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.

44 files changed, 304 insertions, 202 deletions

diff --git a/compiler/rustc_borrowck/src/invalidation.rs b/compiler/rustc_borrowck/src/invalidation.rs
index d4c42a75874..84be50a6416 100644
--- a/compiler/rustc_borrowck/src/invalidation.rs
+++ b/compiler/rustc_borrowck/src/invalidation.rs
@@ -202,7 +202,7 @@ impl<'cx, 'tcx> Visitor<'tcx> for InvalidationGenerator<'cx, 'tcx> {
                 }
             }
             TerminatorKind::Goto { target: _ }
-            | TerminatorKind::UnwindTerminate
+            | TerminatorKind::UnwindTerminate(_)
             | TerminatorKind::Unreachable
             | TerminatorKind::FalseEdge { real_target: _, imaginary_target: _ }
             | TerminatorKind::FalseUnwind { real_target: _, unwind: _ } => {
diff --git a/compiler/rustc_borrowck/src/lib.rs b/compiler/rustc_borrowck/src/lib.rs
index 3f544bf7209..770c180ff2c 100644
--- a/compiler/rustc_borrowck/src/lib.rs
+++ b/compiler/rustc_borrowck/src/lib.rs
@@ -770,7 +770,7 @@ impl<'cx, 'tcx, R> rustc_mir_dataflow::ResultsVisitor<'cx, 'tcx, R> for MirBorro
             }
 
             TerminatorKind::Goto { target: _ }
-            | TerminatorKind::UnwindTerminate
+            | TerminatorKind::UnwindTerminate(_)
             | TerminatorKind::Unreachable
             | TerminatorKind::UnwindResume
             | TerminatorKind::Return
@@ -817,7 +817,7 @@ impl<'cx, 'tcx, R> rustc_mir_dataflow::ResultsVisitor<'cx, 'tcx, R> for MirBorro
                 }
             }
 
-            TerminatorKind::UnwindTerminate
+            TerminatorKind::UnwindTerminate(_)
             | TerminatorKind::Assert { .. }
             | TerminatorKind::Call { .. }
             | TerminatorKind::Drop { .. }
diff --git a/compiler/rustc_borrowck/src/type_check/mod.rs b/compiler/rustc_borrowck/src/type_check/mod.rs
index d91a3d94045..3004291c3e7 100644
--- a/compiler/rustc_borrowck/src/type_check/mod.rs
+++ b/compiler/rustc_borrowck/src/type_check/mod.rs
@@ -1334,7 +1334,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         match &term.kind {
             TerminatorKind::Goto { .. }
             | TerminatorKind::UnwindResume
-            | TerminatorKind::UnwindTerminate
+            | TerminatorKind::UnwindTerminate(_)
             | TerminatorKind::Return
             | TerminatorKind::GeneratorDrop
             | TerminatorKind::Unreachable
@@ -1613,7 +1613,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                     span_mirbug!(self, block_data, "resume on non-cleanup block!")
                 }
             }
-            TerminatorKind::UnwindTerminate => {
+            TerminatorKind::UnwindTerminate(_) => {
                 if !is_cleanup {
                     span_mirbug!(self, block_data, "abort on non-cleanup block!")
                 }
@@ -1697,7 +1697,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                     span_mirbug!(self, ctxt, "unwind on cleanup block")
                 }
             }
-            UnwindAction::Unreachable | UnwindAction::Terminate => (),
+            UnwindAction::Unreachable | UnwindAction::Terminate(_) => (),
         }
     }
 
diff --git a/compiler/rustc_codegen_cranelift/src/base.rs b/compiler/rustc_codegen_cranelift/src/base.rs
index ed371a04c53..9159bc36987 100644
--- a/compiler/rustc_codegen_cranelift/src/base.rs
+++ b/compiler/rustc_codegen_cranelift/src/base.rs
@@ -474,8 +474,8 @@ fn codegen_fn_body(fx: &mut FunctionCx<'_, '_, '_>, start_block: Block) {
                     *destination,
                 );
             }
-            TerminatorKind::UnwindTerminate => {
-                codegen_panic_cannot_unwind(fx, source_info);
+            TerminatorKind::UnwindTerminate(reason) => {
+                codegen_unwind_terminate(fx, source_info, *reason);
             }
             TerminatorKind::UnwindResume => {
                 // FIXME implement unwinding
@@ -971,13 +971,14 @@ pub(crate) fn codegen_panic_nounwind<'tcx>(
     codegen_panic_inner(fx, rustc_hir::LangItem::PanicNounwind, &args, source_info.span);
 }
 
-pub(crate) fn codegen_panic_cannot_unwind<'tcx>(
+pub(crate) fn codegen_unwind_terminate<'tcx>(
     fx: &mut FunctionCx<'_, '_, 'tcx>,
     source_info: mir::SourceInfo,
+    reason: UnwindTerminateReason,
 ) {
     let args = [];
 
-    codegen_panic_inner(fx, rustc_hir::LangItem::PanicCannotUnwind, &args, source_info.span);
+    codegen_panic_inner(fx, reason.lang_item(), &args, source_info.span);
 }
 
 fn codegen_panic_inner<'tcx>(
diff --git a/compiler/rustc_codegen_cranelift/src/constant.rs b/compiler/rustc_codegen_cranelift/src/constant.rs
index 7db5f79eead..a934b0767f1 100644
--- a/compiler/rustc_codegen_cranelift/src/constant.rs
+++ b/compiler/rustc_codegen_cranelift/src/constant.rs
@@ -551,7 +551,7 @@ pub(crate) fn mir_operand_get_const_val<'tcx>(
                     TerminatorKind::Goto { .. }
                     | TerminatorKind::SwitchInt { .. }
                     | TerminatorKind::UnwindResume
-                    | TerminatorKind::UnwindTerminate
+                    | TerminatorKind::UnwindTerminate(_)
                     | TerminatorKind::Return
                     | TerminatorKind::Unreachable
                     | TerminatorKind::Drop { .. }
diff --git a/compiler/rustc_codegen_ssa/src/mir/analyze.rs b/compiler/rustc_codegen_ssa/src/mir/analyze.rs
index 3f5b46333d9..7fda2d5fadf 100644
--- a/compiler/rustc_codegen_ssa/src/mir/analyze.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/analyze.rs
@@ -285,7 +285,7 @@ pub fn cleanup_kinds(mir: &mir::Body<'_>) -> IndexVec<mir::BasicBlock, CleanupKi
             match data.terminator().kind {
                 TerminatorKind::Goto { .. }
                 | TerminatorKind::UnwindResume
-                | TerminatorKind::UnwindTerminate
+                | TerminatorKind::UnwindTerminate(_)
                 | TerminatorKind::Return
                 | TerminatorKind::GeneratorDrop
                 | TerminatorKind::Unreachable
diff --git a/compiler/rustc_codegen_ssa/src/mir/block.rs b/compiler/rustc_codegen_ssa/src/mir/block.rs
index 19228183462..6aef1664394 100644
--- a/compiler/rustc_codegen_ssa/src/mir/block.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/block.rs
@@ -12,7 +12,7 @@ use crate::MemFlags;
 use rustc_ast as ast;
 use rustc_ast::{InlineAsmOptions, InlineAsmTemplatePiece};
 use rustc_hir::lang_items::LangItem;
-use rustc_middle::mir::{self, AssertKind, SwitchTargets};
+use rustc_middle::mir::{self, AssertKind, SwitchTargets, UnwindTerminateReason};
 use rustc_middle::ty::layout::{HasTyCtxt, LayoutOf, ValidityRequirement};
 use rustc_middle::ty::print::{with_no_trimmed_paths, with_no_visible_paths};
 use rustc_middle::ty::{self, Instance, Ty};
@@ -178,7 +178,7 @@ impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> {
             mir::UnwindAction::Cleanup(cleanup) => Some(self.llbb_with_cleanup(fx, cleanup)),
             mir::UnwindAction::Continue => None,
             mir::UnwindAction::Unreachable => None,
-            mir::UnwindAction::Terminate => {
+            mir::UnwindAction::Terminate(reason) => {
                 if fx.mir[self.bb].is_cleanup && base::wants_new_eh_instructions(fx.cx.tcx().sess) {
                     // MSVC SEH will abort automatically if an exception tries to
                     // propagate out from cleanup.
@@ -191,7 +191,7 @@ impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> {
 
                     None
                 } else {
-                    Some(fx.terminate_block())
+                    Some(fx.terminate_block(reason))
                 }
             }
         };
@@ -264,7 +264,7 @@ impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> {
     ) -> MergingSucc {
         let unwind_target = match unwind {
             mir::UnwindAction::Cleanup(cleanup) => Some(self.llbb_with_cleanup(fx, cleanup)),
-            mir::UnwindAction::Terminate => Some(fx.terminate_block()),
+            mir::UnwindAction::Terminate(reason) => Some(fx.terminate_block(reason)),
             mir::UnwindAction::Continue => None,
             mir::UnwindAction::Unreachable => None,
         };
@@ -649,12 +649,13 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
         helper: TerminatorCodegenHelper<'tcx>,
         bx: &mut Bx,
         terminator: &mir::Terminator<'tcx>,
+        reason: UnwindTerminateReason,
     ) {
         let span = terminator.source_info.span;
         self.set_debug_loc(bx, terminator.source_info);
 
         // Obtain the panic entry point.
-        let (fn_abi, llfn) = common::build_langcall(bx, Some(span), LangItem::PanicCannotUnwind);
+        let (fn_abi, llfn) = common::build_langcall(bx, Some(span), reason.lang_item());
 
         // Codegen the actual panic invoke/call.
         let merging_succ = helper.do_call(
@@ -1229,8 +1230,8 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 MergingSucc::False
             }
 
-            mir::TerminatorKind::UnwindTerminate => {
-                self.codegen_terminate_terminator(helper, bx, terminator);
+            mir::TerminatorKind::UnwindTerminate(reason) => {
+                self.codegen_terminate_terminator(helper, bx, terminator, reason);
                 MergingSucc::False
             }
 
@@ -1579,79 +1580,81 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
         })
     }
 
-    fn terminate_block(&mut self) -> Bx::BasicBlock {
-        self.terminate_block.unwrap_or_else(|| {
-            let funclet;
-            let llbb;
-            let mut bx;
-            if base::wants_msvc_seh(self.cx.sess()) {
-                // This is a basic block that we're aborting the program for,
-                // notably in an `extern` function. These basic blocks are inserted
-                // so that we assert that `extern` functions do indeed not panic,
-                // and if they do we abort the process.
-                //
-                // On MSVC these are tricky though (where we're doing funclets). If
-                // we were to do a cleanuppad (like below) the normal functions like
-                // `longjmp` would trigger the abort logic, terminating the
-                // program. Instead we insert the equivalent of `catch(...)` for C++
-                // which magically doesn't trigger when `longjmp` files over this
-                // frame.
-                //
-                // Lots more discussion can be found on #48251 but this codegen is
-                // modeled after clang's for:
-                //
-                //      try {
-                //          foo();
-                //      } catch (...) {
-                //          bar();
-                //      }
-                //
-                // which creates an IR snippet like
-                //
-                //      cs_terminate:
-                //         %cs = catchswitch within none [%cp_terminate] unwind to caller
-                //      cp_terminate:
-                //         %cp = catchpad within %cs [null, i32 64, null]
-                //         ...
-
-                llbb = Bx::append_block(self.cx, self.llfn, "cs_terminate");
-                let cp_llbb = Bx::append_block(self.cx, self.llfn, "cp_terminate");
-
-                let mut cs_bx = Bx::build(self.cx, llbb);
-                let cs = cs_bx.catch_switch(None, None, &[cp_llbb]);
-
-                // The "null" here is actually a RTTI type descriptor for the
-                // C++ personality function, but `catch (...)` has no type so
-                // it's null. The 64 here is actually a bitfield which
-                // represents that this is a catch-all block.
-                bx = Bx::build(self.cx, cp_llbb);
-                let null =
-                    bx.const_null(bx.type_ptr_ext(bx.cx().data_layout().instruction_address_space));
-                let sixty_four = bx.const_i32(64);
-                funclet = Some(bx.catch_pad(cs, &[null, sixty_four, null]));
-            } else {
-                llbb = Bx::append_block(self.cx, self.llfn, "terminate");
-                bx = Bx::build(self.cx, llbb);
+    fn terminate_block(&mut self, reason: UnwindTerminateReason) -> Bx::BasicBlock {
+        if let Some((cached_bb, cached_reason)) = self.terminate_block && reason == cached_reason {
+            return cached_bb;
+        }
 
-                let llpersonality = self.cx.eh_personality();
-                bx.filter_landing_pad(llpersonality);
+        let funclet;
+        let llbb;
+        let mut bx;
+        if base::wants_msvc_seh(self.cx.sess()) {
+            // This is a basic block that we're aborting the program for,
+            // notably in an `extern` function. These basic blocks are inserted
+            // so that we assert that `extern` functions do indeed not panic,
+            // and if they do we abort the process.
+            //
+            // On MSVC these are tricky though (where we're doing funclets). If
+            // we were to do a cleanuppad (like below) the normal functions like
+            // `longjmp` would trigger the abort logic, terminating the
+            // program. Instead we insert the equivalent of `catch(...)` for C++
+            // which magically doesn't trigger when `longjmp` files over this
+            // frame.
+            //
+            // Lots more discussion can be found on #48251 but this codegen is
+            // modeled after clang's for:
+            //
+            //      try {
+            //          foo();
+            //      } catch (...) {
+            //          bar();
+            //      }
+            //
+            // which creates an IR snippet like
+            //
+            //      cs_terminate:
+            //         %cs = catchswitch within none [%cp_terminate] unwind to caller
+            //      cp_terminate:
+            //         %cp = catchpad within %cs [null, i32 64, null]
+            //         ...
+
+            llbb = Bx::append_block(self.cx, self.llfn, "cs_terminate");
+            let cp_llbb = Bx::append_block(self.cx, self.llfn, "cp_terminate");
+
+            let mut cs_bx = Bx::build(self.cx, llbb);
+            let cs = cs_bx.catch_switch(None, None, &[cp_llbb]);
+
+            // The "null" here is actually a RTTI type descriptor for the
+            // C++ personality function, but `catch (...)` has no type so
+            // it's null. The 64 here is actually a bitfield which
+            // represents that this is a catch-all block.
+            bx = Bx::build(self.cx, cp_llbb);
+            let null =
+                bx.const_null(bx.type_ptr_ext(bx.cx().data_layout().instruction_address_space));
+            let sixty_four = bx.const_i32(64);
+            funclet = Some(bx.catch_pad(cs, &[null, sixty_four, null]));
+        } else {
+            llbb = Bx::append_block(self.cx, self.llfn, "terminate");
+            bx = Bx::build(self.cx, llbb);
 
-                funclet = None;
-            }
+            let llpersonality = self.cx.eh_personality();
+            bx.filter_landing_pad(llpersonality);
+
+            funclet = None;
+        }
 
-            self.set_debug_loc(&mut bx, mir::SourceInfo::outermost(self.mir.span));
+        self.set_debug_loc(&mut bx, mir::SourceInfo::outermost(self.mir.span));
 
-            let (fn_abi, fn_ptr) = common::build_langcall(&bx, None, LangItem::PanicCannotUnwind);
-            let fn_ty = bx.fn_decl_backend_type(&fn_abi);
+        let (fn_abi, fn_ptr) = common::build_langcall(&bx, None, reason.lang_item());
+        let fn_ty = bx.fn_decl_backend_type(&fn_abi);
 
-            let llret = bx.call(fn_ty, None, Some(&fn_abi), fn_ptr, &[], funclet.as_ref());
-            bx.do_not_inline(llret);
+        let llret = bx.call(fn_ty, None, Some(&fn_abi), fn_ptr, &[], funclet.as_ref());
+        bx.do_not_inline(llret);
 
-            bx.unreachable();
+        bx.unreachable();
 
-            self.terminate_block = Some(llbb);
-            llbb
-        })
+        self.terminate_block = Some((llbb, reason));
+        llbb
     }
 
     /// Get the backend `BasicBlock` for a MIR `BasicBlock`, either already
diff --git a/compiler/rustc_codegen_ssa/src/mir/mod.rs b/compiler/rustc_codegen_ssa/src/mir/mod.rs
index ccf93f208d5..37a209cec5e 100644
--- a/compiler/rustc_codegen_ssa/src/mir/mod.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/mod.rs
@@ -5,6 +5,7 @@ use rustc_index::IndexVec;
 use rustc_middle::mir;
 use rustc_middle::mir::interpret::ErrorHandled;
 use rustc_middle::mir::traversal;
+use rustc_middle::mir::UnwindTerminateReason;
 use rustc_middle::ty::layout::{FnAbiOf, HasTyCtxt, TyAndLayout};
 use rustc_middle::ty::{self, Instance, Ty, TyCtxt, TypeFoldable, TypeVisitableExt};
 use rustc_target::abi::call::{FnAbi, PassMode};
@@ -83,8 +84,8 @@ pub struct FunctionCx<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> {
     /// Cached unreachable block
     unreachable_block: Option<Bx::BasicBlock>,
 
-    /// Cached terminate upon unwinding block
-    terminate_block: Option<Bx::BasicBlock>,
+    /// Cached terminate upon unwinding block and its reason
+    terminate_block: Option<(Bx::BasicBlock, UnwindTerminateReason)>,
 
     /// The location where each MIR arg/var/tmp/ret is stored. This is
     /// usually an `PlaceRef` representing an alloca, but not always:
@@ -174,7 +175,7 @@ pub fn codegen_mir<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
     let mut start_bx = Bx::build(cx, start_llbb);
 
     if mir.basic_blocks.iter().any(|bb| {
-        bb.is_cleanup || matches!(bb.terminator().unwind(), Some(mir::UnwindAction::Terminate))
+        bb.is_cleanup || matches!(bb.terminator().unwind(), Some(mir::UnwindAction::Terminate(_)))
     }) {
         start_bx.set_personality_fn(cx.eh_personality());
     }
diff --git a/compiler/rustc_const_eval/src/interpret/eval_context.rs b/compiler/rustc_const_eval/src/interpret/eval_context.rs
index 61d3de5c405..90848dbfbc7 100644
--- a/compiler/rustc_const_eval/src/interpret/eval_context.rs
+++ b/compiler/rustc_const_eval/src/interpret/eval_context.rs
@@ -756,6 +756,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
     ///
     /// If `target` is `UnwindAction::Unreachable`, that indicates the function does not allow
     /// unwinding, and doing so is UB.
+    #[cold] // usually we have normal returns, not unwinding
     pub fn unwind_to_block(&mut self, target: mir::UnwindAction) -> InterpResult<'tcx> {
         self.frame_mut().loc = match target {
             mir::UnwindAction::Cleanup(block) => Left(mir::Location { block, statement_index: 0 }),
@@ -763,9 +764,9 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             mir::UnwindAction::Unreachable => {
                 throw_ub_custom!(fluent::const_eval_unreachable_unwind);
             }
-            mir::UnwindAction::Terminate => {
+            mir::UnwindAction::Terminate(reason) => {
                 self.frame_mut().loc = Right(self.frame_mut().body.span);
-                M::unwind_terminate(self)?;
+                M::unwind_terminate(self, reason)?;
                 // This might have pushed a new stack frame, or it terminated execution.
                 // Either way, `loc` will not be updated.
                 return Ok(());
diff --git a/compiler/rustc_const_eval/src/interpret/machine.rs b/compiler/rustc_const_eval/src/interpret/machine.rs
index d3c73b896c0..6be2e406917 100644
--- a/compiler/rustc_const_eval/src/interpret/machine.rs
+++ b/compiler/rustc_const_eval/src/interpret/machine.rs
@@ -222,7 +222,10 @@ pub trait Machine<'mir, 'tcx: 'mir>: Sized {
     fn panic_nounwind(_ecx: &mut InterpCx<'mir, 'tcx, Self>, msg: &str) -> InterpResult<'tcx>;
 
     /// Called when unwinding reached a state where execution should be terminated.
-    fn unwind_terminate(_ecx: &mut InterpCx<'mir, 'tcx, Self>) -> InterpResult<'tcx>;
+    fn unwind_terminate(
+        ecx: &mut InterpCx<'mir, 'tcx, Self>,
+        reason: mir::UnwindTerminateReason,
+    ) -> InterpResult<'tcx>;
 
     /// Called for all binary operations where the LHS has pointer type.
     ///
@@ -462,6 +465,7 @@ pub trait Machine<'mir, 'tcx: 'mir>: Sized {
 
     /// Called immediately after a stack frame got popped, but before jumping back to the caller.
     /// The `locals` have already been destroyed!
+    #[inline(always)]
     fn after_stack_pop(
         _ecx: &mut InterpCx<'mir, 'tcx, Self>,
         _frame: Frame<'mir, 'tcx, Self::Provenance, Self::FrameExtra>,
@@ -501,7 +505,10 @@ pub macro compile_time_machine(<$mir: lifetime, $tcx: lifetime>) {
     }
 
     #[inline(always)]
-    fn unwind_terminate(_ecx: &mut InterpCx<$mir, $tcx, Self>) -> InterpResult<$tcx> {
+    fn unwind_terminate(
+        _ecx: &mut InterpCx<$mir, $tcx, Self>,
+        _reason: mir::UnwindTerminateReason,
+    ) -> InterpResult<$tcx> {
         unreachable!("unwinding cannot happen during compile-time evaluation")
     }
 
diff --git a/compiler/rustc_const_eval/src/interpret/terminator.rs b/compiler/rustc_const_eval/src/interpret/terminator.rs
index b2ebcceceb3..ca7c484ea31 100644
--- a/compiler/rustc_const_eval/src/interpret/terminator.rs
+++ b/compiler/rustc_const_eval/src/interpret/terminator.rs
@@ -196,8 +196,8 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 }
             }
 
-            UnwindTerminate => {
-                M::unwind_terminate(self)?;
+            UnwindTerminate(reason) => {
+                M::unwind_terminate(self, reason)?;
             }
 
             // When we encounter Resume, we've finished unwinding
diff --git a/compiler/rustc_const_eval/src/transform/check_consts/check.rs b/compiler/rustc_const_eval/src/transform/check_consts/check.rs
index e67098a3ac3..f288ddc25d3 100644
--- a/compiler/rustc_const_eval/src/transform/check_consts/check.rs
+++ b/compiler/rustc_const_eval/src/transform/check_consts/check.rs
@@ -1037,7 +1037,7 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
                 self.check_op(ops::Generator(hir::GeneratorKind::Gen))
             }
 
-            TerminatorKind::UnwindTerminate => {
+            TerminatorKind::UnwindTerminate(_) => {
                 // Cleanup blocks are skipped for const checking (see `visit_basic_block_data`).
                 span_bug!(self.span, "`Terminate` terminator outside of cleanup block")
             }
diff --git a/compiler/rustc_const_eval/src/transform/check_consts/post_drop_elaboration.rs b/compiler/rustc_const_eval/src/transform/check_consts/post_drop_elaboration.rs
index a8c61d2c8fd..fd6bc2ee9af 100644
--- a/compiler/rustc_const_eval/src/transform/check_consts/post_drop_elaboration.rs
+++ b/compiler/rustc_const_eval/src/transform/check_consts/post_drop_elaboration.rs
@@ -106,7 +106,7 @@ impl<'tcx> Visitor<'tcx> for CheckLiveDrops<'_, 'tcx> {
                 }
             }
 
-            mir::TerminatorKind::UnwindTerminate
+            mir::TerminatorKind::UnwindTerminate(_)
             | mir::TerminatorKind::Call { .. }
             | mir::TerminatorKind::Assert { .. }
             | mir::TerminatorKind::FalseEdge { .. }
diff --git a/compiler/rustc_const_eval/src/transform/validate.rs b/compiler/rustc_const_eval/src/transform/validate.rs
index 0dfbbf73dce..b829f24ab7a 100644
--- a/compiler/rustc_const_eval/src/transform/validate.rs
+++ b/compiler/rustc_const_eval/src/transform/validate.rs
@@ -10,8 +10,8 @@ use rustc_middle::mir::{
     traversal, BasicBlock, BinOp, Body, BorrowKind, CastKind, CopyNonOverlapping, Local, Location,
     MirPass, MirPhase, NonDivergingIntrinsic, NullOp, Operand, Place, PlaceElem, PlaceRef,
     ProjectionElem, RetagKind, RuntimePhase, Rvalue, SourceScope, Statement, StatementKind,
-    Terminator, TerminatorKind, UnOp, UnwindAction, VarDebugInfo, VarDebugInfoContents,
-    START_BLOCK,
+    Terminator, TerminatorKind, UnOp, UnwindAction, UnwindTerminateReason, VarDebugInfo,
+    VarDebugInfoContents, START_BLOCK,
 };
 use rustc_middle::ty::{self, InstanceDef, ParamEnv, Ty, TyCtxt, TypeVisitableExt};
 use rustc_mir_dataflow::impls::MaybeStorageLive;
@@ -274,7 +274,16 @@ impl<'a, 'tcx> CfgChecker<'a, 'tcx> {
                     self.fail(location, "`UnwindAction::Continue` in no-unwind function");
                 }
             }
-            UnwindAction::Unreachable | UnwindAction::Terminate => (),
+            UnwindAction::Terminate(UnwindTerminateReason::InCleanup) => {
+                if !is_cleanup {
+                    self.fail(
+                        location,
+                        "`UnwindAction::Terminate(InCleanup)` in a non-cleanup block",
+                    );
+                }
+            }
+            // These are allowed everywhere.
+            UnwindAction::Unreachable | UnwindAction::Terminate(UnwindTerminateReason::Abi) => (),
         }
     }
 }
@@ -501,7 +510,7 @@ impl<'a, 'tcx> Visitor<'tcx> for CfgChecker<'a, 'tcx> {
                     self.fail(location, "Cannot `UnwindResume` in a function that cannot unwind")
                 }
             }
-            TerminatorKind::UnwindTerminate => {
+            TerminatorKind::UnwindTerminate(_) => {
                 let bb = location.block;
                 if !self.body.basic_blocks[bb].is_cleanup {
                     self.fail(location, "Cannot `UnwindTerminate` from non-cleanup basic block")
@@ -1233,7 +1242,7 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
             | TerminatorKind::InlineAsm { .. }
             | TerminatorKind::GeneratorDrop
             | TerminatorKind::UnwindResume
-            | TerminatorKind::UnwindTerminate
+            | TerminatorKind::UnwindTerminate(_)
             | TerminatorKind::Return
             | TerminatorKind::Unreachable => {}
         }
diff --git a/compiler/rustc_hir/src/lang_items.rs b/compiler/rustc_hir/src/lang_items.rs
index 302a9498413..23b20543d53 100644
--- a/compiler/rustc_hir/src/lang_items.rs
+++ b/compiler/rustc_hir/src/lang_items.rs
@@ -238,6 +238,7 @@ language_item_table! {
     PanicLocation,           sym::panic_location,      panic_location,             Target::Struct,         GenericRequirement::None;
     PanicImpl,               sym::panic_impl,          panic_impl,                 Target::Fn,             GenericRequirement::None;
     PanicCannotUnwind,       sym::panic_cannot_unwind, panic_cannot_unwind,        Target::Fn,             GenericRequirement::Exact(0);
+    PanicInCleanup,          sym::panic_in_cleanup,    panic_in_cleanup,           Target::Fn,             GenericRequirement::Exact(0);
     /// libstd panic entry point. Necessary for const eval to be able to catch it
     BeginPanic,              sym::begin_panic,         begin_panic_fn,             Target::Fn,             GenericRequirement::None;
 
diff --git a/compiler/rustc_middle/src/mir/mod.rs b/compiler/rustc_middle/src/mir/mod.rs
index 9ef3a1b30e4..6484c30167c 100644
--- 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::*;
diff --git a/compiler/rustc_middle/src/mir/patch.rs b/compiler/rustc_middle/src/mir/patch.rs
index cd74a403ff6..da486c3465a 100644
--- 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
     }
 
diff --git a/compiler/rustc_middle/src/mir/syntax.rs b/compiler/rustc_middle/src/mir/syntax.rs
index e91e822f915..79b64a491f4 100644
--- 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)]
diff --git a/compiler/rustc_middle/src/mir/terminator.rs b/compiler/rustc_middle/src/mir/terminator.rs
index bd87563e2bb..7eddf13b3fb 100644
--- 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),
             },
 
diff --git a/compiler/rustc_middle/src/mir/visit.rs b/compiler/rustc_middle/src/mir/visit.rs
index b3d3366ae10..87b04aabe6a 100644
--- 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 { .. } |
diff --git a/compiler/rustc_mir_build/src/build/scope.rs b/compiler/rustc_mir_build/src/build/scope.rs
index 567e7bfb5bf..4cf6a349af7 100644
--- a/compiler/rustc_mir_build/src/build/scope.rs
+++ b/compiler/rustc_mir_build/src/build/scope.rs
@@ -370,7 +370,7 @@ impl DropTree {
                     let terminator = TerminatorKind::Drop {
                         target: blocks[drop_data.1].unwrap(),
                         // The caller will handle this if needed.
-                        unwind: UnwindAction::Terminate,
+                        unwind: UnwindAction::Terminate(UnwindTerminateReason::InCleanup),
                         place: drop_data.0.local.into(),
                         replace: false,
                     };
@@ -1507,7 +1507,7 @@ impl<'tcx> DropTreeBuilder<'tcx> for Unwind {
             TerminatorKind::Goto { .. }
             | TerminatorKind::SwitchInt { .. }
             | TerminatorKind::UnwindResume
-            | TerminatorKind::UnwindTerminate
+            | TerminatorKind::UnwindTerminate(_)
             | TerminatorKind::Return
             | TerminatorKind::Unreachable
             | TerminatorKind::Yield { .. }
diff --git a/compiler/rustc_mir_build/src/lints.rs b/compiler/rustc_mir_build/src/lints.rs
index 84c80bf41a4..94be38beee4 100644
--- a/compiler/rustc_mir_build/src/lints.rs
+++ b/compiler/rustc_mir_build/src/lints.rs
@@ -186,7 +186,7 @@ impl<'mir, 'tcx, C: TerminatorClassifier<'tcx>> TriColorVisitor<BasicBlocks<'tcx
 
         match self.body[bb].terminator().kind {
             // These terminators return control flow to the caller.
-            TerminatorKind::UnwindTerminate
+            TerminatorKind::UnwindTerminate(_)
             | TerminatorKind::GeneratorDrop
             | TerminatorKind::UnwindResume
             | TerminatorKind::Return
diff --git a/compiler/rustc_mir_dataflow/src/elaborate_drops.rs b/compiler/rustc_mir_dataflow/src/elaborate_drops.rs
index 9e02b027182..ad5f83d9e25 100644
--- a/compiler/rustc_mir_dataflow/src/elaborate_drops.rs
+++ b/compiler/rustc_mir_dataflow/src/elaborate_drops.rs
@@ -80,7 +80,7 @@ impl Unwind {
     fn into_action(self) -> UnwindAction {
         match self {
             Unwind::To(bb) => UnwindAction::Cleanup(bb),
-            Unwind::InCleanup => UnwindAction::Terminate,
+            Unwind::InCleanup => UnwindAction::Terminate(UnwindTerminateReason::InCleanup),
         }
     }
 
diff --git a/compiler/rustc_mir_dataflow/src/framework/direction.rs b/compiler/rustc_mir_dataflow/src/framework/direction.rs
index 8a9e37c5a4f..70451edd500 100644
--- a/compiler/rustc_mir_dataflow/src/framework/direction.rs
+++ b/compiler/rustc_mir_dataflow/src/framework/direction.rs
@@ -1,5 +1,5 @@
 use rustc_middle::mir::{
-    self, BasicBlock, CallReturnPlaces, Location, SwitchTargets, TerminatorEdges, UnwindAction,
+    self, BasicBlock, CallReturnPlaces, Location, SwitchTargets, TerminatorEdges,
 };
 use std::ops::RangeInclusive;
 
@@ -486,10 +486,10 @@ impl Direction for Forward {
                 propagate(target, exit_state);
                 propagate(unwind, exit_state);
             }
-            TerminatorEdges::AssignOnReturn { return_, unwind, place } => {
+            TerminatorEdges::AssignOnReturn { return_, cleanup, place } => {
                 // This must be done *first*, otherwise the unwind path will see the assignments.
-                if let UnwindAction::Cleanup(unwind) = unwind {
-                    propagate(unwind, exit_state);
+                if let Some(cleanup) = cleanup {
+                    propagate(cleanup, exit_state);
                 }
                 if let Some(return_) = return_ {
                     analysis.apply_call_return_effect(exit_state, bb, place);
diff --git a/compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs b/compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs
index 5ed8f20b73f..3ad9d3d4264 100644
--- a/compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs
+++ b/compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs
@@ -131,7 +131,7 @@ where
                 }
             }
 
-            TerminatorKind::UnwindTerminate
+            TerminatorKind::UnwindTerminate(_)
             | TerminatorKind::Assert { .. }
             | TerminatorKind::Call { .. }
             | TerminatorKind::FalseEdge { .. }
diff --git a/compiler/rustc_mir_dataflow/src/impls/storage_liveness.rs b/compiler/rustc_mir_dataflow/src/impls/storage_liveness.rs
index 531390c2f07..94d6eb67d49 100644
--- a/compiler/rustc_mir_dataflow/src/impls/storage_liveness.rs
+++ b/compiler/rustc_mir_dataflow/src/impls/storage_liveness.rs
@@ -291,7 +291,7 @@ impl<'tcx> crate::GenKillAnalysis<'tcx> for MaybeRequiresStorage<'_, '_, 'tcx> {
 
             // Nothing to do for these. Match exhaustively so this fails to compile when new
             // variants are added.
-            TerminatorKind::UnwindTerminate
+            TerminatorKind::UnwindTerminate(_)
             | TerminatorKind::Assert { .. }
             | TerminatorKind::Drop { .. }
             | TerminatorKind::FalseEdge { .. }
@@ -328,7 +328,7 @@ impl<'tcx> crate::GenKillAnalysis<'tcx> for MaybeRequiresStorage<'_, '_, 'tcx> {
             // Nothing to do for these. Match exhaustively so this fails to compile when new
             // variants are added.
             TerminatorKind::Yield { .. }
-            | TerminatorKind::UnwindTerminate
+            | TerminatorKind::UnwindTerminate(_)
             | TerminatorKind::Assert { .. }
             | TerminatorKind::Drop { .. }
             | TerminatorKind::FalseEdge { .. }
diff --git a/compiler/rustc_mir_dataflow/src/move_paths/builder.rs b/compiler/rustc_mir_dataflow/src/move_paths/builder.rs
index 4adf3dec61b..2e3b9577b50 100644
--- a/compiler/rustc_mir_dataflow/src/move_paths/builder.rs
+++ b/compiler/rustc_mir_dataflow/src/move_paths/builder.rs
@@ -371,7 +371,7 @@ impl<'b, 'a, 'tcx> Gatherer<'b, 'a, 'tcx> {
             // need recording.
             | TerminatorKind::Return
             | TerminatorKind::UnwindResume
-            | TerminatorKind::UnwindTerminate
+            | TerminatorKind::UnwindTerminate(_)
             | TerminatorKind::GeneratorDrop
             | TerminatorKind::Unreachable
             | TerminatorKind::Drop { .. } => {}
diff --git a/compiler/rustc_mir_dataflow/src/value_analysis.rs b/compiler/rustc_mir_dataflow/src/value_analysis.rs
index 1eea8eef0ad..6872ef5e985 100644
--- a/compiler/rustc_mir_dataflow/src/value_analysis.rs
+++ b/compiler/rustc_mir_dataflow/src/value_analysis.rs
@@ -270,7 +270,7 @@ pub trait ValueAnalysis<'tcx> {
             }
             TerminatorKind::Goto { .. }
             | TerminatorKind::UnwindResume
-            | TerminatorKind::UnwindTerminate
+            | TerminatorKind::UnwindTerminate(_)
             | TerminatorKind::Return
             | TerminatorKind::Unreachable
             | TerminatorKind::Assert { .. }
diff --git a/compiler/rustc_mir_transform/src/abort_unwinding_calls.rs b/compiler/rustc_mir_transform/src/abort_unwinding_calls.rs
index 5aed89139e2..4500bb7ff0f 100644
--- a/compiler/rustc_mir_transform/src/abort_unwinding_calls.rs
+++ b/compiler/rustc_mir_transform/src/abort_unwinding_calls.rs
@@ -104,7 +104,7 @@ impl<'tcx> MirPass<'tcx> for AbortUnwindingCalls {
 
         for id in calls_to_terminate {
             let cleanup = body.basic_blocks_mut()[id].terminator_mut().unwind_mut().unwrap();
-            *cleanup = UnwindAction::Terminate;
+            *cleanup = UnwindAction::Terminate(UnwindTerminateReason::Abi);
         }
 
         for id in cleanups_to_remove {
diff --git a/compiler/rustc_mir_transform/src/add_call_guards.rs b/compiler/rustc_mir_transform/src/add_call_guards.rs
index fb4705e0754..b814fbf32b1 100644
--- a/compiler/rustc_mir_transform/src/add_call_guards.rs
+++ b/compiler/rustc_mir_transform/src/add_call_guards.rs
@@ -53,8 +53,10 @@ impl AddCallGuards {
                     kind: TerminatorKind::Call { target: Some(ref mut destination), unwind, .. },
                     source_info,
                 }) if pred_count[*destination] > 1
-                    && (matches!(unwind, UnwindAction::Cleanup(_) | UnwindAction::Terminate)
-                        || self == &AllCallEdges) =>
+                    && (matches!(
+                        unwind,
+                        UnwindAction::Cleanup(_) | UnwindAction::Terminate(_)
+                    ) || self == &AllCallEdges) =>
                 {
                     // It's a critical edge, break it
                     let call_guard = BasicBlockData {
diff --git a/compiler/rustc_mir_transform/src/check_unsafety.rs b/compiler/rustc_mir_transform/src/check_unsafety.rs
index e72db1a59a0..0fce9cb19a8 100644
--- a/compiler/rustc_mir_transform/src/check_unsafety.rs
+++ b/compiler/rustc_mir_transform/src/check_unsafety.rs
@@ -58,7 +58,7 @@ impl<'tcx> Visitor<'tcx> for UnsafetyChecker<'_, 'tcx> {
             | TerminatorKind::Assert { .. }
             | TerminatorKind::GeneratorDrop
             | TerminatorKind::UnwindResume
-            | TerminatorKind::UnwindTerminate
+            | TerminatorKind::UnwindTerminate(_)
             | TerminatorKind::Return
             | TerminatorKind::Unreachable
             | TerminatorKind::FalseEdge { .. }
diff --git a/compiler/rustc_mir_transform/src/const_prop_lint.rs b/compiler/rustc_mir_transform/src/const_prop_lint.rs
index 4f8ca916d5b..da8913d604b 100644
--- a/compiler/rustc_mir_transform/src/const_prop_lint.rs
+++ b/compiler/rustc_mir_transform/src/const_prop_lint.rs
@@ -679,7 +679,7 @@ impl<'tcx> Visitor<'tcx> for ConstPropagator<'_, 'tcx> {
             // None of these have Operands to const-propagate.
             TerminatorKind::Goto { .. }
             | TerminatorKind::UnwindResume
-            | TerminatorKind::UnwindTerminate
+            | TerminatorKind::UnwindTerminate(_)
             | TerminatorKind::Return
             | TerminatorKind::Unreachable
             | TerminatorKind::Drop { .. }
diff --git a/compiler/rustc_mir_transform/src/coverage/graph.rs b/compiler/rustc_mir_transform/src/coverage/graph.rs
index d3d4fcd3a52..60461691e7f 100644
--- a/compiler/rustc_mir_transform/src/coverage/graph.rs
+++ b/compiler/rustc_mir_transform/src/coverage/graph.rs
@@ -116,7 +116,7 @@ impl CoverageGraph {
 
             match term.kind {
                 TerminatorKind::Return { .. }
-                | TerminatorKind::UnwindTerminate
+                | TerminatorKind::UnwindTerminate(_)
                 | TerminatorKind::Yield { .. }
                 | TerminatorKind::SwitchInt { .. } => {
                     // The `bb` has more than one _outgoing_ edge, or exits the function. Save the
diff --git a/compiler/rustc_mir_transform/src/coverage/spans.rs b/compiler/rustc_mir_transform/src/coverage/spans.rs
index 6fabaca524a..717763a94a0 100644
--- a/compiler/rustc_mir_transform/src/coverage/spans.rs
+++ b/compiler/rustc_mir_transform/src/coverage/spans.rs
@@ -868,7 +868,7 @@ pub(super) fn filtered_terminator_span(terminator: &Terminator<'_>) -> Option<Sp
 
         // Retain spans from all other terminators
         TerminatorKind::UnwindResume
-        | TerminatorKind::UnwindTerminate
+        | TerminatorKind::UnwindTerminate(_)
         | TerminatorKind::Return
         | TerminatorKind::Yield { .. }
         | TerminatorKind::GeneratorDrop
diff --git a/compiler/rustc_mir_transform/src/dest_prop.rs b/compiler/rustc_mir_transform/src/dest_prop.rs
index 041f7c7221e..d9a132e5cf1 100644
--- a/compiler/rustc_mir_transform/src/dest_prop.rs
+++ b/compiler/rustc_mir_transform/src/dest_prop.rs
@@ -648,7 +648,7 @@ impl WriteInfo {
             }
             TerminatorKind::Goto { .. }
             | TerminatorKind::UnwindResume
-            | TerminatorKind::UnwindTerminate
+            | TerminatorKind::UnwindTerminate(_)
             | TerminatorKind::Return
             | TerminatorKind::Unreachable { .. } => (),
             TerminatorKind::Drop { .. } => {
diff --git a/compiler/rustc_mir_transform/src/elaborate_drops.rs b/compiler/rustc_mir_transform/src/elaborate_drops.rs
index a80ae480089..78d7ffb3698 100644
--- a/compiler/rustc_mir_transform/src/elaborate_drops.rs
+++ b/compiler/rustc_mir_transform/src/elaborate_drops.rs
@@ -362,8 +362,13 @@ impl<'b, 'tcx> ElaborateDropsCtxt<'b, 'tcx> {
                                     UnwindAction::Unreachable => {
                                         Unwind::To(self.patch.unreachable_cleanup_block())
                                     }
-                                    UnwindAction::Terminate => {
-                                        Unwind::To(self.patch.terminate_block())
+                                    UnwindAction::Terminate(reason) => {
+                                        debug_assert_ne!(
+                                            reason,
+                                            UnwindTerminateReason::InCleanup,
+                                            "we are not in a cleanup block, InCleanup reason should be impossible"
+                                        );
+                                        Unwind::To(self.patch.terminate_block(reason))
                                     }
                                 }
                             };
@@ -496,7 +501,8 @@ impl<'b, 'tcx> ElaborateDropsCtxt<'b, 'tcx> {
             if let TerminatorKind::Call {
                 destination,
                 target: Some(_),
-                unwind: UnwindAction::Continue | UnwindAction::Unreachable | UnwindAction::Terminate,
+                unwind:
+                    UnwindAction::Continue | UnwindAction::Unreachable | UnwindAction::Terminate(_),
                 ..
             } = data.terminator().kind
             {
diff --git a/compiler/rustc_mir_transform/src/generator.rs b/compiler/rustc_mir_transform/src/generator.rs
index 96077322575..1e7161189c3 100644
--- a/compiler/rustc_mir_transform/src/generator.rs
+++ b/compiler/rustc_mir_transform/src/generator.rs
@@ -1091,7 +1091,7 @@ fn elaborate_generator_drops<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
                 UnwindAction::Cleanup(tgt) => tgt,
                 UnwindAction::Continue => elaborator.patch.resume_block(),
                 UnwindAction::Unreachable => elaborator.patch.unreachable_cleanup_block(),
-                UnwindAction::Terminate => elaborator.patch.terminate_block(),
+                UnwindAction::Terminate(reason) => elaborator.patch.terminate_block(reason),
             })
         };
         elaborate_drop(
@@ -1239,7 +1239,7 @@ fn can_unwind<'tcx>(tcx: TyCtxt<'tcx>, body: &Body<'tcx>) -> bool {
             // These never unwind.
             TerminatorKind::Goto { .. }
             | TerminatorKind::SwitchInt { .. }
-            | TerminatorKind::UnwindTerminate
+            | TerminatorKind::UnwindTerminate(_)
             | TerminatorKind::Return
             | TerminatorKind::Unreachable
             | TerminatorKind::GeneratorDrop
@@ -1759,7 +1759,7 @@ impl<'tcx> Visitor<'tcx> for EnsureGeneratorFieldAssignmentsNeverAlias<'_> {
             | TerminatorKind::Goto { .. }
             | TerminatorKind::SwitchInt { .. }
             | TerminatorKind::UnwindResume
-            | TerminatorKind::UnwindTerminate
+            | TerminatorKind::UnwindTerminate(_)
             | TerminatorKind::Return
             | TerminatorKind::Unreachable
             | TerminatorKind::Drop { .. }
diff --git a/compiler/rustc_mir_transform/src/inline.rs b/compiler/rustc_mir_transform/src/inline.rs
index 734e93783d1..9551c7a2a8d 100644
--- a/compiler/rustc_mir_transform/src/inline.rs
+++ b/compiler/rustc_mir_transform/src/inline.rs
@@ -906,12 +906,12 @@ impl Integrator<'_, '_> {
                 UnwindAction::Cleanup(_) | UnwindAction::Continue => {
                     bug!("cleanup on cleanup block");
                 }
-                UnwindAction::Unreachable | UnwindAction::Terminate => return unwind,
+                UnwindAction::Unreachable | UnwindAction::Terminate(_) => return unwind,
             }
         }
 
         match unwind {
-            UnwindAction::Unreachable | UnwindAction::Terminate => unwind,
+            UnwindAction::Unreachable | UnwindAction::Terminate(_) => unwind,
             UnwindAction::Cleanup(target) => UnwindAction::Cleanup(self.map_block(target)),
             // Add an unwind edge to the original call's cleanup block
             UnwindAction::Continue => self.cleanup_block,
@@ -1022,10 +1022,10 @@ impl<'tcx> MutVisitor<'tcx> for Integrator<'_, 'tcx> {
                     UnwindAction::Cleanup(tgt) => TerminatorKind::Goto { target: tgt },
                     UnwindAction::Continue => TerminatorKind::UnwindResume,
                     UnwindAction::Unreachable => TerminatorKind::Unreachable,
-                    UnwindAction::Terminate => TerminatorKind::UnwindTerminate,
+                    UnwindAction::Terminate(reason) => TerminatorKind::UnwindTerminate(reason),
                 };
             }
-            TerminatorKind::UnwindTerminate => {}
+            TerminatorKind::UnwindTerminate(_) => {}
             TerminatorKind::Unreachable => {}
             TerminatorKind::FalseEdge { ref mut real_target, ref mut imaginary_target } => {
                 *real_target = self.map_block(*real_target);
diff --git a/compiler/rustc_mir_transform/src/remove_noop_landing_pads.rs b/compiler/rustc_mir_transform/src/remove_noop_landing_pads.rs
index 5782adbb3ff..8c48a667786 100644
--- a/compiler/rustc_mir_transform/src/remove_noop_landing_pads.rs
+++ b/compiler/rustc_mir_transform/src/remove_noop_landing_pads.rs
@@ -72,7 +72,7 @@ impl RemoveNoopLandingPads {
             TerminatorKind::GeneratorDrop
             | TerminatorKind::Yield { .. }
             | TerminatorKind::Return
-            | TerminatorKind::UnwindTerminate
+            | TerminatorKind::UnwindTerminate(_)
             | TerminatorKind::Unreachable
             | TerminatorKind::Call { .. }
             | TerminatorKind::Assert { .. }
diff --git a/compiler/rustc_mir_transform/src/separate_const_switch.rs b/compiler/rustc_mir_transform/src/separate_const_switch.rs
index de1b80585d1..e1e4acccccd 100644
--- a/compiler/rustc_mir_transform/src/separate_const_switch.rs
+++ b/compiler/rustc_mir_transform/src/separate_const_switch.rs
@@ -114,7 +114,7 @@ pub fn separate_const_switch(body: &mut Body<'_>) -> usize {
                         | TerminatorKind::Assert { .. }
                         | TerminatorKind::FalseUnwind { .. }
                         | TerminatorKind::Yield { .. }
-                        | TerminatorKind::UnwindTerminate
+                        | TerminatorKind::UnwindTerminate(_)
                         | TerminatorKind::Return
                         | TerminatorKind::Unreachable
                         | TerminatorKind::InlineAsm { .. }
@@ -166,7 +166,7 @@ pub fn separate_const_switch(body: &mut Body<'_>) -> usize {
             }
 
             TerminatorKind::UnwindResume
-            | TerminatorKind::UnwindTerminate
+            | TerminatorKind::UnwindTerminate(_)
             | TerminatorKind::Return
             | TerminatorKind::Unreachable
             | TerminatorKind::GeneratorDrop
diff --git a/compiler/rustc_mir_transform/src/shim.rs b/compiler/rustc_mir_transform/src/shim.rs
index 079cf9eb4e9..e1000d96932 100644
--- a/compiler/rustc_mir_transform/src/shim.rs
+++ b/compiler/rustc_mir_transform/src/shim.rs
@@ -570,10 +570,10 @@ impl<'tcx> CloneShimBuilder<'tcx> {
                 TerminatorKind::Drop {
                     place: dest_field,
                     target: unwind,
-                    unwind: UnwindAction::Terminate,
+                    unwind: UnwindAction::Terminate(UnwindTerminateReason::InCleanup),
                     replace: false,
                 },
-                true,
+                /* is_cleanup */ true,
             );
             unwind = next_unwind;
         }
@@ -851,10 +851,10 @@ fn build_call_shim<'tcx>(
             TerminatorKind::Drop {
                 place: rcvr_place(),
                 target: BasicBlock::new(4),
-                unwind: UnwindAction::Terminate,
+                unwind: UnwindAction::Terminate(UnwindTerminateReason::InCleanup),
                 replace: false,
             },
-            true,
+            /* is_cleanup */ true,
         );
 
         // BB #4 - resume
diff --git a/compiler/rustc_monomorphize/src/collector.rs b/compiler/rustc_monomorphize/src/collector.rs
index cd7908e75e2..f917e52109a 100644
--- a/compiler/rustc_monomorphize/src/collector.rs
+++ b/compiler/rustc_monomorphize/src/collector.rs
@@ -737,6 +737,13 @@ impl<'a, 'tcx> MirVisitor<'tcx> for MirUsedCollector<'a, 'tcx> {
         let source = self.body.source_info(location).span;
 
         let tcx = self.tcx;
+        let push_mono_lang_item = |this: &mut Self, lang_item: LangItem| {
+            let instance = Instance::mono(tcx, tcx.require_lang_item(lang_item, Some(source)));
+            if should_codegen_locally(tcx, &instance) {
+                this.output.push(create_fn_mono_item(tcx, instance, source));
+            }
+        };
+
         match terminator.kind {
             mir::TerminatorKind::Call { ref func, .. } => {
                 let callee_ty = func.ty(self.body, tcx);
@@ -771,19 +778,10 @@ impl<'a, 'tcx> MirVisitor<'tcx> for MirUsedCollector<'a, 'tcx> {
                     mir::AssertKind::BoundsCheck { .. } => LangItem::PanicBoundsCheck,
                     _ => LangItem::Panic,
                 };
-                let instance = Instance::mono(tcx, tcx.require_lang_item(lang_item, Some(source)));
-                if should_codegen_locally(tcx, &instance) {
-                    self.output.push(create_fn_mono_item(tcx, instance, source));
-                }
+                push_mono_lang_item(self, lang_item);
             }
-            mir::TerminatorKind::UnwindTerminate { .. } => {
-                let instance = Instance::mono(
-                    tcx,
-                    tcx.require_lang_item(LangItem::PanicCannotUnwind, Some(source)),
-                );
-                if should_codegen_locally(tcx, &instance) {
-                    self.output.push(create_fn_mono_item(tcx, instance, source));
-                }
+            mir::TerminatorKind::UnwindTerminate(reason) => {
+                push_mono_lang_item(self, reason.lang_item());
             }
             mir::TerminatorKind::Goto { .. }
             | mir::TerminatorKind::SwitchInt { .. }
@@ -796,14 +794,8 @@ impl<'a, 'tcx> MirVisitor<'tcx> for MirUsedCollector<'a, 'tcx> {
             | mir::TerminatorKind::FalseUnwind { .. } => bug!(),
         }
 
-        if let Some(mir::UnwindAction::Terminate) = terminator.unwind() {
-            let instance = Instance::mono(
-                tcx,
-                tcx.require_lang_item(LangItem::PanicCannotUnwind, Some(source)),
-            );
-            if should_codegen_locally(tcx, &instance) {
-                self.output.push(create_fn_mono_item(tcx, instance, source));
-            }
+        if let Some(mir::UnwindAction::Terminate(reason)) = terminator.unwind() {
+            push_mono_lang_item(self, reason.lang_item());
         }
 
         self.super_terminator(terminator, location);
diff --git a/compiler/rustc_smir/src/rustc_smir/mod.rs b/compiler/rustc_smir/src/rustc_smir/mod.rs
index 392dbafcb3e..94f63006c51 100644
--- a/compiler/rustc_smir/src/rustc_smir/mod.rs
+++ b/compiler/rustc_smir/src/rustc_smir/mod.rs
@@ -607,7 +607,7 @@ impl<'tcx> Stable<'tcx> for mir::UnwindAction {
         match self {
             UnwindAction::Continue => stable_mir::mir::UnwindAction::Continue,
             UnwindAction::Unreachable => stable_mir::mir::UnwindAction::Unreachable,
-            UnwindAction::Terminate => stable_mir::mir::UnwindAction::Terminate,
+            UnwindAction::Terminate(_) => stable_mir::mir::UnwindAction::Terminate,
             UnwindAction::Cleanup(bb) => stable_mir::mir::UnwindAction::Cleanup(bb.as_usize()),
         }
     }
@@ -805,7 +805,7 @@ impl<'tcx> Stable<'tcx> for mir::Terminator<'tcx> {
                 otherwise: targets.otherwise().as_usize(),
             },
             UnwindResume => Terminator::Resume,
-            UnwindTerminate => Terminator::Abort,
+            UnwindTerminate(_) => Terminator::Abort,
             Return => Terminator::Return,
             Unreachable => Terminator::Unreachable,
             Drop { place, target, unwind, replace: _ } => Terminator::Drop {
diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
index 40eadaaa820..07bae08d558 100644
--- a/compiler/rustc_span/src/symbol.rs
+++ b/compiler/rustc_span/src/symbol.rs
@@ -1104,6 +1104,7 @@ symbols! {
         panic_handler,
         panic_impl,
         panic_implementation,
+        panic_in_cleanup,
         panic_info,
         panic_location,
         panic_misaligned_pointer_dereference,