tell people how to set miri flags

21 files changed, 52 insertions, 81 deletions

diff --git a/src/tools/miri/cargo-miri/src/phases.rs b/src/tools/miri/cargo-miri/src/phases.rs
index 3c36f606d84..8d48b9c8ad1 100644
--- a/src/tools/miri/cargo-miri/src/phases.rs
+++ b/src/tools/miri/cargo-miri/src/phases.rs
@@ -23,6 +23,12 @@ Subcommands:
     clean                    Clean the Miri cache & target directory
 
 The cargo options are exactly the same as for `cargo run` and `cargo test`, respectively.
+Furthermore, the following extra flags and environment variables are recognized for `run` and `test`:
+
+    --many-seeds[=from..to]  Run the program/tests many times with different seeds in the given range.
+                             The range defaults to `0..64`.
+
+    MIRIFLAGS                Extra flags to pass to the Miri driver. Use this to pass `-Zmiri-...` flags.
 
 Examples:
     cargo miri run
diff --git a/src/tools/miri/src/diagnostics.rs b/src/tools/miri/src/diagnostics.rs
index 14e29aa423d..47f0913acce 100644
--- a/src/tools/miri/src/diagnostics.rs
+++ b/src/tools/miri/src/diagnostics.rs
@@ -227,8 +227,8 @@ pub fn report_error<'tcx>(
         let helps = match info {
             UnsupportedInIsolation(_) =>
                 vec![
-                    (None, format!("pass the flag `-Zmiri-disable-isolation` to disable isolation;")),
-                    (None, format!("or pass `-Zmiri-isolation-error=warn` to configure Miri to return an error code from isolated operations (if supported for that operation) and continue with a warning")),
+                    (None, format!("set `MIRIFLAGS=-Zmiri-disable-isolation` to disable isolation;")),
+                    (None, format!("or set `MIRIFLAGS=-Zmiri-isolation-error=warn` to make Miri return an error code from isolated operations (if supported for that operation) and continue with a warning")),
                 ],
             UnsupportedForeignItem(_) => {
                 vec![
@@ -463,19 +463,22 @@ pub fn report_leaks<'tcx>(
 ) {
     let mut any_pruned = false;
     for (id, kind, mut alloc) in leaks {
+        let mut title = format!(
+            "memory leaked: {id:?} ({}, size: {:?}, align: {:?})",
+            kind,
+            alloc.size().bytes(),
+            alloc.align.bytes()
+        );
         let Some(backtrace) = alloc.extra.backtrace.take() else {
+            ecx.tcx.dcx().err(title);
             continue;
         };
+        title.push_str(", allocated here:");
         let (backtrace, pruned) = prune_stacktrace(backtrace, &ecx.machine);
         any_pruned |= pruned;
         report_msg(
             DiagLevel::Error,
-            format!(
-                "memory leaked: {id:?} ({}, size: {:?}, align: {:?}), allocated here:",
-                kind,
-                alloc.size().bytes(),
-                alloc.align.bytes()
-            ),
+            title,
             vec![],
             vec![],
             vec![],
@@ -642,15 +645,11 @@ impl<'tcx> MiriMachine<'tcx> {
                     (
                         None,
                         format!(
-                            "This program is using integer-to-pointer casts or (equivalently) `ptr::with_exposed_provenance`,"
+                            "This program is using integer-to-pointer casts or (equivalently) `ptr::with_exposed_provenance`, which means that Miri might miss pointer bugs in this program."
                         ),
                     ),
                     (
                         None,
-                        format!("which means that Miri might miss pointer bugs in this program."),
-                    ),
-                    (
-                        None,
                         format!(
                             "See https://doc.rust-lang.org/nightly/std/ptr/fn.with_exposed_provenance.html for more details on that operation."
                         ),
@@ -664,13 +663,13 @@ impl<'tcx> MiriMachine<'tcx> {
                     (
                         None,
                         format!(
-                            "You can then pass the `-Zmiri-strict-provenance` flag to Miri, to ensure you are not relying on `with_exposed_provenance` semantics."
+                            "You can then set `MIRIFLAGS=-Zmiri-strict-provenance` to ensure you are not relying on `with_exposed_provenance` semantics."
                         ),
                     ),
                     (
                         None,
                         format!(
-                            "Alternatively, the `-Zmiri-permissive-provenance` flag disables this warning."
+                            "Alternatively, `MIRIFLAGS=-Zmiri-permissive-provenance` disables this warning."
                         ),
                     ),
                 ],
diff --git a/src/tools/miri/src/eval.rs b/src/tools/miri/src/eval.rs
index 35f7f43f123..bd11439971c 100644
--- a/src/tools/miri/src/eval.rs
+++ b/src/tools/miri/src/eval.rs
@@ -468,7 +468,7 @@ pub fn eval_entry<'tcx>(
         // Check for thread leaks.
         if !ecx.have_all_terminated() {
             tcx.dcx().err("the main thread terminated without waiting for all remaining threads");
-            tcx.dcx().note("pass `-Zmiri-ignore-leaks` to disable this check");
+            tcx.dcx().note("set `MIRIFLAGS=-Zmiri-ignore-leaks` to disable this check");
             return None;
         }
         // Check for memory leaks.
@@ -476,14 +476,7 @@ pub fn eval_entry<'tcx>(
         let leaks = ecx.find_leaked_allocations(&ecx.machine.static_roots);
         if !leaks.is_empty() {
             report_leaks(&ecx, leaks);
-            let leak_message = "the evaluated program leaked memory, pass `-Zmiri-ignore-leaks` to disable this check";
-            if ecx.machine.collect_leak_backtraces {
-                // If we are collecting leak backtraces, each leak is a distinct error diagnostic.
-                tcx.dcx().note(leak_message);
-            } else {
-                // If we do not have backtraces, we just report an error without any span.
-                tcx.dcx().err(leak_message);
-            };
+            tcx.dcx().note("set `MIRIFLAGS=-Zmiri-ignore-leaks` to disable this check");
             // Ignore the provided return code - let the reported error
             // determine the return code.
             return None;
diff --git a/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_create_main_terminate.stderr b/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_create_main_terminate.stderr
index 078b7d2e0d8..9d6be16b83a 100644
--- a/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_create_main_terminate.stderr
+++ b/src/tools/miri/tests/fail-dep/concurrency/libc_pthread_create_main_terminate.stderr
@@ -1,6 +1,6 @@
 error: the main thread terminated without waiting for all remaining threads
 
-note: pass `-Zmiri-ignore-leaks` to disable this check
+note: set `MIRIFLAGS=-Zmiri-ignore-leaks` to disable this check
 
 error: aborting due to 1 previous error
 
diff --git a/src/tools/miri/tests/fail-dep/libc/aligned_alloc_size_zero_leak.stderr b/src/tools/miri/tests/fail-dep/libc/aligned_alloc_size_zero_leak.stderr
index b0756d57212..91c67823320 100644
--- a/src/tools/miri/tests/fail-dep/libc/aligned_alloc_size_zero_leak.stderr
+++ b/src/tools/miri/tests/fail-dep/libc/aligned_alloc_size_zero_leak.stderr
@@ -9,7 +9,7 @@ LL |         aligned_alloc(2, 0);
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
-note: the evaluated program leaked memory, pass `-Zmiri-ignore-leaks` to disable this check
+note: set `MIRIFLAGS=-Zmiri-ignore-leaks` to disable this check
 
 error: aborting due to 1 previous error
 
diff --git a/src/tools/miri/tests/fail-dep/libc/fs/isolated_stdin.stderr b/src/tools/miri/tests/fail-dep/libc/fs/isolated_stdin.stderr
index 1d6626dda70..9abe145ea9e 100644
--- a/src/tools/miri/tests/fail-dep/libc/fs/isolated_stdin.stderr
+++ b/src/tools/miri/tests/fail-dep/libc/fs/isolated_stdin.stderr
@@ -4,8 +4,8 @@ error: unsupported operation: `read` from stdin not available when isolation is
 LL |         libc::read(0, bytes.as_mut_ptr() as *mut libc::c_void, 512);
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `read` from stdin not available when isolation is enabled
    |
-   = help: pass the flag `-Zmiri-disable-isolation` to disable isolation;
-   = help: or pass `-Zmiri-isolation-error=warn` to configure Miri to return an error code from isolated operations (if supported for that operation) and continue with a warning
+   = help: set `MIRIFLAGS=-Zmiri-disable-isolation` to disable isolation;
+   = help: or set `MIRIFLAGS=-Zmiri-isolation-error=warn` to make Miri return an error code from isolated operations (if supported for that operation) and continue with a warning
    = note: BACKTRACE:
    = note: inside `main` at $DIR/isolated_stdin.rs:LL:CC
 
diff --git a/src/tools/miri/tests/fail-dep/libc/malloc_zero_memory_leak.stderr b/src/tools/miri/tests/fail-dep/libc/malloc_zero_memory_leak.stderr
index 65ce0dcdcdd..657262b8d41 100644
--- a/src/tools/miri/tests/fail-dep/libc/malloc_zero_memory_leak.stderr
+++ b/src/tools/miri/tests/fail-dep/libc/malloc_zero_memory_leak.stderr
@@ -9,7 +9,7 @@ LL |         let _ptr = libc::malloc(0);
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
-note: the evaluated program leaked memory, pass `-Zmiri-ignore-leaks` to disable this check
+note: set `MIRIFLAGS=-Zmiri-ignore-leaks` to disable this check
 
 error: aborting due to 1 previous error
 
diff --git a/src/tools/miri/tests/fail-dep/libc/posix_memalign_size_zero_leak.stderr b/src/tools/miri/tests/fail-dep/libc/posix_memalign_size_zero_leak.stderr
index 7ea0fa31469..2639031f1cc 100644
--- a/src/tools/miri/tests/fail-dep/libc/posix_memalign_size_zero_leak.stderr
+++ b/src/tools/miri/tests/fail-dep/libc/posix_memalign_size_zero_leak.stderr
@@ -9,7 +9,7 @@ LL |     let _ = unsafe { libc::posix_memalign(&mut ptr, align, size) };
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
-note: the evaluated program leaked memory, pass `-Zmiri-ignore-leaks` to disable this check
+note: set `MIRIFLAGS=-Zmiri-ignore-leaks` to disable this check
 
 error: aborting due to 1 previous error
 
diff --git a/src/tools/miri/tests/fail/intrinsics/ptr_metadata_uninit_slice_len.stderr b/src/tools/miri/tests/fail/intrinsics/ptr_metadata_uninit_slice_len.stderr
index 4e2e7218432..217bc82010d 100644
--- a/src/tools/miri/tests/fail/intrinsics/ptr_metadata_uninit_slice_len.stderr
+++ b/src/tools/miri/tests/fail/intrinsics/ptr_metadata_uninit_slice_len.stderr
@@ -4,12 +4,11 @@ warning: integer-to-pointer cast
 LL |         (*p.as_mut_ptr().cast::<[*const i32; 2]>())[0] = 4 as *const i32;
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ integer-to-pointer cast
    |
-   = help: This program is using integer-to-pointer casts or (equivalently) `ptr::with_exposed_provenance`,
-   = help: which means that Miri might miss pointer bugs in this program.
+   = help: This program is using integer-to-pointer casts or (equivalently) `ptr::with_exposed_provenance`, which means that Miri might miss pointer bugs in this program.
    = help: See https://doc.rust-lang.org/nightly/std/ptr/fn.with_exposed_provenance.html for more details on that operation.
    = help: To ensure that Miri does not miss bugs in your program, use Strict Provenance APIs (https://doc.rust-lang.org/nightly/std/ptr/index.html#strict-provenance, https://crates.io/crates/sptr) instead.
-   = help: You can then pass the `-Zmiri-strict-provenance` flag to Miri, to ensure you are not relying on `with_exposed_provenance` semantics.
-   = help: Alternatively, the `-Zmiri-permissive-provenance` flag disables this warning.
+   = help: You can then set `MIRIFLAGS=-Zmiri-strict-provenance` to ensure you are not relying on `with_exposed_provenance` semantics.
+   = help: Alternatively, `MIRIFLAGS=-Zmiri-permissive-provenance` disables this warning.
    = note: BACKTRACE:
    = note: inside `main` at $DIR/ptr_metadata_uninit_slice_len.rs:LL:CC
 
diff --git a/src/tools/miri/tests/fail/memleak.stderr b/src/tools/miri/tests/fail/memleak.stderr
index 8ba78ef6644..a9ee76fbe8a 100644
--- a/src/tools/miri/tests/fail/memleak.stderr
+++ b/src/tools/miri/tests/fail/memleak.stderr
@@ -18,7 +18,7 @@ LL |     std::mem::forget(Box::new(42));
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
-note: the evaluated program leaked memory, pass `-Zmiri-ignore-leaks` to disable this check
+note: set `MIRIFLAGS=-Zmiri-ignore-leaks` to disable this check
 
 error: aborting due to 1 previous error
 
diff --git a/src/tools/miri/tests/fail/memleak_no_backtrace.rs b/src/tools/miri/tests/fail/memleak_no_backtrace.rs
index a1f8d9957ff..1f8d8ba7a7c 100644
--- a/src/tools/miri/tests/fail/memleak_no_backtrace.rs
+++ b/src/tools/miri/tests/fail/memleak_no_backtrace.rs
@@ -1,5 +1,5 @@
 //@compile-flags: -Zmiri-disable-leak-backtraces
-//@error-in-other-file: the evaluated program leaked memory
+//@error-in-other-file: memory leaked
 //@normalize-stderr-test: ".*│.*" -> "$$stripped$$"
 
 fn main() {
diff --git a/src/tools/miri/tests/fail/memleak_no_backtrace.stderr b/src/tools/miri/tests/fail/memleak_no_backtrace.stderr
index 22e8c558061..6850928e150 100644
--- a/src/tools/miri/tests/fail/memleak_no_backtrace.stderr
+++ b/src/tools/miri/tests/fail/memleak_no_backtrace.stderr
@@ -1,4 +1,6 @@
-error: the evaluated program leaked memory, pass `-Zmiri-ignore-leaks` to disable this check
+error: memory leaked: ALLOC (Rust heap, size: 4, align: 4)
+
+note: set `MIRIFLAGS=-Zmiri-ignore-leaks` to disable this check
 
 error: aborting due to 1 previous error
 
diff --git a/src/tools/miri/tests/fail/memleak_rc.64bit.stderr b/src/tools/miri/tests/fail/memleak_rc.64bit.stderr
deleted file mode 100644
index 1c85a0f9d9f..00000000000
--- a/src/tools/miri/tests/fail/memleak_rc.64bit.stderr
+++ /dev/null
@@ -1,25 +0,0 @@
-error: memory leaked: ALLOC (Rust heap, size: 32, align: 8), allocated here:
-  --> RUSTLIB/alloc/src/alloc.rs:LL:CC
-   |
-LL |         __rust_alloc(layout.size(), layout.align())
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: BACKTRACE:
-   = note: inside `std::alloc::alloc` at RUSTLIB/alloc/src/alloc.rs:LL:CC
-   = note: inside `std::alloc::Global::alloc_impl` at RUSTLIB/alloc/src/alloc.rs:LL:CC
-   = note: inside `<std::alloc::Global as std::alloc::Allocator>::allocate` at RUSTLIB/alloc/src/alloc.rs:LL:CC
-   = note: inside `alloc::alloc::exchange_malloc` at RUSTLIB/alloc/src/alloc.rs:LL:CC
-   = note: inside `std::boxed::Box::<std::rc::RcBox<std::cell::RefCell<std::option::Option<Dummy>>>>::new` at RUSTLIB/alloc/src/boxed.rs:LL:CC
-   = note: inside `std::rc::Rc::<std::cell::RefCell<std::option::Option<Dummy>>>::new` at RUSTLIB/alloc/src/rc.rs:LL:CC
-note: inside `main`
-  --> $DIR/memleak_rc.rs:LL:CC
-   |
-LL |     let x = Dummy(Rc::new(RefCell::new(None)));
-   |                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
-
-note: the evaluated program leaked memory, pass `-Zmiri-ignore-leaks` to disable this check
-
-error: aborting due to 1 previous error
-
diff --git a/src/tools/miri/tests/fail/memleak_rc.rs b/src/tools/miri/tests/fail/memleak_rc.rs
index 0927612d08e..2d12c1223cf 100644
--- a/src/tools/miri/tests/fail/memleak_rc.rs
+++ b/src/tools/miri/tests/fail/memleak_rc.rs
@@ -1,6 +1,6 @@
 //@error-in-other-file: memory leaked
-//@stderr-per-bitwidth
 //@normalize-stderr-test: ".*│.*" -> "$$stripped$$"
+//@normalize-stderr-test: "Rust heap, size: [0-9]+, align: [0-9]+" -> "Rust heap, SIZE, ALIGN"
 
 use std::cell::RefCell;
 use std::rc::Rc;
diff --git a/src/tools/miri/tests/fail/memleak_rc.32bit.stderr b/src/tools/miri/tests/fail/memleak_rc.stderr
index 781e1458db9..dbf2daf818c 100644
--- a/src/tools/miri/tests/fail/memleak_rc.32bit.stderr
+++ b/src/tools/miri/tests/fail/memleak_rc.stderr
@@ -1,4 +1,4 @@
-error: memory leaked: ALLOC (Rust heap, size: 16, align: 4), allocated here:
+error: memory leaked: ALLOC (Rust heap, SIZE, ALIGN), allocated here:
   --> RUSTLIB/alloc/src/alloc.rs:LL:CC
    |
 LL |         __rust_alloc(layout.size(), layout.align())
@@ -19,7 +19,7 @@ LL |     let x = Dummy(Rc::new(RefCell::new(None)));
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
-note: the evaluated program leaked memory, pass `-Zmiri-ignore-leaks` to disable this check
+note: set `MIRIFLAGS=-Zmiri-ignore-leaks` to disable this check
 
 error: aborting due to 1 previous error
 
diff --git a/src/tools/miri/tests/fail/shims/fs/isolated_file.stderr b/src/tools/miri/tests/fail/shims/fs/isolated_file.stderr
index 1f08649428a..ec956f83348 100644
--- a/src/tools/miri/tests/fail/shims/fs/isolated_file.stderr
+++ b/src/tools/miri/tests/fail/shims/fs/isolated_file.stderr
@@ -4,8 +4,8 @@ error: unsupported operation: `open` not available when isolation is enabled
 LL |         let fd = cvt_r(|| unsafe { open64(path.as_ptr(), flags, opts.mode as c_int) })?;
    |                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `open` not available when isolation is enabled
    |
-   = help: pass the flag `-Zmiri-disable-isolation` to disable isolation;
-   = help: or pass `-Zmiri-isolation-error=warn` to configure Miri to return an error code from isolated operations (if supported for that operation) and continue with a warning
+   = help: set `MIRIFLAGS=-Zmiri-disable-isolation` to disable isolation;
+   = help: or set `MIRIFLAGS=-Zmiri-isolation-error=warn` to make Miri return an error code from isolated operations (if supported for that operation) and continue with a warning
    = note: BACKTRACE:
    = note: inside closure at RUSTLIB/std/src/sys/pal/PLATFORM/fs.rs:LL:CC
    = note: inside `std::sys::pal::PLATFORM::cvt_r::<i32, {closure@std::sys::pal::PLATFORM::fs::File::open_c::{closure#0}}>` at RUSTLIB/std/src/sys/pal/PLATFORM/mod.rs:LL:CC
diff --git a/src/tools/miri/tests/fail/tls_macro_leak.stderr b/src/tools/miri/tests/fail/tls_macro_leak.stderr
index 40b21f8625a..c7c641a30f1 100644
--- a/src/tools/miri/tests/fail/tls_macro_leak.stderr
+++ b/src/tools/miri/tests/fail/tls_macro_leak.stderr
@@ -27,7 +27,7 @@ LL | |         });
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
-note: the evaluated program leaked memory, pass `-Zmiri-ignore-leaks` to disable this check
+note: set `MIRIFLAGS=-Zmiri-ignore-leaks` to disable this check
 
 error: aborting due to 1 previous error
 
diff --git a/src/tools/miri/tests/fail/tls_static_leak.stderr b/src/tools/miri/tests/fail/tls_static_leak.stderr
index 580b52c1512..f7b90a1118c 100644
--- a/src/tools/miri/tests/fail/tls_static_leak.stderr
+++ b/src/tools/miri/tests/fail/tls_static_leak.stderr
@@ -18,7 +18,7 @@ LL |         TLS.set(Some(Box::leak(Box::new(123))));
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
-note: the evaluated program leaked memory, pass `-Zmiri-ignore-leaks` to disable this check
+note: set `MIRIFLAGS=-Zmiri-ignore-leaks` to disable this check
 
 error: aborting due to 1 previous error
 
diff --git a/src/tools/miri/tests/pass/box.stack.stderr b/src/tools/miri/tests/pass/box.stack.stderr
index 1a4d52ee314..341f84c8992 100644
--- a/src/tools/miri/tests/pass/box.stack.stderr
+++ b/src/tools/miri/tests/pass/box.stack.stderr
@@ -4,12 +4,11 @@ warning: integer-to-pointer cast
 LL |         let r2 = ((r as usize) + 0) as *mut i32;
    |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ integer-to-pointer cast
    |
-   = help: This program is using integer-to-pointer casts or (equivalently) `ptr::with_exposed_provenance`,
-   = help: which means that Miri might miss pointer bugs in this program.
+   = help: This program is using integer-to-pointer casts or (equivalently) `ptr::with_exposed_provenance`, which means that Miri might miss pointer bugs in this program.
    = help: See https://doc.rust-lang.org/nightly/std/ptr/fn.with_exposed_provenance.html for more details on that operation.
    = help: To ensure that Miri does not miss bugs in your program, use Strict Provenance APIs (https://doc.rust-lang.org/nightly/std/ptr/index.html#strict-provenance, https://crates.io/crates/sptr) instead.
-   = help: You can then pass the `-Zmiri-strict-provenance` flag to Miri, to ensure you are not relying on `with_exposed_provenance` semantics.
-   = help: Alternatively, the `-Zmiri-permissive-provenance` flag disables this warning.
+   = help: You can then set `MIRIFLAGS=-Zmiri-strict-provenance` to ensure you are not relying on `with_exposed_provenance` semantics.
+   = help: Alternatively, `MIRIFLAGS=-Zmiri-permissive-provenance` disables this warning.
    = note: BACKTRACE:
    = note: inside `into_raw` at $DIR/box.rs:LL:CC
 note: inside `main`
diff --git a/src/tools/miri/tests/pass/extern_types.stack.stderr b/src/tools/miri/tests/pass/extern_types.stack.stderr
index 275d718129b..03a9167abbc 100644
--- a/src/tools/miri/tests/pass/extern_types.stack.stderr
+++ b/src/tools/miri/tests/pass/extern_types.stack.stderr
@@ -4,12 +4,11 @@ warning: integer-to-pointer cast
 LL |     let x: &Foo = unsafe { &*(16 as *const Foo) };
    |                              ^^^^^^^^^^^^^^^^^^ integer-to-pointer cast
    |
-   = help: This program is using integer-to-pointer casts or (equivalently) `ptr::with_exposed_provenance`,
-   = help: which means that Miri might miss pointer bugs in this program.
+   = help: This program is using integer-to-pointer casts or (equivalently) `ptr::with_exposed_provenance`, which means that Miri might miss pointer bugs in this program.
    = help: See https://doc.rust-lang.org/nightly/std/ptr/fn.with_exposed_provenance.html for more details on that operation.
    = help: To ensure that Miri does not miss bugs in your program, use Strict Provenance APIs (https://doc.rust-lang.org/nightly/std/ptr/index.html#strict-provenance, https://crates.io/crates/sptr) instead.
-   = help: You can then pass the `-Zmiri-strict-provenance` flag to Miri, to ensure you are not relying on `with_exposed_provenance` semantics.
-   = help: Alternatively, the `-Zmiri-permissive-provenance` flag disables this warning.
+   = help: You can then set `MIRIFLAGS=-Zmiri-strict-provenance` to ensure you are not relying on `with_exposed_provenance` semantics.
+   = help: Alternatively, `MIRIFLAGS=-Zmiri-permissive-provenance` disables this warning.
    = note: BACKTRACE:
    = note: inside `main` at $DIR/extern_types.rs:LL:CC
 
diff --git a/src/tools/miri/tests/pass/stacked-borrows/issue-miri-2389.stderr b/src/tools/miri/tests/pass/stacked-borrows/issue-miri-2389.stderr
index 7cbfad3942b..b0e1adf27d1 100644
--- a/src/tools/miri/tests/pass/stacked-borrows/issue-miri-2389.stderr
+++ b/src/tools/miri/tests/pass/stacked-borrows/issue-miri-2389.stderr
@@ -4,12 +4,11 @@ warning: integer-to-pointer cast
 LL |         let wildcard = &root0 as *const Cell<i32> as usize as *const Cell<i32>;
    |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ integer-to-pointer cast
    |
-   = help: This program is using integer-to-pointer casts or (equivalently) `ptr::with_exposed_provenance`,
-   = help: which means that Miri might miss pointer bugs in this program.
+   = help: This program is using integer-to-pointer casts or (equivalently) `ptr::with_exposed_provenance`, which means that Miri might miss pointer bugs in this program.
    = help: See https://doc.rust-lang.org/nightly/std/ptr/fn.with_exposed_provenance.html for more details on that operation.
    = help: To ensure that Miri does not miss bugs in your program, use Strict Provenance APIs (https://doc.rust-lang.org/nightly/std/ptr/index.html#strict-provenance, https://crates.io/crates/sptr) instead.
-   = help: You can then pass the `-Zmiri-strict-provenance` flag to Miri, to ensure you are not relying on `with_exposed_provenance` semantics.
-   = help: Alternatively, the `-Zmiri-permissive-provenance` flag disables this warning.
+   = help: You can then set `MIRIFLAGS=-Zmiri-strict-provenance` to ensure you are not relying on `with_exposed_provenance` semantics.
+   = help: Alternatively, `MIRIFLAGS=-Zmiri-permissive-provenance` disables this warning.
    = note: BACKTRACE:
    = note: inside `main` at $DIR/issue-miri-2389.rs:LL:CC