diff --git a/compiler/rustc_driver_impl/src/lib.rs b/compiler/rustc_driver_impl/src/lib.rs
index b13cc4d0b066d..90f382e72268b 100644
--- a/compiler/rustc_driver_impl/src/lib.rs
+++ b/compiler/rustc_driver_impl/src/lib.rs
@@ -1388,7 +1388,9 @@ pub fn install_ice_hook(
     // opt in to less-verbose backtraces by manually setting "RUST_BACKTRACE"
     // (e.g. `RUST_BACKTRACE=1`)
     if env::var_os("RUST_BACKTRACE").is_none() {
-        if env!("CFG_RELEASE_CHANNEL") == "dev" {
+        // HACK: this check is extremely dumb, but we don't really need it to be smarter since this should only happen in the test suite anyway.
+        let ui_testing = std::env::args().any(|arg| arg == "-Zui-testing");
+        if env!("CFG_RELEASE_CHANNEL") == "dev" && !ui_testing {
             panic::set_backtrace_style(panic::BacktraceStyle::Short);
         } else {
             panic::set_backtrace_style(panic::BacktraceStyle::Full);
diff --git a/compiler/rustc_errors/src/emitter.rs b/compiler/rustc_errors/src/emitter.rs
index 977721a5b8a2d..f938352820df7 100644
--- a/compiler/rustc_errors/src/emitter.rs
+++ b/compiler/rustc_errors/src/emitter.rs
@@ -2216,6 +2216,11 @@ impl HumanEmitter {
                 show_code_change
             {
                 for part in parts {
+                    let snippet = if let Ok(snippet) = sm.span_to_snippet(part.span) {
+                        snippet
+                    } else {
+                        String::new()
+                    };
                     let span_start_pos = sm.lookup_char_pos(part.span.lo()).col_display;
                     let span_end_pos = sm.lookup_char_pos(part.span.hi()).col_display;
 
@@ -2263,13 +2268,80 @@ impl HumanEmitter {
                     }
                     if let DisplaySuggestion::Diff = show_code_change {
                         // Colorize removal with red in diff format.
-                        buffer.set_style_range(
-                            row_num - 2,
-                            (padding as isize + span_start_pos as isize) as usize,
-                            (padding as isize + span_end_pos as isize) as usize,
-                            Style::Removal,
-                            true,
-                        );
+
+                        // Below, there's some tricky buffer indexing going on. `row_num` at this
+                        // point corresponds to:
+                        //
+                        //    |
+                        // LL | CODE
+                        //    | ++++  <- `row_num`
+                        //
+                        // in the buffer. When we have a diff format output, we end up with
+                        //
+                        //    |
+                        // LL - OLDER   <- row_num - 2
+                        // LL + NEWER
+                        //    |         <- row_num
+                        //
+                        // The `row_num - 2` is to select the buffer line that has the "old version
+                        // of the diff" at that point. When the removal is a single line, `i` is
+                        // `0`, `newlines` is `1` so `(newlines - i - 1)` ends up being `0`, so row
+                        // points at `LL - OLDER`. When the removal corresponds to multiple lines,
+                        // we end up with `newlines > 1` and `i` being `0..newlines - 1`.
+                        //
+                        //    |
+                        // LL - OLDER   <- row_num - 2 - (newlines - last_i - 1)
+                        // LL - CODE
+                        // LL - BEING
+                        // LL - REMOVED <- row_num - 2 - (newlines - first_i - 1)
+                        // LL + NEWER
+                        //    |         <- row_num
+
+                        let newlines = snippet.lines().count();
+                        if newlines > 0 && row_num > newlines {
+                            // Account for removals where the part being removed spans multiple
+                            // lines.
+                            // FIXME: We check the number of rows because in some cases, like in
+                            // `tests/ui/lint/invalid-nan-comparison-suggestion.rs`, the rendered
+                            // suggestion will only show the first line of code being replaced. The
+                            // proper way of doing this would be to change the suggestion rendering
+                            // logic to show the whole prior snippet, but the current output is not
+                            // too bad to begin with, so we side-step that issue here.
+                            for (i, line) in snippet.lines().enumerate() {
+                                let line = normalize_whitespace(line);
+                                let row = row_num - 2 - (newlines - i - 1);
+                                // On the first line, we highlight between the start of the part
+                                // span, and the end of that line.
+                                // On the last line, we highlight between the start of the line, and
+                                // the column of the part span end.
+                                // On all others, we highlight the whole line.
+                                let start = if i == 0 {
+                                    (padding as isize + span_start_pos as isize) as usize
+                                } else {
+                                    padding
+                                };
+                                let end = if i == 0 {
+                                    (padding as isize
+                                        + span_start_pos as isize
+                                        + line.len() as isize)
+                                        as usize
+                                } else if i == newlines - 1 {
+                                    (padding as isize + span_end_pos as isize) as usize
+                                } else {
+                                    (padding as isize + line.len() as isize) as usize
+                                };
+                                buffer.set_style_range(row, start, end, Style::Removal, true);
+                            }
+                        } else {
+                            // The removed code fits all in one line.
+                            buffer.set_style_range(
+                                row_num - 2,
+                                (padding as isize + span_start_pos as isize) as usize,
+                                (padding as isize + span_end_pos as isize) as usize,
+                                Style::Removal,
+                                true,
+                            );
+                        }
                     }
 
                     // length of the code after substitution
diff --git a/src/tools/miri/CONTRIBUTING.md b/src/tools/miri/CONTRIBUTING.md
index e97f4bf86d834..dd283b7c0a857 100644
--- a/src/tools/miri/CONTRIBUTING.md
+++ b/src/tools/miri/CONTRIBUTING.md
@@ -212,6 +212,15 @@ Miri comes with a few benchmarks; you can run `./miri bench` to run them with th
 Miri. Note: this will run `./miri install` as a side-effect. Also requires `hyperfine` to be
 installed (`cargo install hyperfine`).
 
+To compare the benchmark results with a baseline, do the following:
+- Before applying your changes, run `./miri bench --save-baseline=baseline.json`.
+- Then do your changes.
+- Then run `./miri bench --load-baseline=baseline.json`; the results will include
+  a comparison with the baseline.
+
+You can run only some of the benchmarks by listing them, e.g. `./miri bench mse`.
+The names refer to the folders in `bench-cargo-miri`.
+
 ## Configuring `rust-analyzer`
 
 To configure `rust-analyzer` and the IDE for working on Miri, copy one of the provided
diff --git a/src/tools/miri/README.md b/src/tools/miri/README.md
index 8f577295d1750..9042c5da57716 100644
--- a/src/tools/miri/README.md
+++ b/src/tools/miri/README.md
@@ -160,14 +160,14 @@ Certain parts of the execution are picked randomly by Miri, such as the exact ba
 allocations are stored at and the interleaving of concurrently executing threads. Sometimes, it can
 be useful to explore multiple different execution, e.g. to make sure that your code does not depend
 on incidental "super-alignment" of new allocations and to test different thread interleavings.
-This can be done with the `--many-seeds` flag:
+This can be done with the `-Zmiri-many-seeds` flag:
 
 ```
-cargo miri test --many-seeds # tries the seeds in 0..64
-cargo miri test --many-seeds=0..16
+MIRIFLAGS="-Zmiri-many-seeds" cargo miri test # tries the seeds in 0..64
+MIRIFLAGS="-Zmiri-many-seeds=0..16" cargo miri test
 ```
 
-The default of 64 different seeds is quite slow, so you probably want to specify a smaller range.
+The default of 64 different seeds can be quite slow, so you often want to specify a smaller range.
 
 ### Running Miri on CI
 
@@ -294,9 +294,10 @@ environment variable. We first document the most relevant and most commonly used
   will always fail and `0.0` means it will never fail. Note that setting it to
   `1.0` will likely cause hangs, since it means programs using
   `compare_exchange_weak` cannot make progress.
-* `-Zmiri-disable-isolation` disables host isolation.  As a consequence,
+* `-Zmiri-disable-isolation` disables host isolation. As a consequence,
   the program has access to host resources such as environment variables, file
   systems, and randomness.
+  This overwrites a previous `-Zmiri-isolation-error`.
 * `-Zmiri-disable-leak-backtraces` disables backtraces reports for memory leaks. By default, a
   backtrace is captured for every allocation when it is created, just in case it leaks. This incurs
   some memory overhead to store data that is almost never used. This flag is implied by
@@ -317,6 +318,15 @@ environment variable. We first document the most relevant and most commonly used
   execution with a "permission denied" error being returned to the program.
   `warn` prints a full backtrace each time that happens; `warn-nobacktrace` is less
   verbose and shown at most once per operation. `hide` hides the warning entirely.
+  This overwrites a previous `-Zmiri-disable-isolation`.
+* `-Zmiri-many-seeds=[<from>]..<to>` runs the program multiple times with different seeds for Miri's
+  RNG. With different seeds, Miri will make different choices to resolve non-determinism such as the
+  order in which concurrent threads are scheduled, or the exact addresses assigned to allocations.
+  This is useful to find bugs that only occur under particular interleavings of concurrent threads,
+  or that otherwise depend on non-determinism. If the `<from>` part is skipped, it defaults to `0`.
+  Can be used without a value; in that case the range defaults to `0..64`.
+* `-Zmiri-many-seeds-keep-going` tells Miri to really try all the seeds in the given range, even if
+  a failing seed has already been found. This is useful to determine which fraction of seeds fails.
 * `-Zmiri-num-cpus` states the number of available CPUs to be reported by miri. By default, the
   number of available CPUs is `1`. Note that this flag does not affect how miri handles threads in
   any way.
@@ -339,8 +349,8 @@ environment variable. We first document the most relevant and most commonly used
   can increase test coverage by running Miri multiple times with different seeds.
 * `-Zmiri-strict-provenance` enables [strict
   provenance](https://github.com/rust-lang/rust/issues/95228) checking in Miri. This means that
-  casting an integer to a pointer yields a result with 'invalid' provenance, i.e., with provenance
-  that cannot be used for any memory access.
+  casting an integer to a pointer will stop execution because the provenance of the pointer
+  cannot be determined.
 * `-Zmiri-symbolic-alignment-check` makes the alignment check more strict.  By default, alignment is
   checked by casting the pointer to an integer, and making sure that is a multiple of the alignment.
   This can lead to cases where a program passes the alignment check by pure chance, because things
@@ -429,6 +439,8 @@ to Miri failing to detect cases of undefined behavior in a program.
   of Rust will be stricter than Tree Borrows. In other words, if you use Tree Borrows,
   even if your code is accepted today, it might be declared UB in the future.
   This is much less likely with Stacked Borrows.
+  Using Tree Borrows currently implies `-Zmiri-strict-provenance` because integer-to-pointer
+  casts are not supported in this mode, but that may change in the future.
 * `-Zmiri-force-page-size=<num>` overrides the default page size for an architecture, in multiples of 1k.
   `4` is default for most targets. This value should always be a power of 2 and nonzero.
 * `-Zmiri-unique-is-unique` performs additional aliasing checks for `core::ptr::Unique` to ensure
diff --git a/src/tools/miri/cargo-miri/src/phases.rs b/src/tools/miri/cargo-miri/src/phases.rs
index 7ca4f414c2051..d7b4421061c6b 100644
--- a/src/tools/miri/cargo-miri/src/phases.rs
+++ b/src/tools/miri/cargo-miri/src/phases.rs
@@ -1,10 +1,10 @@
 //! Implements the various phases of `cargo miri run/test`.
 
+use std::env;
 use std::fs::{self, File};
-use std::io::{BufReader, Write};
+use std::io::BufReader;
 use std::path::{Path, PathBuf};
 use std::process::Command;
-use std::{env, thread};
 
 use rustc_version::VersionMeta;
 
@@ -24,10 +24,7 @@ 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`.
+Furthermore, the following environment variables are recognized for `run` and `test`:
 
     MIRIFLAGS                Extra flags to pass to the Miri driver. Use this to pass `-Zmiri-...` flags.
 
@@ -41,8 +38,6 @@ Examples:
 
 ";
 
-const DEFAULT_MANY_SEEDS: &str = "0..64";
-
 fn show_help() {
     println!("{CARGO_MIRI_HELP}");
 }
@@ -182,17 +177,15 @@ pub fn phase_cargo_miri(mut args: impl Iterator<Item = String>) {
     let target_dir = get_target_dir(&metadata);
     cmd.arg("--target-dir").arg(target_dir);
 
-    // Store many-seeds argument.
-    let mut many_seeds = None;
     // *After* we set all the flags that need setting, forward everything else. Make sure to skip
-    // `--target-dir` (which would otherwise be set twice) and `--many-seeds` (which is our flag, not cargo's).
+    // `--target-dir` (which would otherwise be set twice).
     for arg in
         ArgSplitFlagValue::from_string_iter(&mut args, "--target-dir").filter_map(Result::err)
     {
-        if arg == "--many-seeds" {
-            many_seeds = Some(DEFAULT_MANY_SEEDS.to_owned());
-        } else if let Some(val) = arg.strip_prefix("--many-seeds=") {
-            many_seeds = Some(val.to_owned());
+        if arg == "--many-seeds" || arg.starts_with("--many-seeds=") {
+            show_error!(
+                "ERROR: the `--many-seeds` flag has been removed from cargo-miri; use MIRIFLAGS=-Zmiri-many-seeds instead"
+            );
         } else {
             cmd.arg(arg);
         }
@@ -249,9 +242,6 @@ pub fn phase_cargo_miri(mut args: impl Iterator<Item = String>) {
     // Forward some crucial information to our own re-invocations.
     cmd.env("MIRI_SYSROOT", miri_sysroot);
     cmd.env("MIRI_LOCAL_CRATES", local_crates(&metadata));
-    if let Some(many_seeds) = many_seeds {
-        cmd.env("MIRI_MANY_SEEDS", many_seeds);
-    }
     if verbose > 0 {
         cmd.env("MIRI_VERBOSE", verbose.to_string()); // This makes the other phases verbose.
     }
@@ -407,14 +397,11 @@ pub fn phase_rustc(mut args: impl Iterator<Item = String>, phase: RustcPhase) {
 
             // Alter the `-o` parameter so that it does not overwrite the JSON file we stored above.
             let mut args = env.args;
-            let mut out_filename = None;
             for i in 0..args.len() {
                 if args[i] == "-o" {
-                    out_filename = Some(args[i + 1].clone());
                     args[i + 1].push_str(".miri");
                 }
             }
-            let out_filename = out_filename.expect("rustdoc must pass `-o`");
 
             cmd.args(&args);
             cmd.env("MIRI_BE_RUSTC", "target");
@@ -427,7 +414,7 @@ pub fn phase_rustc(mut args: impl Iterator<Item = String>, phase: RustcPhase) {
                 eprintln!("[cargo-miri rustc inside rustdoc] going to run:\n{cmd:?}");
             }
 
-            exec_with_pipe(cmd, &env.stdin, format!("{out_filename}.stdin"));
+            exec_with_pipe(cmd, &env.stdin);
         }
 
         return;
@@ -589,111 +576,81 @@ pub fn phase_runner(mut binary_args: impl Iterator<Item = String>, phase: Runner
         }
     };
 
-    let many_seeds = env::var("MIRI_MANY_SEEDS");
-    run_many_seeds(many_seeds.ok(), |seed| {
-        let mut cmd = miri();
-
-        // Set missing env vars. We prefer build-time env vars over run-time ones; see
-        // <https://github.com/rust-lang/miri/issues/1661> for the kind of issue that fixes.
-        for (name, val) in &info.env {
-            // `CARGO_MAKEFLAGS` contains information about how to reach the jobserver, but by the time
-            // the program is being run, that jobserver no longer exists (cargo only runs the jobserver
-            // for the build portion of `cargo run`/`cargo test`). Hence we shouldn't forward this.
-            // Also see <https://github.com/rust-lang/rust/pull/113730>.
-            if name == "CARGO_MAKEFLAGS" {
-                continue;
-            }
-            if let Some(old_val) = env::var_os(name) {
-                if *old_val == *val {
-                    // This one did not actually change, no need to re-set it.
-                    // (This keeps the `debug_cmd` below more manageable.)
-                    continue;
-                } else if verbose > 0 {
-                    eprintln!(
-                        "[cargo-miri runner] Overwriting run-time env var {name:?}={old_val:?} with build-time value {val:?}"
-                    );
-                }
-            }
-            cmd.env(name, val);
-        }
+    let mut cmd = miri();
 
-        if phase != RunnerPhase::Rustdoc {
-            // Set the sysroot. Not necessary in rustdoc, where we already set the sysroot in
-            // `phase_rustdoc`. rustdoc will forward that flag when invoking rustc (i.e., us), so the
-            // flag is present in `info.args`.
-            cmd.arg("--sysroot").arg(env::var_os("MIRI_SYSROOT").unwrap());
+    // Set missing env vars. We prefer build-time env vars over run-time ones; see
+    // <https://github.com/rust-lang/miri/issues/1661> for the kind of issue that fixes.
+    for (name, val) in &info.env {
+        // `CARGO_MAKEFLAGS` contains information about how to reach the jobserver, but by the time
+        // the program is being run, that jobserver no longer exists (cargo only runs the jobserver
+        // for the build portion of `cargo run`/`cargo test`). Hence we shouldn't forward this.
+        // Also see <https://github.com/rust-lang/rust/pull/113730>.
+        if name == "CARGO_MAKEFLAGS" {
+            continue;
         }
-        // Forward rustc arguments.
-        // We need to patch "--extern" filenames because we forced a check-only
-        // build without cargo knowing about that: replace `.rlib` suffix by
-        // `.rmeta`.
-        // We also need to remove `--error-format` as cargo specifies that to be JSON,
-        // but when we run here, cargo does not interpret the JSON any more. `--json`
-        // then also needs to be dropped.
-        let mut args = info.args.iter();
-        while let Some(arg) = args.next() {
-            if arg == "--extern" {
-                forward_patched_extern_arg(&mut (&mut args).cloned(), &mut cmd);
-            } else if let Some(suffix) = arg.strip_prefix("--error-format") {
-                assert!(suffix.starts_with('='));
-                // Drop this argument.
-            } else if let Some(suffix) = arg.strip_prefix("--json") {
-                assert!(suffix.starts_with('='));
-                // Drop this argument.
-            } else {
-                cmd.arg(arg);
+        if let Some(old_val) = env::var_os(name) {
+            if *old_val == *val {
+                // This one did not actually change, no need to re-set it.
+                // (This keeps the `debug_cmd` below more manageable.)
+                continue;
+            } else if verbose > 0 {
+                eprintln!(
+                    "[cargo-miri runner] Overwriting run-time env var {name:?}={old_val:?} with build-time value {val:?}"
+                );
             }
         }
-        // Respect `MIRIFLAGS`.
-        if let Ok(a) = env::var("MIRIFLAGS") {
-            let args = flagsplit(&a);
-            cmd.args(args);
-        }
-        // Set the current seed.
-        if let Some(seed) = seed {
-            eprintln!("Trying seed: {seed}");
-            cmd.arg(format!("-Zmiri-seed={seed}"));
-        }
+        cmd.env(name, val);
+    }
 
-        // Then pass binary arguments.
-        cmd.arg("--");
-        cmd.args(&binary_args);
-
-        // Make sure we use the build-time working directory for interpreting Miri/rustc arguments.
-        // But then we need to switch to the run-time one, which we instruct Miri to do by setting `MIRI_CWD`.
-        cmd.current_dir(&info.current_dir);
-        cmd.env("MIRI_CWD", env::current_dir().unwrap());
-
-        // Run it.
-        debug_cmd("[cargo-miri runner]", verbose, &cmd);
-
-        match phase {
-            RunnerPhase::Rustdoc => {
-                cmd.stdin(std::process::Stdio::piped());
-                // the warning is wrong, we have a `wait` inside the `scope` closure.
-                let mut child = cmd.spawn().expect("failed to spawn process");
-                let child_stdin = child.stdin.take().unwrap();
-                // Write stdin in a background thread, as it may block.
-                let exit_status = thread::scope(|s| {
-                    s.spawn(|| {
-                        let mut child_stdin = child_stdin;
-                        // Ignore failure, it is most likely due to the process having terminated.
-                        let _ = child_stdin.write_all(&info.stdin);
-                    });
-                    child.wait().expect("failed to run command")
-                });
-                if !exit_status.success() {
-                    std::process::exit(exit_status.code().unwrap_or(-1));
-                }
-            }
-            RunnerPhase::Cargo => {
-                let exit_status = cmd.status().expect("failed to run command");
-                if !exit_status.success() {
-                    std::process::exit(exit_status.code().unwrap_or(-1));
-                }
-            }
+    if phase != RunnerPhase::Rustdoc {
+        // Set the sysroot. Not necessary in rustdoc, where we already set the sysroot in
+        // `phase_rustdoc`. rustdoc will forward that flag when invoking rustc (i.e., us), so the
+        // flag is present in `info.args`.
+        cmd.arg("--sysroot").arg(env::var_os("MIRI_SYSROOT").unwrap());
+    }
+    // Forward rustc arguments.
+    // We need to patch "--extern" filenames because we forced a check-only
+    // build without cargo knowing about that: replace `.rlib` suffix by
+    // `.rmeta`.
+    // We also need to remove `--error-format` as cargo specifies that to be JSON,
+    // but when we run here, cargo does not interpret the JSON any more. `--json`
+    // then also needs to be dropped.
+    let mut args = info.args.iter();
+    while let Some(arg) = args.next() {
+        if arg == "--extern" {
+            forward_patched_extern_arg(&mut (&mut args).cloned(), &mut cmd);
+        } else if let Some(suffix) = arg.strip_prefix("--error-format") {
+            assert!(suffix.starts_with('='));
+            // Drop this argument.
+        } else if let Some(suffix) = arg.strip_prefix("--json") {
+            assert!(suffix.starts_with('='));
+            // Drop this argument.
+        } else {
+            cmd.arg(arg);
         }
-    });
+    }
+    // Respect `MIRIFLAGS`.
+    if let Ok(a) = env::var("MIRIFLAGS") {
+        let args = flagsplit(&a);
+        cmd.args(args);
+    }
+
+    // Then pass binary arguments.
+    cmd.arg("--");
+    cmd.args(&binary_args);
+
+    // Make sure we use the build-time working directory for interpreting Miri/rustc arguments.
+    // But then we need to switch to the run-time one, which we instruct Miri to do by setting `MIRI_CWD`.
+    cmd.current_dir(&info.current_dir);
+    cmd.env("MIRI_CWD", env::current_dir().unwrap());
+
+    // Run it.
+    debug_cmd("[cargo-miri runner]", verbose, &cmd);
+
+    match phase {
+        RunnerPhase::Rustdoc => exec_with_pipe(cmd, &info.stdin),
+        RunnerPhase::Cargo => exec(cmd),
+    }
 }
 
 pub fn phase_rustdoc(mut args: impl Iterator<Item = String>) {
diff --git a/src/tools/miri/cargo-miri/src/util.rs b/src/tools/miri/cargo-miri/src/util.rs
index 56f38de8de620..43b2a1b61733a 100644
--- a/src/tools/miri/cargo-miri/src/util.rs
+++ b/src/tools/miri/cargo-miri/src/util.rs
@@ -143,43 +143,23 @@ pub fn exec(mut cmd: Command) -> ! {
     }
 }
 
-/// Execute the `Command`, where possible by replacing the current process with a new process
-/// described by the `Command`. Then exit this process with the exit code of the new process.
-/// `input` is also piped to the new process's stdin, on cfg(unix) platforms by writing its
-/// contents to `path` first, then setting stdin to that file.
-pub fn exec_with_pipe<P>(mut cmd: Command, input: &[u8], path: P) -> !
-where
-    P: AsRef<Path>,
-{
-    #[cfg(unix)]
-    {
-        // Write the bytes we want to send to stdin out to a file
-        std::fs::write(&path, input).unwrap();
-        // Open the file for reading, and set our new stdin to it
-        let stdin = File::open(&path).unwrap();
-        cmd.stdin(stdin);
-        // Unlink the file so that it is fully cleaned up as soon as the new process exits
-        std::fs::remove_file(&path).unwrap();
-        // Finally, we can hand off control.
-        exec(cmd)
-    }
-    #[cfg(not(unix))]
-    {
-        drop(path); // We don't need the path, we can pipe the bytes directly
-        cmd.stdin(std::process::Stdio::piped());
-        let mut child = cmd.spawn().expect("failed to spawn process");
-        let child_stdin = child.stdin.take().unwrap();
-        // Write stdin in a background thread, as it may block.
-        let exit_status = std::thread::scope(|s| {
-            s.spawn(|| {
-                let mut child_stdin = child_stdin;
-                // Ignore failure, it is most likely due to the process having terminated.
-                let _ = child_stdin.write_all(input);
-            });
-            child.wait().expect("failed to run command")
+/// Execute the `Command`, then exit this process with the exit code of the new process.
+/// `input` is also piped to the new process's stdin.
+pub fn exec_with_pipe(mut cmd: Command, input: &[u8]) -> ! {
+    // We can't use `exec` since then the background thread will stop running.
+    cmd.stdin(std::process::Stdio::piped());
+    let mut child = cmd.spawn().expect("failed to spawn process");
+    let child_stdin = child.stdin.take().unwrap();
+    // Write stdin in a background thread, as it may block.
+    let exit_status = std::thread::scope(|s| {
+        s.spawn(|| {
+            let mut child_stdin = child_stdin;
+            // Ignore failure, it is most likely due to the process having terminated.
+            let _ = child_stdin.write_all(input);
         });
-        std::process::exit(exit_status.code().unwrap_or(-1))
-    }
+        child.wait().expect("failed to run command")
+    });
+    std::process::exit(exit_status.code().unwrap_or(-1))
 }
 
 pub fn ask_to_run(mut cmd: Command, ask: bool, text: &str) {
@@ -319,24 +299,3 @@ pub fn clean_target_dir(meta: &Metadata) {
 
     remove_dir_all_idem(&target_dir).unwrap_or_else(|err| show_error!("{}", err))
 }
-
-/// Run `f` according to the many-seeds argument. In single-seed mode, `f` will only
-/// be called once, with `None`.
-pub fn run_many_seeds(many_seeds: Option<String>, f: impl Fn(Option<u32>)) {
-    let Some(many_seeds) = many_seeds else {
-        return f(None);
-    };
-    let (from, to) = many_seeds
-        .split_once("..")
-        .unwrap_or_else(|| show_error!("invalid format for `--many-seeds`: expected `from..to`"));
-    let from: u32 = if from.is_empty() {
-        0
-    } else {
-        from.parse().unwrap_or_else(|_| show_error!("invalid `from` in `--many-seeds=from..to"))
-    };
-    let to: u32 =
-        to.parse().unwrap_or_else(|_| show_error!("invalid `to` in `--many-seeds=from..to"));
-    for seed in from..to {
-        f(Some(seed));
-    }
-}
diff --git a/src/tools/miri/ci/ci.sh b/src/tools/miri/ci/ci.sh
index 5da83a1623c60..0751f86da8529 100755
--- a/src/tools/miri/ci/ci.sh
+++ b/src/tools/miri/ci/ci.sh
@@ -66,9 +66,9 @@ function run_tests {
     time MIRIFLAGS="${MIRIFLAGS-} -O -Zmir-opt-level=4 -Cdebug-assertions=yes" MIRI_SKIP_UI_CHECKS=1 ./miri test $TARGET_FLAG tests/{pass,panic}
   fi
   if [ -n "${MANY_SEEDS-}" ]; then
-    # Also run some many-seeds tests. (Also tests `./miri run`.)
+    # Run many-seeds tests. (Also tests `./miri run`.)
     time for FILE in tests/many-seeds/*.rs; do
-      ./miri run "--many-seeds=0..$MANY_SEEDS" $TARGET_FLAG "$FILE"
+      ./miri run "-Zmiri-many-seeds=0..$MANY_SEEDS" $TARGET_FLAG "$FILE"
     done
   fi
   if [ -n "${TEST_BENCH-}" ]; then
diff --git a/src/tools/miri/miri-script/Cargo.lock b/src/tools/miri/miri-script/Cargo.lock
index 0208327a8ddcf..25c6f817575e2 100644
--- a/src/tools/miri/miri-script/Cargo.lock
+++ b/src/tools/miri/miri-script/Cargo.lock
@@ -250,6 +250,8 @@ dependencies = [
  "itertools",
  "path_macro",
  "rustc_version",
+ "serde",
+ "serde_derive",
  "serde_json",
  "shell-words",
  "tempfile",
diff --git a/src/tools/miri/miri-script/Cargo.toml b/src/tools/miri/miri-script/Cargo.toml
index 0ab49bbacfc70..5879b2717e5d6 100644
--- a/src/tools/miri/miri-script/Cargo.toml
+++ b/src/tools/miri/miri-script/Cargo.toml
@@ -23,6 +23,8 @@ xshell = "0.2.6"
 rustc_version = "0.4"
 dunce = "1.0.4"
 directories = "5"
+serde = "1"
 serde_json = "1"
+serde_derive = "1"
 tempfile = "3.13.0"
 clap = { version = "4.5.21", features = ["derive"] }
diff --git a/src/tools/miri/miri-script/src/commands.rs b/src/tools/miri/miri-script/src/commands.rs
index 55005d86346f7..75ac999e8be75 100644
--- a/src/tools/miri/miri-script/src/commands.rs
+++ b/src/tools/miri/miri-script/src/commands.rs
@@ -1,12 +1,16 @@
+use std::collections::HashMap;
 use std::ffi::{OsStr, OsString};
-use std::io::Write;
-use std::ops::{Not, Range};
+use std::fs::File;
+use std::io::{BufReader, BufWriter, Write};
+use std::ops::Not;
 use std::path::PathBuf;
 use std::time::Duration;
 use std::{env, net, process};
 
 use anyhow::{Context, Result, anyhow, bail};
 use path_macro::path;
+use serde_derive::{Deserialize, Serialize};
+use tempfile::TempDir;
 use walkdir::WalkDir;
 use xshell::{Shell, cmd};
 
@@ -174,13 +178,13 @@ impl Command {
             Command::Check { flags } => Self::check(flags),
             Command::Test { bless, flags, target, coverage } =>
                 Self::test(bless, flags, target, coverage),
-            Command::Run { dep, verbose, many_seeds, target, edition, flags } =>
-                Self::run(dep, verbose, many_seeds, target, edition, flags),
+            Command::Run { dep, verbose, target, edition, flags } =>
+                Self::run(dep, verbose, target, edition, flags),
             Command::Doc { flags } => Self::doc(flags),
             Command::Fmt { flags } => Self::fmt(flags),
             Command::Clippy { flags } => Self::clippy(flags),
-            Command::Bench { target, no_install, benches } =>
-                Self::bench(target, no_install, benches),
+            Command::Bench { target, no_install, save_baseline, load_baseline, benches } =>
+                Self::bench(target, no_install, save_baseline, load_baseline, benches),
             Command::Toolchain { flags } => Self::toolchain(flags),
             Command::RustcPull { commit } => Self::rustc_pull(commit.clone()),
             Command::RustcPush { github_user, branch } => Self::rustc_push(github_user, branch),
@@ -379,7 +383,17 @@ impl Command {
         Ok(())
     }
 
-    fn bench(target: Option<String>, no_install: bool, benches: Vec<String>) -> Result<()> {
+    fn bench(
+        target: Option<String>,
+        no_install: bool,
+        save_baseline: Option<String>,
+        load_baseline: Option<String>,
+        benches: Vec<String>,
+    ) -> Result<()> {
+        if save_baseline.is_some() && load_baseline.is_some() {
+            bail!("Only one of `--save-baseline` and `--load-baseline` can be set");
+        }
+
         // The hyperfine to use
         let hyperfine = env::var("HYPERFINE");
         let hyperfine = hyperfine.as_deref().unwrap_or("hyperfine -w 1 -m 5 --shell=none");
@@ -387,19 +401,26 @@ impl Command {
         let Some((program_name, args)) = hyperfine.split_first() else {
             bail!("expected HYPERFINE environment variable to be non-empty");
         };
+
         if !no_install {
             // Make sure we have an up-to-date Miri installed and selected the right toolchain.
             Self::install(vec![])?;
         }
+        let results_json_dir = if save_baseline.is_some() || load_baseline.is_some() {
+            Some(TempDir::new()?)
+        } else {
+            None
+        };
 
+        let miri_dir = miri_dir()?;
         let sh = Shell::new()?;
-        sh.change_dir(miri_dir()?);
+        sh.change_dir(&miri_dir);
         let benches_dir = "bench-cargo-miri";
-        let benches: Vec<OsString> = if benches.is_empty() {
+        let benches: Vec<String> = if benches.is_empty() {
             sh.read_dir(benches_dir)?
                 .into_iter()
                 .filter(|path| path.is_dir())
-                .map(Into::into)
+                .map(|path| path.into_os_string().into_string().unwrap())
                 .collect()
         } else {
             benches.into_iter().map(Into::into).collect()
@@ -414,16 +435,75 @@ impl Command {
         let target_flag = &target_flag;
         let toolchain = active_toolchain()?;
         // Run the requested benchmarks
-        for bench in benches {
+        for bench in &benches {
             let current_bench = path!(benches_dir / bench / "Cargo.toml");
+            let mut export_json = None;
+            if let Some(baseline_temp_dir) = &results_json_dir {
+                export_json = Some(format!(
+                    "--export-json={}",
+                    path!(baseline_temp_dir / format!("{bench}.bench.json")).display()
+                ));
+            }
             // We don't attempt to escape `current_bench`, but we wrap it in quotes.
             // That seems to make Windows CI happy.
             cmd!(
                 sh,
-                "{program_name} {args...} 'cargo +'{toolchain}' miri run '{target_flag}' --manifest-path \"'{current_bench}'\"'"
+                "{program_name} {args...} {export_json...} 'cargo +'{toolchain}' miri run '{target_flag}' --manifest-path \"'{current_bench}'\"'"
             )
             .run()?;
         }
+
+        // Gather/load results for baseline saving.
+
+        #[derive(Serialize, Deserialize)]
+        struct BenchResult {
+            mean: f64,
+            stddev: f64,
+        }
+
+        let gather_results = || -> Result<HashMap<&str, BenchResult>> {
+            let baseline_temp_dir = results_json_dir.unwrap();
+            let mut results = HashMap::new();
+            for bench in &benches {
+                let result = File::open(path!(baseline_temp_dir / format!("{bench}.bench.json")))?;
+                let mut result: serde_json::Value =
+                    serde_json::from_reader(BufReader::new(result))?;
+                let result: BenchResult = serde_json::from_value(result["results"][0].take())?;
+                results.insert(bench as &str, result);
+            }
+            Ok(results)
+        };
+
+        if let Some(baseline_file) = save_baseline {
+            let results = gather_results()?;
+            let baseline = File::create(baseline_file)?;
+            serde_json::to_writer_pretty(BufWriter::new(baseline), &results)?;
+        } else if let Some(baseline_file) = load_baseline {
+            let new_results = gather_results()?;
+            let baseline_results: HashMap<String, BenchResult> = {
+                let f = File::open(baseline_file)?;
+                serde_json::from_reader(BufReader::new(f))?
+            };
+            println!(
+                "Comparison with baseline (relative speed, lower is better for the new results):"
+            );
+            for (bench, new_result) in new_results.iter() {
+                let Some(baseline_result) = baseline_results.get(*bench) else { continue };
+
+                // Compare results (inspired by hyperfine)
+                let ratio = new_result.mean / baseline_result.mean;
+                // https://en.wikipedia.org/wiki/Propagation_of_uncertainty#Example_formulae
+                // Covariance asssumed to be 0, i.e. variables are assumed to be independent
+                let ratio_stddev = ratio
+                    * f64::sqrt(
+                        (new_result.stddev / new_result.mean).powi(2)
+                            + (baseline_result.stddev / baseline_result.mean).powi(2),
+                    );
+
+                println!("  {bench}: {ratio:.2} ± {ratio_stddev:.2}");
+            }
+        }
+
         Ok(())
     }
 
@@ -506,7 +586,6 @@ impl Command {
     fn run(
         dep: bool,
         verbose: bool,
-        many_seeds: Option<Range<u32>>,
         target: Option<String>,
         edition: Option<String>,
         flags: Vec<String>,
@@ -534,48 +613,34 @@ impl Command {
         early_flags.push("--sysroot".into());
         early_flags.push(miri_sysroot.into());
 
-        // Compute everything needed to run the actual command. Also add MIRIFLAGS.
+        // Compute flags.
         let miri_flags = e.sh.var("MIRIFLAGS").unwrap_or_default();
         let miri_flags = flagsplit(&miri_flags);
         let quiet_flag = if verbose { None } else { Some("--quiet") };
-        // This closure runs the command with the given `seed_flag` added between the MIRIFLAGS and
-        // the `flags` given on the command-line.
-        let run_miri = |e: &MiriEnv, seed_flag: Option<String>| -> Result<()> {
-            // The basic command that executes the Miri driver.
-            let mut cmd = if dep {
-                // We invoke the test suite as that has all the logic for running with dependencies.
-                e.cargo_cmd(".", "test")
-                    .args(&["--test", "ui"])
-                    .args(quiet_flag)
-                    .arg("--")
-                    .args(&["--miri-run-dep-mode"])
-            } else {
-                cmd!(e.sh, "{miri_bin}")
-            };
-            cmd.set_quiet(!verbose);
-            // Add Miri flags
-            let mut cmd = cmd.args(&miri_flags).args(&seed_flag).args(&early_flags).args(&flags);
-            // For `--dep` we also need to set the target in the env var.
-            if dep {
-                if let Some(target) = &target {
-                    cmd = cmd.env("MIRI_TEST_TARGET", target);
-                }
-            }
-            // And run the thing.
-            Ok(cmd.run()?)
-        };
-        // Run the closure once or many times.
-        if let Some(seed_range) = many_seeds {
-            e.run_many_times(seed_range, |e, seed| {
-                eprintln!("Trying seed: {seed}");
-                run_miri(e, Some(format!("-Zmiri-seed={seed}"))).inspect_err(|_| {
-                    eprintln!("FAILING SEED: {seed}");
-                })
-            })?;
+
+        // Run Miri.
+        // The basic command that executes the Miri driver.
+        let mut cmd = if dep {
+            // We invoke the test suite as that has all the logic for running with dependencies.
+            e.cargo_cmd(".", "test")
+                .args(&["--test", "ui"])
+                .args(quiet_flag)
+                .arg("--")
+                .args(&["--miri-run-dep-mode"])
         } else {
-            run_miri(&e, None)?;
+            cmd!(e.sh, "{miri_bin}")
+        };
+        cmd.set_quiet(!verbose);
+        // Add Miri flags
+        let mut cmd = cmd.args(&miri_flags).args(&early_flags).args(&flags);
+        // For `--dep` we also need to set the target in the env var.
+        if dep {
+            if let Some(target) = &target {
+                cmd = cmd.env("MIRI_TEST_TARGET", target);
+            }
         }
-        Ok(())
+        // Finally, run the thing.
+        Ok(cmd.run()?)
     }
 
     fn fmt(flags: Vec<String>) -> Result<()> {
diff --git a/src/tools/miri/miri-script/src/main.rs b/src/tools/miri/miri-script/src/main.rs
index 7592e56cfcfee..a80fed8fcb65e 100644
--- a/src/tools/miri/miri-script/src/main.rs
+++ b/src/tools/miri/miri-script/src/main.rs
@@ -1,32 +1,12 @@
-#![allow(clippy::needless_question_mark)]
+#![allow(clippy::needless_question_mark, rustc::internal)]
 
 mod commands;
 mod coverage;
 mod util;
 
-use std::ops::Range;
-
-use anyhow::{Context, Result, anyhow, bail};
+use anyhow::{Result, bail};
 use clap::{Parser, Subcommand};
 
-/// Parses a seed range
-///
-/// This function is used for the `--many-seeds` flag. It expects the range in the form
-/// `<from>..<to>`. `<from>` is inclusive, `<to>` is exclusive. `<from>` can be omitted,
-/// in which case it is assumed to be `0`.
-fn parse_range(val: &str) -> anyhow::Result<Range<u32>> {
-    let (from, to) = val
-        .split_once("..")
-        .ok_or_else(|| anyhow!("invalid format for `--many-seeds`: expected `from..to`"))?;
-    let from: u32 = if from.is_empty() {
-        0
-    } else {
-        from.parse().context("invalid `from` in `--many-seeds=from..to")?
-    };
-    let to: u32 = to.parse().context("invalid `to` in `--many-seeds=from..to")?;
-    Ok(from..to)
-}
-
 #[derive(Clone, Debug, Subcommand)]
 pub enum Command {
     /// Installs the miri driver and cargo-miri to the sysroot of the active toolchain.
@@ -81,9 +61,6 @@ pub enum Command {
         /// Show build progress.
         #[arg(long, short)]
         verbose: bool,
-        /// Run the driver with the seeds in the given range (`..to` or `from..to`, default: `0..64`).
-        #[arg(long, value_parser = parse_range)]
-        many_seeds: Option<Range<u32>>,
         /// The cross-interpretation target.
         #[arg(long)]
         target: Option<String>,
@@ -117,6 +94,14 @@ pub enum Command {
         /// When `true`, skip the `./miri install` step.
         #[arg(long)]
         no_install: bool,
+        /// Store the benchmark result in the given file, so it can be used
+        /// as the baseline for a future run.
+        #[arg(long)]
+        save_baseline: Option<String>,
+        /// Load previous stored benchmark results as baseline, and print an analysis of how the
+        /// current run compares.
+        #[arg(long)]
+        load_baseline: Option<String>,
         /// List of benchmarks to run (default: run all benchmarks).
         benches: Vec<String>,
     },
diff --git a/src/tools/miri/miri-script/src/util.rs b/src/tools/miri/miri-script/src/util.rs
index cf6529d8373ed..c039b4827ee34 100644
--- a/src/tools/miri/miri-script/src/util.rs
+++ b/src/tools/miri/miri-script/src/util.rs
@@ -1,9 +1,7 @@
 use std::ffi::{OsStr, OsString};
 use std::io::BufRead;
-use std::ops::Range;
 use std::path::{Path, PathBuf};
-use std::sync::atomic::{AtomicBool, AtomicU32, Ordering};
-use std::{env, iter, thread};
+use std::{env, iter};
 
 use anyhow::{Context, Result, anyhow, bail};
 use dunce::canonicalize;
@@ -29,7 +27,6 @@ pub fn flagsplit(flags: &str) -> Vec<String> {
 }
 
 /// Some extra state we track for building Miri, such as the right RUSTFLAGS.
-#[derive(Clone)]
 pub struct MiriEnv {
     /// miri_dir is the root of the miri repository checkout we are working in.
     pub miri_dir: PathBuf,
@@ -240,53 +237,4 @@ impl MiriEnv {
 
         Ok(())
     }
-
-    /// Run the given closure many times in parallel with access to the shell, once for each value in the `range`.
-    pub fn run_many_times(
-        &self,
-        range: Range<u32>,
-        run: impl Fn(&Self, u32) -> Result<()> + Sync,
-    ) -> Result<()> {
-        // `next` is atomic so threads can concurrently fetch their next value to run.
-        let next = AtomicU32::new(range.start);
-        let end = range.end; // exclusive!
-        let failed = AtomicBool::new(false);
-        thread::scope(|s| {
-            let mut handles = Vec::new();
-            // Spawn one worker per core.
-            for _ in 0..thread::available_parallelism()?.get() {
-                // Create a copy of the environment for this thread.
-                let local_miri = self.clone();
-                let handle = s.spawn(|| -> Result<()> {
-                    let local_miri = local_miri; // move the copy into this thread.
-                    // Each worker thread keeps asking for numbers until we're all done.
-                    loop {
-                        let cur = next.fetch_add(1, Ordering::Relaxed);
-                        if cur >= end {
-                            // We hit the upper limit and are done.
-                            break;
-                        }
-                        // Run the command with this seed.
-                        run(&local_miri, cur).inspect_err(|_| {
-                            // If we failed, tell everyone about this.
-                            failed.store(true, Ordering::Relaxed);
-                        })?;
-                        // Check if some other command failed (in which case we'll stop as well).
-                        if failed.load(Ordering::Relaxed) {
-                            return Ok(());
-                        }
-                    }
-                    Ok(())
-                });
-                handles.push(handle);
-            }
-            // Wait for all workers to be done.
-            for handle in handles {
-                handle.join().unwrap()?;
-            }
-            // If all workers succeeded, we can't have failed.
-            assert!(!failed.load(Ordering::Relaxed));
-            Ok(())
-        })
-    }
 }
diff --git a/src/tools/miri/src/alloc_addresses/mod.rs b/src/tools/miri/src/alloc_addresses/mod.rs
index f7295fd7d8a5e..3d0fc5590eb81 100644
--- a/src/tools/miri/src/alloc_addresses/mod.rs
+++ b/src/tools/miri/src/alloc_addresses/mod.rs
@@ -9,7 +9,6 @@ use std::cmp::max;
 use rand::Rng;
 use rustc_abi::{Align, Size};
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
-use rustc_span::Span;
 
 use self::reuse_pool::ReusePool;
 use crate::concurrency::VClock;
@@ -319,17 +318,12 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         match global_state.provenance_mode {
             ProvenanceMode::Default => {
                 // The first time this happens at a particular location, print a warning.
-                thread_local! {
-                    // `Span` is non-`Send`, so we use a thread-local instead.
-                    static PAST_WARNINGS: RefCell<FxHashSet<Span>> = RefCell::default();
+                let mut int2ptr_warned = this.machine.int2ptr_warned.borrow_mut();
+                let first = int2ptr_warned.is_empty();
+                if int2ptr_warned.insert(this.cur_span()) {
+                    // Newly inserted, so first time we see this span.
+                    this.emit_diagnostic(NonHaltingDiagnostic::Int2Ptr { details: first });
                 }
-                PAST_WARNINGS.with_borrow_mut(|past_warnings| {
-                    let first = past_warnings.is_empty();
-                    if past_warnings.insert(this.cur_span()) {
-                        // Newly inserted, so first time we see this span.
-                        this.emit_diagnostic(NonHaltingDiagnostic::Int2Ptr { details: first });
-                    }
-                });
             }
             ProvenanceMode::Strict => {
                 throw_machine_stop!(TerminationInfo::Int2PtrWithStrictProvenance);
diff --git a/src/tools/miri/src/bin/miri.rs b/src/tools/miri/src/bin/miri.rs
index 5248c9d186b46..8832016d0fa15 100644
--- a/src/tools/miri/src/bin/miri.rs
+++ b/src/tools/miri/src/bin/miri.rs
@@ -26,11 +26,17 @@ extern crate rustc_span;
 
 use std::env::{self, VarError};
 use std::num::NonZero;
+use std::ops::Range;
 use std::path::PathBuf;
 use std::str::FromStr;
+use std::sync::atomic::{AtomicI32, Ordering};
+use std::sync::{Arc, Once};
 
-use miri::{BacktraceStyle, BorrowTrackerMethod, ProvenanceMode, RetagFields, ValidationMode};
+use miri::{
+    BacktraceStyle, BorrowTrackerMethod, MiriConfig, ProvenanceMode, RetagFields, ValidationMode,
+};
 use rustc_abi::ExternAbi;
+use rustc_data_structures::sync;
 use rustc_data_structures::sync::Lrc;
 use rustc_driver::Compilation;
 use rustc_hir::def_id::LOCAL_CRATE;
@@ -52,7 +58,69 @@ use rustc_span::def_id::DefId;
 use tracing::debug;
 
 struct MiriCompilerCalls {
-    miri_config: miri::MiriConfig,
+    miri_config: Option<MiriConfig>,
+    many_seeds: Option<ManySeedsConfig>,
+}
+
+struct ManySeedsConfig {
+    seeds: Range<u32>,
+    keep_going: bool,
+}
+
+impl MiriCompilerCalls {
+    fn new(miri_config: MiriConfig, many_seeds: Option<ManySeedsConfig>) -> Self {
+        Self { miri_config: Some(miri_config), many_seeds }
+    }
+}
+
+fn entry_fn(tcx: TyCtxt<'_>) -> (DefId, EntryFnType) {
+    if let Some(entry_def) = tcx.entry_fn(()) {
+        return entry_def;
+    }
+    // Look for a symbol in the local crate named `miri_start`, and treat that as the entry point.
+    let sym = tcx.exported_symbols(LOCAL_CRATE).iter().find_map(|(sym, _)| {
+        if sym.symbol_name_for_local_instance(tcx).name == "miri_start" { Some(sym) } else { None }
+    });
+    if let Some(ExportedSymbol::NonGeneric(id)) = sym {
+        let start_def_id = id.expect_local();
+        let start_span = tcx.def_span(start_def_id);
+
+        let expected_sig = ty::Binder::dummy(tcx.mk_fn_sig(
+            [tcx.types.isize, Ty::new_imm_ptr(tcx, Ty::new_imm_ptr(tcx, tcx.types.u8))],
+            tcx.types.isize,
+            false,
+            hir::Safety::Safe,
+            ExternAbi::Rust,
+        ));
+
+        let correct_func_sig = check_function_signature(
+            tcx,
+            ObligationCause::new(start_span, start_def_id, ObligationCauseCode::Misc),
+            *id,
+            expected_sig,
+        )
+        .is_ok();
+
+        if correct_func_sig {
+            (*id, EntryFnType::Start)
+        } else {
+            tcx.dcx().fatal(
+                "`miri_start` must have the following signature:\n\
+                        fn miri_start(argc: isize, argv: *const *const u8) -> isize",
+            );
+        }
+    } else {
+        tcx.dcx().fatal(
+            "Miri can only run programs that have a main function.\n\
+            Alternatively, you can export a `miri_start` function:\n\
+            \n\
+            #[cfg(miri)]\n\
+            #[no_mangle]\n\
+            fn miri_start(argc: isize, argv: *const *const u8) -> isize {\
+            \n    // Call the actual start function that your project implements, based on your target's conventions.\n\
+            }"
+        );
+    }
 }
 
 impl rustc_driver::Callbacks for MiriCompilerCalls {
@@ -87,7 +155,7 @@ impl rustc_driver::Callbacks for MiriCompilerCalls {
         }
 
         let (entry_def_id, entry_type) = entry_fn(tcx);
-        let mut config = self.miri_config.clone();
+        let mut config = self.miri_config.take().expect("after_analysis must only be called once");
 
         // Add filename to `miri` arguments.
         config.args.insert(0, tcx.sess.io.input.filestem().to_string());
@@ -111,12 +179,36 @@ impl rustc_driver::Callbacks for MiriCompilerCalls {
                     optimizations is usually marginal at best.");
         }
 
-        if let Some(return_code) = miri::eval_entry(tcx, entry_def_id, entry_type, config) {
-            std::process::exit(i32::try_from(return_code).expect("Return value was too large!"));
+        if let Some(many_seeds) = self.many_seeds.take() {
+            assert!(config.seed.is_none());
+            let exit_code = sync::IntoDynSyncSend(AtomicI32::new(rustc_driver::EXIT_SUCCESS));
+            sync::par_for_each_in(many_seeds.seeds, |seed| {
+                let mut config = config.clone();
+                config.seed = Some(seed.into());
+                eprintln!("Trying seed: {seed}");
+                let return_code = miri::eval_entry(tcx, entry_def_id, entry_type, config)
+                    .unwrap_or(rustc_driver::EXIT_FAILURE);
+                if return_code != rustc_driver::EXIT_SUCCESS {
+                    eprintln!("FAILING SEED: {seed}");
+                    if !many_seeds.keep_going {
+                        // `abort_if_errors` would actually not stop, since `par_for_each` waits for the
+                        // rest of the to finish, so we just exit immediately.
+                        std::process::exit(return_code);
+                    }
+                    exit_code.store(return_code, Ordering::Relaxed);
+                }
+            });
+            std::process::exit(exit_code.0.into_inner());
+        } else {
+            let return_code = miri::eval_entry(tcx, entry_def_id, entry_type, config)
+                .unwrap_or_else(|| {
+                    tcx.dcx().abort_if_errors();
+                    rustc_driver::EXIT_FAILURE
+                });
+            std::process::exit(return_code);
         }
-        tcx.dcx().abort_if_errors();
 
-        Compilation::Stop
+        // Unreachable.
     }
 }
 
@@ -241,21 +333,26 @@ fn rustc_logger_config() -> rustc_log::LoggerConfig {
     cfg
 }
 
+/// The global logger can only be set once per process, so track
+/// whether that already happened.
+static LOGGER_INITED: Once = Once::new();
+
 fn init_early_loggers(early_dcx: &EarlyDiagCtxt) {
-    // Now for rustc. We only initialize `rustc` if the env var is set (so the user asked for it).
+    // We only initialize `rustc` if the env var is set (so the user asked for it).
     // If it is not set, we avoid initializing now so that we can initialize later with our custom
-    // settings, and *not* log anything for what happens before `miri` gets started.
+    // settings, and *not* log anything for what happens before `miri` starts interpreting.
     if env::var_os("RUSTC_LOG").is_some() {
-        rustc_driver::init_logger(early_dcx, rustc_logger_config());
+        LOGGER_INITED.call_once(|| {
+            rustc_driver::init_logger(early_dcx, rustc_logger_config());
+        });
     }
 }
 
 fn init_late_loggers(early_dcx: &EarlyDiagCtxt, tcx: TyCtxt<'_>) {
-    // If `RUSTC_LOG` is not set, then `init_early_loggers` did not call
-    // `rustc_driver::init_logger`, so we have to do this now.
-    if env::var_os("RUSTC_LOG").is_none() {
+    // If the logger is not yet initialized, initialize it.
+    LOGGER_INITED.call_once(|| {
         rustc_driver::init_logger(early_dcx, rustc_logger_config());
-    }
+    });
 
     // If `MIRI_BACKTRACE` is set and `RUSTC_CTFE_BACKTRACE` is not, set `RUSTC_CTFE_BACKTRACE`.
     // Do this late, so we ideally only apply this to Miri's errors.
@@ -270,25 +367,14 @@ fn init_late_loggers(early_dcx: &EarlyDiagCtxt, tcx: TyCtxt<'_>) {
 }
 
 /// Execute a compiler with the given CLI arguments and callbacks.
-fn run_compiler(
-    mut args: Vec<String>,
-    target_crate: bool,
+fn run_compiler_and_exit(
+    args: &[String],
     callbacks: &mut (dyn rustc_driver::Callbacks + Send),
-    using_internal_features: std::sync::Arc<std::sync::atomic::AtomicBool>,
+    using_internal_features: Arc<std::sync::atomic::AtomicBool>,
 ) -> ! {
-    // Don't insert `MIRI_DEFAULT_ARGS`, in particular, `--cfg=miri`, if we are building
-    // a "host" crate. That may cause procedural macros (and probably build scripts) to
-    // depend on Miri-only symbols, such as `miri_resolve_frame`:
-    // https://github.com/rust-lang/miri/issues/1760
-    if target_crate {
-        // Some options have different defaults in Miri than in plain rustc; apply those by making
-        // them the first arguments after the binary name (but later arguments can overwrite them).
-        args.splice(1..1, miri::MIRI_DEFAULT_ARGS.iter().map(ToString::to_string));
-    }
-
     // Invoke compiler, and handle return code.
     let exit_code = rustc_driver::catch_with_exit_code(move || {
-        rustc_driver::RunCompiler::new(&args, callbacks)
+        rustc_driver::RunCompiler::new(args, callbacks)
             .set_using_internal_features(using_internal_features)
             .run();
         Ok(())
@@ -311,6 +397,18 @@ fn parse_rate(input: &str) -> Result<f64, &'static str> {
     }
 }
 
+/// Parses a seed range
+///
+/// This function is used for the `-Zmiri-many-seeds` flag. It expects the range in the form
+/// `<from>..<to>`. `<from>` is inclusive, `<to>` is exclusive. `<from>` can be omitted,
+/// in which case it is assumed to be `0`.
+fn parse_range(val: &str) -> Result<Range<u32>, &'static str> {
+    let (from, to) = val.split_once("..").ok_or("expected `from..to`")?;
+    let from: u32 = if from.is_empty() { 0 } else { from.parse().map_err(|_| "invalid `from`")? };
+    let to: u32 = to.parse().map_err(|_| "invalid `to`")?;
+    Ok(from..to)
+}
+
 #[cfg(any(target_os = "linux", target_os = "macos"))]
 fn jemalloc_magic() {
     // These magic runes are copied from
@@ -349,56 +447,6 @@ fn jemalloc_magic() {
     }
 }
 
-fn entry_fn(tcx: TyCtxt<'_>) -> (DefId, EntryFnType) {
-    if let Some(entry_def) = tcx.entry_fn(()) {
-        return entry_def;
-    }
-    // Look for a symbol in the local crate named `miri_start`, and treat that as the entry point.
-    let sym = tcx.exported_symbols(LOCAL_CRATE).iter().find_map(|(sym, _)| {
-        if sym.symbol_name_for_local_instance(tcx).name == "miri_start" { Some(sym) } else { None }
-    });
-    if let Some(ExportedSymbol::NonGeneric(id)) = sym {
-        let start_def_id = id.expect_local();
-        let start_span = tcx.def_span(start_def_id);
-
-        let expected_sig = ty::Binder::dummy(tcx.mk_fn_sig(
-            [tcx.types.isize, Ty::new_imm_ptr(tcx, Ty::new_imm_ptr(tcx, tcx.types.u8))],
-            tcx.types.isize,
-            false,
-            hir::Safety::Safe,
-            ExternAbi::Rust,
-        ));
-
-        let correct_func_sig = check_function_signature(
-            tcx,
-            ObligationCause::new(start_span, start_def_id, ObligationCauseCode::Misc),
-            *id,
-            expected_sig,
-        )
-        .is_ok();
-
-        if correct_func_sig {
-            (*id, EntryFnType::Start)
-        } else {
-            tcx.dcx().fatal(
-                "`miri_start` must have the following signature:\n\
-                        fn miri_start(argc: isize, argv: *const *const u8) -> isize",
-            );
-        }
-    } else {
-        tcx.dcx().fatal(
-            "Miri can only run programs that have a main function.\n\
-            Alternatively, you can export a `miri_start` function:\n\
-            \n\
-            #[cfg(miri)]\n\
-            #[no_mangle]\n\
-            fn miri_start(argc: isize, argv: *const *const u8) -> isize {\
-            \n    // Call the actual start function that your project implements, based on your target's conventions.\n\
-            }"
-        );
-    }
-}
-
 fn main() {
     #[cfg(any(target_os = "linux", target_os = "macos"))]
     jemalloc_magic();
@@ -431,10 +479,21 @@ fn main() {
             panic!("invalid `MIRI_BE_RUSTC` value: {crate_kind:?}")
         };
 
-        // We cannot use `rustc_driver::main` as we need to adjust the CLI arguments.
-        run_compiler(
-            args,
-            target_crate,
+        let mut args = args;
+        // Don't insert `MIRI_DEFAULT_ARGS`, in particular, `--cfg=miri`, if we are building
+        // a "host" crate. That may cause procedural macros (and probably build scripts) to
+        // depend on Miri-only symbols, such as `miri_resolve_frame`:
+        // https://github.com/rust-lang/miri/issues/1760
+        if target_crate {
+            // Splice in the default arguments after the program name.
+            // Some options have different defaults in Miri than in plain rustc; apply those by making
+            // them the first arguments after the binary name (but later arguments can overwrite them).
+            args.splice(1..1, miri::MIRI_DEFAULT_ARGS.iter().map(ToString::to_string));
+        }
+
+        // We cannot use `rustc_driver::main` as we want it to use `args` as the CLI arguments.
+        run_compiler_and_exit(
+            &args,
             &mut MiriBeRustCompilerCalls { target_crate },
             using_internal_features,
         )
@@ -448,13 +507,13 @@ fn main() {
     init_early_loggers(&early_dcx);
 
     // Parse our arguments and split them across `rustc` and `miri`.
-    let mut miri_config = miri::MiriConfig::default();
+    let mut many_seeds: Option<Range<u32>> = None;
+    let mut many_seeds_keep_going = false;
+    let mut miri_config = MiriConfig::default();
     miri_config.env = env_snapshot;
 
     let mut rustc_args = vec![];
     let mut after_dashdash = false;
-    // If user has explicitly enabled/disabled isolation
-    let mut isolation_enabled: Option<bool> = None;
 
     // Note that we require values to be given with `=`, not with a space.
     // This matches how rustc parses `-Z`.
@@ -463,6 +522,8 @@ fn main() {
         if rustc_args.is_empty() {
             // Very first arg: binary name.
             rustc_args.push(arg);
+            // Also add the default arguments.
+            rustc_args.extend(miri::MIRI_DEFAULT_ARGS.iter().map(ToString::to_string));
         } else if after_dashdash {
             // Everything that comes after `--` is forwarded to the interpreted crate.
             miri_config.args.push(arg);
@@ -476,6 +537,7 @@ fn main() {
             miri_config.borrow_tracker = None;
         } else if arg == "-Zmiri-tree-borrows" {
             miri_config.borrow_tracker = Some(BorrowTrackerMethod::TreeBorrows);
+            miri_config.provenance_mode = ProvenanceMode::Strict;
         } else if arg == "-Zmiri-unique-is-unique" {
             miri_config.unique_is_unique = true;
         } else if arg == "-Zmiri-disable-data-race-detector" {
@@ -485,19 +547,7 @@ fn main() {
             miri_config.check_alignment = miri::AlignmentCheck::None;
         } else if arg == "-Zmiri-symbolic-alignment-check" {
             miri_config.check_alignment = miri::AlignmentCheck::Symbolic;
-        } else if arg == "-Zmiri-disable-abi-check" {
-            eprintln!(
-                "WARNING: the flag `-Zmiri-disable-abi-check` no longer has any effect; \
-                    ABI checks cannot be disabled any more"
-            );
         } else if arg == "-Zmiri-disable-isolation" {
-            if matches!(isolation_enabled, Some(true)) {
-                show_error!(
-                    "-Zmiri-disable-isolation cannot be used along with -Zmiri-isolation-error"
-                );
-            } else {
-                isolation_enabled = Some(false);
-            }
             miri_config.isolated_op = miri::IsolatedOp::Allow;
         } else if arg == "-Zmiri-disable-leak-backtraces" {
             miri_config.collect_leak_backtraces = false;
@@ -506,14 +556,6 @@ fn main() {
         } else if arg == "-Zmiri-track-weak-memory-loads" {
             miri_config.track_outdated_loads = true;
         } else if let Some(param) = arg.strip_prefix("-Zmiri-isolation-error=") {
-            if matches!(isolation_enabled, Some(false)) {
-                show_error!(
-                    "-Zmiri-isolation-error cannot be used along with -Zmiri-disable-isolation"
-                );
-            } else {
-                isolation_enabled = Some(true);
-            }
-
             miri_config.isolated_op = match param {
                 "abort" => miri::IsolatedOp::Reject(miri::RejectOpWith::Abort),
                 "hide" => miri::IsolatedOp::Reject(miri::RejectOpWith::NoWarning),
@@ -544,17 +586,21 @@ fn main() {
                 _ => show_error!("`-Zmiri-retag-fields` can only be `all`, `none`, or `scalar`"),
             };
         } else if let Some(param) = arg.strip_prefix("-Zmiri-seed=") {
-            if miri_config.seed.is_some() {
-                show_error!("Cannot specify -Zmiri-seed multiple times!");
-            }
             let seed = param.parse::<u64>().unwrap_or_else(|_| {
                 show_error!("-Zmiri-seed must be an integer that fits into u64")
             });
             miri_config.seed = Some(seed);
-        } else if let Some(_param) = arg.strip_prefix("-Zmiri-env-exclude=") {
-            show_error!(
-                "`-Zmiri-env-exclude` has been removed; unset env vars before starting Miri instead"
-            );
+        } else if let Some(param) = arg.strip_prefix("-Zmiri-many-seeds=") {
+            let range = parse_range(param).unwrap_or_else(|err| {
+                show_error!(
+                    "-Zmiri-many-seeds requires a range in the form `from..to` or `..to`: {err}"
+                )
+            });
+            many_seeds = Some(range);
+        } else if arg == "-Zmiri-many-seeds" {
+            many_seeds = Some(0..64);
+        } else if arg == "-Zmiri-many-seeds-keep-going" {
+            many_seeds_keep_going = true;
         } else if let Some(param) = arg.strip_prefix("-Zmiri-env-forward=") {
             miri_config.forwarded_env_vars.push(param.to_owned());
         } else if let Some(param) = arg.strip_prefix("-Zmiri-env-set=") {
@@ -657,21 +703,41 @@ fn main() {
             "-Zmiri-unique-is-unique only has an effect when -Zmiri-tree-borrows is also used"
         );
     }
-    // Tree Borrows + permissive provenance does not work.
-    if miri_config.provenance_mode == ProvenanceMode::Permissive
-        && matches!(miri_config.borrow_tracker, Some(BorrowTrackerMethod::TreeBorrows))
-    {
-        show_error!(
-            "Tree Borrows does not support integer-to-pointer casts, and is hence not compatible with permissive provenance"
-        );
+    // Tree Borrows implies strict provenance, and is not compatible with native calls.
+    if matches!(miri_config.borrow_tracker, Some(BorrowTrackerMethod::TreeBorrows)) {
+        if miri_config.provenance_mode != ProvenanceMode::Strict {
+            show_error!(
+                "Tree Borrows does not support integer-to-pointer casts, and hence requires strict provenance"
+            );
+        }
+        if miri_config.native_lib.is_some() {
+            show_error!("Tree Borrows is not compatible with calling native functions");
+        }
+    }
+    // Native calls and strict provenance are not compatible.
+    if miri_config.native_lib.is_some() && miri_config.provenance_mode == ProvenanceMode::Strict {
+        show_error!("strict provenance is not compatible with calling native functions");
+    }
+    // You can set either one seed or many.
+    if many_seeds.is_some() && miri_config.seed.is_some() {
+        show_error!("Only one of `-Zmiri-seed` and `-Zmiri-many-seeds can be set");
+    }
+
+    // Ensure we have parallelism for many-seeds mode.
+    if many_seeds.is_some() && !rustc_args.iter().any(|arg| arg.starts_with("-Zthreads=")) {
+        rustc_args.push(format!(
+            "-Zthreads={}",
+            std::thread::available_parallelism().map_or(1, |n| n.get())
+        ));
     }
+    let many_seeds =
+        many_seeds.map(|seeds| ManySeedsConfig { seeds, keep_going: many_seeds_keep_going });
 
     debug!("rustc arguments: {:?}", rustc_args);
     debug!("crate arguments: {:?}", miri_config.args);
-    run_compiler(
-        rustc_args,
-        /* target_crate: */ true,
-        &mut MiriCompilerCalls { miri_config },
+    run_compiler_and_exit(
+        &rustc_args,
+        &mut MiriCompilerCalls::new(miri_config, many_seeds),
         using_internal_features,
     )
 }
diff --git a/src/tools/miri/src/borrow_tracker/stacked_borrows/mod.rs b/src/tools/miri/src/borrow_tracker/stacked_borrows/mod.rs
index ea75131078ee7..bcc8668dbc122 100644
--- a/src/tools/miri/src/borrow_tracker/stacked_borrows/mod.rs
+++ b/src/tools/miri/src/borrow_tracker/stacked_borrows/mod.rs
@@ -5,7 +5,6 @@ pub mod diagnostics;
 mod item;
 mod stack;
 
-use std::cell::RefCell;
 use std::fmt::Write;
 use std::{cmp, mem};
 
@@ -822,16 +821,9 @@ trait EvalContextPrivExt<'tcx, 'ecx>: crate::MiriInterpCxExt<'tcx> {
         let size = match size {
             Some(size) => size,
             None => {
-                // The first time this happens, show a warning.
-                thread_local! { static WARNING_SHOWN: RefCell<bool> = const { RefCell::new(false) }; }
-                WARNING_SHOWN.with_borrow_mut(|shown| {
-                    if *shown {
-                        return;
-                    }
-                    // Not yet shown. Show it!
-                    *shown = true;
+                if !this.machine.sb_extern_type_warned.replace(true) {
                     this.emit_diagnostic(NonHaltingDiagnostic::ExternTypeReborrow);
-                });
+                }
                 return interp_ok(place.clone());
             }
         };
diff --git a/src/tools/miri/src/diagnostics.rs b/src/tools/miri/src/diagnostics.rs
index 6b5646d5473fc..1a12d4139c719 100644
--- a/src/tools/miri/src/diagnostics.rs
+++ b/src/tools/miri/src/diagnostics.rs
@@ -12,7 +12,7 @@ use crate::*;
 /// Details of premature program termination.
 pub enum TerminationInfo {
     Exit {
-        code: i64,
+        code: i32,
         leak_check: bool,
     },
     Abort(String),
@@ -214,7 +214,7 @@ pub fn prune_stacktrace<'tcx>(
 pub fn report_error<'tcx>(
     ecx: &InterpCx<'tcx, MiriMachine<'tcx>>,
     e: InterpErrorInfo<'tcx>,
-) -> Option<(i64, bool)> {
+) -> Option<(i32, bool)> {
     use InterpErrorKind::*;
     use UndefinedBehaviorInfo::*;
 
diff --git a/src/tools/miri/src/eval.rs b/src/tools/miri/src/eval.rs
index 1df1d08802a82..eaf4b30c66069 100644
--- a/src/tools/miri/src/eval.rs
+++ b/src/tools/miri/src/eval.rs
@@ -249,6 +249,13 @@ impl<'tcx> MainThreadState<'tcx> {
                 // Figure out exit code.
                 let ret_place = this.machine.main_fn_ret_place.clone().unwrap();
                 let exit_code = this.read_target_isize(&ret_place)?;
+                // Rust uses `isize` but the underlying type of an exit code is `i32`.
+                // Do a saturating cast.
+                let exit_code = i32::try_from(exit_code).unwrap_or(if exit_code >= 0 {
+                    i32::MAX
+                } else {
+                    i32::MIN
+                });
                 // Deal with our thread-local memory. We do *not* want to actually free it, instead we consider TLS
                 // to be like a global `static`, so that all memory reached by it is considered to "not leak".
                 this.terminate_active_thread(TlsAllocAction::Leak)?;
@@ -421,7 +428,7 @@ pub fn create_ecx<'tcx>(
 }
 
 /// Evaluates the entry function specified by `entry_id`.
-/// Returns `Some(return_code)` if program executed completed.
+/// Returns `Some(return_code)` if program execution completed.
 /// Returns `None` if an evaluation error occurred.
 #[expect(clippy::needless_lifetimes)]
 pub fn eval_entry<'tcx>(
@@ -429,7 +436,7 @@ pub fn eval_entry<'tcx>(
     entry_id: DefId,
     entry_type: EntryFnType,
     config: MiriConfig,
-) -> Option<i64> {
+) -> Option<i32> {
     // Copy setting before we move `config`.
     let ignore_leaks = config.ignore_leaks;
 
diff --git a/src/tools/miri/src/helpers.rs b/src/tools/miri/src/helpers.rs
index bd4a773e23e10..adfec33beac60 100644
--- a/src/tools/miri/src/helpers.rs
+++ b/src/tools/miri/src/helpers.rs
@@ -1,6 +1,4 @@
-use std::collections::BTreeSet;
 use std::num::NonZero;
-use std::sync::Mutex;
 use std::time::Duration;
 use std::{cmp, iter};
 
@@ -332,19 +330,10 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         base: &P,
         name: &str,
     ) -> InterpResult<'tcx, P> {
-        if let Some(field) = self.try_project_field_named(base, name)? {
-            return interp_ok(field);
-        }
-        bug!("No field named {} in type {}", name, base.layout().ty);
-    }
-
-    /// Search if `base` (which must be a struct or union type) contains the `name` field.
-    fn projectable_has_field<P: Projectable<'tcx, Provenance>>(
-        &self,
-        base: &P,
-        name: &str,
-    ) -> bool {
-        self.try_project_field_named(base, name).unwrap().is_some()
+        interp_ok(
+            self.try_project_field_named(base, name)?
+                .unwrap_or_else(|| bug!("no field named {} in type {}", name, base.layout().ty)),
+        )
     }
 
     /// Write an int of the appropriate size to `dest`. The target type may be signed or unsigned,
@@ -650,11 +639,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         match reject_with {
             RejectOpWith::Abort => isolation_abort_error(op_name),
             RejectOpWith::WarningWithoutBacktrace => {
-                // This exists to reduce verbosity; make sure we emit the warning at most once per
-                // operation.
-                static EMITTED_WARNINGS: Mutex<BTreeSet<String>> = Mutex::new(BTreeSet::new());
-
-                let mut emitted_warnings = EMITTED_WARNINGS.lock().unwrap();
+                let mut emitted_warnings = this.machine.reject_in_isolation_warned.borrow_mut();
                 if !emitted_warnings.contains(op_name) {
                     // First time we are seeing this.
                     emitted_warnings.insert(op_name.to_owned());
@@ -662,6 +647,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                         .dcx()
                         .warn(format!("{op_name} was made to return an error due to isolation"));
                 }
+
                 interp_ok(())
             }
             RejectOpWith::Warning => {
diff --git a/src/tools/miri/src/machine.rs b/src/tools/miri/src/machine.rs
index 33cefd607646a..5e8f616a37ea0 100644
--- a/src/tools/miri/src/machine.rs
+++ b/src/tools/miri/src/machine.rs
@@ -3,7 +3,7 @@
 
 use std::any::Any;
 use std::borrow::Cow;
-use std::cell::RefCell;
+use std::cell::{Cell, RefCell};
 use std::collections::hash_map::Entry;
 use std::path::Path;
 use std::{fmt, process};
@@ -595,6 +595,21 @@ pub struct MiriMachine<'tcx> {
 
     /// A cache of "data range" computations for unions (i.e., the offsets of non-padding bytes).
     union_data_ranges: FxHashMap<Ty<'tcx>, RangeSet>,
+
+    /// Caches the sanity-checks for various pthread primitives.
+    pub(crate) pthread_mutex_sanity: Cell<bool>,
+    pub(crate) pthread_rwlock_sanity: Cell<bool>,
+    pub(crate) pthread_condvar_sanity: Cell<bool>,
+
+    /// Remembers whether we already warned about an extern type with Stacked Borrows.
+    pub(crate) sb_extern_type_warned: Cell<bool>,
+    /// Remember whether we already warned about sharing memory with a native call.
+    #[cfg(unix)]
+    pub(crate) native_call_mem_warned: Cell<bool>,
+    /// Remembers which shims have already shown the warning about erroring in isolation.
+    pub(crate) reject_in_isolation_warned: RefCell<FxHashSet<String>>,
+    /// Remembers which int2ptr casts we have already warned about.
+    pub(crate) int2ptr_warned: RefCell<FxHashSet<Span>>,
 }
 
 impl<'tcx> MiriMachine<'tcx> {
@@ -732,6 +747,14 @@ impl<'tcx> MiriMachine<'tcx> {
             const_cache: RefCell::new(FxHashMap::default()),
             symbolic_alignment: RefCell::new(FxHashMap::default()),
             union_data_ranges: FxHashMap::default(),
+            pthread_mutex_sanity: Cell::new(false),
+            pthread_rwlock_sanity: Cell::new(false),
+            pthread_condvar_sanity: Cell::new(false),
+            sb_extern_type_warned: Cell::new(false),
+            #[cfg(unix)]
+            native_call_mem_warned: Cell::new(false),
+            reject_in_isolation_warned: Default::default(),
+            int2ptr_warned: Default::default(),
         }
     }
 
@@ -844,6 +867,14 @@ impl VisitProvenance for MiriMachine<'_> {
             const_cache: _,
             symbolic_alignment: _,
             union_data_ranges: _,
+            pthread_mutex_sanity: _,
+            pthread_rwlock_sanity: _,
+            pthread_condvar_sanity: _,
+            sb_extern_type_warned: _,
+            #[cfg(unix)]
+            native_call_mem_warned: _,
+            reject_in_isolation_warned: _,
+            int2ptr_warned: _,
         } = self;
 
         threads.visit_provenance(visit);
diff --git a/src/tools/miri/src/shims/foreign_items.rs b/src/tools/miri/src/shims/foreign_items.rs
index 8c8850ba7e0a8..6c8ccc8398590 100644
--- a/src/tools/miri/src/shims/foreign_items.rs
+++ b/src/tools/miri/src/shims/foreign_items.rs
@@ -428,7 +428,7 @@ trait EvalContextExtPriv<'tcx>: crate::MiriInterpCxExt<'tcx> {
             "exit" => {
                 let [code] = this.check_shim(abi, Conv::C, link_name, args)?;
                 let code = this.read_scalar(code)?.to_i32()?;
-                throw_machine_stop!(TerminationInfo::Exit { code: code.into(), leak_check: false });
+                throw_machine_stop!(TerminationInfo::Exit { code, leak_check: false });
             }
             "abort" => {
                 let [] = this.check_shim(abi, Conv::C, link_name, args)?;
diff --git a/src/tools/miri/src/shims/native_lib.rs b/src/tools/miri/src/shims/native_lib.rs
index 345ca3fbcc197..87be5a521d13f 100644
--- a/src/tools/miri/src/shims/native_lib.rs
+++ b/src/tools/miri/src/shims/native_lib.rs
@@ -1,5 +1,4 @@
 //! Implements calling functions from a native library.
-use std::cell::RefCell;
 use std::ops::Deref;
 
 use libffi::high::call as ffi;
@@ -173,17 +172,11 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                     // Wildcard pointer, whatever it points to must be already exposed.
                     continue;
                 };
-                // The first time this happens at a particular location, print a warning.
-                thread_local! {
-                    static HAVE_WARNED: RefCell<bool> = const { RefCell::new(false) };
+                // The first time this happens, print a warning.
+                if !this.machine.native_call_mem_warned.replace(true) {
+                    // Newly set, so first time we get here.
+                    this.emit_diagnostic(NonHaltingDiagnostic::NativeCallSharedMem);
                 }
-                HAVE_WARNED.with_borrow_mut(|have_warned| {
-                    if !*have_warned {
-                        // Newly inserted, so first time we see this span.
-                        this.emit_diagnostic(NonHaltingDiagnostic::NativeCallSharedMem);
-                        *have_warned = true;
-                    }
-                });
 
                 this.prepare_for_native_call(alloc_id, prov)?;
             }
diff --git a/src/tools/miri/src/shims/unix/sync.rs b/src/tools/miri/src/shims/unix/sync.rs
index 416cf020dcc99..5b0a9398b4b6a 100644
--- a/src/tools/miri/src/shims/unix/sync.rs
+++ b/src/tools/miri/src/shims/unix/sync.rs
@@ -1,5 +1,3 @@
-use std::sync::atomic::{AtomicBool, Ordering};
-
 use rustc_abi::Size;
 
 use crate::concurrency::sync::LAZY_INIT_COOKIE;
@@ -136,8 +134,7 @@ fn mutex_init_offset<'tcx>(ecx: &MiriInterpCx<'tcx>) -> InterpResult<'tcx, Size>
 
     // Sanity-check this against PTHREAD_MUTEX_INITIALIZER (but only once):
     // the `init` field must start out not equal to INIT_COOKIE.
-    static SANITY: AtomicBool = AtomicBool::new(false);
-    if !SANITY.swap(true, Ordering::Relaxed) {
+    if !ecx.machine.pthread_mutex_sanity.replace(true) {
         let check_static_initializer = |name| {
             let static_initializer = ecx.eval_path(&["libc", name]);
             let init_field =
@@ -248,8 +245,7 @@ fn rwlock_init_offset<'tcx>(ecx: &MiriInterpCx<'tcx>) -> InterpResult<'tcx, Size
 
     // Sanity-check this against PTHREAD_RWLOCK_INITIALIZER (but only once):
     // the `init` field must start out not equal to LAZY_INIT_COOKIE.
-    static SANITY: AtomicBool = AtomicBool::new(false);
-    if !SANITY.swap(true, Ordering::Relaxed) {
+    if !ecx.machine.pthread_rwlock_sanity.replace(true) {
         let static_initializer = ecx.eval_path(&["libc", "PTHREAD_RWLOCK_INITIALIZER"]);
         let init_field = static_initializer.offset(offset, ecx.machine.layouts.u32, ecx).unwrap();
         let init = ecx.read_scalar(&init_field).unwrap().to_u32().unwrap();
@@ -357,8 +353,7 @@ fn cond_init_offset<'tcx>(ecx: &MiriInterpCx<'tcx>) -> InterpResult<'tcx, Size>
 
     // Sanity-check this against PTHREAD_COND_INITIALIZER (but only once):
     // the `init` field must start out not equal to LAZY_INIT_COOKIE.
-    static SANITY: AtomicBool = AtomicBool::new(false);
-    if !SANITY.swap(true, Ordering::Relaxed) {
+    if !ecx.machine.pthread_condvar_sanity.replace(true) {
         let static_initializer = ecx.eval_path(&["libc", "PTHREAD_COND_INITIALIZER"]);
         let init_field = static_initializer.offset(offset, ecx.machine.layouts.u32, ecx).unwrap();
         let init = ecx.read_scalar(&init_field).unwrap().to_u32().unwrap();
diff --git a/src/tools/miri/src/shims/windows/foreign_items.rs b/src/tools/miri/src/shims/windows/foreign_items.rs
index fe4d2158ff956..0bf56c3d005fd 100644
--- a/src/tools/miri/src/shims/windows/foreign_items.rs
+++ b/src/tools/miri/src/shims/windows/foreign_items.rs
@@ -552,8 +552,9 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
             // Miscellaneous
             "ExitProcess" => {
                 let [code] = this.check_shim(abi, sys_conv, link_name, args)?;
-                let code = this.read_scalar(code)?.to_u32()?;
-                throw_machine_stop!(TerminationInfo::Exit { code: code.into(), leak_check: false });
+                // Windows technically uses u32, but we unify everything to a Unix-style i32.
+                let code = this.read_scalar(code)?.to_i32()?;
+                throw_machine_stop!(TerminationInfo::Exit { code, leak_check: false });
             }
             "SystemFunction036" => {
                 // used by getrandom 0.1
diff --git a/src/tools/miri/tests/pass/0weak_memory_consistency.rs b/src/tools/miri/tests/pass/0weak_memory_consistency.rs
index ce5b8be07f0c9..b33aefaf1d599 100644
--- a/src/tools/miri/tests/pass/0weak_memory_consistency.rs
+++ b/src/tools/miri/tests/pass/0weak_memory_consistency.rs
@@ -40,7 +40,7 @@ fn static_atomic_bool(val: bool) -> &'static AtomicBool {
     Box::leak(Box::new(AtomicBool::new(val)))
 }
 
-// Spins until it acquires a pre-determined value.
+/// Spins until it acquires a pre-determined value.
 fn loads_value(loc: &AtomicI32, ord: Ordering, val: i32) -> i32 {
     while loc.load(ord) != val {
         std::hint::spin_loop();
@@ -186,31 +186,6 @@ fn test_mixed_access() {
     assert_eq!(r2, 2);
 }
 
-// The following two tests are taken from Repairing Sequential Consistency in C/C++11
-// by Lahav et al.
-// https://plv.mpi-sws.org/scfix/paper.pdf
-
-// Test case SB
-fn test_sc_store_buffering() {
-    let x = static_atomic(0);
-    let y = static_atomic(0);
-
-    let j1 = spawn(move || {
-        x.store(1, SeqCst);
-        y.load(SeqCst)
-    });
-
-    let j2 = spawn(move || {
-        y.store(1, SeqCst);
-        x.load(SeqCst)
-    });
-
-    let a = j1.join().unwrap();
-    let b = j2.join().unwrap();
-
-    assert_ne!((a, b), (0, 0));
-}
-
 fn test_single_thread() {
     let x = AtomicI32::new(42);
 
@@ -257,178 +232,6 @@ fn test_sync_through_rmw_and_fences() {
     assert_ne!((a, b), (0, 0));
 }
 
-// Test case by @SabrinaJewson
-// https://github.com/rust-lang/miri/issues/2301#issuecomment-1221502757
-// Demonstrating C++20 SC access changes
-fn test_iriw_sc_rlx() {
-    let x = static_atomic_bool(false);
-    let y = static_atomic_bool(false);
-
-    let a = spawn(move || x.store(true, Relaxed));
-    let b = spawn(move || y.store(true, Relaxed));
-    let c = spawn(move || {
-        while !x.load(SeqCst) {}
-        y.load(SeqCst)
-    });
-    let d = spawn(move || {
-        while !y.load(SeqCst) {}
-        x.load(SeqCst)
-    });
-
-    a.join().unwrap();
-    b.join().unwrap();
-    let c = c.join().unwrap();
-    let d = d.join().unwrap();
-
-    assert!(c || d);
-}
-
-// Similar to `test_iriw_sc_rlx` but with fences instead of SC accesses.
-fn test_cpp20_sc_fence_fix() {
-    let x = static_atomic_bool(false);
-    let y = static_atomic_bool(false);
-
-    let thread1 = spawn(|| {
-        let a = x.load(Relaxed);
-        fence(SeqCst);
-        let b = y.load(Relaxed);
-        (a, b)
-    });
-
-    let thread2 = spawn(|| {
-        x.store(true, Relaxed);
-    });
-    let thread3 = spawn(|| {
-        y.store(true, Relaxed);
-    });
-
-    let thread4 = spawn(|| {
-        let c = y.load(Relaxed);
-        fence(SeqCst);
-        let d = x.load(Relaxed);
-        (c, d)
-    });
-
-    let (a, b) = thread1.join().unwrap();
-    thread2.join().unwrap();
-    thread3.join().unwrap();
-    let (c, d) = thread4.join().unwrap();
-    let bad = a == true && b == false && c == true && d == false;
-    assert!(!bad);
-}
-
-// https://plv.mpi-sws.org/scfix/paper.pdf
-// 2.2 Second Problem: SC Fences are Too Weak
-fn test_cpp20_rwc_syncs() {
-    /*
-    int main() {
-        atomic_int x = 0;
-        atomic_int y = 0;
-        {{{ x.store(1,mo_relaxed);
-        ||| { r1=x.load(mo_relaxed).readsvalue(1);
-              fence(mo_seq_cst);
-              r2=y.load(mo_relaxed); }
-        ||| { y.store(1,mo_relaxed);
-              fence(mo_seq_cst);
-              r3=x.load(mo_relaxed); }
-        }}}
-        return 0;
-    }
-    */
-    let x = static_atomic(0);
-    let y = static_atomic(0);
-
-    let j1 = spawn(move || {
-        x.store(1, Relaxed);
-    });
-
-    let j2 = spawn(move || {
-        loads_value(&x, Relaxed, 1);
-        fence(SeqCst);
-        y.load(Relaxed)
-    });
-
-    let j3 = spawn(move || {
-        y.store(1, Relaxed);
-        fence(SeqCst);
-        x.load(Relaxed)
-    });
-
-    j1.join().unwrap();
-    let b = j2.join().unwrap();
-    let c = j3.join().unwrap();
-
-    assert!((b, c) != (0, 0));
-}
-
-/// This checks that the *last* thing the SC fence does is act like a release fence.
-/// See <https://github.com/rust-lang/miri/pull/4057#issuecomment-2522296601>.
-fn test_sc_fence_release() {
-    let x = static_atomic(0);
-    let y = static_atomic(0);
-    let z = static_atomic(0);
-    let k = static_atomic(0);
-
-    let j1 = spawn(move || {
-        x.store(1, Relaxed);
-        fence(SeqCst);
-        k.store(1, Relaxed);
-    });
-    let j2 = spawn(move || {
-        y.store(1, Relaxed);
-        fence(SeqCst);
-        z.store(1, Relaxed);
-    });
-
-    let j3 = spawn(move || {
-        let kval = k.load(Acquire);
-        let yval = y.load(Relaxed);
-        (kval, yval)
-    });
-    let j4 = spawn(move || {
-        let zval = z.load(Acquire);
-        let xval = x.load(Relaxed);
-        (zval, xval)
-    });
-
-    j1.join().unwrap();
-    j2.join().unwrap();
-    let (kval, yval) = j3.join().unwrap();
-    let (zval, xval) = j4.join().unwrap();
-
-    let bad = kval == 1 && yval == 0 && zval == 1 && xval == 0;
-    assert!(!bad);
-}
-
-/// Test that SC fences and accesses sync correctly with each other.
-fn test_sc_fence_access() {
-    /*
-        Wx1 sc
-        Ry0 sc
-        ||
-        Wy1 rlx
-        SC-fence
-        Rx0 rlx
-    */
-    let x = static_atomic(0);
-    let y = static_atomic(0);
-
-    let j1 = spawn(move || {
-        x.store(1, SeqCst);
-        y.load(SeqCst)
-    });
-    let j2 = spawn(move || {
-        y.store(1, Relaxed);
-        fence(SeqCst);
-        x.load(Relaxed)
-    });
-
-    let v1 = j1.join().unwrap();
-    let v2 = j2.join().unwrap();
-    let bad = v1 == 0 && v2 == 0;
-    assert!(!bad);
-}
-
 pub fn main() {
     for _ in 0..50 {
         test_single_thread();
@@ -437,12 +240,6 @@ pub fn main() {
         test_message_passing();
         test_wrc();
         test_corr();
-        test_sc_store_buffering();
         test_sync_through_rmw_and_fences();
-        test_iriw_sc_rlx();
-        test_cpp20_sc_fence_fix();
-        test_cpp20_rwc_syncs();
-        test_sc_fence_release();
-        test_sc_fence_access();
     }
 }
diff --git a/src/tools/miri/tests/pass/0weak_memory_consistency_sc.rs b/src/tools/miri/tests/pass/0weak_memory_consistency_sc.rs
new file mode 100644
index 0000000000000..45cc5e6e72214
--- /dev/null
+++ b/src/tools/miri/tests/pass/0weak_memory_consistency_sc.rs
@@ -0,0 +1,354 @@
+//@compile-flags: -Zmiri-ignore-leaks -Zmiri-disable-stacked-borrows -Zmiri-disable-validation -Zmiri-provenance-gc=10000
+// This test's runtime explodes if the GC interval is set to 1 (which we do in CI), so we
+// override it internally back to the default frequency.
+
+// The following tests check whether our weak memory emulation produces
+// any inconsistent execution outcomes
+// This file here focuses on SC accesses and fences.
+
+use std::sync::atomic::Ordering::*;
+use std::sync::atomic::{AtomicBool, AtomicI32, Ordering, fence};
+use std::thread::spawn;
+
+// We can't create static items because we need to run each test
+// multiple times
+fn static_atomic(val: i32) -> &'static AtomicI32 {
+    Box::leak(Box::new(AtomicI32::new(val)))
+}
+fn static_atomic_bool(val: bool) -> &'static AtomicBool {
+    Box::leak(Box::new(AtomicBool::new(val)))
+}
+
+/// Spins until it acquires a pre-determined value.
+fn loads_value(loc: &AtomicI32, ord: Ordering, val: i32) -> i32 {
+    while loc.load(ord) != val {
+        std::hint::spin_loop();
+    }
+    val
+}
+
+// Test case SB taken from Repairing Sequential Consistency in C/C++11
+// by Lahav et al.
+// https://plv.mpi-sws.org/scfix/paper.pdf
+fn test_sc_store_buffering() {
+    let x = static_atomic(0);
+    let y = static_atomic(0);
+
+    let j1 = spawn(move || {
+        x.store(1, SeqCst);
+        y.load(SeqCst)
+    });
+
+    let j2 = spawn(move || {
+        y.store(1, SeqCst);
+        x.load(SeqCst)
+    });
+
+    let a = j1.join().unwrap();
+    let b = j2.join().unwrap();
+
+    assert_ne!((a, b), (0, 0));
+}
+
+// Test case by @SabrinaJewson
+// https://github.com/rust-lang/miri/issues/2301#issuecomment-1221502757
+// Demonstrating C++20 SC access changes
+fn test_iriw_sc_rlx() {
+    let x = static_atomic_bool(false);
+    let y = static_atomic_bool(false);
+
+    let a = spawn(move || x.store(true, Relaxed));
+    let b = spawn(move || y.store(true, Relaxed));
+    let c = spawn(move || {
+        while !x.load(SeqCst) {}
+        y.load(SeqCst)
+    });
+    let d = spawn(move || {
+        while !y.load(SeqCst) {}
+        x.load(SeqCst)
+    });
+
+    a.join().unwrap();
+    b.join().unwrap();
+    let c = c.join().unwrap();
+    let d = d.join().unwrap();
+
+    assert!(c || d);
+}
+
+// Similar to `test_iriw_sc_rlx` but with fences instead of SC accesses.
+fn test_cpp20_sc_fence_fix() {
+    let x = static_atomic_bool(false);
+    let y = static_atomic_bool(false);
+
+    let thread1 = spawn(|| {
+        let a = x.load(Relaxed);
+        fence(SeqCst);
+        let b = y.load(Relaxed);
+        (a, b)
+    });
+
+    let thread2 = spawn(|| {
+        x.store(true, Relaxed);
+    });
+    let thread3 = spawn(|| {
+        y.store(true, Relaxed);
+    });
+
+    let thread4 = spawn(|| {
+        let c = y.load(Relaxed);
+        fence(SeqCst);
+        let d = x.load(Relaxed);
+        (c, d)
+    });
+
+    let (a, b) = thread1.join().unwrap();
+    thread2.join().unwrap();
+    thread3.join().unwrap();
+    let (c, d) = thread4.join().unwrap();
+    let bad = a == true && b == false && c == true && d == false;
+    assert!(!bad);
+}
+
+// https://plv.mpi-sws.org/scfix/paper.pdf
+// 2.2 Second Problem: SC Fences are Too Weak
+fn test_cpp20_rwc_syncs() {
+    /*
+    int main() {
+        atomic_int x = 0;
+        atomic_int y = 0;
+        {{{ x.store(1,mo_relaxed);
+        ||| { r1=x.load(mo_relaxed).readsvalue(1);
+              fence(mo_seq_cst);
+              r2=y.load(mo_relaxed); }
+        ||| { y.store(1,mo_relaxed);
+              fence(mo_seq_cst);
+              r3=x.load(mo_relaxed); }
+        }}}
+        return 0;
+    }
+    */
+    let x = static_atomic(0);
+    let y = static_atomic(0);
+
+    let j1 = spawn(move || {
+        x.store(1, Relaxed);
+    });
+
+    let j2 = spawn(move || {
+        loads_value(&x, Relaxed, 1);
+        fence(SeqCst);
+        y.load(Relaxed)
+    });
+
+    let j3 = spawn(move || {
+        y.store(1, Relaxed);
+        fence(SeqCst);
+        x.load(Relaxed)
+    });
+
+    j1.join().unwrap();
+    let b = j2.join().unwrap();
+    let c = j3.join().unwrap();
+
+    assert!((b, c) != (0, 0));
+}
+
+/// This checks that the *last* thing the SC fence does is act like a release fence.
+/// See <https://github.com/rust-lang/miri/pull/4057#issuecomment-2522296601>.
+/// Test by Ori Lahav.
+fn test_sc_fence_release() {
+    let x = static_atomic(0);
+    let y = static_atomic(0);
+    let z = static_atomic(0);
+    let k = static_atomic(0);
+
+    let j1 = spawn(move || {
+        x.store(1, Relaxed);
+        fence(SeqCst);
+        k.store(1, Relaxed);
+    });
+    let j2 = spawn(move || {
+        y.store(1, Relaxed);
+        fence(SeqCst);
+        z.store(1, Relaxed);
+    });
+
+    let j3 = spawn(move || {
+        let kval = k.load(Acquire); // bad case: loads 1
+        let yval = y.load(Relaxed); // bad case: loads 0
+        (kval, yval)
+    });
+    let j4 = spawn(move || {
+        let zval = z.load(Acquire); // bad case: loads 1
+        let xval = x.load(Relaxed); // bad case: loads 0
+        (zval, xval)
+    });
+
+    j1.join().unwrap();
+    j2.join().unwrap();
+    let (kval, yval) = j3.join().unwrap();
+    let (zval, xval) = j4.join().unwrap();
+
+    let bad = kval == 1 && yval == 0 && zval == 1 && xval == 0;
+    assert!(!bad);
+}
+
+/// Test that SC fences and accesses sync correctly with each other.
+/// Test by Ori Lahav.
+fn test_sc_fence_access() {
+    /*
+        Wx1 sc
+        Ry0 sc
+        ||
+        Wy1 rlx
+        SC-fence
+        Rx0 rlx
+    */
+    let x = static_atomic(0);
+    let y = static_atomic(0);
+
+    let j1 = spawn(move || {
+        x.store(1, SeqCst);
+        y.load(SeqCst)
+    });
+    let j2 = spawn(move || {
+        y.store(1, Relaxed);
+        fence(SeqCst);
+        // If this sees a 0, the fence must have been *before* the x.store(1).
+        x.load(Relaxed)
+    });
+
+    let yval = j1.join().unwrap();
+    let xval = j2.join().unwrap();
+    let bad = yval == 0 && xval == 0;
+    assert!(!bad);
+}
+
+/// Test that SC fences and accesses sync correctly with each other
+/// when mediated by a release-acquire pair.
+/// Test by Ori Lahav (https://github.com/rust-lang/miri/pull/4057#issuecomment-2525268730).
+fn test_sc_fence_access_relacq() {
+    let x = static_atomic(0);
+    let y = static_atomic(0);
+    let z = static_atomic(0);
+
+    let j1 = spawn(move || {
+        x.store(1, SeqCst);
+        y.load(SeqCst) // bad case: loads 0
+    });
+    let j2 = spawn(move || {
+        y.store(1, Relaxed);
+        z.store(1, Release)
+    });
+    let j3 = spawn(move || {
+        let zval = z.load(Acquire); // bad case: loads 1
+        // If we see 1 here, the rel-acq pair makes the fence happen after the z.store(1).
+        fence(SeqCst);
+        // If this sees a 0, the fence must have been *before* the x.store(1).
+        let xval = x.load(Relaxed); // bad case: loads 0
+        (zval, xval)
+    });
+
+    let yval = j1.join().unwrap();
+    j2.join().unwrap();
+    let (zval, xval) = j3.join().unwrap();
+    let bad = yval == 0 && zval == 1 && xval == 0;
+    assert!(!bad);
+}
+
+/// A test that involves multiple SC fences and accesses.
+/// Test by Ori Lahav (https://github.com/rust-lang/miri/pull/4057#issuecomment-2525268730).
+fn test_sc_multi_fence() {
+    let x = static_atomic(0);
+    let y = static_atomic(0);
+    let z = static_atomic(0);
+
+    let j1 = spawn(move || {
+        x.store(1, SeqCst);
+        y.load(SeqCst) // bad case: loads 0
+    });
+    let j2 = spawn(move || {
+        y.store(1, Relaxed);
+        // In the bad case this fence is *after* the j1 y.load, since
+        // otherwise that load would pick up the 1 we just stored.
+        fence(SeqCst);
+        z.load(Relaxed) // bad case: loads 0
+    });
+    let j3 = spawn(move || {
+        z.store(1, Relaxed);
+    });
+    let j4 = spawn(move || {
+        let zval = z.load(Relaxed); // bad case: loads 1
+        // In the bad case this fence is *after* the one above since
+        // otherwise, the j2 load of z would load 1.
+        fence(SeqCst);
+        // Since that fence is in turn after the j1 y.load, our fence is
+        // after the j1 x.store, which means we must pick up that store.
+        let xval = x.load(Relaxed); // bad case: loads 0
+        (zval, xval)
+    });
+
+    let yval = j1.join().unwrap();
+    let zval1 = j2.join().unwrap();
+    j3.join().unwrap();
+    let (zval2, xval) = j4.join().unwrap();
+    let bad = yval == 0 && zval1 == 0 && zval2 == 1 && xval == 0;
+    assert!(!bad);
+}
+
+fn test_sc_relaxed() {
+    /*
+    y:=1 rlx
+    Fence sc
+    a:=x rlx
+    Fence acq
+    b:=z rlx // 0
+    ||
+    z:=1 rlx
+    x:=1 sc
+    c:=y sc // 0
+    */
+
+    let x = static_atomic(0);
+    let y = static_atomic(0);
+    let z = static_atomic(0);
+
+    let j1 = spawn(move || {
+        y.store(1, Relaxed);
+        fence(SeqCst);
+        // If the relaxed load here is removed, then the "bad" behavior becomes allowed
+        // by C++20 (and by RC11 / scfix as well).
+        let _a = x.load(Relaxed);
+        fence(Acquire);
+        // If we see 0 here this means in some sense we are "before" the store to z below.
+        let b = z.load(Relaxed);
+        b
+    });
+    let j2 = spawn(move || {
+        z.store(1, Relaxed);
+        x.store(1, SeqCst);
+        // If we see 0 here, this means in some sense we are "before" the store to y above.
+        let c = y.load(SeqCst);
+        c
+    });
+
+    let b = j1.join().unwrap();
+    let c = j2.join().unwrap();
+    let bad = b == 0 && c == 0;
+    assert!(!bad);
+}
+
+pub fn main() {
+    for _ in 0..50 {
+        test_sc_store_buffering();
+        test_iriw_sc_rlx();
+        test_cpp20_sc_fence_fix();
+        test_cpp20_rwc_syncs();
+        test_sc_fence_release();
+        test_sc_fence_access();
+        test_sc_fence_access_relacq();
+        test_sc_multi_fence();
+        test_sc_relaxed();
+    }
+}
diff --git a/src/tools/miri/tests/pass/ptr_int_casts.rs b/src/tools/miri/tests/pass/ptr_int_casts.rs
index 4e274f62981d1..94391eac3b274 100644
--- a/src/tools/miri/tests/pass/ptr_int_casts.rs
+++ b/src/tools/miri/tests/pass/ptr_int_casts.rs
@@ -1,7 +1,4 @@
-//@revisions: stack tree
-// Tree Borrows doesn't support int2ptr casts, but let's make sure we don't immediately crash either.
-//@[tree]compile-flags: -Zmiri-tree-borrows
-//@[stack]compile-flags: -Zmiri-permissive-provenance
+//@compile-flags: -Zmiri-permissive-provenance
 use std::{mem, ptr};
 
 fn eq_ref<T>(x: &T, y: &T) -> bool {
diff --git a/src/tools/miri/tests/pass/ptr_int_from_exposed.rs b/src/tools/miri/tests/pass/ptr_int_from_exposed.rs
index 9a76c8dd34972..98f8f15608e1d 100644
--- a/src/tools/miri/tests/pass/ptr_int_from_exposed.rs
+++ b/src/tools/miri/tests/pass/ptr_int_from_exposed.rs
@@ -1,7 +1,4 @@
-//@revisions: stack tree
-// Tree Borrows doesn't support int2ptr casts, but let's make sure we don't immediately crash either.
-//@[tree]compile-flags: -Zmiri-tree-borrows
-//@[stack]compile-flags: -Zmiri-permissive-provenance
+//@compile-flags: -Zmiri-permissive-provenance
 
 use std::ptr;
 
diff --git a/tests/ui/error-emitter/multiline-removal-suggestion.rs b/tests/ui/error-emitter/multiline-removal-suggestion.rs
new file mode 100644
index 0000000000000..0249166938188
--- /dev/null
+++ b/tests/ui/error-emitter/multiline-removal-suggestion.rs
@@ -0,0 +1,57 @@
+// Make sure suggestion for removal of a span that covers multiple lines is properly highlighted.
+//@ compile-flags: --error-format=human --color=always
+//@ edition:2018
+// ignore-tidy-tab
+// We use `\t` instead of spaces for indentation to ensure that the highlighting logic properly
+// accounts for replaced characters (like we do for `\t` with `    `). The naïve way of highlighting
+// could be counting chars of the original code, instead of operating on the code as it is being
+// displayed.
+use std::collections::{HashMap, HashSet};
+fn foo() -> Vec<(bool, HashSet<u8>)> {
+	let mut hm = HashMap::<bool, Vec<HashSet<u8>>>::new();
+	hm.into_iter()
+		.map(|(is_true, ts)| {
+			ts.into_iter()
+				.map(|t| {
+					(
+						is_true,
+						t,
+					)
+				}).flatten()
+		})
+		.flatten()
+		.collect()
+}
+fn bar() -> Vec<(bool, HashSet<u8>)> {
+	let mut hm = HashMap::<bool, Vec<HashSet<u8>>>::new();
+	hm.into_iter()
+		.map(|(is_true, ts)| {
+			ts.into_iter()
+				.map(|t| (is_true, t))
+				.flatten()
+		})
+		.flatten()
+		.collect()
+}
+fn baz() -> Vec<(bool, HashSet<u8>)> {
+	let mut hm = HashMap::<bool, Vec<HashSet<u8>>>::new();
+	hm.into_iter()
+		.map(|(is_true, ts)| {
+			ts.into_iter().map(|t| {
+				(is_true, t)
+			}).flatten()
+		})
+		.flatten()
+		.collect()
+}
+fn bay() -> Vec<(bool, HashSet<u8>)> {
+	let mut hm = HashMap::<bool, Vec<HashSet<u8>>>::new();
+	hm.into_iter()
+		.map(|(is_true, ts)| {
+			ts.into_iter()
+				.map(|t| (is_true, t)).flatten()
+		})
+		.flatten()
+		.collect()
+}
+fn main() {}
diff --git a/tests/ui/error-emitter/multiline-removal-suggestion.svg b/tests/ui/error-emitter/multiline-removal-suggestion.svg
new file mode 100644
index 0000000000000..a1f6795c875e7
--- /dev/null
+++ b/tests/ui/error-emitter/multiline-removal-suggestion.svg
@@ -0,0 +1,504 @@
+<svg width="1902px" height="4322px" xmlns="http://www.w3.org/2000/svg">
+  <style>
+    .fg { fill: #AAAAAA }
+    .bg { background: #000000 }
+    .fg-ansi256-009 { fill: #FF5555 }
+    .fg-ansi256-010 { fill: #55FF55 }
+    .fg-ansi256-012 { fill: #5555FF }
+    .fg-ansi256-014 { fill: #55FFFF }
+    .container {
+      padding: 0 10px;
+      line-height: 18px;
+    }
+    .bold { font-weight: bold; }
+    tspan {
+      font: 14px SFMono-Regular, Consolas, Liberation Mono, Menlo, monospace;
+      white-space: pre;
+      line-height: 18px;
+    }
+  </style>
+
+  <rect width="100%" height="100%" y="0" rx="4.5" class="bg" />
+
+  <text xml:space="preserve" class="container fg">
+    <tspan x="10px" y="28px"><tspan class="fg-ansi256-009 bold">error[E0277]</tspan><tspan class="bold">: `(bool, HashSet&lt;u8&gt;)` is not an iterator</tspan>
+</tspan>
+    <tspan x="10px" y="46px"><tspan>  </tspan><tspan class="fg-ansi256-012 bold">--&gt; </tspan><tspan>$DIR/multiline-removal-suggestion.rs:20:8</tspan>
+</tspan>
+    <tspan x="10px" y="64px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="82px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>                 }).flatten()</tspan>
+</tspan>
+    <tspan x="10px" y="100px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>                    </tspan><tspan class="fg-ansi256-009 bold">^^^^^^^</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">`(bool, HashSet&lt;u8&gt;)` is not an iterator</tspan>
+</tspan>
+    <tspan x="10px" y="118px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="136px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">= </tspan><tspan class="bold">help</tspan><tspan>: the trait `Iterator` is not implemented for `(bool, HashSet&lt;u8&gt;)`</tspan>
+</tspan>
+    <tspan x="10px" y="154px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">= </tspan><tspan class="bold">note</tspan><tspan>: required for `(bool, HashSet&lt;u8&gt;)` to implement `IntoIterator`</tspan>
+</tspan>
+    <tspan x="10px" y="172px"><tspan class="fg-ansi256-010 bold">note</tspan><tspan>: required by a bound in `flatten`</tspan>
+</tspan>
+    <tspan x="10px" y="190px"><tspan>  </tspan><tspan class="fg-ansi256-012 bold">--&gt; </tspan><tspan>$SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL</tspan>
+</tspan>
+    <tspan x="10px" y="208px"><tspan class="fg-ansi256-014 bold">help</tspan><tspan>: consider removing this method call, as the receiver has type `std::vec::IntoIter&lt;HashSet&lt;u8&gt;&gt;` and `std::vec::IntoIter&lt;HashSet&lt;u8&gt;&gt;: Iterator` trivially holds</tspan>
+</tspan>
+    <tspan x="10px" y="226px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="244px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-009">- </tspan><tspan>            ts.into_iter()</tspan>
+</tspan>
+    <tspan x="10px" y="262px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-009">-                 .map(|t| {</tspan>
+</tspan>
+    <tspan x="10px" y="280px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-009">-                     (</tspan>
+</tspan>
+    <tspan x="10px" y="298px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-009">-                         is_true,</tspan>
+</tspan>
+    <tspan x="10px" y="316px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-009">-                         t,</tspan>
+</tspan>
+    <tspan x="10px" y="334px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-009">-                     )</tspan>
+</tspan>
+    <tspan x="10px" y="352px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-009">-                 })</tspan><tspan>.flatten()</tspan>
+</tspan>
+    <tspan x="10px" y="370px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-010">+ </tspan><tspan>            ts.into_iter().flatten()</tspan>
+</tspan>
+    <tspan x="10px" y="388px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="406px">
+</tspan>
+    <tspan x="10px" y="424px"><tspan class="fg-ansi256-009 bold">error[E0277]</tspan><tspan class="bold">: `(bool, HashSet&lt;u8&gt;)` is not an iterator</tspan>
+</tspan>
+    <tspan x="10px" y="442px"><tspan>  </tspan><tspan class="fg-ansi256-012 bold">--&gt; </tspan><tspan>$DIR/multiline-removal-suggestion.rs:12:2</tspan>
+</tspan>
+    <tspan x="10px" y="460px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="478px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">/</tspan><tspan>     hm.into_iter()</tspan>
+</tspan>
+    <tspan x="10px" y="496px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">|</tspan><tspan>         .map(|(is_true, ts)| {</tspan>
+</tspan>
+    <tspan x="10px" y="514px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">|</tspan><tspan>             ts.into_iter()</tspan>
+</tspan>
+    <tspan x="10px" y="532px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">|</tspan><tspan>                 .map(|t| {</tspan>
+</tspan>
+    <tspan x="10px" y="550px"><tspan class="fg-ansi256-012 bold">...</tspan><tspan>  </tspan><tspan class="fg-ansi256-009 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="568px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">|</tspan><tspan>                 }).flatten()</tspan>
+</tspan>
+    <tspan x="10px" y="586px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">|</tspan><tspan>         })</tspan>
+</tspan>
+    <tspan x="10px" y="604px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">|__________^</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">`(bool, HashSet&lt;u8&gt;)` is not an iterator</tspan>
+</tspan>
+    <tspan x="10px" y="622px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="640px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">= </tspan><tspan class="bold">help</tspan><tspan>: the trait `Iterator` is not implemented for `(bool, HashSet&lt;u8&gt;)`</tspan>
+</tspan>
+    <tspan x="10px" y="658px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">= </tspan><tspan class="bold">note</tspan><tspan>: required for `(bool, HashSet&lt;u8&gt;)` to implement `IntoIterator`</tspan>
+</tspan>
+    <tspan x="10px" y="676px"><tspan class="fg-ansi256-010 bold">note</tspan><tspan>: required by a bound in `Flatten`</tspan>
+</tspan>
+    <tspan x="10px" y="694px"><tspan>  </tspan><tspan class="fg-ansi256-012 bold">--&gt; </tspan><tspan>$SRC_DIR/core/src/iter/adapters/flatten.rs:LL:COL</tspan>
+</tspan>
+    <tspan x="10px" y="712px">
+</tspan>
+    <tspan x="10px" y="730px"><tspan class="fg-ansi256-009 bold">error[E0599]</tspan><tspan class="bold">: the method `collect` exists for struct `Flatten&lt;Map&lt;IntoIter&lt;bool, Vec&lt;HashSet&lt;u8&gt;&gt;&gt;, {closure@multiline-removal-suggestion.rs:13:8}&gt;&gt;`, but its trait bounds were not satisfied</tspan>
+</tspan>
+    <tspan x="10px" y="748px"><tspan>  </tspan><tspan class="fg-ansi256-012 bold">--&gt; </tspan><tspan>$DIR/multiline-removal-suggestion.rs:23:4</tspan>
+</tspan>
+    <tspan x="10px" y="766px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="784px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">/</tspan><tspan>     hm.into_iter()</tspan>
+</tspan>
+    <tspan x="10px" y="802px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>         .map(|(is_true, ts)| {</tspan>
+</tspan>
+    <tspan x="10px" y="820px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>             ts.into_iter()</tspan>
+</tspan>
+    <tspan x="10px" y="838px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>                 .map(|t| {</tspan>
+</tspan>
+    <tspan x="10px" y="856px"><tspan class="fg-ansi256-012 bold">...</tspan><tspan>  </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="874px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>         .flatten()</tspan>
+</tspan>
+    <tspan x="10px" y="892px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>         .collect()</tspan>
+</tspan>
+    <tspan x="10px" y="910px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>         </tspan><tspan class="fg-ansi256-012 bold">-</tspan><tspan class="fg-ansi256-009 bold">^^^^^^^</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">method cannot be called due to unsatisfied trait bounds</tspan>
+</tspan>
+    <tspan x="10px" y="928px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|_________|</tspan>
+</tspan>
+    <tspan x="10px" y="946px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="964px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="982px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">= </tspan><tspan class="bold">note</tspan><tspan>: the following trait bounds were not satisfied:</tspan>
+</tspan>
+    <tspan x="10px" y="1000px"><tspan>           `&lt;Flatten&lt;Map&lt;std::vec::IntoIter&lt;HashSet&lt;u8&gt;&gt;, {closure@$DIR/multiline-removal-suggestion.rs:15:10: 15:13}&gt;&gt; as IntoIterator&gt;::IntoIter = _`</tspan>
+</tspan>
+    <tspan x="10px" y="1018px"><tspan>           which is required by `Flatten&lt;Map&lt;std::collections::hash_map::IntoIter&lt;bool, Vec&lt;HashSet&lt;u8&gt;&gt;&gt;, {closure@$DIR/multiline-removal-suggestion.rs:13:8: 13:23}&gt;&gt;: Iterator`</tspan>
+</tspan>
+    <tspan x="10px" y="1036px"><tspan>           `&lt;Flatten&lt;Map&lt;std::vec::IntoIter&lt;HashSet&lt;u8&gt;&gt;, {closure@$DIR/multiline-removal-suggestion.rs:15:10: 15:13}&gt;&gt; as IntoIterator&gt;::Item = _`</tspan>
+</tspan>
+    <tspan x="10px" y="1054px"><tspan>           which is required by `Flatten&lt;Map&lt;std::collections::hash_map::IntoIter&lt;bool, Vec&lt;HashSet&lt;u8&gt;&gt;&gt;, {closure@$DIR/multiline-removal-suggestion.rs:13:8: 13:23}&gt;&gt;: Iterator`</tspan>
+</tspan>
+    <tspan x="10px" y="1072px"><tspan>           `Flatten&lt;Map&lt;std::vec::IntoIter&lt;HashSet&lt;u8&gt;&gt;, {closure@$DIR/multiline-removal-suggestion.rs:15:10: 15:13}&gt;&gt;: IntoIterator`</tspan>
+</tspan>
+    <tspan x="10px" y="1090px"><tspan>           which is required by `Flatten&lt;Map&lt;std::collections::hash_map::IntoIter&lt;bool, Vec&lt;HashSet&lt;u8&gt;&gt;&gt;, {closure@$DIR/multiline-removal-suggestion.rs:13:8: 13:23}&gt;&gt;: Iterator`</tspan>
+</tspan>
+    <tspan x="10px" y="1108px"><tspan>           `Flatten&lt;Map&lt;std::collections::hash_map::IntoIter&lt;bool, Vec&lt;HashSet&lt;u8&gt;&gt;&gt;, {closure@$DIR/multiline-removal-suggestion.rs:13:8: 13:23}&gt;&gt;: Iterator`</tspan>
+</tspan>
+    <tspan x="10px" y="1126px"><tspan>           which is required by `&amp;mut Flatten&lt;Map&lt;std::collections::hash_map::IntoIter&lt;bool, Vec&lt;HashSet&lt;u8&gt;&gt;&gt;, {closure@$DIR/multiline-removal-suggestion.rs:13:8: 13:23}&gt;&gt;: Iterator`</tspan>
+</tspan>
+    <tspan x="10px" y="1144px">
+</tspan>
+    <tspan x="10px" y="1162px"><tspan class="fg-ansi256-009 bold">error[E0277]</tspan><tspan class="bold">: `(bool, HashSet&lt;u8&gt;)` is not an iterator</tspan>
+</tspan>
+    <tspan x="10px" y="1180px"><tspan>  </tspan><tspan class="fg-ansi256-012 bold">--&gt; </tspan><tspan>$DIR/multiline-removal-suggestion.rs:31:6</tspan>
+</tspan>
+    <tspan x="10px" y="1198px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="1216px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>                 .flatten()</tspan>
+</tspan>
+    <tspan x="10px" y="1234px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>                  </tspan><tspan class="fg-ansi256-009 bold">^^^^^^^</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">`(bool, HashSet&lt;u8&gt;)` is not an iterator</tspan>
+</tspan>
+    <tspan x="10px" y="1252px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="1270px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">= </tspan><tspan class="bold">help</tspan><tspan>: the trait `Iterator` is not implemented for `(bool, HashSet&lt;u8&gt;)`</tspan>
+</tspan>
+    <tspan x="10px" y="1288px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">= </tspan><tspan class="bold">note</tspan><tspan>: required for `(bool, HashSet&lt;u8&gt;)` to implement `IntoIterator`</tspan>
+</tspan>
+    <tspan x="10px" y="1306px"><tspan class="fg-ansi256-010 bold">note</tspan><tspan>: required by a bound in `flatten`</tspan>
+</tspan>
+    <tspan x="10px" y="1324px"><tspan>  </tspan><tspan class="fg-ansi256-012 bold">--&gt; </tspan><tspan>$SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL</tspan>
+</tspan>
+    <tspan x="10px" y="1342px"><tspan class="fg-ansi256-014 bold">help</tspan><tspan>: consider removing this method call, as the receiver has type `std::vec::IntoIter&lt;HashSet&lt;u8&gt;&gt;` and `std::vec::IntoIter&lt;HashSet&lt;u8&gt;&gt;: Iterator` trivially holds</tspan>
+</tspan>
+    <tspan x="10px" y="1360px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="1378px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-009">- </tspan><tspan>            ts.into_iter()</tspan>
+</tspan>
+    <tspan x="10px" y="1396px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-009">-                 .map(|t| (is_true, t))</tspan>
+</tspan>
+    <tspan x="10px" y="1414px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-010">+ </tspan><tspan>            ts.into_iter()</tspan>
+</tspan>
+    <tspan x="10px" y="1432px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="1450px">
+</tspan>
+    <tspan x="10px" y="1468px"><tspan class="fg-ansi256-009 bold">error[E0277]</tspan><tspan class="bold">: `(bool, HashSet&lt;u8&gt;)` is not an iterator</tspan>
+</tspan>
+    <tspan x="10px" y="1486px"><tspan>  </tspan><tspan class="fg-ansi256-012 bold">--&gt; </tspan><tspan>$DIR/multiline-removal-suggestion.rs:27:2</tspan>
+</tspan>
+    <tspan x="10px" y="1504px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="1522px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">/</tspan><tspan>     hm.into_iter()</tspan>
+</tspan>
+    <tspan x="10px" y="1540px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">|</tspan><tspan>         .map(|(is_true, ts)| {</tspan>
+</tspan>
+    <tspan x="10px" y="1558px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">|</tspan><tspan>             ts.into_iter()</tspan>
+</tspan>
+    <tspan x="10px" y="1576px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">|</tspan><tspan>                 .map(|t| (is_true, t))</tspan>
+</tspan>
+    <tspan x="10px" y="1594px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">|</tspan><tspan>                 .flatten()</tspan>
+</tspan>
+    <tspan x="10px" y="1612px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">|</tspan><tspan>         })</tspan>
+</tspan>
+    <tspan x="10px" y="1630px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">|__________^</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">`(bool, HashSet&lt;u8&gt;)` is not an iterator</tspan>
+</tspan>
+    <tspan x="10px" y="1648px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="1666px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">= </tspan><tspan class="bold">help</tspan><tspan>: the trait `Iterator` is not implemented for `(bool, HashSet&lt;u8&gt;)`</tspan>
+</tspan>
+    <tspan x="10px" y="1684px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">= </tspan><tspan class="bold">note</tspan><tspan>: required for `(bool, HashSet&lt;u8&gt;)` to implement `IntoIterator`</tspan>
+</tspan>
+    <tspan x="10px" y="1702px"><tspan class="fg-ansi256-010 bold">note</tspan><tspan>: required by a bound in `Flatten`</tspan>
+</tspan>
+    <tspan x="10px" y="1720px"><tspan>  </tspan><tspan class="fg-ansi256-012 bold">--&gt; </tspan><tspan>$SRC_DIR/core/src/iter/adapters/flatten.rs:LL:COL</tspan>
+</tspan>
+    <tspan x="10px" y="1738px">
+</tspan>
+    <tspan x="10px" y="1756px"><tspan class="fg-ansi256-009 bold">error[E0599]</tspan><tspan class="bold">: the method `collect` exists for struct `Flatten&lt;Map&lt;IntoIter&lt;bool, Vec&lt;HashSet&lt;u8&gt;&gt;&gt;, {closure@multiline-removal-suggestion.rs:28:8}&gt;&gt;`, but its trait bounds were not satisfied</tspan>
+</tspan>
+    <tspan x="10px" y="1774px"><tspan>  </tspan><tspan class="fg-ansi256-012 bold">--&gt; </tspan><tspan>$DIR/multiline-removal-suggestion.rs:34:4</tspan>
+</tspan>
+    <tspan x="10px" y="1792px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="1810px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">/</tspan><tspan>     hm.into_iter()</tspan>
+</tspan>
+    <tspan x="10px" y="1828px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>         .map(|(is_true, ts)| {</tspan>
+</tspan>
+    <tspan x="10px" y="1846px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>             ts.into_iter()</tspan>
+</tspan>
+    <tspan x="10px" y="1864px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>                 .map(|t| (is_true, t))</tspan>
+</tspan>
+    <tspan x="10px" y="1882px"><tspan class="fg-ansi256-012 bold">...</tspan><tspan>  </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="1900px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>         .flatten()</tspan>
+</tspan>
+    <tspan x="10px" y="1918px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>         .collect()</tspan>
+</tspan>
+    <tspan x="10px" y="1936px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>         </tspan><tspan class="fg-ansi256-012 bold">-</tspan><tspan class="fg-ansi256-009 bold">^^^^^^^</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">method cannot be called due to unsatisfied trait bounds</tspan>
+</tspan>
+    <tspan x="10px" y="1954px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|_________|</tspan>
+</tspan>
+    <tspan x="10px" y="1972px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="1990px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="2008px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">= </tspan><tspan class="bold">note</tspan><tspan>: the following trait bounds were not satisfied:</tspan>
+</tspan>
+    <tspan x="10px" y="2026px"><tspan>           `&lt;Flatten&lt;Map&lt;std::vec::IntoIter&lt;HashSet&lt;u8&gt;&gt;, {closure@$DIR/multiline-removal-suggestion.rs:30:10: 30:13}&gt;&gt; as IntoIterator&gt;::IntoIter = _`</tspan>
+</tspan>
+    <tspan x="10px" y="2044px"><tspan>           which is required by `Flatten&lt;Map&lt;std::collections::hash_map::IntoIter&lt;bool, Vec&lt;HashSet&lt;u8&gt;&gt;&gt;, {closure@$DIR/multiline-removal-suggestion.rs:28:8: 28:23}&gt;&gt;: Iterator`</tspan>
+</tspan>
+    <tspan x="10px" y="2062px"><tspan>           `&lt;Flatten&lt;Map&lt;std::vec::IntoIter&lt;HashSet&lt;u8&gt;&gt;, {closure@$DIR/multiline-removal-suggestion.rs:30:10: 30:13}&gt;&gt; as IntoIterator&gt;::Item = _`</tspan>
+</tspan>
+    <tspan x="10px" y="2080px"><tspan>           which is required by `Flatten&lt;Map&lt;std::collections::hash_map::IntoIter&lt;bool, Vec&lt;HashSet&lt;u8&gt;&gt;&gt;, {closure@$DIR/multiline-removal-suggestion.rs:28:8: 28:23}&gt;&gt;: Iterator`</tspan>
+</tspan>
+    <tspan x="10px" y="2098px"><tspan>           `Flatten&lt;Map&lt;std::vec::IntoIter&lt;HashSet&lt;u8&gt;&gt;, {closure@$DIR/multiline-removal-suggestion.rs:30:10: 30:13}&gt;&gt;: IntoIterator`</tspan>
+</tspan>
+    <tspan x="10px" y="2116px"><tspan>           which is required by `Flatten&lt;Map&lt;std::collections::hash_map::IntoIter&lt;bool, Vec&lt;HashSet&lt;u8&gt;&gt;&gt;, {closure@$DIR/multiline-removal-suggestion.rs:28:8: 28:23}&gt;&gt;: Iterator`</tspan>
+</tspan>
+    <tspan x="10px" y="2134px"><tspan>           `Flatten&lt;Map&lt;std::collections::hash_map::IntoIter&lt;bool, Vec&lt;HashSet&lt;u8&gt;&gt;&gt;, {closure@$DIR/multiline-removal-suggestion.rs:28:8: 28:23}&gt;&gt;: Iterator`</tspan>
+</tspan>
+    <tspan x="10px" y="2152px"><tspan>           which is required by `&amp;mut Flatten&lt;Map&lt;std::collections::hash_map::IntoIter&lt;bool, Vec&lt;HashSet&lt;u8&gt;&gt;&gt;, {closure@$DIR/multiline-removal-suggestion.rs:28:8: 28:23}&gt;&gt;: Iterator`</tspan>
+</tspan>
+    <tspan x="10px" y="2170px">
+</tspan>
+    <tspan x="10px" y="2188px"><tspan class="fg-ansi256-009 bold">error[E0277]</tspan><tspan class="bold">: `(bool, HashSet&lt;u8&gt;)` is not an iterator</tspan>
+</tspan>
+    <tspan x="10px" y="2206px"><tspan>  </tspan><tspan class="fg-ansi256-012 bold">--&gt; </tspan><tspan>$DIR/multiline-removal-suggestion.rs:42:7</tspan>
+</tspan>
+    <tspan x="10px" y="2224px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="2242px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>             }).flatten()</tspan>
+</tspan>
+    <tspan x="10px" y="2260px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>                </tspan><tspan class="fg-ansi256-009 bold">^^^^^^^</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">`(bool, HashSet&lt;u8&gt;)` is not an iterator</tspan>
+</tspan>
+    <tspan x="10px" y="2278px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="2296px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">= </tspan><tspan class="bold">help</tspan><tspan>: the trait `Iterator` is not implemented for `(bool, HashSet&lt;u8&gt;)`</tspan>
+</tspan>
+    <tspan x="10px" y="2314px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">= </tspan><tspan class="bold">note</tspan><tspan>: required for `(bool, HashSet&lt;u8&gt;)` to implement `IntoIterator`</tspan>
+</tspan>
+    <tspan x="10px" y="2332px"><tspan class="fg-ansi256-010 bold">note</tspan><tspan>: required by a bound in `flatten`</tspan>
+</tspan>
+    <tspan x="10px" y="2350px"><tspan>  </tspan><tspan class="fg-ansi256-012 bold">--&gt; </tspan><tspan>$SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL</tspan>
+</tspan>
+    <tspan x="10px" y="2368px"><tspan class="fg-ansi256-014 bold">help</tspan><tspan>: consider removing this method call, as the receiver has type `std::vec::IntoIter&lt;HashSet&lt;u8&gt;&gt;` and `std::vec::IntoIter&lt;HashSet&lt;u8&gt;&gt;: Iterator` trivially holds</tspan>
+</tspan>
+    <tspan x="10px" y="2386px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="2404px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-009">- </tspan><tspan>            ts.into_iter()</tspan><tspan class="fg-ansi256-009">.map(|t| {</tspan>
+</tspan>
+    <tspan x="10px" y="2422px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-009">-                 (is_true, t)</tspan>
+</tspan>
+    <tspan x="10px" y="2440px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-009">-             })</tspan><tspan>.flatten()</tspan>
+</tspan>
+    <tspan x="10px" y="2458px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-010">+ </tspan><tspan>            ts.into_iter().flatten()</tspan>
+</tspan>
+    <tspan x="10px" y="2476px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="2494px">
+</tspan>
+    <tspan x="10px" y="2512px"><tspan class="fg-ansi256-009 bold">error[E0277]</tspan><tspan class="bold">: `(bool, HashSet&lt;u8&gt;)` is not an iterator</tspan>
+</tspan>
+    <tspan x="10px" y="2530px"><tspan>  </tspan><tspan class="fg-ansi256-012 bold">--&gt; </tspan><tspan>$DIR/multiline-removal-suggestion.rs:38:2</tspan>
+</tspan>
+    <tspan x="10px" y="2548px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="2566px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">/</tspan><tspan>     hm.into_iter()</tspan>
+</tspan>
+    <tspan x="10px" y="2584px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">|</tspan><tspan>         .map(|(is_true, ts)| {</tspan>
+</tspan>
+    <tspan x="10px" y="2602px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">|</tspan><tspan>             ts.into_iter().map(|t| {</tspan>
+</tspan>
+    <tspan x="10px" y="2620px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">|</tspan><tspan>                 (is_true, t)</tspan>
+</tspan>
+    <tspan x="10px" y="2638px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">|</tspan><tspan>             }).flatten()</tspan>
+</tspan>
+    <tspan x="10px" y="2656px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">|</tspan><tspan>         })</tspan>
+</tspan>
+    <tspan x="10px" y="2674px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">|__________^</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">`(bool, HashSet&lt;u8&gt;)` is not an iterator</tspan>
+</tspan>
+    <tspan x="10px" y="2692px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="2710px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">= </tspan><tspan class="bold">help</tspan><tspan>: the trait `Iterator` is not implemented for `(bool, HashSet&lt;u8&gt;)`</tspan>
+</tspan>
+    <tspan x="10px" y="2728px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">= </tspan><tspan class="bold">note</tspan><tspan>: required for `(bool, HashSet&lt;u8&gt;)` to implement `IntoIterator`</tspan>
+</tspan>
+    <tspan x="10px" y="2746px"><tspan class="fg-ansi256-010 bold">note</tspan><tspan>: required by a bound in `Flatten`</tspan>
+</tspan>
+    <tspan x="10px" y="2764px"><tspan>  </tspan><tspan class="fg-ansi256-012 bold">--&gt; </tspan><tspan>$SRC_DIR/core/src/iter/adapters/flatten.rs:LL:COL</tspan>
+</tspan>
+    <tspan x="10px" y="2782px">
+</tspan>
+    <tspan x="10px" y="2800px"><tspan class="fg-ansi256-009 bold">error[E0599]</tspan><tspan class="bold">: the method `collect` exists for struct `Flatten&lt;Map&lt;IntoIter&lt;bool, Vec&lt;HashSet&lt;u8&gt;&gt;&gt;, {closure@multiline-removal-suggestion.rs:39:8}&gt;&gt;`, but its trait bounds were not satisfied</tspan>
+</tspan>
+    <tspan x="10px" y="2818px"><tspan>  </tspan><tspan class="fg-ansi256-012 bold">--&gt; </tspan><tspan>$DIR/multiline-removal-suggestion.rs:45:4</tspan>
+</tspan>
+    <tspan x="10px" y="2836px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="2854px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">/</tspan><tspan>     hm.into_iter()</tspan>
+</tspan>
+    <tspan x="10px" y="2872px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>         .map(|(is_true, ts)| {</tspan>
+</tspan>
+    <tspan x="10px" y="2890px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>             ts.into_iter().map(|t| {</tspan>
+</tspan>
+    <tspan x="10px" y="2908px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>                 (is_true, t)</tspan>
+</tspan>
+    <tspan x="10px" y="2926px"><tspan class="fg-ansi256-012 bold">...</tspan><tspan>  </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="2944px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>         .flatten()</tspan>
+</tspan>
+    <tspan x="10px" y="2962px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>         .collect()</tspan>
+</tspan>
+    <tspan x="10px" y="2980px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>         </tspan><tspan class="fg-ansi256-012 bold">-</tspan><tspan class="fg-ansi256-009 bold">^^^^^^^</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">method cannot be called due to unsatisfied trait bounds</tspan>
+</tspan>
+    <tspan x="10px" y="2998px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|_________|</tspan>
+</tspan>
+    <tspan x="10px" y="3016px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="3034px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="3052px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">= </tspan><tspan class="bold">note</tspan><tspan>: the following trait bounds were not satisfied:</tspan>
+</tspan>
+    <tspan x="10px" y="3070px"><tspan>           `&lt;Flatten&lt;Map&lt;std::vec::IntoIter&lt;HashSet&lt;u8&gt;&gt;, {closure@$DIR/multiline-removal-suggestion.rs:40:23: 40:26}&gt;&gt; as IntoIterator&gt;::IntoIter = _`</tspan>
+</tspan>
+    <tspan x="10px" y="3088px"><tspan>           which is required by `Flatten&lt;Map&lt;std::collections::hash_map::IntoIter&lt;bool, Vec&lt;HashSet&lt;u8&gt;&gt;&gt;, {closure@$DIR/multiline-removal-suggestion.rs:39:8: 39:23}&gt;&gt;: Iterator`</tspan>
+</tspan>
+    <tspan x="10px" y="3106px"><tspan>           `&lt;Flatten&lt;Map&lt;std::vec::IntoIter&lt;HashSet&lt;u8&gt;&gt;, {closure@$DIR/multiline-removal-suggestion.rs:40:23: 40:26}&gt;&gt; as IntoIterator&gt;::Item = _`</tspan>
+</tspan>
+    <tspan x="10px" y="3124px"><tspan>           which is required by `Flatten&lt;Map&lt;std::collections::hash_map::IntoIter&lt;bool, Vec&lt;HashSet&lt;u8&gt;&gt;&gt;, {closure@$DIR/multiline-removal-suggestion.rs:39:8: 39:23}&gt;&gt;: Iterator`</tspan>
+</tspan>
+    <tspan x="10px" y="3142px"><tspan>           `Flatten&lt;Map&lt;std::vec::IntoIter&lt;HashSet&lt;u8&gt;&gt;, {closure@$DIR/multiline-removal-suggestion.rs:40:23: 40:26}&gt;&gt;: IntoIterator`</tspan>
+</tspan>
+    <tspan x="10px" y="3160px"><tspan>           which is required by `Flatten&lt;Map&lt;std::collections::hash_map::IntoIter&lt;bool, Vec&lt;HashSet&lt;u8&gt;&gt;&gt;, {closure@$DIR/multiline-removal-suggestion.rs:39:8: 39:23}&gt;&gt;: Iterator`</tspan>
+</tspan>
+    <tspan x="10px" y="3178px"><tspan>           `Flatten&lt;Map&lt;std::collections::hash_map::IntoIter&lt;bool, Vec&lt;HashSet&lt;u8&gt;&gt;&gt;, {closure@$DIR/multiline-removal-suggestion.rs:39:8: 39:23}&gt;&gt;: Iterator`</tspan>
+</tspan>
+    <tspan x="10px" y="3196px"><tspan>           which is required by `&amp;mut Flatten&lt;Map&lt;std::collections::hash_map::IntoIter&lt;bool, Vec&lt;HashSet&lt;u8&gt;&gt;&gt;, {closure@$DIR/multiline-removal-suggestion.rs:39:8: 39:23}&gt;&gt;: Iterator`</tspan>
+</tspan>
+    <tspan x="10px" y="3214px">
+</tspan>
+    <tspan x="10px" y="3232px"><tspan class="fg-ansi256-009 bold">error[E0277]</tspan><tspan class="bold">: `(bool, HashSet&lt;u8&gt;)` is not an iterator</tspan>
+</tspan>
+    <tspan x="10px" y="3250px"><tspan>  </tspan><tspan class="fg-ansi256-012 bold">--&gt; </tspan><tspan>$DIR/multiline-removal-suggestion.rs:52:28</tspan>
+</tspan>
+    <tspan x="10px" y="3268px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="3286px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>                 .map(|t| (is_true, t)).flatten()</tspan>
+</tspan>
+    <tspan x="10px" y="3304px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>                                        </tspan><tspan class="fg-ansi256-009 bold">^^^^^^^</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">`(bool, HashSet&lt;u8&gt;)` is not an iterator</tspan>
+</tspan>
+    <tspan x="10px" y="3322px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="3340px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">= </tspan><tspan class="bold">help</tspan><tspan>: the trait `Iterator` is not implemented for `(bool, HashSet&lt;u8&gt;)`</tspan>
+</tspan>
+    <tspan x="10px" y="3358px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">= </tspan><tspan class="bold">note</tspan><tspan>: required for `(bool, HashSet&lt;u8&gt;)` to implement `IntoIterator`</tspan>
+</tspan>
+    <tspan x="10px" y="3376px"><tspan class="fg-ansi256-010 bold">note</tspan><tspan>: required by a bound in `flatten`</tspan>
+</tspan>
+    <tspan x="10px" y="3394px"><tspan>  </tspan><tspan class="fg-ansi256-012 bold">--&gt; </tspan><tspan>$SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL</tspan>
+</tspan>
+    <tspan x="10px" y="3412px"><tspan class="fg-ansi256-014 bold">help</tspan><tspan>: consider removing this method call, as the receiver has type `std::vec::IntoIter&lt;HashSet&lt;u8&gt;&gt;` and `std::vec::IntoIter&lt;HashSet&lt;u8&gt;&gt;: Iterator` trivially holds</tspan>
+</tspan>
+    <tspan x="10px" y="3430px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="3448px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-009">- </tspan><tspan>            ts.into_iter()</tspan>
+</tspan>
+    <tspan x="10px" y="3466px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-009">-                 .map(|t| (is_true, t))</tspan><tspan>.flatten()</tspan>
+</tspan>
+    <tspan x="10px" y="3484px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-010">+ </tspan><tspan>            ts.into_iter().flatten()</tspan>
+</tspan>
+    <tspan x="10px" y="3502px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="3520px">
+</tspan>
+    <tspan x="10px" y="3538px"><tspan class="fg-ansi256-009 bold">error[E0277]</tspan><tspan class="bold">: `(bool, HashSet&lt;u8&gt;)` is not an iterator</tspan>
+</tspan>
+    <tspan x="10px" y="3556px"><tspan>  </tspan><tspan class="fg-ansi256-012 bold">--&gt; </tspan><tspan>$DIR/multiline-removal-suggestion.rs:49:2</tspan>
+</tspan>
+    <tspan x="10px" y="3574px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="3592px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">/</tspan><tspan>     hm.into_iter()</tspan>
+</tspan>
+    <tspan x="10px" y="3610px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">|</tspan><tspan>         .map(|(is_true, ts)| {</tspan>
+</tspan>
+    <tspan x="10px" y="3628px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">|</tspan><tspan>             ts.into_iter()</tspan>
+</tspan>
+    <tspan x="10px" y="3646px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">|</tspan><tspan>                 .map(|t| (is_true, t)).flatten()</tspan>
+</tspan>
+    <tspan x="10px" y="3664px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">|</tspan><tspan>         })</tspan>
+</tspan>
+    <tspan x="10px" y="3682px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">|__________^</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">`(bool, HashSet&lt;u8&gt;)` is not an iterator</tspan>
+</tspan>
+    <tspan x="10px" y="3700px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="3718px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">= </tspan><tspan class="bold">help</tspan><tspan>: the trait `Iterator` is not implemented for `(bool, HashSet&lt;u8&gt;)`</tspan>
+</tspan>
+    <tspan x="10px" y="3736px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">= </tspan><tspan class="bold">note</tspan><tspan>: required for `(bool, HashSet&lt;u8&gt;)` to implement `IntoIterator`</tspan>
+</tspan>
+    <tspan x="10px" y="3754px"><tspan class="fg-ansi256-010 bold">note</tspan><tspan>: required by a bound in `Flatten`</tspan>
+</tspan>
+    <tspan x="10px" y="3772px"><tspan>  </tspan><tspan class="fg-ansi256-012 bold">--&gt; </tspan><tspan>$SRC_DIR/core/src/iter/adapters/flatten.rs:LL:COL</tspan>
+</tspan>
+    <tspan x="10px" y="3790px">
+</tspan>
+    <tspan x="10px" y="3808px"><tspan class="fg-ansi256-009 bold">error[E0599]</tspan><tspan class="bold">: the method `collect` exists for struct `Flatten&lt;Map&lt;IntoIter&lt;bool, Vec&lt;HashSet&lt;u8&gt;&gt;&gt;, {closure@multiline-removal-suggestion.rs:50:8}&gt;&gt;`, but its trait bounds were not satisfied</tspan>
+</tspan>
+    <tspan x="10px" y="3826px"><tspan>  </tspan><tspan class="fg-ansi256-012 bold">--&gt; </tspan><tspan>$DIR/multiline-removal-suggestion.rs:55:4</tspan>
+</tspan>
+    <tspan x="10px" y="3844px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="3862px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">/</tspan><tspan>     hm.into_iter()</tspan>
+</tspan>
+    <tspan x="10px" y="3880px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>         .map(|(is_true, ts)| {</tspan>
+</tspan>
+    <tspan x="10px" y="3898px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>             ts.into_iter()</tspan>
+</tspan>
+    <tspan x="10px" y="3916px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>                 .map(|t| (is_true, t)).flatten()</tspan>
+</tspan>
+    <tspan x="10px" y="3934px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>         })</tspan>
+</tspan>
+    <tspan x="10px" y="3952px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>         .flatten()</tspan>
+</tspan>
+    <tspan x="10px" y="3970px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>         .collect()</tspan>
+</tspan>
+    <tspan x="10px" y="3988px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>         </tspan><tspan class="fg-ansi256-012 bold">-</tspan><tspan class="fg-ansi256-009 bold">^^^^^^^</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">method cannot be called due to unsatisfied trait bounds</tspan>
+</tspan>
+    <tspan x="10px" y="4006px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|_________|</tspan>
+</tspan>
+    <tspan x="10px" y="4024px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="4042px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
+</tspan>
+    <tspan x="10px" y="4060px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">= </tspan><tspan class="bold">note</tspan><tspan>: the following trait bounds were not satisfied:</tspan>
+</tspan>
+    <tspan x="10px" y="4078px"><tspan>           `&lt;Flatten&lt;Map&lt;std::vec::IntoIter&lt;HashSet&lt;u8&gt;&gt;, {closure@$DIR/multiline-removal-suggestion.rs:52:10: 52:13}&gt;&gt; as IntoIterator&gt;::IntoIter = _`</tspan>
+</tspan>
+    <tspan x="10px" y="4096px"><tspan>           which is required by `Flatten&lt;Map&lt;std::collections::hash_map::IntoIter&lt;bool, Vec&lt;HashSet&lt;u8&gt;&gt;&gt;, {closure@$DIR/multiline-removal-suggestion.rs:50:8: 50:23}&gt;&gt;: Iterator`</tspan>
+</tspan>
+    <tspan x="10px" y="4114px"><tspan>           `&lt;Flatten&lt;Map&lt;std::vec::IntoIter&lt;HashSet&lt;u8&gt;&gt;, {closure@$DIR/multiline-removal-suggestion.rs:52:10: 52:13}&gt;&gt; as IntoIterator&gt;::Item = _`</tspan>
+</tspan>
+    <tspan x="10px" y="4132px"><tspan>           which is required by `Flatten&lt;Map&lt;std::collections::hash_map::IntoIter&lt;bool, Vec&lt;HashSet&lt;u8&gt;&gt;&gt;, {closure@$DIR/multiline-removal-suggestion.rs:50:8: 50:23}&gt;&gt;: Iterator`</tspan>
+</tspan>
+    <tspan x="10px" y="4150px"><tspan>           `Flatten&lt;Map&lt;std::vec::IntoIter&lt;HashSet&lt;u8&gt;&gt;, {closure@$DIR/multiline-removal-suggestion.rs:52:10: 52:13}&gt;&gt;: IntoIterator`</tspan>
+</tspan>
+    <tspan x="10px" y="4168px"><tspan>           which is required by `Flatten&lt;Map&lt;std::collections::hash_map::IntoIter&lt;bool, Vec&lt;HashSet&lt;u8&gt;&gt;&gt;, {closure@$DIR/multiline-removal-suggestion.rs:50:8: 50:23}&gt;&gt;: Iterator`</tspan>
+</tspan>
+    <tspan x="10px" y="4186px"><tspan>           `Flatten&lt;Map&lt;std::collections::hash_map::IntoIter&lt;bool, Vec&lt;HashSet&lt;u8&gt;&gt;&gt;, {closure@$DIR/multiline-removal-suggestion.rs:50:8: 50:23}&gt;&gt;: Iterator`</tspan>
+</tspan>
+    <tspan x="10px" y="4204px"><tspan>           which is required by `&amp;mut Flatten&lt;Map&lt;std::collections::hash_map::IntoIter&lt;bool, Vec&lt;HashSet&lt;u8&gt;&gt;&gt;, {closure@$DIR/multiline-removal-suggestion.rs:50:8: 50:23}&gt;&gt;: Iterator`</tspan>
+</tspan>
+    <tspan x="10px" y="4222px">
+</tspan>
+    <tspan x="10px" y="4240px"><tspan class="fg-ansi256-009 bold">error</tspan><tspan class="bold">: aborting due to 12 previous errors</tspan>
+</tspan>
+    <tspan x="10px" y="4258px">
+</tspan>
+    <tspan x="10px" y="4276px"><tspan class="bold">Some errors have detailed explanations: E0277, E0599.</tspan>
+</tspan>
+    <tspan x="10px" y="4294px"><tspan class="bold">For more information about an error, try `rustc --explain E0277`.</tspan>
+</tspan>
+    <tspan x="10px" y="4312px">
+</tspan>
+  </text>
+
+</svg>
diff --git a/tests/ui/panics/default-backtrace-ice.rs b/tests/ui/panics/default-backtrace-ice.rs
index 718d1da5bb759..7953283f02813 100644
--- a/tests/ui/panics/default-backtrace-ice.rs
+++ b/tests/ui/panics/default-backtrace-ice.rs
@@ -1,6 +1,8 @@
 //@ unset-rustc-env:RUST_BACKTRACE
 //@ compile-flags:-Z treat-err-as-bug=1
 //@ error-pattern:stack backtrace:
+// Verify this is a full backtrace, not a short backtrace.
+//@ error-pattern:__rust_begin_short_backtrace
 //@ failure-status:101
 //@ ignore-msvc
 //@ normalize-stderr-test: "note: .*" -> ""
diff --git a/tests/ui/panics/default-backtrace-ice.stderr b/tests/ui/panics/default-backtrace-ice.stderr
index 23b863568bc74..046b2cca7f9be 100644
--- a/tests/ui/panics/default-backtrace-ice.stderr
+++ b/tests/ui/panics/default-backtrace-ice.stderr
@@ -1,5 +1,5 @@
 error: internal compiler error[E0425]: cannot find value `missing_ident` in this scope
-  --> $DIR/default-backtrace-ice.rs:21:13
+  --> $DIR/default-backtrace-ice.rs:23:13
    |
 LL | fn main() { missing_ident; }
    |             ^^^^^^^^^^^^^ not found in this scope
diff --git a/tests/ui/panics/issue-47429-short-backtraces.rs b/tests/ui/panics/issue-47429-short-backtraces.rs
index 0d216fdd6530f..56b9cfcd36153 100644
--- a/tests/ui/panics/issue-47429-short-backtraces.rs
+++ b/tests/ui/panics/issue-47429-short-backtraces.rs
@@ -9,6 +9,8 @@
 // This is needed to avoid test output differences across std being built with v0 symbols vs legacy
 // symbols.
 //@ normalize-stderr-test: "begin_panic::<&str>" -> "begin_panic"
+// This variant occurs on macOS with `rust.debuginfo-level = "line-tables-only"` (#133997)
+//@ normalize-stderr-test: " begin_panic<&str>" -> " std::panicking::begin_panic"
 // And this is for differences between std with and without debuginfo.
 //@ normalize-stderr-test: "\n +at [^\n]+" -> ""
 
diff --git a/tests/ui/panics/issue-47429-short-backtraces.run.stderr b/tests/ui/panics/issue-47429-short-backtraces.run.stderr
index 1078a2fbc9025..6a22e0215fee1 100644
--- a/tests/ui/panics/issue-47429-short-backtraces.run.stderr
+++ b/tests/ui/panics/issue-47429-short-backtraces.run.stderr
@@ -1,4 +1,4 @@
-thread 'main' panicked at $DIR/issue-47429-short-backtraces.rs:24:5:
+thread 'main' panicked at $DIR/issue-47429-short-backtraces.rs:26:5:
 explicit panic
 stack backtrace:
    0: std::panicking::begin_panic
diff --git a/tests/ui/panics/runtime-switch.rs b/tests/ui/panics/runtime-switch.rs
index 10dce25090932..e06f05d5fe8e5 100644
--- a/tests/ui/panics/runtime-switch.rs
+++ b/tests/ui/panics/runtime-switch.rs
@@ -9,6 +9,8 @@
 // This is needed to avoid test output differences across std being built with v0 symbols vs legacy
 // symbols.
 //@ normalize-stderr-test: "begin_panic::<&str>" -> "begin_panic"
+// This variant occurs on macOS with `rust.debuginfo-level = "line-tables-only"` (#133997)
+//@ normalize-stderr-test: " begin_panic<&str>" -> " std::panicking::begin_panic"
 // And this is for differences between std with and without debuginfo.
 //@ normalize-stderr-test: "\n +at [^\n]+" -> ""
 
diff --git a/tests/ui/panics/runtime-switch.run.stderr b/tests/ui/panics/runtime-switch.run.stderr
index abbb91eba60e0..35be010d6be71 100644
--- a/tests/ui/panics/runtime-switch.run.stderr
+++ b/tests/ui/panics/runtime-switch.run.stderr
@@ -1,4 +1,4 @@
-thread 'main' panicked at $DIR/runtime-switch.rs:27:5:
+thread 'main' panicked at $DIR/runtime-switch.rs:29:5:
 explicit panic
 stack backtrace:
    0: std::panicking::begin_panic
diff --git a/tests/ui/panics/short-ice-remove-middle-frames-2.rs b/tests/ui/panics/short-ice-remove-middle-frames-2.rs
index c2f04cd122c73..9b6d34d97b2f2 100644
--- a/tests/ui/panics/short-ice-remove-middle-frames-2.rs
+++ b/tests/ui/panics/short-ice-remove-middle-frames-2.rs
@@ -12,6 +12,8 @@
 // This is needed to avoid test output differences across std being built with v0 symbols vs legacy
 // symbols.
 //@ normalize-stderr-test: "begin_panic::<&str>" -> "begin_panic"
+// This variant occurs on macOS with `rust.debuginfo-level = "line-tables-only"` (#133997)
+//@ normalize-stderr-test: " begin_panic<&str>" -> " std::panicking::begin_panic"
 // And this is for differences between std with and without debuginfo.
 //@ normalize-stderr-test: "\n +at [^\n]+" -> ""
 
diff --git a/tests/ui/panics/short-ice-remove-middle-frames-2.run.stderr b/tests/ui/panics/short-ice-remove-middle-frames-2.run.stderr
index 67577f3568e91..ab23ce7806257 100644
--- a/tests/ui/panics/short-ice-remove-middle-frames-2.run.stderr
+++ b/tests/ui/panics/short-ice-remove-middle-frames-2.run.stderr
@@ -1,4 +1,4 @@
-thread 'main' panicked at $DIR/short-ice-remove-middle-frames-2.rs:61:5:
+thread 'main' panicked at $DIR/short-ice-remove-middle-frames-2.rs:63:5:
 debug!!!
 stack backtrace:
    0: std::panicking::begin_panic
diff --git a/tests/ui/panics/short-ice-remove-middle-frames.rs b/tests/ui/panics/short-ice-remove-middle-frames.rs
index c035e7e69bc63..b1af247130b1b 100644
--- a/tests/ui/panics/short-ice-remove-middle-frames.rs
+++ b/tests/ui/panics/short-ice-remove-middle-frames.rs
@@ -13,6 +13,8 @@
 // This is needed to avoid test output differences across std being built with v0 symbols vs legacy
 // symbols.
 //@ normalize-stderr-test: "begin_panic::<&str>" -> "begin_panic"
+// This variant occurs on macOS with `rust.debuginfo-level = "line-tables-only"` (#133997)
+//@ normalize-stderr-test: " begin_panic<&str>" -> " std::panicking::begin_panic"
 // And this is for differences between std with and without debuginfo.
 //@ normalize-stderr-test: "\n +at [^\n]+" -> ""
 
diff --git a/tests/ui/panics/short-ice-remove-middle-frames.run.stderr b/tests/ui/panics/short-ice-remove-middle-frames.run.stderr
index 63fa466ab24ad..d2616911e3bf8 100644
--- a/tests/ui/panics/short-ice-remove-middle-frames.run.stderr
+++ b/tests/ui/panics/short-ice-remove-middle-frames.run.stderr
@@ -1,4 +1,4 @@
-thread 'main' panicked at $DIR/short-ice-remove-middle-frames.rs:57:5:
+thread 'main' panicked at $DIR/short-ice-remove-middle-frames.rs:59:5:
 debug!!!
 stack backtrace:
    0: std::panicking::begin_panic