Rename impl_constness to constness

The current code is a basis for `is_const_fn_raw`, and `impl_constness`
is no longer a valid name, which is previously used for determining the
constness of impls, and not items in general.

compiler/rustc_const_eval/src/const_eval/fn_queries.rs

@@ -17,13 +17,14 @@ 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 parent_id = tcx.local_parent(def_id);
-    tcx.def_kind(parent_id) == DefKind::Impl
+    tcx.def_kind(parent_id) == DefKind::Impl && tcx.constness(parent_id) == hir::Constness::Const
-        && tcx.impl_constness(parent_id) == hir::Constness::Const
 }
 
-/// Checks whether the function has a `const` modifier or, in case it is an intrinsic, whether
+/// Checks whether an item is considered to be `const`. If it is a constructor, it is const. If
-/// said intrinsic has a `rustc_const_{un,}stable` attribute.
+/// it is a trait impl/function, return if it has a `const` modifier. If it is an intrinsic,
-fn impl_constness(tcx: TyCtxt<'_>, def_id: DefId) -> hir::Constness {
+/// 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 def_id = def_id.expect_local();
     let node = tcx.hir().get_by_def_id(def_id);
 
@@ -77,5 +78,5 @@ fn is_promotable_const_fn(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
 }
 
 pub fn provide(providers: &mut Providers) {
-    *providers = Providers { impl_constness, is_promotable_const_fn, ..*providers };
+    *providers = Providers { constness, is_promotable_const_fn, ..*providers };
 }

compiler/rustc_const_eval/src/transform/check_consts/check.rs

@@ -753,7 +753,7 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
                                 callee = did;
                             }
 
-                            if let hir::Constness::NotConst = tcx.impl_constness(data.impl_def_id) {
+                            if let hir::Constness::NotConst = tcx.constness(data.impl_def_id) {
                                 self.check_op(ops::FnCallNonConst {
                                     caller,
                                     callee,

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

@@ -214,7 +214,7 @@ provide! { <'tcx> tcx, def_id, other, cdata,
     impl_parent => { table }
     impl_polarity => { table_direct }
     impl_defaultness => { table_direct }
-    impl_constness => { table_direct }
+    constness => { table_direct }
     coerce_unsized_info => { table }
     mir_const_qualif => { table }
     rendered_const => { table }

compiler/rustc_metadata/src/rmeta/encoder.rs

@@ -1070,7 +1070,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
         };
 
         record!(self.tables.kind[def_id] <- EntryKind::Variant(self.lazy(data)));
-        self.tables.impl_constness.set(def_id.index, hir::Constness::Const);
+        self.tables.constness.set(def_id.index, hir::Constness::Const);
         record_array!(self.tables.children[def_id] <- variant.fields.iter().map(|f| {
             assert!(f.did.is_local());
             f.did.index
@@ -1099,7 +1099,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
         };
 
         record!(self.tables.kind[def_id] <- EntryKind::Variant(self.lazy(data)));
-        self.tables.impl_constness.set(def_id.index, hir::Constness::Const);
+        self.tables.constness.set(def_id.index, 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));
@@ -1182,7 +1182,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
         };
 
         record!(self.tables.repr_options[def_id] <- adt_def.repr());
-        self.tables.impl_constness.set(def_id.index, hir::Constness::Const);
+        self.tables.constness.set(def_id.index, 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 {
@@ -1233,7 +1233,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
                     }
                 };
                 self.tables.asyncness.set(def_id.index, m_sig.header.asyncness);
-                self.tables.impl_constness.set(def_id.index, hir::Constness::NotConst);
+                self.tables.constness.set(def_id.index, hir::Constness::NotConst);
                 record!(self.tables.kind[def_id] <- EntryKind::AssocFn(self.lazy(AssocFnData {
                     container,
                     has_self: trait_item.fn_has_self_parameter,
@@ -1297,7 +1297,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
                 } else {
                     hir::Constness::NotConst
                 };
-                self.tables.impl_constness.set(def_id.index, constness);
+                self.tables.constness.set(def_id.index, constness);
                 record!(self.tables.kind[def_id] <- EntryKind::AssocFn(self.lazy(AssocFnData {
                     container,
                     has_self: impl_item.fn_has_self_parameter,
@@ -1420,7 +1420,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
             hir::ItemKind::Fn(ref sig, .., body) => {
                 self.tables.asyncness.set(def_id.index, sig.header.asyncness);
                 record_array!(self.tables.fn_arg_names[def_id] <- self.tcx.hir().body_param_names(body));
-                self.tables.impl_constness.set(def_id.index, sig.header.constness);
+                self.tables.constness.set(def_id.index, sig.header.constness);
                 EntryKind::Fn
             }
             hir::ItemKind::Macro(ref macro_def, _) => {
@@ -1444,7 +1444,7 @@ 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());
-                self.tables.impl_constness.set(def_id.index, hir::Constness::Const);
+                self.tables.constness.set(def_id.index, hir::Constness::Const);
 
                 // Encode def_ids for each field and method
                 // for methods, write all the stuff get_trait_method
@@ -1475,7 +1475,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
             }
             hir::ItemKind::Impl(hir::Impl { defaultness, constness, .. }) => {
                 self.tables.impl_defaultness.set(def_id.index, *defaultness);
-                self.tables.impl_constness.set(def_id.index, *constness);
+                self.tables.constness.set(def_id.index, *constness);
 
                 let trait_ref = self.tcx.impl_trait_ref(def_id);
                 if let Some(trait_ref) = trait_ref {
@@ -1941,7 +1941,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
                 } else {
                     hir::Constness::NotConst
                 };
-                self.tables.impl_constness.set(def_id.index, constness);
+                self.tables.constness.set(def_id.index, constness);
                 record!(self.tables.kind[def_id] <- EntryKind::ForeignFn);
             }
             hir::ForeignItemKind::Static(..) => {

compiler/rustc_metadata/src/rmeta/mod.rs

@@ -364,7 +364,7 @@ define_tables! {
     thir_abstract_const: Table<DefIndex, LazyValue<&'static [thir::abstract_const::Node<'static>]>>,
     impl_parent: Table<DefIndex, RawDefId>,
     impl_polarity: Table<DefIndex, ty::ImplPolarity>,
-    impl_constness: Table<DefIndex, hir::Constness>,
+    constness: Table<DefIndex, hir::Constness>,
     is_intrinsic: Table<DefIndex, ()>,
     impl_defaultness: Table<DefIndex, hir::Defaultness>,
     // FIXME(eddyb) perhaps compute this on the fly if cheap enough?

compiler/rustc_middle/src/query/mod.rs

@@ -592,9 +592,9 @@ rustc_queries! {
     /// not have the feature gate active).
     ///
     /// **Do not call this function manually.** It is only meant to cache the base data for the
-    /// `is_const_fn` function.
+    /// `is_const_fn` function. Consider using `is_const_fn` or `is_const_fn_raw` instead.
-    query impl_constness(key: DefId) -> hir::Constness {
+    query constness(key: DefId) -> hir::Constness {
-        desc { |tcx| "checking if item is const fn: `{}`", tcx.def_path_str(key) }
+        desc { |tcx| "checking if item is const: `{}`", tcx.def_path_str(key) }
         cache_on_disk_if { key.is_local() }
         separate_provide_extern
     }

compiler/rustc_middle/src/ty/mod.rs

@@ -2309,7 +2309,7 @@ impl<'tcx> TyCtxt<'tcx> {
     #[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
+            && self.constness(def_id) == hir::Constness::Const
     }
 
     #[inline]

compiler/rustc_middle/src/ty/util.rs

@@ -376,7 +376,7 @@ impl<'tcx> TyCtxt<'tcx> {
         let (did, constness) = self.find_map_relevant_impl(drop_trait, ty, |impl_did| {
             if let Some(item_id) = self.associated_item_def_ids(impl_did).first() {
                 if validate(self, impl_did).is_ok() {
-                    return Some((*item_id, self.impl_constness(impl_did)));
+                    return Some((*item_id, self.constness(impl_did)));
                 }
             }
             None

compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs

@@ -970,7 +970,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
 
                 if let Some(impl_def_id) = relevant_impl {
                     // Check that `impl Drop` is actually const, if there is a custom impl
-                    if self.tcx().impl_constness(impl_def_id) == hir::Constness::Const {
+                    if self.tcx().constness(impl_def_id) == hir::Constness::Const {
                         candidates.vec.push(ConstDestructCandidate(Some(impl_def_id)));
                     }
                 } else {

compiler/rustc_trait_selection/src/traits/select/mod.rs

@@ -1119,8 +1119,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
             if obligation.is_const() {
                 match candidate {
                     // const impl
-                    ImplCandidate(def_id)
+                    ImplCandidate(def_id) if tcx.constness(def_id) == hir::Constness::Const => {}
-                        if tcx.impl_constness(def_id) == hir::Constness::Const => {}
                     // const param
                     ParamCandidate(trait_pred) if trait_pred.is_const_if_const() => {}
                     // auto trait impl