Auto merge of #129994 - matthiaskrgr:rollup-zkj4ekl, r=matthiaskrgr

Rollup of 8 pull requests

Successful merges:

 - #128820 (fix: get llvm type of global val)
 - #129028 (`impl_trait_overcaptures`: Don't worry about uncaptured contravariant lifetimes if they outlive a captured lifetime)
 - #129471 ([rustdoc] Sort impl associated items by kinds and then by appearance)
 - #129706 (Rename dump of coroutine by-move-body to be more consistent, fix ICE in dump_mir)
 - #129720 (Simplify DestProp memory management)
 - #129796 (Unify scraped examples with other code examples)
 - #129938 (Elaborate on deriving vs implementing `Copy`)
 - #129973 (run_make_support: rename `Command::stdin` to `stdin_buf` and add `std{in,out,err}` config helpers)

r? `@ghost`
`@rustbot` modify labels: rollup

7 files changed, 342 insertions, 159 deletions

diff --git a/compiler/rustc_codegen_llvm/src/consts.rs b/compiler/rustc_codegen_llvm/src/consts.rs
index b143e28c5f9..d60122fccee 100644
--- a/compiler/rustc_codegen_llvm/src/consts.rs
+++ b/compiler/rustc_codegen_llvm/src/consts.rs
@@ -390,7 +390,7 @@ impl<'ll> CodegenCx<'ll, '_> {
             let val_llty = self.val_ty(v);
 
             let g = self.get_static_inner(def_id, val_llty);
-            let llty = self.val_ty(g);
+            let llty = llvm::LLVMGlobalGetValueType(g);
 
             let g = if val_llty == llty {
                 g
diff --git a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
index 138cc3219aa..3bf4d496408 100644
--- a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
@@ -974,6 +974,7 @@ unsafe extern "C" {
     pub fn LLVMGetAlignment(Global: &Value) -> c_uint;
     pub fn LLVMSetAlignment(Global: &Value, Bytes: c_uint);
     pub fn LLVMSetDLLStorageClass(V: &Value, C: DLLStorageClass);
+    pub fn LLVMGlobalGetValueType(Global: &Value) -> &Type;
 
     // Operations on global variables
     pub fn LLVMIsAGlobalVariable(GlobalVar: &Value) -> Option<&Value>;
diff --git a/compiler/rustc_lint/src/impl_trait_overcaptures.rs b/compiler/rustc_lint/src/impl_trait_overcaptures.rs
index 8824e1dfe50..c43c650a9f9 100644
--- a/compiler/rustc_lint/src/impl_trait_overcaptures.rs
+++ b/compiler/rustc_lint/src/impl_trait_overcaptures.rs
@@ -1,19 +1,29 @@
-use rustc_data_structures::fx::FxIndexSet;
+use std::assert_matches::debug_assert_matches;
+use std::cell::LazyCell;
+
+use rustc_data_structures::fx::{FxHashMap, FxIndexMap, FxIndexSet};
 use rustc_data_structures::unord::UnordSet;
 use rustc_errors::{Applicability, LintDiagnostic};
 use rustc_hir as hir;
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::{DefId, LocalDefId};
+use rustc_infer::infer::outlives::env::OutlivesEnvironment;
+use rustc_infer::infer::TyCtxtInferExt;
 use rustc_macros::LintDiagnostic;
-use rustc_middle::bug;
 use rustc_middle::middle::resolve_bound_vars::ResolvedArg;
+use rustc_middle::ty::relate::{
+    structurally_relate_consts, structurally_relate_tys, Relate, RelateResult, TypeRelation,
+};
 use rustc_middle::ty::{
     self, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable, TypeVisitableExt, TypeVisitor,
 };
+use rustc_middle::{bug, span_bug};
 use rustc_session::lint::FutureIncompatibilityReason;
 use rustc_session::{declare_lint, declare_lint_pass};
 use rustc_span::edition::Edition;
-use rustc_span::Span;
+use rustc_span::{Span, Symbol};
+use rustc_trait_selection::traits::outlives_bounds::InferCtxtExt;
+use rustc_trait_selection::traits::ObligationCtxt;
 
 use crate::{fluent_generated as fluent, LateContext, LateLintPass};
 
@@ -119,20 +129,41 @@ impl<'tcx> LateLintPass<'tcx> for ImplTraitOvercaptures {
     }
 }
 
+#[derive(PartialEq, Eq, Hash, Debug, Copy, Clone)]
+enum ParamKind {
+    // Early-bound var.
+    Early(Symbol, u32),
+    // Late-bound var on function, not within a binder. We can capture these.
+    Free(DefId, Symbol),
+    // Late-bound var in a binder. We can't capture these yet.
+    Late,
+}
+
 fn check_fn(tcx: TyCtxt<'_>, parent_def_id: LocalDefId) {
     let sig = tcx.fn_sig(parent_def_id).instantiate_identity();
 
-    let mut in_scope_parameters = FxIndexSet::default();
+    let mut in_scope_parameters = FxIndexMap::default();
     // Populate the in_scope_parameters list first with all of the generics in scope
     let mut current_def_id = Some(parent_def_id.to_def_id());
     while let Some(def_id) = current_def_id {
         let generics = tcx.generics_of(def_id);
         for param in &generics.own_params {
-            in_scope_parameters.insert(param.def_id);
+            in_scope_parameters.insert(param.def_id, ParamKind::Early(param.name, param.index));
         }
         current_def_id = generics.parent;
     }
 
+    for bound_var in sig.bound_vars() {
+        let ty::BoundVariableKind::Region(ty::BoundRegionKind::BrNamed(def_id, name)) = bound_var
+        else {
+            span_bug!(tcx.def_span(parent_def_id), "unexpected non-lifetime binder on fn sig");
+        };
+
+        in_scope_parameters.insert(def_id, ParamKind::Free(def_id, name));
+    }
+
+    let sig = tcx.liberate_late_bound_regions(parent_def_id.to_def_id(), sig);
+
     // Then visit the signature to walk through all the binders (incl. the late-bound
     // vars on the function itself, which we need to count too).
     sig.visit_with(&mut VisitOpaqueTypes {
@@ -140,21 +171,45 @@ fn check_fn(tcx: TyCtxt<'_>, parent_def_id: LocalDefId) {
         parent_def_id,
         in_scope_parameters,
         seen: Default::default(),
+        // Lazily compute these two, since they're likely a bit expensive.
+        variances: LazyCell::new(|| {
+            let mut functional_variances = FunctionalVariances {
+                tcx: tcx,
+                variances: FxHashMap::default(),
+                ambient_variance: ty::Covariant,
+                generics: tcx.generics_of(parent_def_id),
+            };
+            functional_variances.relate(sig, sig).unwrap();
+            functional_variances.variances
+        }),
+        outlives_env: LazyCell::new(|| {
+            let param_env = tcx.param_env(parent_def_id);
+            let infcx = tcx.infer_ctxt().build();
+            let ocx = ObligationCtxt::new(&infcx);
+            let assumed_wf_tys = ocx.assumed_wf_types(param_env, parent_def_id).unwrap_or_default();
+            let implied_bounds =
+                infcx.implied_bounds_tys_compat(param_env, parent_def_id, &assumed_wf_tys, false);
+            OutlivesEnvironment::with_bounds(param_env, implied_bounds)
+        }),
     });
 }
 
-struct VisitOpaqueTypes<'tcx> {
+struct VisitOpaqueTypes<'tcx, VarFn, OutlivesFn> {
     tcx: TyCtxt<'tcx>,
     parent_def_id: LocalDefId,
-    in_scope_parameters: FxIndexSet<DefId>,
+    in_scope_parameters: FxIndexMap<DefId, ParamKind>,
+    variances: LazyCell<FxHashMap<DefId, ty::Variance>, VarFn>,
+    outlives_env: LazyCell<OutlivesEnvironment<'tcx>, OutlivesFn>,
     seen: FxIndexSet<LocalDefId>,
 }
 
-impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for VisitOpaqueTypes<'tcx> {
-    fn visit_binder<T: TypeVisitable<TyCtxt<'tcx>>>(
-        &mut self,
-        t: &ty::Binder<'tcx, T>,
-    ) -> Self::Result {
+impl<'tcx, VarFn, OutlivesFn> TypeVisitor<TyCtxt<'tcx>>
+    for VisitOpaqueTypes<'tcx, VarFn, OutlivesFn>
+where
+    VarFn: FnOnce() -> FxHashMap<DefId, ty::Variance>,
+    OutlivesFn: FnOnce() -> OutlivesEnvironment<'tcx>,
+{
+    fn visit_binder<T: TypeVisitable<TyCtxt<'tcx>>>(&mut self, t: &ty::Binder<'tcx, T>) {
         // When we get into a binder, we need to add its own bound vars to the scope.
         let mut added = vec![];
         for arg in t.bound_vars() {
@@ -163,8 +218,8 @@ impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for VisitOpaqueTypes<'tcx> {
                 ty::BoundVariableKind::Region(ty::BoundRegionKind::BrNamed(def_id, ..))
                 | ty::BoundVariableKind::Ty(ty::BoundTyKind::Param(def_id, _)) => {
                     added.push(def_id);
-                    let unique = self.in_scope_parameters.insert(def_id);
-                    assert!(unique);
+                    let unique = self.in_scope_parameters.insert(def_id, ParamKind::Late);
+                    assert_eq!(unique, None);
                 }
                 _ => {
                     self.tcx.dcx().span_delayed_bug(
@@ -184,7 +239,7 @@ impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for VisitOpaqueTypes<'tcx> {
         }
     }
 
-    fn visit_ty(&mut self, t: Ty<'tcx>) -> Self::Result {
+    fn visit_ty(&mut self, t: Ty<'tcx>) {
         if !t.has_aliases() {
             return;
         }
@@ -207,89 +262,126 @@ impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for VisitOpaqueTypes<'tcx> {
             && let hir::OpaqueTyOrigin::FnReturn(parent_def_id) = opaque.origin
             && parent_def_id == self.parent_def_id
         {
-            // Compute the set of args that are captured by the opaque...
-            let mut captured = FxIndexSet::default();
-            let variances = self.tcx.variances_of(opaque_def_id);
-            let mut current_def_id = Some(opaque_def_id.to_def_id());
-            while let Some(def_id) = current_def_id {
-                let generics = self.tcx.generics_of(def_id);
-                for param in &generics.own_params {
-                    // A param is captured if it's invariant.
-                    if variances[param.index as usize] != ty::Invariant {
-                        continue;
-                    }
-                    // We need to turn all `ty::Param`/`ConstKind::Param` and
-                    // `ReEarlyParam`/`ReBound` into def ids.
-                    captured.insert(extract_def_id_from_arg(
-                        self.tcx,
-                        generics,
-                        opaque_ty.args[param.index as usize],
-                    ));
-                }
-                current_def_id = generics.parent;
-            }
-
-            // Compute the set of in scope params that are not captured. Get their spans,
-            // since that's all we really care about them for emitting the diagnostic.
-            let uncaptured_spans: Vec<_> = self
-                .in_scope_parameters
-                .iter()
-                .filter(|def_id| !captured.contains(*def_id))
-                .map(|def_id| self.tcx.def_span(def_id))
-                .collect();
-
             let opaque_span = self.tcx.def_span(opaque_def_id);
             let new_capture_rules =
                 opaque_span.at_least_rust_2024() || self.tcx.features().lifetime_capture_rules_2024;
-
-            // If we have uncaptured args, and if the opaque doesn't already have
-            // `use<>` syntax on it, and we're < edition 2024, then warn the user.
             if !new_capture_rules
                 && !opaque.bounds.iter().any(|bound| matches!(bound, hir::GenericBound::Use(..)))
-                && !uncaptured_spans.is_empty()
             {
-                let suggestion = if let Ok(snippet) =
-                    self.tcx.sess.source_map().span_to_snippet(opaque_span)
-                    && snippet.starts_with("impl ")
-                {
-                    let (lifetimes, others): (Vec<_>, Vec<_>) = captured
-                        .into_iter()
-                        .partition(|def_id| self.tcx.def_kind(*def_id) == DefKind::LifetimeParam);
-                    // Take all lifetime params first, then all others (ty/ct).
-                    let generics: Vec<_> = lifetimes
-                        .into_iter()
-                        .chain(others)
-                        .map(|def_id| self.tcx.item_name(def_id).to_string())
-                        .collect();
-                    // Make sure that we're not trying to name any APITs
-                    if generics.iter().all(|name| !name.starts_with("impl ")) {
-                        Some((
-                            format!(" + use<{}>", generics.join(", ")),
-                            opaque_span.shrink_to_hi(),
-                        ))
+                // Compute the set of args that are captured by the opaque...
+                let mut captured = FxIndexSet::default();
+                let mut captured_regions = FxIndexSet::default();
+                let variances = self.tcx.variances_of(opaque_def_id);
+                let mut current_def_id = Some(opaque_def_id.to_def_id());
+                while let Some(def_id) = current_def_id {
+                    let generics = self.tcx.generics_of(def_id);
+                    for param in &generics.own_params {
+                        // A param is captured if it's invariant.
+                        if variances[param.index as usize] != ty::Invariant {
+                            continue;
+                        }
+
+                        let arg = opaque_ty.args[param.index as usize];
+                        // We need to turn all `ty::Param`/`ConstKind::Param` and
+                        // `ReEarlyParam`/`ReBound` into def ids.
+                        captured.insert(extract_def_id_from_arg(self.tcx, generics, arg));
+
+                        captured_regions.extend(arg.as_region());
+                    }
+                    current_def_id = generics.parent;
+                }
+
+                // Compute the set of in scope params that are not captured.
+                let mut uncaptured_args: FxIndexSet<_> = self
+                    .in_scope_parameters
+                    .iter()
+                    .filter(|&(def_id, _)| !captured.contains(def_id))
+                    .collect();
+                // Remove the set of lifetimes that are in-scope that outlive some other captured
+                // lifetime and are contravariant (i.e. covariant in argument position).
+                uncaptured_args.retain(|&(def_id, kind)| {
+                    let Some(ty::Bivariant | ty::Contravariant) = self.variances.get(def_id) else {
+                        // Keep all covariant/invariant args. Also if variance is `None`,
+                        // then that means it's either not a lifetime, or it didn't show up
+                        // anywhere in the signature.
+                        return true;
+                    };
+                    // We only computed variance of lifetimes...
+                    debug_assert_matches!(self.tcx.def_kind(def_id), DefKind::LifetimeParam);
+                    let uncaptured = match *kind {
+                        ParamKind::Early(name, index) => ty::Region::new_early_param(
+                            self.tcx,
+                            ty::EarlyParamRegion { name, index },
+                        ),
+                        ParamKind::Free(def_id, name) => ty::Region::new_late_param(
+                            self.tcx,
+                            self.parent_def_id.to_def_id(),
+                            ty::BoundRegionKind::BrNamed(def_id, name),
+                        ),
+                        // Totally ignore late bound args from binders.
+                        ParamKind::Late => return true,
+                    };
+                    // Does this region outlive any captured region?
+                    !captured_regions.iter().any(|r| {
+                        self.outlives_env
+                            .free_region_map()
+                            .sub_free_regions(self.tcx, *r, uncaptured)
+                    })
+                });
+
+                // If we have uncaptured args, and if the opaque doesn't already have
+                // `use<>` syntax on it, and we're < edition 2024, then warn the user.
+                if !uncaptured_args.is_empty() {
+                    let suggestion = if let Ok(snippet) =
+                        self.tcx.sess.source_map().span_to_snippet(opaque_span)
+                        && snippet.starts_with("impl ")
+                    {
+                        let (lifetimes, others): (Vec<_>, Vec<_>) =
+                            captured.into_iter().partition(|def_id| {
+                                self.tcx.def_kind(*def_id) == DefKind::LifetimeParam
+                            });
+                        // Take all lifetime params first, then all others (ty/ct).
+                        let generics: Vec<_> = lifetimes
+                            .into_iter()
+                            .chain(others)
+                            .map(|def_id| self.tcx.item_name(def_id).to_string())
+                            .collect();
+                        // Make sure that we're not trying to name any APITs
+                        if generics.iter().all(|name| !name.starts_with("impl ")) {
+                            Some((
+                                format!(" + use<{}>", generics.join(", ")),
+                                opaque_span.shrink_to_hi(),
+                            ))
+                        } else {
+                            None
+                        }
                     } else {
                         None
-                    }
-                } else {
-                    None
-                };
-
-                self.tcx.emit_node_span_lint(
-                    IMPL_TRAIT_OVERCAPTURES,
-                    self.tcx.local_def_id_to_hir_id(opaque_def_id),
-                    opaque_span,
-                    ImplTraitOvercapturesLint {
-                        self_ty: t,
-                        num_captured: uncaptured_spans.len(),
-                        uncaptured_spans,
-                        suggestion,
-                    },
-                );
+                    };
+
+                    let uncaptured_spans: Vec<_> = uncaptured_args
+                        .into_iter()
+                        .map(|(def_id, _)| self.tcx.def_span(def_id))
+                        .collect();
+
+                    self.tcx.emit_node_span_lint(
+                        IMPL_TRAIT_OVERCAPTURES,
+                        self.tcx.local_def_id_to_hir_id(opaque_def_id),
+                        opaque_span,
+                        ImplTraitOvercapturesLint {
+                            self_ty: t,
+                            num_captured: uncaptured_spans.len(),
+                            uncaptured_spans,
+                            suggestion,
+                        },
+                    );
+                }
             }
+
             // Otherwise, if we are edition 2024, have `use<>` syntax, and
             // have no uncaptured args, then we should warn to the user that
             // it's redundant to capture all args explicitly.
-            else if new_capture_rules
+            if new_capture_rules
                 && let Some((captured_args, capturing_span)) =
                     opaque.bounds.iter().find_map(|bound| match *bound {
                         hir::GenericBound::Use(a, s) => Some((a, s)),
@@ -327,7 +419,7 @@ impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for VisitOpaqueTypes<'tcx> {
                 if self
                     .in_scope_parameters
                     .iter()
-                    .all(|def_id| explicitly_captured.contains(def_id))
+                    .all(|(def_id, _)| explicitly_captured.contains(def_id))
                 {
                     self.tcx.emit_node_span_lint(
                         IMPL_TRAIT_REDUNDANT_CAPTURES,
@@ -396,7 +488,11 @@ fn extract_def_id_from_arg<'tcx>(
             ty::ReBound(
                 _,
                 ty::BoundRegion { kind: ty::BoundRegionKind::BrNamed(def_id, ..), .. },
-            ) => def_id,
+            )
+            | ty::ReLateParam(ty::LateParamRegion {
+                scope: _,
+                bound_region: ty::BoundRegionKind::BrNamed(def_id, ..),
+            }) => def_id,
             _ => unreachable!(),
         },
         ty::GenericArgKind::Type(ty) => {
@@ -413,3 +509,106 @@ fn extract_def_id_from_arg<'tcx>(
         }
     }
 }
+
+/// Computes the variances of regions that appear in the type, but considering
+/// late-bound regions too, which don't have their variance computed usually.
+///
+/// Like generalization, this is a unary operation implemented on top of the binary
+/// relation infrastructure, mostly because it's much easier to have the relation
+/// track the variance for you, rather than having to do it yourself.
+struct FunctionalVariances<'tcx> {
+    tcx: TyCtxt<'tcx>,
+    variances: FxHashMap<DefId, ty::Variance>,
+    ambient_variance: ty::Variance,
+    generics: &'tcx ty::Generics,
+}
+
+impl<'tcx> TypeRelation<TyCtxt<'tcx>> for FunctionalVariances<'tcx> {
+    fn cx(&self) -> TyCtxt<'tcx> {
+        self.tcx
+    }
+
+    fn relate_with_variance<T: ty::relate::Relate<TyCtxt<'tcx>>>(
+        &mut self,
+        variance: rustc_type_ir::Variance,
+        _: ty::VarianceDiagInfo<TyCtxt<'tcx>>,
+        a: T,
+        b: T,
+    ) -> RelateResult<'tcx, T> {
+        let old_variance = self.ambient_variance;
+        self.ambient_variance = self.ambient_variance.xform(variance);
+        self.relate(a, b).unwrap();
+        self.ambient_variance = old_variance;
+        Ok(a)
+    }
+
+    fn tys(&mut self, a: Ty<'tcx>, b: Ty<'tcx>) -> RelateResult<'tcx, Ty<'tcx>> {
+        structurally_relate_tys(self, a, b).unwrap();
+        Ok(a)
+    }
+
+    fn regions(
+        &mut self,
+        a: ty::Region<'tcx>,
+        _: ty::Region<'tcx>,
+    ) -> RelateResult<'tcx, ty::Region<'tcx>> {
+        let def_id = match *a {
+            ty::ReEarlyParam(ebr) => self.generics.region_param(ebr, self.tcx).def_id,
+            ty::ReBound(
+                _,
+                ty::BoundRegion { kind: ty::BoundRegionKind::BrNamed(def_id, ..), .. },
+            )
+            | ty::ReLateParam(ty::LateParamRegion {
+                scope: _,
+                bound_region: ty::BoundRegionKind::BrNamed(def_id, ..),
+            }) => def_id,
+            _ => {
+                return Ok(a);
+            }
+        };
+
+        if let Some(variance) = self.variances.get_mut(&def_id) {
+            *variance = unify(*variance, self.ambient_variance);
+        } else {
+            self.variances.insert(def_id, self.ambient_variance);
+        }
+
+        Ok(a)
+    }
+
+    fn consts(
+        &mut self,
+        a: ty::Const<'tcx>,
+        b: ty::Const<'tcx>,
+    ) -> RelateResult<'tcx, ty::Const<'tcx>> {
+        structurally_relate_consts(self, a, b).unwrap();
+        Ok(a)
+    }
+
+    fn binders<T>(
+        &mut self,
+        a: ty::Binder<'tcx, T>,
+        b: ty::Binder<'tcx, T>,
+    ) -> RelateResult<'tcx, ty::Binder<'tcx, T>>
+    where
+        T: Relate<TyCtxt<'tcx>>,
+    {
+        self.relate(a.skip_binder(), b.skip_binder()).unwrap();
+        Ok(a)
+    }
+}
+
+/// What is the variance that satisfies the two variances?
+fn unify(a: ty::Variance, b: ty::Variance) -> ty::Variance {
+    match (a, b) {
+        // Bivariance is lattice bottom.
+        (ty::Bivariant, other) | (other, ty::Bivariant) => other,
+        // Invariant is lattice top.
+        (ty::Invariant, _) | (_, ty::Invariant) => ty::Invariant,
+        // If type is required to be covariant and contravariant, then it's invariant.
+        (ty::Contravariant, ty::Covariant) | (ty::Covariant, ty::Contravariant) => ty::Invariant,
+        // Otherwise, co + co = co, contra + contra = contra.
+        (ty::Contravariant, ty::Contravariant) => ty::Contravariant,
+        (ty::Covariant, ty::Covariant) => ty::Covariant,
+    }
+}
diff --git a/compiler/rustc_lint/src/lib.rs b/compiler/rustc_lint/src/lib.rs
index c5a5c5b30af..bb7de4739fb 100644
--- a/compiler/rustc_lint/src/lib.rs
+++ b/compiler/rustc_lint/src/lib.rs
@@ -30,6 +30,7 @@
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![doc(rust_logo)]
 #![feature(array_windows)]
+#![feature(assert_matches)]
 #![feature(box_patterns)]
 #![feature(control_flow_enum)]
 #![feature(extract_if)]
diff --git a/compiler/rustc_middle/src/mir/pretty.rs b/compiler/rustc_middle/src/mir/pretty.rs
index 9906be60e3e..a98e6943d68 100644
--- a/compiler/rustc_middle/src/mir/pretty.rs
+++ b/compiler/rustc_middle/src/mir/pretty.rs
@@ -612,7 +612,9 @@ fn write_mir_sig(tcx: TyCtxt<'_>, body: &Body<'_>, w: &mut dyn io::Write) -> io:
     let def_id = body.source.def_id();
     let kind = tcx.def_kind(def_id);
     let is_function = match kind {
-        DefKind::Fn | DefKind::AssocFn | DefKind::Ctor(..) => true,
+        DefKind::Fn | DefKind::AssocFn | DefKind::Ctor(..) | DefKind::SyntheticCoroutineBody => {
+            true
+        }
         _ => tcx.is_closure_like(def_id),
     };
     match (kind, body.source.promoted) {
diff --git a/compiler/rustc_mir_transform/src/coroutine/by_move_body.rs b/compiler/rustc_mir_transform/src/coroutine/by_move_body.rs
index ebe8d2eff4f..cf39c136b01 100644
--- a/compiler/rustc_mir_transform/src/coroutine/by_move_body.rs
+++ b/compiler/rustc_mir_transform/src/coroutine/by_move_body.rs
@@ -207,11 +207,12 @@ pub fn coroutine_by_move_body_def_id<'tcx>(
 
     let mut by_move_body = body.clone();
     MakeByMoveBody { tcx, field_remapping, by_move_coroutine_ty }.visit_body(&mut by_move_body);
-    dump_mir(tcx, false, "coroutine_by_move", &0, &by_move_body, |_, _| Ok(()));
 
-    let body_def = tcx.create_def(coroutine_def_id, kw::Empty, DefKind::SyntheticCoroutineBody);
+    // This will always be `{closure#1}`, since the original coroutine is `{closure#0}`.
+    let body_def = tcx.create_def(parent_def_id, kw::Empty, DefKind::SyntheticCoroutineBody);
     by_move_body.source =
         mir::MirSource::from_instance(InstanceKind::Item(body_def.def_id().to_def_id()));
+    dump_mir(tcx, false, "built", &"after", &by_move_body, |_, _| Ok(()));
 
     // Inherited from the by-ref coroutine.
     body_def.codegen_fn_attrs(tcx.codegen_fn_attrs(coroutine_def_id).clone());
diff --git a/compiler/rustc_mir_transform/src/dest_prop.rs b/compiler/rustc_mir_transform/src/dest_prop.rs
index 8940a21d7fa..67bee36b8a5 100644
--- a/compiler/rustc_mir_transform/src/dest_prop.rs
+++ b/compiler/rustc_mir_transform/src/dest_prop.rs
@@ -163,7 +163,8 @@ impl<'tcx> crate::MirPass<'tcx> for DestinationPropagation {
 
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
         let def_id = body.source.def_id();
-        let mut allocations = Allocations::default();
+        let mut candidates = Candidates::default();
+        let mut write_info = WriteInfo::default();
         trace!(func = ?tcx.def_path_str(def_id));
 
         let borrowed = rustc_mir_dataflow::impls::borrowed_locals(body);
@@ -191,12 +192,7 @@ impl<'tcx> crate::MirPass<'tcx> for DestinationPropagation {
         loop {
             // PERF: Can we do something smarter than recalculating the candidates and liveness
             // results?
-            let mut candidates = find_candidates(
-                body,
-                &borrowed,
-                &mut allocations.candidates,
-                &mut allocations.candidates_reverse,
-            );
+            candidates.reset_and_find(body, &borrowed);
             trace!(?candidates);
             dest_prop_mir_dump(tcx, body, &points, &live, round_count);
 
@@ -204,7 +200,7 @@ impl<'tcx> crate::MirPass<'tcx> for DestinationPropagation {
                 &mut candidates,
                 &points,
                 &live,
-                &mut allocations.write_info,
+                &mut write_info,
                 body,
             );
 
@@ -253,20 +249,8 @@ impl<'tcx> crate::MirPass<'tcx> for DestinationPropagation {
     }
 }
 
-/// Container for the various allocations that we need.
-///
-/// We store these here and hand out `&mut` access to them, instead of dropping and recreating them
-/// frequently. Everything with a `&'alloc` lifetime points into here.
-#[derive(Default)]
-struct Allocations {
-    candidates: FxIndexMap<Local, Vec<Local>>,
-    candidates_reverse: FxIndexMap<Local, Vec<Local>>,
-    write_info: WriteInfo,
-    // PERF: Do this for `MaybeLiveLocals` allocations too.
-}
-
-#[derive(Debug)]
-struct Candidates<'alloc> {
+#[derive(Debug, Default)]
+struct Candidates {
     /// The set of candidates we are considering in this optimization.
     ///
     /// We will always merge the key into at most one of its values.
@@ -281,11 +265,12 @@ struct Candidates<'alloc> {
     ///
     /// We will still report that we would like to merge `_1` and `_2` in an attempt to allow us to
     /// remove that assignment.
-    c: &'alloc mut FxIndexMap<Local, Vec<Local>>,
+    c: FxIndexMap<Local, Vec<Local>>,
+
     /// A reverse index of the `c` set; if the `c` set contains `a => Place { local: b, proj }`,
     /// then this contains `b => a`.
     // PERF: Possibly these should be `SmallVec`s?
-    reverse: &'alloc mut FxIndexMap<Local, Vec<Local>>,
+    reverse: FxIndexMap<Local, Vec<Local>>,
 }
 
 //////////////////////////////////////////////////////////
@@ -358,19 +343,40 @@ impl<'a, 'tcx> MutVisitor<'tcx> for Merger<'a, 'tcx> {
 //
 // This section enforces bullet point 2
 
-struct FilterInformation<'a, 'body, 'alloc, 'tcx> {
-    body: &'body Body<'tcx>,
+struct FilterInformation<'a, 'tcx> {
+    body: &'a Body<'tcx>,
     points: &'a DenseLocationMap,
     live: &'a SparseIntervalMatrix<Local, PointIndex>,
-    candidates: &'a mut Candidates<'alloc>,
-    write_info: &'alloc mut WriteInfo,
+    candidates: &'a mut Candidates,
+    write_info: &'a mut WriteInfo,
     at: Location,
 }
 
 // We first implement some utility functions which we will expose removing candidates according to
 // different needs. Throughout the liveness filtering, the `candidates` are only ever accessed
 // through these methods, and not directly.
-impl<'alloc> Candidates<'alloc> {
+impl Candidates {
+    /// Collects the candidates for merging.
+    ///
+    /// This is responsible for enforcing the first and third bullet point.
+    fn reset_and_find<'tcx>(&mut self, body: &Body<'tcx>, borrowed: &BitSet<Local>) {
+        self.c.clear();
+        self.reverse.clear();
+        let mut visitor = FindAssignments { body, candidates: &mut self.c, borrowed };
+        visitor.visit_body(body);
+        // Deduplicate candidates.
+        for (_, cands) in self.c.iter_mut() {
+            cands.sort();
+            cands.dedup();
+        }
+        // Generate the reverse map.
+        for (src, cands) in self.c.iter() {
+            for dest in cands.iter().copied() {
+                self.reverse.entry(dest).or_default().push(*src);
+            }
+        }
+    }
+
     /// Just `Vec::retain`, but the condition is inverted and we add debugging output
     fn vec_filter_candidates(
         src: Local,
@@ -445,7 +451,7 @@ enum CandidateFilter {
     Remove,
 }
 
-impl<'a, 'body, 'alloc, 'tcx> FilterInformation<'a, 'body, 'alloc, 'tcx> {
+impl<'a, 'tcx> FilterInformation<'a, 'tcx> {
     /// Filters the set of candidates to remove those that conflict.
     ///
     /// The steps we take are exactly those that are outlined at the top of the file. For each
@@ -463,12 +469,12 @@ impl<'a, 'body, 'alloc, 'tcx> FilterInformation<'a, 'body, 'alloc, 'tcx> {
     /// before the statement/terminator will correctly report locals that are read in the
     /// statement/terminator to be live. We are additionally conservative by treating all written to
     /// locals as also being read from.
-    fn filter_liveness<'b>(
-        candidates: &mut Candidates<'alloc>,
+    fn filter_liveness(
+        candidates: &mut Candidates,
         points: &DenseLocationMap,
         live: &SparseIntervalMatrix<Local, PointIndex>,
-        write_info_alloc: &'alloc mut WriteInfo,
-        body: &'b Body<'tcx>,
+        write_info: &mut WriteInfo,
+        body: &Body<'tcx>,
     ) {
         let mut this = FilterInformation {
             body,
@@ -477,7 +483,7 @@ impl<'a, 'body, 'alloc, 'tcx> FilterInformation<'a, 'body, 'alloc, 'tcx> {
             candidates,
             // We don't actually store anything at this scope, we just keep things here to be able
             // to reuse the allocation.
-            write_info: write_info_alloc,
+            write_info,
             // Doesn't matter what we put here, will be overwritten before being used
             at: Location::START,
         };
@@ -734,40 +740,13 @@ fn places_to_candidate_pair<'tcx>(
     Some((a, b))
 }
 
-/// Collects the candidates for merging
-///
-/// This is responsible for enforcing the first and third bullet point.
-fn find_candidates<'alloc, 'tcx>(
-    body: &Body<'tcx>,
-    borrowed: &BitSet<Local>,
-    candidates: &'alloc mut FxIndexMap<Local, Vec<Local>>,
-    candidates_reverse: &'alloc mut FxIndexMap<Local, Vec<Local>>,
-) -> Candidates<'alloc> {
-    candidates.clear();
-    candidates_reverse.clear();
-    let mut visitor = FindAssignments { body, candidates, borrowed };
-    visitor.visit_body(body);
-    // Deduplicate candidates
-    for (_, cands) in candidates.iter_mut() {
-        cands.sort();
-        cands.dedup();
-    }
-    // Generate the reverse map
-    for (src, cands) in candidates.iter() {
-        for dest in cands.iter().copied() {
-            candidates_reverse.entry(dest).or_default().push(*src);
-        }
-    }
-    Candidates { c: candidates, reverse: candidates_reverse }
-}
-
-struct FindAssignments<'a, 'alloc, 'tcx> {
+struct FindAssignments<'a, 'tcx> {
     body: &'a Body<'tcx>,
-    candidates: &'alloc mut FxIndexMap<Local, Vec<Local>>,
+    candidates: &'a mut FxIndexMap<Local, Vec<Local>>,
     borrowed: &'a BitSet<Local>,
 }
 
-impl<'tcx> Visitor<'tcx> for FindAssignments<'_, '_, 'tcx> {
+impl<'tcx> Visitor<'tcx> for FindAssignments<'_, 'tcx> {
     fn visit_statement(&mut self, statement: &Statement<'tcx>, _: Location) {
         if let StatementKind::Assign(box (
             lhs,
@@ -819,9 +798,9 @@ fn is_local_required(local: Local, body: &Body<'_>) -> bool {
 /////////////////////////////////////////////////////////
 // MIR Dump
 
-fn dest_prop_mir_dump<'body, 'tcx>(
+fn dest_prop_mir_dump<'tcx>(
     tcx: TyCtxt<'tcx>,
-    body: &'body Body<'tcx>,
+    body: &Body<'tcx>,
     points: &DenseLocationMap,
     live: &SparseIntervalMatrix<Local, PointIndex>,
     round: usize,