miri/

diagnostics.rs

use std::fmt::{self, Write};
use std::num::NonZero;

use rustc_abi::{Align, Size};
use rustc_errors::{Diag, DiagMessage, Level};
use rustc_span::{DUMMY_SP, SpanData, Symbol};

use crate::borrow_tracker::stacked_borrows::diagnostics::TagHistory;
use crate::borrow_tracker::tree_borrows::diagnostics as tree_diagnostics;
use crate::*;

/// Details of premature program termination.
pub enum TerminationInfo {
    Exit {
        code: i64,
        leak_check: bool,
    },
    Abort(String),
    UnsupportedInIsolation(String),
    StackedBorrowsUb {
        msg: String,
        help: Vec<String>,
        history: Option<TagHistory>,
    },
    TreeBorrowsUb {
        title: String,
        details: Vec<String>,
        history: tree_diagnostics::HistoryData,
    },
    Int2PtrWithStrictProvenance,
    Deadlock,
    MultipleSymbolDefinitions {
        link_name: Symbol,
        first: SpanData,
        first_crate: Symbol,
        second: SpanData,
        second_crate: Symbol,
    },
    SymbolShimClashing {
        link_name: Symbol,
        span: SpanData,
    },
    DataRace {
        involves_non_atomic: bool,
        ptr: interpret::Pointer<AllocId>,
        op1: RacingOp,
        op2: RacingOp,
        extra: Option<&'static str>,
        retag_explain: bool,
    },
    UnsupportedForeignItem(String),
}

pub struct RacingOp {
    pub action: String,
    pub thread_info: String,
    pub span: SpanData,
}

impl fmt::Display for TerminationInfo {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        use TerminationInfo::*;
        match self {
            Exit { code, .. } => write!(f, "the evaluated program completed with exit code {code}"),
            Abort(msg) => write!(f, "{msg}"),
            UnsupportedInIsolation(msg) => write!(f, "{msg}"),
            Int2PtrWithStrictProvenance =>
                write!(
                    f,
                    "integer-to-pointer casts and `ptr::with_exposed_provenance` are not supported with `-Zmiri-strict-provenance`"
                ),
            StackedBorrowsUb { msg, .. } => write!(f, "{msg}"),
            TreeBorrowsUb { title, .. } => write!(f, "{title}"),
            Deadlock => write!(f, "the evaluated program deadlocked"),
            MultipleSymbolDefinitions { link_name, .. } =>
                write!(f, "multiple definitions of symbol `{link_name}`"),
            SymbolShimClashing { link_name, .. } =>
                write!(f, "found `{link_name}` symbol definition that clashes with a built-in shim",),
            DataRace { involves_non_atomic, ptr, op1, op2, .. } =>
                write!(
                    f,
                    "{} detected between (1) {} on {} and (2) {} on {} at {ptr:?}. (2) just happened here",
                    if *involves_non_atomic { "Data race" } else { "Race condition" },
                    op1.action,
                    op1.thread_info,
                    op2.action,
                    op2.thread_info
                ),
            UnsupportedForeignItem(msg) => write!(f, "{msg}"),
        }
    }
}

impl fmt::Debug for TerminationInfo {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "{self}")
    }
}

impl MachineStopType for TerminationInfo {
    fn diagnostic_message(&self) -> DiagMessage {
        self.to_string().into()
    }
    fn add_args(
        self: Box<Self>,
        _: &mut dyn FnMut(std::borrow::Cow<'static, str>, rustc_errors::DiagArgValue),
    ) {
    }
}

/// Miri specific diagnostics
pub enum NonHaltingDiagnostic {
    /// (new_tag, new_perm, (alloc_id, base_offset, orig_tag))
    ///
    /// new_perm is `None` for base tags.
    CreatedPointerTag(NonZero<u64>, Option<String>, Option<(AllocId, AllocRange, ProvenanceExtra)>),
    /// This `Item` was popped from the borrow stack. The string explains the reason.
    PoppedPointerTag(Item, String),
    CreatedAlloc(AllocId, Size, Align, MemoryKind),
    FreedAlloc(AllocId),
    AccessedAlloc(AllocId, AccessKind),
    RejectedIsolatedOp(String),
    ProgressReport {
        block_count: u64, // how many basic blocks have been run so far
    },
    Int2Ptr {
        details: bool,
    },
    WeakMemoryOutdatedLoad {
        ptr: Pointer,
    },
    ExternTypeReborrow,
}

/// Level of Miri specific diagnostics
pub enum DiagLevel {
    Error,
    Warning,
    Note,
}

/// Generate a note/help text without a span.
macro_rules! note {
    ($($tt:tt)*) => { (None, format!($($tt)*)) };
}
/// Generate a note/help text with a span.
macro_rules! note_span {
    ($span:expr, $($tt:tt)*) => { (Some($span), format!($($tt)*)) };
}

/// Attempts to prune a stacktrace to omit the Rust runtime, and returns a bool indicating if any
/// frames were pruned. If the stacktrace does not have any local frames, we conclude that it must
/// be pointing to a problem in the Rust runtime itself, and do not prune it at all.
pub fn prune_stacktrace<'tcx>(
    mut stacktrace: Vec<FrameInfo<'tcx>>,
    machine: &MiriMachine<'tcx>,
) -> (Vec<FrameInfo<'tcx>>, bool) {
    match machine.backtrace_style {
        BacktraceStyle::Off => {
            // Remove all frames marked with `caller_location` -- that attribute indicates we
            // usually want to point at the caller, not them.
            stacktrace.retain(|frame| !frame.instance.def.requires_caller_location(machine.tcx));
            // Retain one frame so that we can print a span for the error itself
            stacktrace.truncate(1);
            (stacktrace, false)
        }
        BacktraceStyle::Short => {
            let original_len = stacktrace.len();
            // Only prune frames if there is at least one local frame. This check ensures that if
            // we get a backtrace that never makes it to the user code because it has detected a
            // bug in the Rust runtime, we don't prune away every frame.
            let has_local_frame = stacktrace.iter().any(|frame| machine.is_local(frame));
            if has_local_frame {
                // Remove all frames marked with `caller_location` -- that attribute indicates we
                // usually want to point at the caller, not them.
                stacktrace
                    .retain(|frame| !frame.instance.def.requires_caller_location(machine.tcx));

                // This is part of the logic that `std` uses to select the relevant part of a
                // backtrace. But here, we only look for __rust_begin_short_backtrace, not
                // __rust_end_short_backtrace because the end symbol comes from a call to the default
                // panic handler.
                stacktrace = stacktrace
                    .into_iter()
                    .take_while(|frame| {
                        let def_id = frame.instance.def_id();
                        let path = machine.tcx.def_path_str(def_id);
                        !path.contains("__rust_begin_short_backtrace")
                    })
                    .collect::<Vec<_>>();

                // After we prune frames from the bottom, there are a few left that are part of the
                // Rust runtime. So we remove frames until we get to a local symbol, which should be
                // main or a test.
                // This len check ensures that we don't somehow remove every frame, as doing so breaks
                // the primary error message.
                while stacktrace.len() > 1
                    && stacktrace.last().map_or(false, |frame| !machine.is_local(frame))
                {
                    stacktrace.pop();
                }
            }
            let was_pruned = stacktrace.len() != original_len;
            (stacktrace, was_pruned)
        }
        BacktraceStyle::Full => (stacktrace, false),
    }
}

/// Emit a custom diagnostic without going through the miri-engine machinery.
///
/// Returns `Some` if this was regular program termination with a given exit code and a `bool` indicating whether a leak check should happen; `None` otherwise.
pub fn report_error<'tcx>(
    ecx: &InterpCx<'tcx, MiriMachine<'tcx>>,
    e: InterpErrorInfo<'tcx>,
) -> Option<(i64, bool)> {
    use InterpErrorKind::*;
    use UndefinedBehaviorInfo::*;

    let mut msg = vec![];

    let (title, helps) = if let MachineStop(info) = e.kind() {
        let info = info.downcast_ref::<TerminationInfo>().expect("invalid MachineStop payload");
        use TerminationInfo::*;
        let title = match info {
            &Exit { code, leak_check } => return Some((code, leak_check)),
            Abort(_) => Some("abnormal termination"),
            UnsupportedInIsolation(_) | Int2PtrWithStrictProvenance | UnsupportedForeignItem(_) =>
                Some("unsupported operation"),
            StackedBorrowsUb { .. } | TreeBorrowsUb { .. } | DataRace { .. } =>
                Some("Undefined Behavior"),
            Deadlock => Some("deadlock"),
            MultipleSymbolDefinitions { .. } | SymbolShimClashing { .. } => None,
        };
        #[rustfmt::skip]
        let helps = match info {
            UnsupportedInIsolation(_) =>
                vec![
                    note!("set `MIRIFLAGS=-Zmiri-disable-isolation` to disable isolation;"),
                    note!("or set `MIRIFLAGS=-Zmiri-isolation-error=warn` to make Miri return an error code from isolated operations (if supported for that operation) and continue with a warning"),
                ],
            UnsupportedForeignItem(_) => {
                vec![
                    note!("if this is a basic API commonly used on this target, please report an issue with Miri"),
                    note!("however, note that Miri does not aim to support every FFI function out there; for instance, we will not support APIs for things such as GUIs, scripting languages, or databases"),
                ]
            }
            StackedBorrowsUb { help, history, .. } => {
                msg.extend(help.clone());
                let mut helps = vec![
                    note!("this indicates a potential bug in the program: it performed an invalid operation, but the Stacked Borrows rules it violated are still experimental"),
                    note!("see https://github.com/rust-lang/unsafe-code-guidelines/blob/master/wip/stacked-borrows.md for further information"),
                ];
                if let Some(TagHistory {created, invalidated, protected}) = history.clone() {
                    helps.push((Some(created.1), created.0));
                    if let Some((msg, span)) = invalidated {
                        helps.push(note_span!(span, "{msg}"));
                    }
                    if let Some((protector_msg, protector_span)) = protected {
                        helps.push(note_span!(protector_span, "{protector_msg}"));
                    }
                }
                helps
            },
            TreeBorrowsUb { title: _, details, history } => {
                let mut helps = vec![
                    note!("this indicates a potential bug in the program: it performed an invalid operation, but the Tree Borrows rules it violated are still experimental")
                ];
                for m in details {
                    helps.push(note!("{m}"));
                }
                for event in history.events.clone() {
                    helps.push(event);
                }
                helps
            }
            MultipleSymbolDefinitions { first, first_crate, second, second_crate, .. } =>
                vec![
                    note_span!(*first, "it's first defined here, in crate `{first_crate}`"),
                    note_span!(*second, "then it's defined here again, in crate `{second_crate}`"),
                ],
            SymbolShimClashing { link_name, span } =>
                vec![note_span!(*span, "the `{link_name}` symbol is defined here")],
            Int2PtrWithStrictProvenance =>
                vec![note!("use Strict Provenance APIs (https://doc.rust-lang.org/nightly/std/ptr/index.html#strict-provenance, https://crates.io/crates/sptr) instead")],
            DataRace { op1, extra, retag_explain, .. } => {
                let mut helps = vec![note_span!(op1.span, "and (1) occurred earlier here")];
                if let Some(extra) = extra {
                    helps.push(note!("{extra}"));
                    helps.push(note!("see https://doc.rust-lang.org/nightly/std/sync/atomic/index.html#memory-model-for-atomic-accesses for more information about the Rust memory model"));
                }
                if *retag_explain {
                    helps.push(note!("retags occur on all (re)borrows and as well as when references are copied or moved"));
                    helps.push(note!("retags permit optimizations that insert speculative reads or writes"));
                    helps.push(note!("therefore from the perspective of data races, a retag has the same implications as a read or write"));
                }
                helps.push(note!("this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior"));
                helps.push(note!("see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information"));
                helps
            }
                ,
            _ => vec![],
        };
        (title, helps)
    } else {
        let title = match e.kind() {
            UndefinedBehavior(ValidationError(validation_err))
                if matches!(
                    validation_err.kind,
                    ValidationErrorKind::PointerAsInt { .. } | ValidationErrorKind::PartialPointer
                ) =>
            {
                ecx.handle_ice(); // print interpreter backtrace (this is outside the eval `catch_unwind`)
                bug!(
                    "This validation error should be impossible in Miri: {}",
                    format_interp_error(ecx.tcx.dcx(), e)
                );
            }
            UndefinedBehavior(_) => "Undefined Behavior",
            ResourceExhaustion(_) => "resource exhaustion",
            Unsupported(
                // We list only the ones that can actually happen.
                UnsupportedOpInfo::Unsupported(_)
                | UnsupportedOpInfo::UnsizedLocal
                | UnsupportedOpInfo::ExternTypeField,
            ) => "unsupported operation",
            InvalidProgram(
                // We list only the ones that can actually happen.
                InvalidProgramInfo::AlreadyReported(_) | InvalidProgramInfo::Layout(..),
            ) => "post-monomorphization error",
            _ => {
                ecx.handle_ice(); // print interpreter backtrace (this is outside the eval `catch_unwind`)
                bug!(
                    "This error should be impossible in Miri: {}",
                    format_interp_error(ecx.tcx.dcx(), e)
                );
            }
        };
        #[rustfmt::skip]
        let helps = match e.kind() {
            Unsupported(_) =>
                vec![
                    note!("this is likely not a bug in the program; it indicates that the program performed an operation that Miri does not support"),
                ],
            UndefinedBehavior(AlignmentCheckFailed { .. })
                if ecx.machine.check_alignment == AlignmentCheck::Symbolic
            =>
                vec![
                    note!("this usually indicates that your program performed an invalid operation and caused Undefined Behavior"),
                    note!("but due to `-Zmiri-symbolic-alignment-check`, alignment errors can also be false positives"),
                ],
            UndefinedBehavior(info) => {
                let mut helps = vec![
                    note!("this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior"),
                    note!("see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information"),
                ];
                match info {
                    PointerUseAfterFree(alloc_id, _) | PointerOutOfBounds { alloc_id, .. } => {
                        if let Some(span) = ecx.machine.allocated_span(*alloc_id) {
                            helps.push(note_span!(span, "{:?} was allocated here:", alloc_id));
                        }
                        if let Some(span) = ecx.machine.deallocated_span(*alloc_id) {
                            helps.push(note_span!(span, "{:?} was deallocated here:", alloc_id));
                        }
                    }
                    AbiMismatchArgument { .. } | AbiMismatchReturn { .. } => {
                        helps.push(note!("this means these two types are not *guaranteed* to be ABI-compatible across all targets"));
                        helps.push(note!("if you think this code should be accepted anyway, please report an issue with Miri"));
                    }
                    _ => {},
                }
                helps
            }
            InvalidProgram(
                InvalidProgramInfo::AlreadyReported(_)
            ) => {
                // This got already reported. No point in reporting it again.
                return None;
            }
            _ =>
                vec![],
        };
        (Some(title), helps)
    };

    let stacktrace = ecx.generate_stacktrace();
    let (stacktrace, mut any_pruned) = prune_stacktrace(stacktrace, &ecx.machine);

    let mut show_all_threads = false;

    // We want to dump the allocation if this is `InvalidUninitBytes`.
    // Since `format_interp_error` consumes `e`, we compute the outut early.
    let mut extra = String::new();
    match e.kind() {
        UndefinedBehavior(InvalidUninitBytes(Some((alloc_id, access)))) => {
            writeln!(
                extra,
                "Uninitialized memory occurred at {alloc_id:?}{range:?}, in this allocation:",
                range = access.bad,
            )
            .unwrap();
            writeln!(extra, "{:?}", ecx.dump_alloc(*alloc_id)).unwrap();
        }
        MachineStop(info) => {
            let info = info.downcast_ref::<TerminationInfo>().expect("invalid MachineStop payload");
            match info {
                TerminationInfo::Deadlock => {
                    show_all_threads = true;
                }
                _ => {}
            }
        }
        _ => {}
    }

    msg.insert(0, format_interp_error(ecx.tcx.dcx(), e));

    report_msg(
        DiagLevel::Error,
        if let Some(title) = title { format!("{title}: {}", msg[0]) } else { msg[0].clone() },
        msg,
        vec![],
        helps,
        &stacktrace,
        Some(ecx.active_thread()),
        &ecx.machine,
    );

    eprint!("{extra}"); // newlines are already in the string

    if show_all_threads {
        for (thread, stack) in ecx.machine.threads.all_stacks() {
            if thread != ecx.active_thread() {
                let stacktrace = Frame::generate_stacktrace_from_stack(stack);
                let (stacktrace, was_pruned) = prune_stacktrace(stacktrace, &ecx.machine);
                any_pruned |= was_pruned;
                report_msg(
                    DiagLevel::Error,
                    format!("deadlock: the evaluated program deadlocked"),
                    vec![format!("the evaluated program deadlocked")],
                    vec![],
                    vec![],
                    &stacktrace,
                    Some(thread),
                    &ecx.machine,
                )
            }
        }
    }

    // Include a note like `std` does when we omit frames from a backtrace
    if any_pruned {
        ecx.tcx.dcx().note(
            "some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace",
        );
    }

    // Debug-dump all locals.
    for (i, frame) in ecx.active_thread_stack().iter().enumerate() {
        trace!("-------------------");
        trace!("Frame {}", i);
        trace!("    return: {:?}", frame.return_place);
        for (i, local) in frame.locals.iter().enumerate() {
            trace!("    local {}: {:?}", i, local);
        }
    }

    None
}

pub fn report_leaks<'tcx>(
    ecx: &InterpCx<'tcx, MiriMachine<'tcx>>,
    leaks: Vec<(AllocId, MemoryKind, Allocation<Provenance, AllocExtra<'tcx>, MiriAllocBytes>)>,
) {
    let mut any_pruned = false;
    for (id, kind, alloc) in leaks {
        let mut title = format!(
            "memory leaked: {id:?} ({}, size: {:?}, align: {:?})",
            kind,
            alloc.size().bytes(),
            alloc.align.bytes()
        );
        let Some(backtrace) = alloc.extra.backtrace else {
            ecx.tcx.dcx().err(title);
            continue;
        };
        title.push_str(", allocated here:");
        let (backtrace, pruned) = prune_stacktrace(backtrace, &ecx.machine);
        any_pruned |= pruned;
        report_msg(
            DiagLevel::Error,
            title,
            vec![],
            vec![],
            vec![],
            &backtrace,
            None, // we don't know the thread this is from
            &ecx.machine,
        );
    }
    if any_pruned {
        ecx.tcx.dcx().note(
            "some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace",
        );
    }
}

/// Report an error or note (depending on the `error` argument) with the given stacktrace.
/// Also emits a full stacktrace of the interpreter stack.
/// We want to present a multi-line span message for some errors. Diagnostics do not support this
/// directly, so we pass the lines as a `Vec<String>` and display each line after the first with an
/// additional `span_label` or `note` call.
pub fn report_msg<'tcx>(
    diag_level: DiagLevel,
    title: String,
    span_msg: Vec<String>,
    notes: Vec<(Option<SpanData>, String)>,
    helps: Vec<(Option<SpanData>, String)>,
    stacktrace: &[FrameInfo<'tcx>],
    thread: Option<ThreadId>,
    machine: &MiriMachine<'tcx>,
) {
    let span = stacktrace.first().map_or(DUMMY_SP, |fi| fi.span);
    let sess = machine.tcx.sess;
    let level = match diag_level {
        DiagLevel::Error => Level::Error,
        DiagLevel::Warning => Level::Warning,
        DiagLevel::Note => Level::Note,
    };
    let mut err = Diag::<()>::new(sess.dcx(), level, title);
    err.span(span);

    // Show main message.
    if span != DUMMY_SP {
        for line in span_msg {
            err.span_label(span, line);
        }
    } else {
        // Make sure we show the message even when it is a dummy span.
        for line in span_msg {
            err.note(line);
        }
        err.note("(no span available)");
    }

    // Show note and help messages.
    let mut extra_span = false;
    for (span_data, note) in notes {
        if let Some(span_data) = span_data {
            err.span_note(span_data.span(), note);
            extra_span = true;
        } else {
            err.note(note);
        }
    }
    for (span_data, help) in helps {
        if let Some(span_data) = span_data {
            err.span_help(span_data.span(), help);
            extra_span = true;
        } else {
            err.help(help);
        }
    }

    // Add backtrace
    let mut backtrace_title = String::from("BACKTRACE");
    if extra_span {
        write!(backtrace_title, " (of the first span)").unwrap();
    }
    if let Some(thread) = thread {
        let thread_name = machine.threads.get_thread_display_name(thread);
        if thread_name != "main" {
            // Only print thread name if it is not `main`.
            write!(backtrace_title, " on thread `{thread_name}`").unwrap();
        };
    }
    write!(backtrace_title, ":").unwrap();
    err.note(backtrace_title);
    for (idx, frame_info) in stacktrace.iter().enumerate() {
        let is_local = machine.is_local(frame_info);
        // No span for non-local frames and the first frame (which is the error site).
        if is_local && idx > 0 {
            err.subdiagnostic(frame_info.as_note(machine.tcx));
        } else {
            let sm = sess.source_map();
            let span = sm.span_to_embeddable_string(frame_info.span);
            err.note(format!("{frame_info} at {span}"));
        }
    }

    err.emit();
}

impl<'tcx> MiriMachine<'tcx> {
    pub fn emit_diagnostic(&self, e: NonHaltingDiagnostic) {
        use NonHaltingDiagnostic::*;

        let stacktrace = Frame::generate_stacktrace_from_stack(self.threads.active_thread_stack());
        let (stacktrace, _was_pruned) = prune_stacktrace(stacktrace, self);

        let (title, diag_level) = match &e {
            RejectedIsolatedOp(_) =>
                ("operation rejected by isolation".to_string(), DiagLevel::Warning),
            Int2Ptr { .. } => ("integer-to-pointer cast".to_string(), DiagLevel::Warning),
            ExternTypeReborrow =>
                ("reborrow of reference to `extern type`".to_string(), DiagLevel::Warning),
            CreatedPointerTag(..)
            | PoppedPointerTag(..)
            | CreatedAlloc(..)
            | AccessedAlloc(..)
            | FreedAlloc(..)
            | ProgressReport { .. }
            | WeakMemoryOutdatedLoad { .. } =>
                ("tracking was triggered".to_string(), DiagLevel::Note),
        };

        let msg = match &e {
            CreatedPointerTag(tag, None, _) => format!("created base tag {tag:?}"),
            CreatedPointerTag(tag, Some(perm), None) =>
                format!("created {tag:?} with {perm} derived from unknown tag"),
            CreatedPointerTag(tag, Some(perm), Some((alloc_id, range, orig_tag))) =>
                format!(
                    "created tag {tag:?} with {perm} at {alloc_id:?}{range:?} derived from {orig_tag:?}"
                ),
            PoppedPointerTag(item, cause) => format!("popped tracked tag for item {item:?}{cause}"),
            CreatedAlloc(AllocId(id), size, align, kind) =>
                format!(
                    "created {kind} allocation of {size} bytes (alignment {align} bytes) with id {id}",
                    size = size.bytes(),
                    align = align.bytes(),
                ),
            AccessedAlloc(AllocId(id), access_kind) =>
                format!("{access_kind} to allocation with id {id}"),
            FreedAlloc(AllocId(id)) => format!("freed allocation with id {id}"),
            RejectedIsolatedOp(ref op) =>
                format!("{op} was made to return an error due to isolation"),
            ProgressReport { .. } =>
                format!("progress report: current operation being executed is here"),
            Int2Ptr { .. } => format!("integer-to-pointer cast"),
            WeakMemoryOutdatedLoad { ptr } =>
                format!("weak memory emulation: outdated value returned from load at {ptr}"),
            ExternTypeReborrow =>
                format!("reborrow of a reference to `extern type` is not properly supported"),
        };

        let notes = match &e {
            ProgressReport { block_count } => {
                vec![note!("so far, {block_count} basic blocks have been executed")]
            }
            _ => vec![],
        };

        let helps = match &e {
            Int2Ptr { details: true } => {
                let mut v = vec![
                    note!(
                        "this program is using integer-to-pointer casts or (equivalently) `ptr::with_exposed_provenance`, which means that Miri might miss pointer bugs in this program"
                    ),
                    note!(
                        "see https://doc.rust-lang.org/nightly/std/ptr/fn.with_exposed_provenance.html for more details on that operation"
                    ),
                    note!(
                        "to ensure that Miri does not miss bugs in your program, use Strict Provenance APIs (https://doc.rust-lang.org/nightly/std/ptr/index.html#strict-provenance, https://crates.io/crates/sptr) instead"
                    ),
                    note!(
                        "you can then set `MIRIFLAGS=-Zmiri-strict-provenance` to ensure you are not relying on `with_exposed_provenance` semantics"
                    ),
                ];
                if self.borrow_tracker.as_ref().is_some_and(|b| {
                    matches!(b.borrow().borrow_tracker_method(), BorrowTrackerMethod::TreeBorrows)
                }) {
                    v.push(
                        note!("Tree Borrows does not support integer-to-pointer casts, so the program is likely to go wrong when this pointer gets used")
                    );
                } else {
                    v.push(
                        note!("alternatively, `MIRIFLAGS=-Zmiri-permissive-provenance` disables this warning")
                    );
                }
                v
            }
            ExternTypeReborrow => {
                vec![
                    note!(
                        "`extern type` are not compatible with the Stacked Borrows aliasing model implemented by Miri; Miri may miss bugs in this code"
                    ),
                    note!(
                        "try running with `MIRIFLAGS=-Zmiri-tree-borrows` to use the more permissive but also even more experimental Tree Borrows aliasing checks instead"
                    ),
                ]
            }
            _ => vec![],
        };

        report_msg(
            diag_level,
            title,
            vec![msg],
            notes,
            helps,
            &stacktrace,
            Some(self.threads.active_thread()),
            self,
        );
    }
}

impl<'tcx> EvalContextExt<'tcx> for crate::MiriInterpCx<'tcx> {}
pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
    fn emit_diagnostic(&self, e: NonHaltingDiagnostic) {
        let this = self.eval_context_ref();
        this.machine.emit_diagnostic(e);
    }

    /// We had a panic in Miri itself, try to print something useful.
    fn handle_ice(&self) {
        eprintln!();
        eprintln!(
            "Miri caused an ICE during evaluation. Here's the interpreter backtrace at the time of the panic:"
        );
        let this = self.eval_context_ref();
        let stacktrace = this.generate_stacktrace();
        report_msg(
            DiagLevel::Note,
            "the place in the program where the ICE was triggered".to_string(),
            vec![],
            vec![],
            vec![],
            &stacktrace,
            Some(this.active_thread()),
            &this.machine,
        );
    }
}