/nested_panic_caught.stderr | 1 +
 src/tools/miri/tests/pass/panic/thread_panic.stderr        | 1 +
 32 files changed, 38 insertions(+)

diff --git a/library/std/src/panicking.rs b/library/std/src/panicking.rs
index 0052fcbb94a..5699937cdb4 100644
--- a/library/std/src/panicking.rs
+++ b/library/std/src/panicking.rs
@@ -277,6 +277,13 @@ fn default_hook(info: &PanicInfo<'_>) {
                         "note: run with `RUST_BACKTRACE=1` environment variable to display a \
                              backtrace"
                     );
+                    if cfg!(miri) {
+                        let _ = writeln!(
+                            err,
+                            "note: in Miri, you may have to set `-Zmiri-env-forward=RUST_BACKTRACE` \
+                                for the environment variable to have an effect"
+                        );
+                    }
                 }
             }
             // If backtraces aren't supported or are forced-off, do nothing.
diff --git a/src/tools/miri/tests/fail/function_calls/exported_symbol_bad_unwind1.stderr b/src/tools/miri/tests/fail/function_calls/exported_symbol_bad_unwind1.stderr
index ab32883a035..42beed4ecde 100644
--- a/src/tools/miri/tests/fail/function_calls/exported_symbol_bad_unwind1.stderr
+++ b/src/tools/miri/tests/fail/function_calls/exported_symbol_bad_unwind1.stderr
@@ -1,6 +1,7 @@
 thread 'main' panicked at $DIR/exported_symbol_bad_unwind1.rs:LL:CC:
 explicit panic
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+note: in Miri, you may have to set `-Zmiri-env-forward=RUST_BACKTRACE` for the environment variable to have an effect
 error: Undefined Behavior: unwinding past a stack frame that does not allow unwinding
   --> $DIR/exported_symbol_bad_unwind1.rs:LL:CC
    |
diff --git a/src/tools/miri/tests/fail/function_calls/exported_symbol_bad_unwind2.both.stderr b/src/tools/miri/tests/fail/function_calls/exported_symbol_bad_unwind2.both.stderr
index 9774e1e1a79..d88781ed225 100644
--- a/src/tools/miri/tests/fail/function_calls/exported_symbol_bad_unwind2.both.stderr
+++ b/src/tools/miri/tests/fail/function_calls/exported_symbol_bad_unwind2.both.stderr
@@ -1,6 +1,7 @@
 thread 'main' panicked at $DIR/exported_symbol_bad_unwind2.rs:LL:CC:
 explicit panic
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+note: in Miri, you may have to set `-Zmiri-env-forward=RUST_BACKTRACE` for the environment variable to have an effect
 thread 'main' panicked at RUSTLIB/core/src/panicking.rs:LL:CC:
 panic in a function that cannot unwind
 stack backtrace:
diff --git a/src/tools/miri/tests/fail/function_calls/exported_symbol_bad_unwind2.definition.stderr b/src/tools/miri/tests/fail/function_calls/exported_symbol_bad_unwind2.definition.stderr
index 9774e1e1a79..d88781ed225 100644
--- a/src/tools/miri/tests/fail/function_calls/exported_symbol_bad_unwind2.definition.stderr
+++ b/src/tools/miri/tests/fail/function_calls/exported_symbol_bad_unwind2.definition.stderr
@@ -1,6 +1,7 @@
 thread 'main' panicked at $DIR/exported_symbol_bad_unwind2.rs:LL:CC:
 explicit panic
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+note: in Miri, you may have to set `-Zmiri-env-forward=RUST_BACKTRACE` for the environment variable to have an effect
 thread 'main' panicked at RUSTLIB/core/src/panicking.rs:LL:CC:
 panic in a function that cannot unwind
 stack backtrace:
diff --git a/src/tools/miri/tests/fail/function_calls/exported_symbol_bad_unwind2.extern_block.stderr b/src/tools/miri/tests/fail/function_calls/exported_symbol_bad_unwind2.extern_block.stderr
index f89cee0b863..bc3e4858716 100644
--- a/src/tools/miri/tests/fail/function_calls/exported_symbol_bad_unwind2.extern_block.stderr
+++ b/src/tools/miri/tests/fail/function_calls/exported_symbol_bad_unwind2.extern_block.stderr
@@ -1,6 +1,7 @@
 thread 'main' panicked at $DIR/exported_symbol_bad_unwind2.rs:LL:CC:
 explicit panic
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+note: in Miri, you may have to set `-Zmiri-env-forward=RUST_BACKTRACE` for the environment variable to have an effect
 error: Undefined Behavior: unwinding past a stack frame that does not allow unwinding
   --> $DIR/exported_symbol_bad_unwind2.rs:LL:CC
    |
diff --git a/src/tools/miri/tests/fail/function_calls/return_pointer_on_unwind.stderr b/src/tools/miri/tests/fail/function_calls/return_pointer_on_unwind.stderr
index 7f035eb5e85..a2fa4c1d590 100644
--- a/src/tools/miri/tests/fail/function_calls/return_pointer_on_unwind.stderr
+++ b/src/tools/miri/tests/fail/function_calls/return_pointer_on_unwind.stderr
@@ -1,6 +1,7 @@
 thread 'main' panicked at $DIR/return_pointer_on_unwind.rs:LL:CC:
 explicit panic
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+note: in Miri, you may have to set `-Zmiri-env-forward=RUST_BACKTRACE` for the environment variable to have an effect
 error: Undefined Behavior: using uninitialized data, but this operation requires initialized memory
   --> $DIR/return_pointer_on_unwind.rs:LL:CC
    |
diff --git a/src/tools/miri/tests/fail/intrinsics/uninit_uninhabited_type.stderr b/src/tools/miri/tests/fail/intrinsics/uninit_uninhabited_type.stderr
index 4723eddaa67..447f7cae6ce 100644
--- a/src/tools/miri/tests/fail/intrinsics/uninit_uninhabited_type.stderr
+++ b/src/tools/miri/tests/fail/intrinsics/uninit_uninhabited_type.stderr
@@ -1,6 +1,7 @@
 thread 'main' panicked at RUSTLIB/core/src/panicking.rs:LL:CC:
 aborted execution: attempted to instantiate uninhabited type `!`
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+note: in Miri, you may have to set `-Zmiri-env-forward=RUST_BACKTRACE` for the environment variable to have an effect
 thread caused non-unwinding panic. aborting.
 error: abnormal termination: the program aborted execution
   --> RUSTLIB/std/src/sys/pal/PLATFORM/mod.rs:LL:CC
diff --git a/src/tools/miri/tests/fail/intrinsics/zero_fn_ptr.stderr b/src/tools/miri/tests/fail/intrinsics/zero_fn_ptr.stderr
index 9c6dd10079e..bae34149807 100644
--- a/src/tools/miri/tests/fail/intrinsics/zero_fn_ptr.stderr
+++ b/src/tools/miri/tests/fail/intrinsics/zero_fn_ptr.stderr
@@ -1,6 +1,7 @@
 thread 'main' panicked at RUSTLIB/core/src/panicking.rs:LL:CC:
 aborted execution: attempted to zero-initialize type `fn()`, which is invalid
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+note: in Miri, you may have to set `-Zmiri-env-forward=RUST_BACKTRACE` for the environment variable to have an effect
 thread caused non-unwinding panic. aborting.
 error: abnormal termination: the program aborted execution
   --> RUSTLIB/std/src/sys/pal/PLATFORM/mod.rs:LL:CC
diff --git a/src/tools/miri/tests/fail/panic/bad_unwind.stderr b/src/tools/miri/tests/fail/panic/bad_unwind.stderr
index e4af01feb8d..230e8337c7c 100644
--- a/src/tools/miri/tests/fail/panic/bad_unwind.stderr
+++ b/src/tools/miri/tests/fail/panic/bad_unwind.stderr
@@ -1,6 +1,7 @@
 thread 'main' panicked at $DIR/bad_unwind.rs:LL:CC:
 explicit panic
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+note: in Miri, you may have to set `-Zmiri-env-forward=RUST_BACKTRACE` for the environment variable to have an effect
 error: Undefined Behavior: unwinding past a stack frame that does not allow unwinding
   --> $DIR/bad_unwind.rs:LL:CC
    |
diff --git a/src/tools/miri/tests/fail/panic/double_panic.stderr b/src/tools/miri/tests/fail/panic/double_panic.stderr
index e3cacbd27ba..3b7a1511fa0 100644
--- a/src/tools/miri/tests/fail/panic/double_panic.stderr
+++ b/src/tools/miri/tests/fail/panic/double_panic.stderr
@@ -1,6 +1,7 @@
 thread 'main' panicked at $DIR/double_panic.rs:LL:CC:
 first
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+note: in Miri, you may have to set `-Zmiri-env-forward=RUST_BACKTRACE` for the environment variable to have an effect
 thread 'main' panicked at $DIR/double_panic.rs:LL:CC:
 second
 stack backtrace:
diff --git a/src/tools/miri/tests/fail/panic/panic_abort1.stderr b/src/tools/miri/tests/fail/panic/panic_abort1.stderr
index 60455693619..7694cc70b22 100644
--- a/src/tools/miri/tests/fail/panic/panic_abort1.stderr
+++ b/src/tools/miri/tests/fail/panic/panic_abort1.stderr
@@ -1,6 +1,7 @@
 thread 'main' panicked at $DIR/panic_abort1.rs:LL:CC:
 panicking from libstd
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+note: in Miri, you may have to set `-Zmiri-env-forward=RUST_BACKTRACE` for the environment variable to have an effect
 error: abnormal termination: the program aborted execution
   --> RUSTLIB/panic_abort/src/lib.rs:LL:CC
    |
diff --git a/src/tools/miri/tests/fail/panic/panic_abort2.stderr b/src/tools/miri/tests/fail/panic/panic_abort2.stderr
index 7bb27e4baa0..e6a4380ea51 100644
--- a/src/tools/miri/tests/fail/panic/panic_abort2.stderr
+++ b/src/tools/miri/tests/fail/panic/panic_abort2.stderr
@@ -1,6 +1,7 @@
 thread 'main' panicked at $DIR/panic_abort2.rs:LL:CC:
 42-panicking from libstd
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+note: in Miri, you may have to set `-Zmiri-env-forward=RUST_BACKTRACE` for the environment variable to have an effect
 error: abnormal termination: the program aborted execution
   --> RUSTLIB/panic_abort/src/lib.rs:LL:CC
    |
diff --git a/src/tools/miri/tests/fail/panic/panic_abort3.stderr b/src/tools/miri/tests/fail/panic/panic_abort3.stderr
index b46e8c20795..23e2021eeef 100644
--- a/src/tools/miri/tests/fail/panic/panic_abort3.stderr
+++ b/src/tools/miri/tests/fail/panic/panic_abort3.stderr
@@ -1,6 +1,7 @@
 thread 'main' panicked at $DIR/panic_abort3.rs:LL:CC:
 panicking from libcore
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+note: in Miri, you may have to set `-Zmiri-env-forward=RUST_BACKTRACE` for the environment variable to have an effect
 error: abnormal termination: the program aborted execution
   --> RUSTLIB/panic_abort/src/lib.rs:LL:CC
    |
diff --git a/src/tools/miri/tests/fail/panic/panic_abort4.stderr b/src/tools/miri/tests/fail/panic/panic_abort4.stderr
index b15f720e43f..20a0ddb9019 100644
--- a/src/tools/miri/tests/fail/panic/panic_abort4.stderr
+++ b/src/tools/miri/tests/fail/panic/panic_abort4.stderr
@@ -1,6 +1,7 @@
 thread 'main' panicked at $DIR/panic_abort4.rs:LL:CC:
 42-panicking from libcore
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+note: in Miri, you may have to set `-Zmiri-env-forward=RUST_BACKTRACE` for the environment variable to have an effect
 error: abnormal termination: the program aborted execution
   --> RUSTLIB/panic_abort/src/lib.rs:LL:CC
    |
diff --git a/src/tools/miri/tests/fail/terminate-terminator.stderr b/src/tools/miri/tests/fail/terminate-terminator.stderr
index 8dbc802bf59..f737adc561d 100644
--- a/src/tools/miri/tests/fail/terminate-terminator.stderr
+++ b/src/tools/miri/tests/fail/terminate-terminator.stderr
@@ -3,6 +3,7 @@ warning: You have explicitly enabled MIR optimizations, overriding Miri's defaul
 thread 'main' panicked at $DIR/terminate-terminator.rs:LL:CC:
 explicit panic
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+note: in Miri, you may have to set `-Zmiri-env-forward=RUST_BACKTRACE` for the environment variable to have an effect
 thread 'main' panicked at RUSTLIB/core/src/panicking.rs:LL:CC:
 panic in a function that cannot unwind
 stack backtrace:
diff --git a/src/tools/miri/tests/fail/unwind-action-terminate.stderr b/src/tools/miri/tests/fail/unwind-action-terminate.stderr
index 1323a397100..7e722f7be32 100644
--- a/src/tools/miri/tests/fail/unwind-action-terminate.stderr
+++ b/src/tools/miri/tests/fail/unwind-action-terminate.stderr
@@ -1,6 +1,7 @@
 thread 'main' panicked at $DIR/unwind-action-terminate.rs:LL:CC:
 explicit panic
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+note: in Miri, you may have to set `-Zmiri-env-forward=RUST_BACKTRACE` for the environment variable to have an effect
 thread 'main' panicked at RUSTLIB/core/src/panicking.rs:LL:CC:
 panic in a function that cannot unwind
 stack backtrace:
diff --git a/src/tools/miri/tests/panic/div-by-zero-2.stderr b/src/tools/miri/tests/panic/div-by-zero-2.stderr
index 0f088ddd1a5..f0b84ea6fd6 100644
--- a/src/tools/miri/tests/panic/div-by-zero-2.stderr
+++ b/src/tools/miri/tests/panic/div-by-zero-2.stderr
@@ -1,3 +1,4 @@
 thread 'main' panicked at $DIR/div-by-zero-2.rs:LL:CC:
 attempt to divide by zero
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+note: in Miri, you may have to set `-Zmiri-env-forward=RUST_BACKTRACE` for the environment variable to have an effect
diff --git a/src/tools/miri/tests/panic/function_calls/exported_symbol_good_unwind.stderr b/src/tools/miri/tests/panic/function_calls/exported_symbol_good_unwind.stderr
index acc0e58885f..f77f6f01119 100644
--- a/src/tools/miri/tests/panic/function_calls/exported_symbol_good_unwind.stderr
+++ b/src/tools/miri/tests/panic/function_calls/exported_symbol_good_unwind.stderr
@@ -1,6 +1,7 @@
 thread 'main' panicked at $DIR/exported_symbol_good_unwind.rs:LL:CC:
 explicit panic
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+note: in Miri, you may have to set `-Zmiri-env-forward=RUST_BACKTRACE` for the environment variable to have an effect
 thread 'main' panicked at $DIR/exported_symbol_good_unwind.rs:LL:CC:
 explicit panic
 thread 'main' panicked at $DIR/exported_symbol_good_unwind.rs:LL:CC:
diff --git a/src/tools/miri/tests/panic/oob_subslice.stderr b/src/tools/miri/tests/panic/oob_subslice.stderr
index 2bccb60352e..c116f8eb525 100644
--- a/src/tools/miri/tests/panic/oob_subslice.stderr
+++ b/src/tools/miri/tests/panic/oob_subslice.stderr
@@ -1,3 +1,4 @@
 thread 'main' panicked at $DIR/oob_subslice.rs:LL:CC:
 range end index 5 out of range for slice of length 4
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+note: in Miri, you may have to set `-Zmiri-env-forward=RUST_BACKTRACE` for the environment variable to have an effect
diff --git a/src/tools/miri/tests/panic/overflowing-lsh-neg.stderr b/src/tools/miri/tests/panic/overflowing-lsh-neg.stderr
index 2cff81c58af..1d057ea5eb4 100644
--- a/src/tools/miri/tests/panic/overflowing-lsh-neg.stderr
+++ b/src/tools/miri/tests/panic/overflowing-lsh-neg.stderr
@@ -1,3 +1,4 @@
 thread 'main' panicked at $DIR/overflowing-lsh-neg.rs:LL:CC:
 attempt to shift left with overflow
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+note: in Miri, you may have to set `-Zmiri-env-forward=RUST_BACKTRACE` for the environment variable to have an effect
diff --git a/src/tools/miri/tests/panic/overflowing-rsh-1.stderr b/src/tools/miri/tests/panic/overflowing-rsh-1.stderr
index 13117df5fc3..d1a79400bfa 100644
--- a/src/tools/miri/tests/panic/overflowing-rsh-1.stderr
+++ b/src/tools/miri/tests/panic/overflowing-rsh-1.stderr
@@ -1,3 +1,4 @@
 thread 'main' panicked at $DIR/overflowing-rsh-1.rs:LL:CC:
 attempt to shift right with overflow
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+note: in Miri, you may have to set `-Zmiri-env-forward=RUST_BACKTRACE` for the environment variable to have an effect
diff --git a/src/tools/miri/tests/panic/overflowing-rsh-2.stderr b/src/tools/miri/tests/panic/overflowing-rsh-2.stderr
index 986a66f8991..612b0c0c4c2 100644
--- a/src/tools/miri/tests/panic/overflowing-rsh-2.stderr
+++ b/src/tools/miri/tests/panic/overflowing-rsh-2.stderr
@@ -1,3 +1,4 @@
 thread 'main' panicked at $DIR/overflowing-rsh-2.rs:LL:CC:
 attempt to shift right with overflow
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+note: in Miri, you may have to set `-Zmiri-env-forward=RUST_BACKTRACE` for the environment variable to have an effect
diff --git a/src/tools/miri/tests/panic/panic2.stderr b/src/tools/miri/tests/panic/panic2.stderr
index bee1af2bef6..792c71346fd 100644
--- a/src/tools/miri/tests/panic/panic2.stderr
+++ b/src/tools/miri/tests/panic/panic2.stderr
@@ -1,3 +1,4 @@
 thread 'main' panicked at $DIR/panic2.rs:LL:CC:
 42-panicking from libstd
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+note: in Miri, you may have to set `-Zmiri-env-forward=RUST_BACKTRACE` for the environment variable to have an effect
diff --git a/src/tools/miri/tests/panic/panic3.stderr b/src/tools/miri/tests/panic/panic3.stderr
index 8dac000d291..f8016bc3912 100644
--- a/src/tools/miri/tests/panic/panic3.stderr
+++ b/src/tools/miri/tests/panic/panic3.stderr
@@ -1,3 +1,4 @@
 thread 'main' panicked at $DIR/panic3.rs:LL:CC:
 panicking from libcore
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+note: in Miri, you may have to set `-Zmiri-env-forward=RUST_BACKTRACE` for the environment variable to have an effect
diff --git a/src/tools/miri/tests/panic/panic4.stderr b/src/tools/miri/tests/panic/panic4.stderr
index 13437fe7f07..67410bf3b1a 100644
--- a/src/tools/miri/tests/panic/panic4.stderr
+++ b/src/tools/miri/tests/panic/panic4.stderr
@@ -1,3 +1,4 @@
 thread 'main' panicked at $DIR/panic4.rs:LL:CC:
 42-panicking from libcore
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+note: in Miri, you may have to set `-Zmiri-env-forward=RUST_BACKTRACE` for the environment variable to have an effect
diff --git a/src/tools/miri/tests/panic/transmute_fat2.stderr b/src/tools/miri/tests/panic/transmute_fat2.stderr
index 1f09a2c1a08..2ee01d46931 100644
--- a/src/tools/miri/tests/panic/transmute_fat2.stderr
+++ b/src/tools/miri/tests/panic/transmute_fat2.stderr
@@ -1,3 +1,4 @@
 thread 'main' panicked at $DIR/transmute_fat2.rs:LL:CC:
 index out of bounds: the len is 0 but the index is 0
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+note: in Miri, you may have to set `-Zmiri-env-forward=RUST_BACKTRACE` for the environment variable to have an effect
diff --git a/src/tools/miri/tests/panic/unsupported_foreign_function.stderr b/src/tools/miri/tests/panic/unsupported_foreign_function.stderr
index 4db1e290961..d0a7d8dafc5 100644
--- a/src/tools/miri/tests/panic/unsupported_foreign_function.stderr
+++ b/src/tools/miri/tests/panic/unsupported_foreign_function.stderr
@@ -1,3 +1,4 @@
 thread 'main' panicked at $DIR/unsupported_foreign_function.rs:LL:CC:
 unsupported Miri functionality: can't call foreign function `foo` on $OS
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+note: in Miri, you may have to set `-Zmiri-env-forward=RUST_BACKTRACE` for the environment variable to have an effect
diff --git a/src/tools/miri/tests/panic/unsupported_syscall.stderr b/src/tools/miri/tests/panic/unsupported_syscall.stderr
index 40ba6671d5b..f802159cb1c 100644
--- a/src/tools/miri/tests/panic/unsupported_syscall.stderr
+++ b/src/tools/miri/tests/panic/unsupported_syscall.stderr
@@ -1,3 +1,4 @@
 thread 'main' panicked at $DIR/unsupported_syscall.rs:LL:CC:
 unsupported Miri functionality: can't execute syscall with ID 0
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+note: in Miri, you may have to set `-Zmiri-env-forward=RUST_BACKTRACE` for the environment variable to have an effect
diff --git a/src/tools/miri/tests/pass/panic/catch_panic.stderr b/src/tools/miri/tests/pass/panic/catch_panic.stderr
index cbcd626e39f..a472a5d80cb 100644
--- a/src/tools/miri/tests/pass/panic/catch_panic.stderr
+++ b/src/tools/miri/tests/pass/panic/catch_panic.stderr
@@ -1,6 +1,7 @@
 thread 'main' panicked at $DIR/catch_panic.rs:LL:CC:
 Hello from std::panic
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+note: in Miri, you may have to set `-Zmiri-env-forward=RUST_BACKTRACE` for the environment variable to have an effect
 Caught panic message (&str): Hello from std::panic
 thread 'main' panicked at $DIR/catch_panic.rs:LL:CC:
 Hello from std::panic: 1
diff --git a/src/tools/miri/tests/pass/panic/concurrent-panic.stderr b/src/tools/miri/tests/pass/panic/concurrent-panic.stderr
index 0bb3dcd8d24..b2a5cf4922c 100644
--- a/src/tools/miri/tests/pass/panic/concurrent-panic.stderr
+++ b/src/tools/miri/tests/pass/panic/concurrent-panic.stderr
@@ -3,6 +3,7 @@ Thread 1 reported it has started
 thread '<unnamed>' panicked at $DIR/concurrent-panic.rs:LL:CC:
 panic in thread 2
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+note: in Miri, you may have to set `-Zmiri-env-forward=RUST_BACKTRACE` for the environment variable to have an effect
 Thread 2 blocking on thread 1
 Thread 2 reported it has started
 Unlocking mutex
diff --git a/src/tools/miri/tests/pass/panic/nested_panic_caught.stderr b/src/tools/miri/tests/pass/panic/nested_panic_caught.stderr
index 4684beb3338..3efb4be40f9 100644
--- a/src/tools/miri/tests/pass/panic/nested_panic_caught.stderr
+++ b/src/tools/miri/tests/pass/panic/nested_panic_caught.stderr
@@ -1,6 +1,7 @@
 thread 'main' panicked at $DIR/nested_panic_caught.rs:LL:CC:
 once
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+note: in Miri, you may have to set `-Zmiri-env-forward=RUST_BACKTRACE` for the environment variable to have an effect
 thread 'main' panicked at $DIR/nested_panic_caught.rs:LL:CC:
 twice
 stack backtrace:
diff --git a/src/tools/miri/tests/pass/panic/thread_panic.stderr b/src/tools/miri/tests/pass/panic/thread_panic.stderr
index badd409d13f..bdfe4f98ba3 100644
--- a/src/tools/miri/tests/pass/panic/thread_panic.stderr
+++ b/src/tools/miri/tests/pass/panic/thread_panic.stderr
@@ -1,5 +1,6 @@
 thread '<unnamed>' panicked at $DIR/thread_panic.rs:LL:CC:
 Hello!
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+note: in Miri, you may have to set `-Zmiri-env-forward=RUST_BACKTRACE` for the environment variable to have an effect
 thread 'childthread' panicked at $DIR/thread_panic.rs:LL:CC:
 Hello, world!