Auto merge of #115045 - RalfJung:unwind-terminate-reason, r=davidtwco

when terminating during unwinding, show the reason why With this, the output on double-panic becomes something like that: ``` thread 'main' panicked at src/tools/miri/tests/fail/panic/double_panic.rs:15:5: first note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace thread 'main' panicked at src/tools/miri/tests/fail/panic/double_panic.rs:10:9: second stack backtrace: 0: 0xbe273a - std::backtrace_rs::backtrace::miri::trace_unsynchronized::<&mut [closure@std::sys_common::backtrace::_print_fmt::{closure#1}]> at /home/r/src/rust/rustc.3/library/std/src/../../backtrace/src/backtrace/miri.rs:99:5 1: 0xbe22e6 - std::backtrace_rs::backtrace::miri::trace::<&mut [closure@std::sys_common::backtrace::_print_fmt::{closure#1}]> at /home/r/src/rust/rustc.3/library/std/src/../../backtrace/src/backtrace/miri.rs:62:14 2: 0xbe1086 - std::backtrace_rs::backtrace::trace_unsynchronized::<[closure@std::sys_common::backtrace::_print_fmt::{closure#1}]> at /home/r/src/rust/rustc.3/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5 3: 0xba3afd - std::sys_common::backtrace::_print_fmt at /home/r/src/rust/rustc.3/library/std/src/sys_common/backtrace.rs:67:5 4: 0xba2471 - <std::sys_common::backtrace::_print::DisplayBacktrace as std::fmt::Display>::fmt at /home/r/src/rust/rustc.3/library/std/src/sys_common/backtrace.rs:44:22 5: 0xbcf754 - core::fmt::rt::Argument::<'_>::fmt at /home/r/src/rust/rustc.3/library/core/src/fmt/rt.rs:138:9 6: 0x9b8f81 - std::fmt::write at /home/r/src/rust/rustc.3/library/core/src/fmt/mod.rs:1094:17 7: 0x21391d - <std::sys::unix::stdio::Stderr as std::io::Write>::write_fmt at /home/r/src/rust/rustc.3/library/std/src/io/mod.rs:1714:15 8: 0xba37b1 - std::sys_common::backtrace::_print at /home/r/src/rust/rustc.3/library/std/src/sys_common/backtrace.rs:47:5 9: 0xba365b - std::sys_common::backtrace::print at /home/r/src/rust/rustc.3/library/std/src/sys_common/backtrace.rs:34:9 10: 0x143c67 - std::panic_hook_with_disk_dump::{closure#1} at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:278:22 11: 0x144187 - std::panic_hook_with_disk_dump at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:312:9 12: 0x143659 - std::panicking::default_hook at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:239:5 13: 0x1482a7 - std::panicking::rust_panic_with_hook at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:729:13 14: 0x1475d5 - std::rt::begin_panic::<&str>::{closure#0} at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:650:9 15: 0xba496a - std::sys_common::backtrace::__rust_end_short_backtrace::<[closure@std::rt::begin_panic<&str>::{closure#0}], !> at /home/r/src/rust/rustc.3/library/std/src/sys_common/backtrace.rs:170:18 16: 0x147599 - std::rt::begin_panic::<&str> at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:649:12 17: 0x31916 - <Foo as std::ops::Drop>::drop at src/tools/miri/tests/fail/panic/double_panic.rs:10:9 18: 0x1a2b5e - std::ptr::drop_in_place::<Foo> - shim(Some(Foo)) at /home/r/src/rust/rustc.3/library/core/src/ptr/mod.rs:497:1 19: 0x202bf - main at src/tools/miri/tests/fail/panic/double_panic.rs:16:1 20: 0xcc6a8 - <fn() as std::ops::FnOnce<()>>::call_once - shim(fn()) at /home/r/src/rust/rustc.3/library/core/src/ops/function.rs:250:5 21: 0xba47d9 - std::sys_common::backtrace::__rust_begin_short_backtrace::<fn(), ()> at /home/r/src/rust/rustc.3/library/std/src/sys_common/backtrace.rs:154:18 22: 0x141a6a - std::rt::lang_start::<()>::{closure#0} at /home/r/src/rust/rustc.3/library/std/src/rt.rs:166:18 23: 0xcca18 - std::ops::function::impls::<impl std::ops::FnOnce<()> for &dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe>::call_once at /home/r/src/rust/rustc.3/library/core/src/ops/function.rs:284:13 24: 0x146469 - std::panicking::try::do_call::<&dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe, i32> at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:524:40 25: 0x145e09 - std::panicking::try::<i32, &dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe> at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:488:19 26: 0x7b0ac - std::panic::catch_unwind::<&dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe, i32> at /home/r/src/rust/rustc.3/library/std/src/panic.rs:142:14 27: 0x14189b - std::rt::lang_start_internal::{closure#2} at /home/r/src/rust/rustc.3/library/std/src/rt.rs:148:48 28: 0x146481 - std::panicking::try::do_call::<[closure@std::rt::lang_start_internal::{closure#2}], isize> at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:524:40 29: 0x145e2c - std::panicking::try::<isize, [closure@std::rt::lang_start_internal::{closure#2}]> at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:488:19 30: 0x7b0d5 - std::panic::catch_unwind::<[closure@std::rt::lang_start_internal::{closure#2}], isize> at /home/r/src/rust/rustc.3/library/std/src/panic.rs:142:14 31: 0x1418b0 - std::rt::lang_start_internal at /home/r/src/rust/rustc.3/library/std/src/rt.rs:148:20 32: 0x141a97 - std::rt::lang_start::<()> at /home/r/src/rust/rustc.3/library/std/src/rt.rs:165:17 thread 'main' panicked at /home/r/src/rust/rustc.3/library/core/src/panicking.rs:126:5: panic in a destructor during cleanup stack backtrace: 0: 0xe9f6d7 - std::backtrace_rs::backtrace::miri::trace_unsynchronized::<&mut [closure@std::sys_common::backtrace::_print_fmt::{closure#1}]> at /home/r/src/rust/rustc.3/library/std/src/../../backtrace/src/backtrace/miri.rs:99:5 1: 0xe9f27d - std::backtrace_rs::backtrace::miri::trace::<&mut [closure@std::sys_common::backtrace::_print_fmt::{closure#1}]> at /home/r/src/rust/rustc.3/library/std/src/../../backtrace/src/backtrace/miri.rs:62:14 2: 0xe9e016 - std::backtrace_rs::backtrace::trace_unsynchronized::<[closure@std::sys_common::backtrace::_print_fmt::{closure#1}]> at /home/r/src/rust/rustc.3/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5 3: 0xba3afd - std::sys_common::backtrace::_print_fmt at /home/r/src/rust/rustc.3/library/std/src/sys_common/backtrace.rs:67:5 4: 0xba2471 - <std::sys_common::backtrace::_print::DisplayBacktrace as std::fmt::Display>::fmt at /home/r/src/rust/rustc.3/library/std/src/sys_common/backtrace.rs:44:22 5: 0xbcf754 - core::fmt::rt::Argument::<'_>::fmt at /home/r/src/rust/rustc.3/library/core/src/fmt/rt.rs:138:9 6: 0x9b8f81 - std::fmt::write at /home/r/src/rust/rustc.3/library/core/src/fmt/mod.rs:1094:17 7: 0x4d0895 - <std::sys::unix::stdio::Stderr as std::io::Write>::write_fmt at /home/r/src/rust/rustc.3/library/std/src/io/mod.rs:1714:15 8: 0xba37b1 - std::sys_common::backtrace::_print at /home/r/src/rust/rustc.3/library/std/src/sys_common/backtrace.rs:47:5 9: 0xba365b - std::sys_common::backtrace::print at /home/r/src/rust/rustc.3/library/std/src/sys_common/backtrace.rs:34:9 10: 0x400bd4 - std::panic_hook_with_disk_dump::{closure#1} at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:278:22 11: 0x144187 - std::panic_hook_with_disk_dump at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:312:9 12: 0x143659 - std::panicking::default_hook at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:239:5 13: 0x1482a7 - std::panicking::rust_panic_with_hook at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:729:13 14: 0x40403b - std::panicking::begin_panic_handler::{closure#0} at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:619:13 15: 0xe618b3 - std::sys_common::backtrace::__rust_end_short_backtrace::<[closure@std::panicking::begin_panic_handler::{closure#0}], !> at /home/r/src/rust/rustc.3/library/std/src/sys_common/backtrace.rs:170:18 16: 0x403fc8 - std::panicking::begin_panic_handler at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:617:5 17: 0xee23e9 - core::panicking::panic_nounwind_fmt at /home/r/src/rust/rustc.3/library/core/src/panicking.rs:96:14 18: 0xee29e6 - core::panicking::panic_nounwind at /home/r/src/rust/rustc.3/library/core/src/panicking.rs:126:5 19: 0xee365e - core::panicking::panic_in_cleanup at /home/r/src/rust/rustc.3/library/core/src/panicking.rs:206:5 20: 0x2028a - main at src/tools/miri/tests/fail/panic/double_panic.rs:13:1 21: 0x3895ee - <fn() as std::ops::FnOnce<()>>::call_once - shim(fn()) at /home/r/src/rust/rustc.3/library/core/src/ops/function.rs:250:5 22: 0xe61725 - std::sys_common::backtrace::__rust_begin_short_backtrace::<fn(), ()> at /home/r/src/rust/rustc.3/library/std/src/sys_common/backtrace.rs:154:18 23: 0x3fe9aa - std::rt::lang_start::<()>::{closure#0} at /home/r/src/rust/rustc.3/library/std/src/rt.rs:166:18 24: 0x389962 - std::ops::function::impls::<impl std::ops::FnOnce<()> for &dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe>::call_once at /home/r/src/rust/rustc.3/library/core/src/ops/function.rs:284:13 25: 0x4033b9 - std::panicking::try::do_call::<&dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe, i32> at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:524:40 26: 0x402d58 - std::panicking::try::<i32, &dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe> at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:488:19 27: 0x337ff7 - std::panic::catch_unwind::<&dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe, i32> at /home/r/src/rust/rustc.3/library/std/src/panic.rs:142:14 28: 0x3fe7e7 - std::rt::lang_start_internal::{closure#2} at /home/r/src/rust/rustc.3/library/std/src/rt.rs:148:48 29: 0x4033d6 - std::panicking::try::do_call::<[closure@std::rt::lang_start_internal::{closure#2}], isize> at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:524:40 30: 0x402d7f - std::panicking::try::<isize, [closure@std::rt::lang_start_internal::{closure#2}]> at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:488:19 31: 0x338028 - std::panic::catch_unwind::<[closure@std::rt::lang_start_internal::{closure#2}], isize> at /home/r/src/rust/rustc.3/library/std/src/panic.rs:142:14 32: 0x1418b0 - std::rt::lang_start_internal at /home/r/src/rust/rustc.3/library/std/src/rt.rs:148:20 33: 0x3fe9dc - std::rt::lang_start::<()> at /home/r/src/rust/rustc.3/library/std/src/rt.rs:165:17 thread caused non-unwinding panic. aborting. ``` If we also land https://github.com/rust-lang/rust/pull/115020, the 2nd backtrace disappears, hopefully making the "panic in a destructor during cleanup" easier to see. Fixes https://github.com/rust-lang/rust/issues/114954.
2023-08-25 08:47:18 +00:00 · 2023-08-25 08:47:18 +00:00 · b60f7b51a2
commit b60f7b51a2
parent 4535d33e33 df5a248cb1
105 changed files with 488 additions and 304 deletions
--- a/compiler/rustc_middle/src/mir/mod.rs
+++ b/compiler/rustc_middle/src/mir/mod.rs
@ -1275,9 +1275,11 @@ impl<O> AssertKind<O> {
        matches!(self, OverflowNeg(..) | Overflow(Add | Sub | Mul | Shl | Shr, ..))
    }

-    /// Getting a description does not require `O` to be printable, and does not
-    /// require allocation.
-    /// The caller is expected to handle `BoundsCheck` and `MisalignedPointerDereference` separately.
+    /// Get the message that is printed at runtime when this assertion fails.
+    ///
+    /// The caller is expected to handle `BoundsCheck` and `MisalignedPointerDereference` by
+    /// invoking the appropriate lang item (panic_bounds_check/panic_misaligned_pointer_dereference)
+    /// instead of printing a static message.
    pub fn description(&self) -> &'static str {
        use AssertKind::*;
        match self {
@ -1303,6 +1305,11 @@ impl<O> AssertKind<O> {
    }

    /// Format the message arguments for the `assert(cond, msg..)` terminator in MIR printing.
+    ///
+    /// Needs to be kept in sync with the run-time behavior (which is defined by
+    /// `AssertKind::description` and the lang items mentioned in its docs).
+    /// Note that we deliberately show more details here than we do at runtime, such as the actual
+    /// numbers that overflowed -- it is much easier to do so here than at runtime.
    pub fn fmt_assert_args<W: Write>(&self, f: &mut W) -> fmt::Result
    where
        O: Debug,
@ -1358,6 +1365,12 @@ impl<O> AssertKind<O> {
        }
    }

+    /// Format the diagnostic message for use in a lint (e.g. when the assertion fails during const-eval).
+    ///
+    /// Needs to be kept in sync with the run-time behavior (which is defined by
+    /// `AssertKind::description` and the lang items mentioned in its docs).
+    /// Note that we deliberately show more details here than we do at runtime, such as the actual
+    /// numbers that overflowed -- it is much easier to do so here than at runtime.
    pub fn diagnostic_message(&self) -> DiagnosticMessage {
        use crate::fluent_generated::*;
        use AssertKind::*;
--- a/compiler/rustc_middle/src/mir/patch.rs
+++ b/compiler/rustc_middle/src/mir/patch.rs
@ -14,7 +14,8 @@ pub struct MirPatch<'tcx> {
    resume_block: Option<BasicBlock>,
    // Only for unreachable in cleanup path.
    unreachable_cleanup_block: Option<BasicBlock>,
-    terminate_block: Option<BasicBlock>,
+    // Cached block for UnwindTerminate (with reason)
+    terminate_block: Option<(BasicBlock, UnwindTerminateReason)>,
    body_span: Span,
    next_local: usize,
 }
@ -35,13 +36,15 @@ impl<'tcx> MirPatch<'tcx> {

        for (bb, block) in body.basic_blocks.iter_enumerated() {
            // Check if we already have a resume block
-            if let TerminatorKind::UnwindResume = block.terminator().kind && block.statements.is_empty() {
+            if matches!(block.terminator().kind, TerminatorKind::UnwindResume)
+                && block.statements.is_empty()
+            {
                result.resume_block = Some(bb);
                continue;
            }

            // Check if we already have an unreachable block
-            if let TerminatorKind::Unreachable = block.terminator().kind
+            if matches!(block.terminator().kind, TerminatorKind::Unreachable)
                && block.statements.is_empty()
                && block.is_cleanup
            {
@ -50,8 +53,10 @@ impl<'tcx> MirPatch<'tcx> {
            }

            // Check if we already have a terminate block
-            if let TerminatorKind::UnwindTerminate = block.terminator().kind && block.statements.is_empty() {
-                result.terminate_block = Some(bb);
+            if let TerminatorKind::UnwindTerminate(reason) = block.terminator().kind
+                && block.statements.is_empty()
+            {
+                result.terminate_block = Some((bb, reason));
                continue;
            }
        }
@ -93,20 +98,20 @@ impl<'tcx> MirPatch<'tcx> {
        bb
    }

-    pub fn terminate_block(&mut self) -> BasicBlock {
-        if let Some(bb) = self.terminate_block {
-            return bb;
+    pub fn terminate_block(&mut self, reason: UnwindTerminateReason) -> BasicBlock {
+        if let Some((cached_bb, cached_reason)) = self.terminate_block && reason == cached_reason {
+            return cached_bb;
        }

        let bb = self.new_block(BasicBlockData {
            statements: vec![],
            terminator: Some(Terminator {
                source_info: SourceInfo::outermost(self.body_span),
-                kind: TerminatorKind::UnwindTerminate,
+                kind: TerminatorKind::UnwindTerminate(reason),
            }),
            is_cleanup: true,
        });
-        self.terminate_block = Some(bb);
+        self.terminate_block = Some((bb, reason));
        bb
    }

--- a/compiler/rustc_middle/src/mir/syntax.rs
+++ b/compiler/rustc_middle/src/mir/syntax.rs
@ -621,7 +621,7 @@ pub enum TerminatorKind<'tcx> {
    ///
    /// Used to prevent unwinding for foreign items or with `-C unwind=abort`. Only permitted in
    /// cleanup blocks.
-    UnwindTerminate,
+    UnwindTerminate(UnwindTerminateReason),

    /// Returns from the function.
    ///
@ -813,7 +813,7 @@ impl TerminatorKind<'_> {
            TerminatorKind::Goto { .. } => "Goto",
            TerminatorKind::SwitchInt { .. } => "SwitchInt",
            TerminatorKind::UnwindResume => "UnwindResume",
-            TerminatorKind::UnwindTerminate => "UnwindTerminate",
+            TerminatorKind::UnwindTerminate(_) => "UnwindTerminate",
            TerminatorKind::Return => "Return",
            TerminatorKind::Unreachable => "Unreachable",
            TerminatorKind::Drop { .. } => "Drop",
@ -842,11 +842,22 @@ pub enum UnwindAction {
    /// Terminates the execution if unwind happens.
    ///
    /// Depending on the platform and situation this may cause a non-unwindable panic or abort.
-    Terminate,
+    Terminate(UnwindTerminateReason),
    /// Cleanups to be done.
    Cleanup(BasicBlock),
 }

+/// The reason we are terminating the process during unwinding.
+#[derive(Copy, Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, Hash, HashStable)]
+#[derive(TypeFoldable, TypeVisitable)]
+pub enum UnwindTerminateReason {
+    /// Unwinding is just not possible given the ABI of this function.
+    Abi,
+    /// We were already cleaning up for an ongoing unwind, and a *second*, *nested* unwind was
+    /// triggered by the drop glue.
+    InCleanup,
+}
+
 /// Information about an assertion failure.
 #[derive(Clone, Hash, HashStable, PartialEq, Debug)]
 #[derive(TyEncodable, TyDecodable, TypeFoldable, TypeVisitable)]
--- a/compiler/rustc_middle/src/mir/terminator.rs
+++ b/compiler/rustc_middle/src/mir/terminator.rs
@ -1,3 +1,4 @@
+use rustc_hir::LangItem;
 use smallvec::SmallVec;

 use super::{BasicBlock, InlineAsmOperand, Operand, SourceInfo, TerminatorKind, UnwindAction};
@ -100,6 +101,40 @@ impl<'a> Iterator for SwitchTargetsIter<'a> {

 impl<'a> ExactSizeIterator for SwitchTargetsIter<'a> {}

+impl UnwindAction {
+    fn cleanup_block(self) -> Option<BasicBlock> {
+        match self {
+            UnwindAction::Cleanup(bb) => Some(bb),
+            UnwindAction::Continue | UnwindAction::Unreachable | UnwindAction::Terminate(_) => None,
+        }
+    }
+}
+
+impl UnwindTerminateReason {
+    pub fn as_str(self) -> &'static str {
+        // Keep this in sync with the messages in `core/src/panicking.rs`.
+        match self {
+            UnwindTerminateReason::Abi => "panic in a function that cannot unwind",
+            UnwindTerminateReason::InCleanup => "panic in a destructor during cleanup",
+        }
+    }
+
+    /// A short representation of this used for MIR printing.
+    pub fn as_short_str(self) -> &'static str {
+        match self {
+            UnwindTerminateReason::Abi => "abi",
+            UnwindTerminateReason::InCleanup => "cleanup",
+        }
+    }
+
+    pub fn lang_item(self) -> LangItem {
+        match self {
+            UnwindTerminateReason::Abi => LangItem::PanicCannotUnwind,
+            UnwindTerminateReason::InCleanup => LangItem::PanicInCleanup,
+        }
+    }
+}
+
 #[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)]
 pub struct Terminator<'tcx> {
    pub source_info: SourceInfo,
@ -156,7 +191,7 @@ impl<'tcx> TerminatorKind<'tcx> {
                Some(t).into_iter().chain((&[]).into_iter().copied())
            }
            UnwindResume
-            | UnwindTerminate
+            | UnwindTerminate(_)
            | GeneratorDrop
            | Return
            | Unreachable
@ -198,7 +233,7 @@ impl<'tcx> TerminatorKind<'tcx> {
                Some(t).into_iter().chain(&mut [])
            }
            UnwindResume
-            | UnwindTerminate
+            | UnwindTerminate(_)
            | GeneratorDrop
            | Return
            | Unreachable
@ -215,7 +250,7 @@ impl<'tcx> TerminatorKind<'tcx> {
        match *self {
            TerminatorKind::Goto { .. }
            | TerminatorKind::UnwindResume
-            | TerminatorKind::UnwindTerminate
+            | TerminatorKind::UnwindTerminate(_)
            | TerminatorKind::Return
            | TerminatorKind::Unreachable
            | TerminatorKind::GeneratorDrop
@ -234,7 +269,7 @@ impl<'tcx> TerminatorKind<'tcx> {
        match *self {
            TerminatorKind::Goto { .. }
            | TerminatorKind::UnwindResume
-            | TerminatorKind::UnwindTerminate
+            | TerminatorKind::UnwindTerminate(_)
            | TerminatorKind::Return
            | TerminatorKind::Unreachable
            | TerminatorKind::GeneratorDrop
@ -271,18 +306,28 @@ impl<'tcx> Debug for TerminatorKind<'tcx> {
        let labels = self.fmt_successor_labels();
        assert_eq!(successor_count, labels.len());

-        let unwind = match self.unwind() {
-            // Not needed or included in successors
-            None | Some(UnwindAction::Cleanup(_)) => None,
-            Some(UnwindAction::Continue) => Some("unwind continue"),
-            Some(UnwindAction::Unreachable) => Some("unwind unreachable"),
-            Some(UnwindAction::Terminate) => Some("unwind terminate"),
+        // `Cleanup` is already included in successors
+        let show_unwind = !matches!(self.unwind(), None | Some(UnwindAction::Cleanup(_)));
+        let fmt_unwind = |fmt: &mut Formatter<'_>| -> fmt::Result {
+            write!(fmt, "unwind ")?;
+            match self.unwind() {
+                // Not needed or included in successors
+                None | Some(UnwindAction::Cleanup(_)) => unreachable!(),
+                Some(UnwindAction::Continue) => write!(fmt, "continue"),
+                Some(UnwindAction::Unreachable) => write!(fmt, "unreachable"),
+                Some(UnwindAction::Terminate(reason)) => {
+                    write!(fmt, "terminate({})", reason.as_short_str())
+                }
+            }
        };

-        match (successor_count, unwind) {
-            (0, None) => Ok(()),
-            (0, Some(unwind)) => write!(fmt, " -> {unwind}"),
-            (1, None) => write!(fmt, " -> {:?}", self.successors().next().unwrap()),
+        match (successor_count, show_unwind) {
+            (0, false) => Ok(()),
+            (0, true) => {
+                write!(fmt, " -> ")?;
+                fmt_unwind(fmt)
+            }
+            (1, false) => write!(fmt, " -> {:?}", self.successors().next().unwrap()),
            _ => {
                write!(fmt, " -> [")?;
                for (i, target) in self.successors().enumerate() {
@ -291,8 +336,9 @@ impl<'tcx> Debug for TerminatorKind<'tcx> {
                    }
                    write!(fmt, "{}: {:?}", labels[i], target)?;
                }
-                if let Some(unwind) = unwind {
-                    write!(fmt, ", {unwind}")?;
+                if show_unwind {
+                    write!(fmt, ", ")?;
+                    fmt_unwind(fmt)?;
                }
                write!(fmt, "]")
            }
@ -312,7 +358,9 @@ impl<'tcx> TerminatorKind<'tcx> {
            Return => write!(fmt, "return"),
            GeneratorDrop => write!(fmt, "generator_drop"),
            UnwindResume => write!(fmt, "resume"),
-            UnwindTerminate => write!(fmt, "abort"),
+            UnwindTerminate(reason) => {
+                write!(fmt, "abort({})", reason.as_short_str())
+            }
            Yield { value, resume_arg, .. } => write!(fmt, "{resume_arg:?} = yield({value:?})"),
            Unreachable => write!(fmt, "unreachable"),
            Drop { place, .. } => write!(fmt, "drop({place:?})"),
@ -391,7 +439,7 @@ impl<'tcx> TerminatorKind<'tcx> {
    pub fn fmt_successor_labels(&self) -> Vec<Cow<'static, str>> {
        use self::TerminatorKind::*;
        match *self {
-            Return | UnwindResume | UnwindTerminate | Unreachable | GeneratorDrop => vec![],
+            Return | UnwindResume | UnwindTerminate(_) | Unreachable | GeneratorDrop => vec![],
            Goto { .. } => vec!["".into()],
            SwitchInt { ref targets, .. } => targets
                .values
@ -443,7 +491,8 @@ pub enum TerminatorEdges<'mir, 'tcx> {
    /// Special action for `Yield`, `Call` and `InlineAsm` terminators.
    AssignOnReturn {
        return_: Option<BasicBlock>,
-        unwind: UnwindAction,
+        /// The cleanup block, if it exists.
+        cleanup: Option<BasicBlock>,
        place: CallReturnPlaces<'mir, 'tcx>,
    },
    /// Special edge for `SwitchInt`.
@ -486,7 +535,7 @@ impl<'tcx> TerminatorKind<'tcx> {
    pub fn edges(&self) -> TerminatorEdges<'_, 'tcx> {
        use TerminatorKind::*;
        match *self {
-            Return | UnwindResume | UnwindTerminate | GeneratorDrop | Unreachable => {
+            Return | UnwindResume | UnwindTerminate(_) | GeneratorDrop | Unreachable => {
                TerminatorEdges::None
            }

@ -496,7 +545,7 @@ impl<'tcx> TerminatorKind<'tcx> {
            | Drop { target, unwind, place: _, replace: _ }
            | FalseUnwind { real_target: target, unwind } => match unwind {
                UnwindAction::Cleanup(unwind) => TerminatorEdges::Double(target, unwind),
-                UnwindAction::Continue | UnwindAction::Terminate | UnwindAction::Unreachable => {
+                UnwindAction::Continue | UnwindAction::Terminate(_) | UnwindAction::Unreachable => {
                    TerminatorEdges::Single(target)
                }
            },
@ -508,7 +557,7 @@ impl<'tcx> TerminatorKind<'tcx> {
            Yield { resume: target, drop, resume_arg, value: _ } => {
                TerminatorEdges::AssignOnReturn {
                    return_: Some(target),
-                    unwind: drop.map_or(UnwindAction::Terminate, UnwindAction::Cleanup),
+                    cleanup: drop,
                    place: CallReturnPlaces::Yield(resume_arg),
                }
            }
@ -516,7 +565,7 @@ impl<'tcx> TerminatorKind<'tcx> {
            Call { unwind, destination, target, func: _, args: _, fn_span: _, call_source: _ } => {
                TerminatorEdges::AssignOnReturn {
                    return_: target,
-                    unwind,
+                    cleanup: unwind.cleanup_block(),
                    place: CallReturnPlaces::Call(destination),
                }
            }
@ -530,7 +579,7 @@ impl<'tcx> TerminatorKind<'tcx> {
                unwind,
            } => TerminatorEdges::AssignOnReturn {
                return_: destination,
-                unwind,
+                cleanup: unwind.cleanup_block(),
                place: CallReturnPlaces::InlineAsm(operands),
            },

--- a/compiler/rustc_middle/src/mir/visit.rs
+++ b/compiler/rustc_middle/src/mir/visit.rs
@ -470,7 +470,7 @@ macro_rules! make_mir_visitor {
                match kind {
                    TerminatorKind::Goto { .. } |
                    TerminatorKind::UnwindResume |
-                    TerminatorKind::UnwindTerminate |
+                    TerminatorKind::UnwindTerminate(_) |
                    TerminatorKind::GeneratorDrop |
                    TerminatorKind::Unreachable |
                    TerminatorKind::FalseEdge { .. } |