Merge impl_constness and is_const_fn_raw.

compiler/rustc_const_eval/src/const_eval/fn_queries.rs

@@ -1,7 +1,8 @@
 use rustc_hir as hir;
+use rustc_hir::def::DefKind;
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_middle::ty::query::Providers;
-use rustc_middle::ty::TyCtxt;
+use rustc_middle::ty::{DefIdTree, TyCtxt};
 use rustc_span::symbol::Symbol;
 use rustc_target::spec::abi::Abi;
 
@@ -16,44 +17,47 @@ pub fn is_unstable_const_fn(tcx: TyCtxt<'_>, def_id: DefId) -> Option<Symbol> {
 }
 
 pub fn is_parent_const_impl_raw(tcx: TyCtxt<'_>, def_id: LocalDefId) -> bool {
-    let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
-    let parent_id = tcx.hir().get_parent_node(hir_id);
-    matches!(
-        tcx.hir().get(parent_id),
-        hir::Node::Item(hir::Item {
-            kind: hir::ItemKind::Impl(hir::Impl { constness: hir::Constness::Const, .. }),
-            ..
-        })
-    )
+    let parent_id = tcx.local_parent(def_id).unwrap();
+    tcx.def_kind(parent_id) == DefKind::Impl
+        && tcx.impl_constness(parent_id) == hir::Constness::Const
 }
 
 /// Checks whether the function has a `const` modifier or, in case it is an intrinsic, whether
 /// said intrinsic has a `rustc_const_{un,}stable` attribute.
-fn is_const_fn_raw(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
+fn impl_constness(tcx: TyCtxt<'_>, def_id: DefId) -> hir::Constness {
     let def_id = def_id.expect_local();
     let node = tcx.hir().get_by_def_id(def_id);
 
-    if let hir::Node::ForeignItem(hir::ForeignItem { kind: hir::ForeignItemKind::Fn(..), .. }) =
-        node
-    {
-        // Intrinsics use `rustc_const_{un,}stable` attributes to indicate constness. All other
-        // foreign items cannot be evaluated at compile-time.
-        let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
-        if let Abi::RustIntrinsic | Abi::PlatformIntrinsic = tcx.hir().get_foreign_abi(hir_id) {
-            tcx.lookup_const_stability(def_id).is_some()
-        } else {
-            false
-        }
-    } else if let Some(fn_kind) = node.fn_kind() {
-        if fn_kind.constness() == hir::Constness::Const {
-            return true;
+    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.
+            let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
+            let is_const = if let Abi::RustIntrinsic | Abi::PlatformIntrinsic =
+                tcx.hir().get_foreign_abi(hir_id)
+            {
+                tcx.lookup_const_stability(def_id).is_some()
+            } else {
+                false
+            };
+            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;
+                }
 
-        // If the function itself is not annotated with `const`, it may still be a `const fn`
-        // if it resides in a const trait impl.
-        is_parent_const_impl_raw(tcx, def_id)
-    } else {
-        matches!(node, hir::Node::Ctor(_))
+                // 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
+            }
+        }
     }
 }
 
@@ -77,5 +81,5 @@ fn is_promotable_const_fn(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
 }
 
 pub fn provide(providers: &mut Providers) {
-    *providers = Providers { is_const_fn_raw, is_promotable_const_fn, ..*providers };
+    *providers = Providers { impl_constness, is_promotable_const_fn, ..*providers };
 }

compiler/rustc_metadata/src/rmeta/decoder.rs

@@ -14,7 +14,6 @@ use rustc_data_structures::sync::{Lock, LockGuard, Lrc, OnceCell};
 use rustc_data_structures::unhash::UnhashMap;
 use rustc_expand::base::{SyntaxExtension, SyntaxExtensionKind};
 use rustc_expand::proc_macro::{AttrProcMacro, BangProcMacro, ProcMacroDerive};
-use rustc_hir as hir;
 use rustc_hir::def::{CtorKind, CtorOf, DefKind, Res};
 use rustc_hir::def_id::{CrateNum, DefId, DefIndex, CRATE_DEF_INDEX, LOCAL_CRATE};
 use rustc_hir::definitions::{DefKey, DefPath, DefPathData, DefPathHash};
@@ -1419,19 +1418,6 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
         }
     }
 
-    // This replicates some of the logic of the crate-local `is_const_fn_raw` query, because we
-    // don't serialize constness for tuple variant and tuple struct constructors.
-    fn is_const_fn_raw(self, id: DefIndex) -> bool {
-        let constness = match self.kind(id) {
-            EntryKind::AssocFn(_) | EntryKind::Fn | EntryKind::ForeignFn => {
-                self.root.tables.impl_constness.get(self, id).unwrap().decode(self)
-            }
-            EntryKind::Variant(..) | EntryKind::Struct(..) => hir::Constness::Const,
-            _ => hir::Constness::NotConst,
-        };
-        constness == hir::Constness::Const
-    }
-
     fn is_foreign_item(self, id: DefIndex) -> bool {
         match self.kind(id) {
             EntryKind::ForeignStatic | EntryKind::ForeignFn => true,

compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs

@@ -163,7 +163,6 @@ provide! { <'tcx> tcx, def_id, other, cdata,
     associated_item_def_ids => { cdata.get_associated_item_def_ids(tcx, def_id.index) }
     associated_item => { cdata.get_associated_item(def_id.index) }
     inherent_impls => { cdata.get_inherent_implementations_for_type(tcx, def_id.index) }
-    is_const_fn_raw => { cdata.is_const_fn_raw(def_id.index) }
     is_foreign_item => { cdata.is_foreign_item(def_id.index) }
     item_attrs => { tcx.arena.alloc_from_iter(cdata.get_item_attrs(def_id.index, tcx.sess)) }
     trait_of_item => { cdata.get_trait_of_item(def_id.index) }

compiler/rustc_metadata/src/rmeta/encoder.rs

@@ -1048,6 +1048,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
         };
 
         record!(self.tables.kind[def_id] <- EntryKind::Variant(self.lazy(data)));
+        record!(self.tables.impl_constness[def_id] <- hir::Constness::Const);
         record!(self.tables.children[def_id] <- variant.fields.iter().map(|f| {
             assert!(f.did.is_local());
             f.did.index
@@ -1077,6 +1078,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
         };
 
         record!(self.tables.kind[def_id] <- EntryKind::Variant(self.lazy(data)));
+        record!(self.tables.impl_constness[def_id] <- hir::Constness::Const);
         self.encode_item_type(def_id);
         if variant.ctor_kind == CtorKind::Fn {
             record!(self.tables.fn_sig[def_id] <- tcx.fn_sig(def_id));
@@ -1155,6 +1157,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
         };
 
         record!(self.tables.repr_options[def_id] <- adt_def.repr());
+        record!(self.tables.impl_constness[def_id] <- hir::Constness::Const);
         record!(self.tables.kind[def_id] <- EntryKind::Struct(self.lazy(data)));
         self.encode_item_type(def_id);
         if variant.ctor_kind == CtorKind::Fn {
@@ -1417,6 +1420,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
             hir::ItemKind::Struct(ref struct_def, _) => {
                 let adt_def = self.tcx.adt_def(def_id);
                 record!(self.tables.repr_options[def_id] <- adt_def.repr());
+                record!(self.tables.impl_constness[def_id] <- hir::Constness::Const);
 
                 // Encode def_ids for each field and method
                 // for methods, write all the stuff get_trait_method

compiler/rustc_middle/src/query/mod.rs

@@ -559,7 +559,7 @@ rustc_queries! {
     ///
     /// **Do not call this function manually.** It is only meant to cache the base data for the
     /// `is_const_fn` function.
-    query is_const_fn_raw(key: DefId) -> bool {
+    query impl_constness(key: DefId) -> hir::Constness {
         desc { |tcx| "checking if item is const fn: `{}`", tcx.def_path_str(key) }
         separate_provide_extern
     }
@@ -1329,11 +1329,6 @@ rustc_queries! {
         separate_provide_extern
     }
 
-    query impl_constness(def_id: DefId) -> hir::Constness {
-        desc { |tcx| "looking up whether `{}` is a const impl", tcx.def_path_str(def_id) }
-        separate_provide_extern
-    }
-
     query check_item_well_formed(key: LocalDefId) -> () {
         desc { |tcx| "checking that `{}` is well-formed", tcx.def_path_str(key.to_def_id()) }
     }

compiler/rustc_middle/src/ty/mod.rs

@@ -289,6 +289,11 @@ pub struct ClosureSizeProfileData<'tcx> {
 pub trait DefIdTree: Copy {
     fn parent(self, id: DefId) -> Option<DefId>;
 
+    #[inline]
+    fn local_parent(self, id: LocalDefId) -> Option<LocalDefId> {
+        Some(self.parent(id.to_def_id())?.expect_local())
+    }
+
     fn is_descendant_of(self, mut descendant: DefId, ancestor: DefId) -> bool {
         if descendant.krate != ancestor.krate {
             return false;
@@ -2256,6 +2261,12 @@ impl<'tcx> TyCtxt<'tcx> {
     pub fn is_object_safe(self, key: DefId) -> bool {
         self.object_safety_violations(key).is_empty()
     }
+
+    #[inline]
+    pub fn is_const_fn_raw(self, def_id: DefId) -> bool {
+        matches!(self.def_kind(def_id), DefKind::Fn | DefKind::AssocFn | DefKind::Ctor(..))
+            && self.impl_constness(def_id) == hir::Constness::Const
+    }
 }
 
 /// Yields the parent function's `LocalDefId` if `def_id` is an `impl Trait` definition.

compiler/rustc_passes/src/check_attr.rs

@@ -1859,7 +1859,7 @@ impl CheckAttrVisitor<'_> {
     ) -> bool {
         match target {
             Target::Fn | Target::Method(_)
-                if self.tcx.is_const_fn_raw(self.tcx.hir().local_def_id(hir_id)) =>
+                if self.tcx.is_const_fn_raw(self.tcx.hir().local_def_id(hir_id).to_def_id()) =>
             {
                 true
             }

compiler/rustc_ty_utils/src/ty.rs

@@ -77,15 +77,6 @@ fn impl_defaultness(tcx: TyCtxt<'_>, def_id: DefId) -> hir::Defaultness {
     }
 }
 
-fn impl_constness(tcx: TyCtxt<'_>, def_id: DefId) -> hir::Constness {
-    let item = tcx.hir().expect_item(def_id.expect_local());
-    if let hir::ItemKind::Impl(impl_) = &item.kind {
-        impl_.constness
-    } else {
-        bug!("`impl_constness` called on {:?}", item);
-    }
-}
-
 /// Calculates the `Sized` constraint.
 ///
 /// In fact, there are only a few options for the types in the constraint:
@@ -498,7 +489,6 @@ pub fn provide(providers: &mut ty::query::Providers) {
         instance_def_size_estimate,
         issue33140_self_ty,
         impl_defaultness,
-        impl_constness,
         conservative_is_privately_uninhabited: conservative_is_privately_uninhabited_raw,
         ..*providers
     };