Auto merge of #102906 - nbdd0121:mir, r=wesleywiser,tmiasko

Refactor unwind in MIR

This makes unwinding from current `Option<BasicBlock>` into
```rust
enum UnwindAction {
	Continue,
	Cleanup(BasicBlock),
	Unreachable,
	Terminate,
}
```

cc `@JakobDegen` `@RalfJung` `@Amanieu`

9 files changed, 74 insertions, 78 deletions

diff --git a/compiler/rustc_const_eval/src/const_eval/machine.rs b/compiler/rustc_const_eval/src/const_eval/machine.rs
index c87ea18af4f..a5dfd1072f0 100644
--- a/compiler/rustc_const_eval/src/const_eval/machine.rs
+++ b/compiler/rustc_const_eval/src/const_eval/machine.rs
@@ -23,7 +23,7 @@ use rustc_target::spec::abi::Abi as CallAbi;
 
 use crate::interpret::{
     self, compile_time_machine, AllocId, ConstAllocation, FnVal, Frame, ImmTy, InterpCx,
-    InterpResult, OpTy, PlaceTy, Pointer, Scalar, StackPopUnwind,
+    InterpResult, OpTy, PlaceTy, Pointer, Scalar,
 };
 
 use super::error::*;
@@ -271,7 +271,7 @@ impl<'mir, 'tcx: 'mir> CompileTimeEvalContext<'mir, 'tcx> {
                         /* with_caller_location = */ false,
                         dest,
                         ret,
-                        StackPopUnwind::NotAllowed,
+                        mir::UnwindAction::Unreachable,
                     )?;
                     Ok(ControlFlow::Break(()))
                 } else {
@@ -401,7 +401,7 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir,
         args: &[OpTy<'tcx>],
         dest: &PlaceTy<'tcx>,
         ret: Option<mir::BasicBlock>,
-        _unwind: StackPopUnwind, // unwinding is not supported in consts
+        _unwind: mir::UnwindAction, // unwinding is not supported in consts
     ) -> InterpResult<'tcx, Option<(&'mir mir::Body<'tcx>, ty::Instance<'tcx>)>> {
         debug!("find_mir_or_eval_fn: {:?}", instance);
 
@@ -450,7 +450,7 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir,
         args: &[OpTy<'tcx>],
         dest: &PlaceTy<'tcx, Self::Provenance>,
         target: Option<mir::BasicBlock>,
-        _unwind: StackPopUnwind,
+        _unwind: mir::UnwindAction,
     ) -> InterpResult<'tcx> {
         // Shared intrinsics.
         if ecx.emulate_intrinsic(instance, args, dest, target)? {
@@ -526,7 +526,7 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir,
     fn assert_panic(
         ecx: &mut InterpCx<'mir, 'tcx, Self>,
         msg: &AssertMessage<'tcx>,
-        _unwind: Option<mir::BasicBlock>,
+        _unwind: mir::UnwindAction,
     ) -> InterpResult<'tcx> {
         use rustc_middle::mir::AssertKind::*;
         // Convert `AssertKind<Operand>` to `AssertKind<Scalar>`.
diff --git a/compiler/rustc_const_eval/src/interpret/eval_context.rs b/compiler/rustc_const_eval/src/interpret/eval_context.rs
index 0918ffcd982..3e58a58aef7 100644
--- a/compiler/rustc_const_eval/src/interpret/eval_context.rs
+++ b/compiler/rustc_const_eval/src/interpret/eval_context.rs
@@ -139,17 +139,6 @@ pub struct FrameInfo<'tcx> {
     pub lint_root: Option<hir::HirId>,
 }
 
-/// Unwind information.
-#[derive(Clone, Copy, Eq, PartialEq, Debug)]
-pub enum StackPopUnwind {
-    /// The cleanup block.
-    Cleanup(mir::BasicBlock),
-    /// No cleanup needs to be done.
-    Skip,
-    /// Unwinding is not allowed (UB).
-    NotAllowed,
-}
-
 #[derive(Clone, Copy, Eq, PartialEq, Debug)] // Miri debug-prints these
 pub enum StackPopCleanup {
     /// Jump to the next block in the caller, or cause UB if None (that's a function
@@ -157,7 +146,7 @@ pub enum StackPopCleanup {
     /// we can validate it at that layout.
     /// `ret` stores the block we jump to on a normal return, while `unwind`
     /// stores the block used for cleanup during unwinding.
-    Goto { ret: Option<mir::BasicBlock>, unwind: StackPopUnwind },
+    Goto { ret: Option<mir::BasicBlock>, unwind: mir::UnwindAction },
     /// The root frame of the stack: nowhere else to jump to.
     /// `cleanup` says whether locals are deallocated. Static computation
     /// wants them leaked to intern what they need (and just throw away
@@ -735,18 +724,22 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
     /// *Unwind* to the given `target` basic block.
     /// Do *not* use for returning! Use `return_to_block` instead.
     ///
-    /// If `target` is `StackPopUnwind::Skip`, that indicates the function does not need cleanup
+    /// If `target` is `UnwindAction::Continue`, that indicates the function does not need cleanup
     /// during unwinding, and we will just keep propagating that upwards.
     ///
-    /// If `target` is `StackPopUnwind::NotAllowed`, that indicates the function does not allow
+    /// If `target` is `UnwindAction::Unreachable`, that indicates the function does not allow
     /// unwinding, and doing so is UB.
-    pub fn unwind_to_block(&mut self, target: StackPopUnwind) -> InterpResult<'tcx> {
+    pub fn unwind_to_block(&mut self, target: mir::UnwindAction) -> InterpResult<'tcx> {
         self.frame_mut().loc = match target {
-            StackPopUnwind::Cleanup(block) => Left(mir::Location { block, statement_index: 0 }),
-            StackPopUnwind::Skip => Right(self.frame_mut().body.span),
-            StackPopUnwind::NotAllowed => {
+            mir::UnwindAction::Cleanup(block) => Left(mir::Location { block, statement_index: 0 }),
+            mir::UnwindAction::Continue => Right(self.frame_mut().body.span),
+            mir::UnwindAction::Unreachable => {
                 throw_ub_format!("unwinding past a stack frame that does not allow unwinding")
             }
+            mir::UnwindAction::Terminate => {
+                self.frame_mut().loc = Right(self.frame_mut().body.span);
+                M::abort(self, "panic in a function that cannot unwind".to_owned())?;
+            }
         };
         Ok(())
     }
diff --git a/compiler/rustc_const_eval/src/interpret/machine.rs b/compiler/rustc_const_eval/src/interpret/machine.rs
index aca68dc454b..0291cca7378 100644
--- a/compiler/rustc_const_eval/src/interpret/machine.rs
+++ b/compiler/rustc_const_eval/src/interpret/machine.rs
@@ -18,7 +18,7 @@ use crate::const_eval::CheckAlignment;
 
 use super::{
     AllocBytes, AllocId, AllocRange, Allocation, ConstAllocation, Frame, ImmTy, InterpCx,
-    InterpResult, MemoryKind, OpTy, Operand, PlaceTy, Pointer, Provenance, Scalar, StackPopUnwind,
+    InterpResult, MemoryKind, OpTy, Operand, PlaceTy, Pointer, Provenance, Scalar,
 };
 
 /// Data returned by Machine::stack_pop,
@@ -185,7 +185,7 @@ pub trait Machine<'mir, 'tcx>: Sized {
         args: &[OpTy<'tcx, Self::Provenance>],
         destination: &PlaceTy<'tcx, Self::Provenance>,
         target: Option<mir::BasicBlock>,
-        unwind: StackPopUnwind,
+        unwind: mir::UnwindAction,
     ) -> InterpResult<'tcx, Option<(&'mir mir::Body<'tcx>, ty::Instance<'tcx>)>>;
 
     /// Execute `fn_val`. It is the hook's responsibility to advance the instruction
@@ -197,7 +197,7 @@ pub trait Machine<'mir, 'tcx>: Sized {
         args: &[OpTy<'tcx, Self::Provenance>],
         destination: &PlaceTy<'tcx, Self::Provenance>,
         target: Option<mir::BasicBlock>,
-        unwind: StackPopUnwind,
+        unwind: mir::UnwindAction,
     ) -> InterpResult<'tcx>;
 
     /// Directly process an intrinsic without pushing a stack frame. It is the hook's
@@ -208,17 +208,17 @@ pub trait Machine<'mir, 'tcx>: Sized {
         args: &[OpTy<'tcx, Self::Provenance>],
         destination: &PlaceTy<'tcx, Self::Provenance>,
         target: Option<mir::BasicBlock>,
-        unwind: StackPopUnwind,
+        unwind: mir::UnwindAction,
     ) -> InterpResult<'tcx>;
 
     /// Called to evaluate `Assert` MIR terminators that trigger a panic.
     fn assert_panic(
         ecx: &mut InterpCx<'mir, 'tcx, Self>,
         msg: &mir::AssertMessage<'tcx>,
-        unwind: Option<mir::BasicBlock>,
+        unwind: mir::UnwindAction,
     ) -> InterpResult<'tcx>;
 
-    /// Called to evaluate `Abort` MIR terminator.
+    /// Called to abort evaluation.
     fn abort(_ecx: &mut InterpCx<'mir, 'tcx, Self>, _msg: String) -> InterpResult<'tcx, !> {
         throw_unsup_format!("aborting execution is not supported")
     }
@@ -487,7 +487,7 @@ pub macro compile_time_machine(<$mir: lifetime, $tcx: lifetime>) {
         _args: &[OpTy<$tcx>],
         _destination: &PlaceTy<$tcx, Self::Provenance>,
         _target: Option<mir::BasicBlock>,
-        _unwind: StackPopUnwind,
+        _unwind: mir::UnwindAction,
     ) -> InterpResult<$tcx> {
         match fn_val {}
     }
diff --git a/compiler/rustc_const_eval/src/interpret/mod.rs b/compiler/rustc_const_eval/src/interpret/mod.rs
index 86de4e4e32c..898d62361ab 100644
--- a/compiler/rustc_const_eval/src/interpret/mod.rs
+++ b/compiler/rustc_const_eval/src/interpret/mod.rs
@@ -20,9 +20,7 @@ mod visitor;
 
 pub use rustc_middle::mir::interpret::*; // have all the `interpret` symbols in one place: here
 
-pub use self::eval_context::{
-    Frame, FrameInfo, InterpCx, LocalState, LocalValue, StackPopCleanup, StackPopUnwind,
-};
+pub use self::eval_context::{Frame, FrameInfo, InterpCx, LocalState, LocalValue, StackPopCleanup};
 pub use self::intern::{intern_const_alloc_recursive, InternKind};
 pub use self::machine::{compile_time_machine, AllocMap, Machine, MayLeak, StackPopJump};
 pub use self::memory::{AllocKind, AllocRef, AllocRefMut, FnVal, Memory, MemoryKind};
diff --git a/compiler/rustc_const_eval/src/interpret/terminator.rs b/compiler/rustc_const_eval/src/interpret/terminator.rs
index 2d9fee9852c..a07702f7d9b 100644
--- a/compiler/rustc_const_eval/src/interpret/terminator.rs
+++ b/compiler/rustc_const_eval/src/interpret/terminator.rs
@@ -13,7 +13,7 @@ use rustc_target::spec::abi::Abi;
 
 use super::{
     FnVal, ImmTy, Immediate, InterpCx, InterpResult, MPlaceTy, Machine, MemoryKind, OpTy, Operand,
-    PlaceTy, Scalar, StackPopCleanup, StackPopUnwind,
+    PlaceTy, Scalar, StackPopCleanup,
 };
 
 impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
@@ -60,7 +60,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 ref args,
                 destination,
                 target,
-                ref cleanup,
+                unwind,
                 from_hir_call: _,
                 fn_span: _,
             } => {
@@ -106,11 +106,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                     with_caller_location,
                     &destination,
                     target,
-                    match (cleanup, fn_abi.can_unwind) {
-                        (Some(cleanup), true) => StackPopUnwind::Cleanup(*cleanup),
-                        (None, true) => StackPopUnwind::Skip,
-                        (_, false) => StackPopUnwind::NotAllowed,
-                    },
+                    if fn_abi.can_unwind { unwind } else { mir::UnwindAction::Unreachable },
                 )?;
                 // Sanity-check that `eval_fn_call` either pushed a new frame or
                 // did a jump to another block.
@@ -137,19 +133,20 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 self.drop_in_place(&place, instance, target, unwind)?;
             }
 
-            Assert { ref cond, expected, ref msg, target, cleanup } => {
+            Assert { ref cond, expected, ref msg, target, unwind } => {
                 let ignored =
                     M::ignore_optional_overflow_checks(self) && msg.is_optional_overflow_check();
                 let cond_val = self.read_scalar(&self.eval_operand(cond, None)?)?.to_bool()?;
                 if ignored || expected == cond_val {
                     self.go_to_block(target);
                 } else {
-                    M::assert_panic(self, msg, cleanup)?;
+                    M::assert_panic(self, msg, unwind)?;
                 }
             }
 
-            Abort => {
-                M::abort(self, "the program aborted execution".to_owned())?;
+            Terminate => {
+                // FIXME: maybe should call `panic_no_unwind` lang item instead.
+                M::abort(self, "panic in a function that cannot unwind".to_owned())?;
             }
 
             // When we encounter Resume, we've finished unwinding
@@ -351,7 +348,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         with_caller_location: bool,
         destination: &PlaceTy<'tcx, M::Provenance>,
         target: Option<mir::BasicBlock>,
-        mut unwind: StackPopUnwind,
+        mut unwind: mir::UnwindAction,
     ) -> InterpResult<'tcx> {
         trace!("eval_fn_call: {:#?}", fn_val);
 
@@ -410,9 +407,9 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                     }
                 }
 
-                if !matches!(unwind, StackPopUnwind::NotAllowed) && !callee_fn_abi.can_unwind {
-                    // The callee cannot unwind.
-                    unwind = StackPopUnwind::NotAllowed;
+                if !callee_fn_abi.can_unwind {
+                    // The callee cannot unwind, so force the `Unreachable` unwind handling.
+                    unwind = mir::UnwindAction::Unreachable;
                 }
 
                 self.push_stack_frame(
@@ -676,7 +673,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         place: &PlaceTy<'tcx, M::Provenance>,
         instance: ty::Instance<'tcx>,
         target: mir::BasicBlock,
-        unwind: Option<mir::BasicBlock>,
+        unwind: mir::UnwindAction,
     ) -> InterpResult<'tcx> {
         trace!("drop_in_place: {:?},\n  {:?}, {:?}", *place, place.layout.ty, instance);
         // We take the address of the object. This may well be unaligned, which is fine
@@ -717,10 +714,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             false,
             &ret.into(),
             Some(target),
-            match unwind {
-                Some(cleanup) => StackPopUnwind::Cleanup(cleanup),
-                None => StackPopUnwind::Skip,
-            },
+            unwind,
         )
     }
 }
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 20c0852fe33..9dad9479053 100644
--- a/compiler/rustc_const_eval/src/transform/check_consts/check.rs
+++ b/compiler/rustc_const_eval/src/transform/check_consts/check.rs
@@ -1031,9 +1031,9 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
                 self.check_op(ops::Generator(hir::GeneratorKind::Gen))
             }
 
-            TerminatorKind::Abort => {
+            TerminatorKind::Terminate => {
                 // Cleanup blocks are skipped for const checking (see `visit_basic_block_data`).
-                span_bug!(self.span, "`Abort` terminator outside of cleanup block")
+                span_bug!(self.span, "`Terminate` terminator outside of cleanup block")
             }
 
             TerminatorKind::Assert { .. }
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 f01ab4c5d61..1f1640fd80a 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
@@ -104,7 +104,7 @@ impl<'tcx> Visitor<'tcx> for CheckLiveDrops<'_, 'tcx> {
                 }
             }
 
-            mir::TerminatorKind::Abort
+            mir::TerminatorKind::Terminate
             | mir::TerminatorKind::Call { .. }
             | mir::TerminatorKind::Assert { .. }
             | mir::TerminatorKind::FalseEdge { .. }
diff --git a/compiler/rustc_const_eval/src/transform/promote_consts.rs b/compiler/rustc_const_eval/src/transform/promote_consts.rs
index 6774e5a5837..7919aed097a 100644
--- a/compiler/rustc_const_eval/src/transform/promote_consts.rs
+++ b/compiler/rustc_const_eval/src/transform/promote_consts.rs
@@ -807,7 +807,7 @@ impl<'a, 'tcx> Promoter<'a, 'tcx> {
                         kind: TerminatorKind::Call {
                             func,
                             args,
-                            cleanup: None,
+                            unwind: UnwindAction::Continue,
                             destination: Place::from(new_temp),
                             target: Some(new_target),
                             from_hir_call,
diff --git a/compiler/rustc_const_eval/src/transform/validate.rs b/compiler/rustc_const_eval/src/transform/validate.rs
index e798c9d236e..0f56fda18f5 100644
--- a/compiler/rustc_const_eval/src/transform/validate.rs
+++ b/compiler/rustc_const_eval/src/transform/validate.rs
@@ -10,7 +10,7 @@ use rustc_middle::mir::{
     traversal, BasicBlock, BinOp, Body, BorrowKind, CastKind, CopyNonOverlapping, Local, Location,
     MirPass, MirPhase, NonDivergingIntrinsic, Operand, Place, PlaceElem, PlaceRef, ProjectionElem,
     RetagKind, RuntimePhase, Rvalue, SourceScope, Statement, StatementKind, Terminator,
-    TerminatorKind, UnOp, VarDebugInfo, VarDebugInfoContents, START_BLOCK,
+    TerminatorKind, UnOp, UnwindAction, VarDebugInfo, VarDebugInfoContents, START_BLOCK,
 };
 use rustc_middle::ty::{self, InstanceDef, ParamEnv, Ty, TyCtxt, TypeVisitableExt};
 use rustc_mir_dataflow::impls::MaybeStorageLive;
@@ -232,6 +232,24 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         }
     }
 
+    fn check_unwind_edge(&mut self, location: Location, unwind: UnwindAction) {
+        let is_cleanup = self.body.basic_blocks[location.block].is_cleanup;
+        match unwind {
+            UnwindAction::Cleanup(unwind) => {
+                if is_cleanup {
+                    self.fail(location, "unwind on cleanup block");
+                }
+                self.check_edge(location, unwind, EdgeKind::Unwind);
+            }
+            UnwindAction::Continue => {
+                if is_cleanup {
+                    self.fail(location, "unwind on cleanup block");
+                }
+            }
+            UnwindAction::Unreachable | UnwindAction::Terminate => (),
+        }
+    }
+
     /// Check if src can be assigned into dest.
     /// This is not precise, it will accept some incorrect assignments.
     fn mir_assign_valid_types(&self, src: Ty<'tcx>, dest: Ty<'tcx>) -> bool {
@@ -902,11 +920,9 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
             }
             TerminatorKind::Drop { target, unwind, .. } => {
                 self.check_edge(location, *target, EdgeKind::Normal);
-                if let Some(unwind) = unwind {
-                    self.check_edge(location, *unwind, EdgeKind::Unwind);
-                }
+                self.check_unwind_edge(location, *unwind);
             }
-            TerminatorKind::Call { func, args, destination, target, cleanup, .. } => {
+            TerminatorKind::Call { func, args, destination, target, unwind, .. } => {
                 let func_ty = func.ty(&self.body.local_decls, self.tcx);
                 match func_ty.kind() {
                     ty::FnPtr(..) | ty::FnDef(..) => {}
@@ -918,9 +934,7 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
                 if let Some(target) = target {
                     self.check_edge(location, *target, EdgeKind::Normal);
                 }
-                if let Some(cleanup) = cleanup {
-                    self.check_edge(location, *cleanup, EdgeKind::Unwind);
-                }
+                self.check_unwind_edge(location, *unwind);
 
                 // The call destination place and Operand::Move place used as an argument might be
                 // passed by a reference to the callee. Consequently they must be non-overlapping.
@@ -946,7 +960,7 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
                     );
                 }
             }
-            TerminatorKind::Assert { cond, target, cleanup, .. } => {
+            TerminatorKind::Assert { cond, target, unwind, .. } => {
                 let cond_ty = cond.ty(&self.body.local_decls, self.tcx);
                 if cond_ty != self.tcx.types.bool {
                     self.fail(
@@ -958,9 +972,7 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
                     );
                 }
                 self.check_edge(location, *target, EdgeKind::Normal);
-                if let Some(cleanup) = cleanup {
-                    self.check_edge(location, *cleanup, EdgeKind::Unwind);
-                }
+                self.check_unwind_edge(location, *unwind);
             }
             TerminatorKind::Yield { resume, drop, .. } => {
                 if self.body.generator.is_none() {
@@ -992,17 +1004,13 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
                     );
                 }
                 self.check_edge(location, *real_target, EdgeKind::Normal);
-                if let Some(unwind) = unwind {
-                    self.check_edge(location, *unwind, EdgeKind::Unwind);
-                }
+                self.check_unwind_edge(location, *unwind);
             }
-            TerminatorKind::InlineAsm { destination, cleanup, .. } => {
+            TerminatorKind::InlineAsm { destination, unwind, .. } => {
                 if let Some(destination) = destination {
                     self.check_edge(location, *destination, EdgeKind::Normal);
                 }
-                if let Some(cleanup) = cleanup {
-                    self.check_edge(location, *cleanup, EdgeKind::Unwind);
-                }
+                self.check_unwind_edge(location, *unwind);
             }
             TerminatorKind::GeneratorDrop => {
                 if self.body.generator.is_none() {
@@ -1015,10 +1023,13 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
                     );
                 }
             }
-            TerminatorKind::Resume | TerminatorKind::Abort => {
+            TerminatorKind::Resume | TerminatorKind::Terminate => {
                 let bb = location.block;
                 if !self.body.basic_blocks[bb].is_cleanup {
-                    self.fail(location, "Cannot `Resume` or `Abort` from non-cleanup basic block")
+                    self.fail(
+                        location,
+                        "Cannot `Resume` or `Terminate` from non-cleanup basic block",
+                    )
                 }
             }
             TerminatorKind::Return => {