3 files changed, 26 insertions, 66 deletions
diff --git a/compiler/rustc_const_eval/src/const_eval/fn_queries.rs b/compiler/rustc_const_eval/src/const_eval/fn_queries.rs
index cdcebb61c2e..f1674d04f8d 100644
--- a/compiler/rustc_const_eval/src/const_eval/fn_queries.rs
+++ b/compiler/rustc_const_eval/src/const_eval/fn_queries.rs
@@ -25,10 +25,12 @@ pub fn is_parent_const_impl_raw(tcx: TyCtxt<'_>, def_id: LocalDefId) -> bool {
 /// report whether said intrinsic has a `rustc_const_{un,}stable` attribute. Otherwise, return
 /// `Constness::NotConst`.
 fn constness(tcx: TyCtxt<'_>, def_id: DefId) -> hir::Constness {
-    let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
-    match tcx.hir().get(hir_id) {
-        hir::Node::Ctor(_) => hir::Constness::Const,
+    let def_id = def_id.expect_local();
+    let node = tcx.hir().get_by_def_id(def_id);
 
+    match node {
+        hir::Node::Ctor(_) => hir::Constness::Const,
+        hir::Node::Item(hir::Item { kind: hir::ItemKind::Impl(impl_), .. }) => impl_.constness,
         hir::Node::ForeignItem(hir::ForeignItem { kind: hir::ForeignItemKind::Fn(..), .. }) => {
             // Intrinsics use `rustc_const_{un,}stable` attributes to indicate constness. All other
             // foreign items cannot be evaluated at compile-time.
@@ -39,62 +41,20 @@ fn constness(tcx: TyCtxt<'_>, def_id: DefId) -> hir::Constness {
             };
             if is_const { hir::Constness::Const } else { hir::Constness::NotConst }
         }
+        _ => {
+            if let Some(fn_kind) = node.fn_kind() {
+                if fn_kind.constness() == hir::Constness::Const {
+                    return hir::Constness::Const;
+                }
 
-        hir::Node::TraitItem(hir::TraitItem { kind: hir::TraitItemKind::Fn(..), .. })
-            if tcx.is_const_default_method(def_id) =>
-        {
-            hir::Constness::Const
-        }
-
-        hir::Node::Item(hir::Item { kind: hir::ItemKind::Const(..), .. })
-        | hir::Node::Item(hir::Item { kind: hir::ItemKind::Static(..), .. })
-        | hir::Node::TraitItem(hir::TraitItem { kind: hir::TraitItemKind::Const(..), .. })
-        | hir::Node::AnonConst(_)
-        | hir::Node::ImplItem(hir::ImplItem { kind: hir::ImplItemKind::Const(..), .. })
-        | hir::Node::ImplItem(hir::ImplItem {
-            kind:
-                hir::ImplItemKind::Fn(
-                    hir::FnSig {
-                        header: hir::FnHeader { constness: hir::Constness::Const, .. },
-                        ..
-                    },
-                    ..,
-                ),
-            ..
-        }) => hir::Constness::Const,
-
-        hir::Node::ImplItem(hir::ImplItem {
-            kind: hir::ImplItemKind::Type(..) | hir::ImplItemKind::Fn(..),
-            ..
-        }) => {
-            let parent_hir_id = tcx.hir().get_parent_node(hir_id);
-            match tcx.hir().get(parent_hir_id) {
-                hir::Node::Item(hir::Item {
-                    kind: hir::ItemKind::Impl(hir::Impl { constness, .. }),
-                    ..
-                }) => *constness,
-                _ => span_bug!(
-                    tcx.def_span(parent_hir_id.owner),
-                    "impl item's parent node is not an impl",
-                ),
+                // If the function itself is not annotated with `const`, it may still be a `const fn`
+                // if it resides in a const trait impl.
+                let is_const = is_parent_const_impl_raw(tcx, def_id);
+                if is_const { hir::Constness::Const } else { hir::Constness::NotConst }
+            } else {
+                hir::Constness::NotConst
             }
         }
-
-        hir::Node::Item(hir::Item {
-            kind: hir::ItemKind::Fn(hir::FnSig { header: hir::FnHeader { constness, .. }, .. }, ..),
-            ..
-        })
-        | hir::Node::TraitItem(hir::TraitItem {
-            kind:
-                hir::TraitItemKind::Fn(hir::FnSig { header: hir::FnHeader { constness, .. }, .. }, ..),
-            ..
-        })
-        | hir::Node::Item(hir::Item {
-            kind: hir::ItemKind::Impl(hir::Impl { constness, .. }),
-            ..
-        }) => *constness,
-
-        _ => hir::Constness::NotConst,
     }
 }
 
diff --git a/compiler/rustc_const_eval/src/const_eval/machine.rs b/compiler/rustc_const_eval/src/const_eval/machine.rs
index e5acacd9188..35d58d2f638 100644
--- a/compiler/rustc_const_eval/src/const_eval/machine.rs
+++ b/compiler/rustc_const_eval/src/const_eval/machine.rs
@@ -2,10 +2,10 @@ use rustc_hir::def::DefKind;
 use rustc_middle::mir;
 use rustc_middle::ty::{self, Ty, TyCtxt};
 use std::borrow::Borrow;
-use std::collections::hash_map::Entry;
 use std::hash::Hash;
 
-use rustc_data_structures::fx::FxHashMap;
+use rustc_data_structures::fx::FxIndexMap;
+use rustc_data_structures::fx::IndexEntry;
 use std::fmt;
 
 use rustc_ast::Mutability;
@@ -107,18 +107,18 @@ impl<'mir, 'tcx> CompileTimeInterpreter<'mir, 'tcx> {
     }
 }
 
-impl<K: Hash + Eq, V> interpret::AllocMap<K, V> for FxHashMap<K, V> {
+impl<K: Hash + Eq, V> interpret::AllocMap<K, V> for FxIndexMap<K, V> {
     #[inline(always)]
     fn contains_key<Q: ?Sized + Hash + Eq>(&mut self, k: &Q) -> bool
     where
         K: Borrow<Q>,
     {
-        FxHashMap::contains_key(self, k)
+        FxIndexMap::contains_key(self, k)
     }
 
     #[inline(always)]
     fn insert(&mut self, k: K, v: V) -> Option<V> {
-        FxHashMap::insert(self, k, v)
+        FxIndexMap::insert(self, k, v)
     }
 
     #[inline(always)]
@@ -126,7 +126,7 @@ impl<K: Hash + Eq, V> interpret::AllocMap<K, V> for FxHashMap<K, V> {
     where
         K: Borrow<Q>,
     {
-        FxHashMap::remove(self, k)
+        FxIndexMap::remove(self, k)
     }
 
     #[inline(always)]
@@ -148,8 +148,8 @@ impl<K: Hash + Eq, V> interpret::AllocMap<K, V> for FxHashMap<K, V> {
     #[inline(always)]
     fn get_mut_or<E>(&mut self, k: K, vacant: impl FnOnce() -> Result<V, E>) -> Result<&mut V, E> {
         match self.entry(k) {
-            Entry::Occupied(e) => Ok(e.into_mut()),
-            Entry::Vacant(e) => {
+            IndexEntry::Occupied(e) => Ok(e.into_mut()),
+            IndexEntry::Vacant(e) => {
                 let v = vacant()?;
                 Ok(e.insert(v))
             }
diff --git a/compiler/rustc_const_eval/src/const_eval/valtrees.rs b/compiler/rustc_const_eval/src/const_eval/valtrees.rs
index a964fe8465e..f4da1188395 100644
--- a/compiler/rustc_const_eval/src/const_eval/valtrees.rs
+++ b/compiler/rustc_const_eval/src/const_eval/valtrees.rs
@@ -212,7 +212,7 @@ fn create_pointee_place<'tcx>(
 ) -> MPlaceTy<'tcx> {
     let tcx = ecx.tcx.tcx;
 
-    if !ty.is_sized(ecx.tcx, ty::ParamEnv::empty()) {
+    if !ty.is_sized(*ecx.tcx, ty::ParamEnv::empty()) {
         // We need to create `Allocation`s for custom DSTs
 
         let (unsized_inner_ty, num_elems) = get_info_on_unsized_field(ty, valtree, tcx);
@@ -398,7 +398,7 @@ fn valtree_into_mplace<'tcx>(
 
                 let mut place_inner = match ty.kind() {
                     ty::Str | ty::Slice(_) => ecx.mplace_index(&place, i as u64).unwrap(),
-                    _ if !ty.is_sized(ecx.tcx, ty::ParamEnv::empty())
+                    _ if !ty.is_sized(*ecx.tcx, ty::ParamEnv::empty())
                         && i == branches.len() - 1 =>
                     {
                         // Note: For custom DSTs we need to manually process the last unsized field.