Retire is_foreign_item query.

compiler/rustc_hir_analysis/src/collect.rs

@@ -73,7 +73,6 @@ pub fn provide(providers: &mut Providers) {
         fn_sig,
         impl_trait_ref,
         impl_polarity,
-        is_foreign_item,
         generator_kind,
         collect_mod_item_types,
         is_type_alias_impl_trait,
@@ -1466,10 +1465,6 @@ fn compute_sig_of_foreign_fn_decl<'tcx>(
     fty
 }
 
-fn is_foreign_item(tcx: TyCtxt<'_>, def_id: LocalDefId) -> bool {
-    matches!(tcx.hir().get_by_def_id(def_id), Node::ForeignItem(..))
-}
-
 fn generator_kind(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Option<hir::GeneratorKind> {
     match tcx.hir().get_by_def_id(def_id) {
         Node::Expr(&rustc_hir::Expr {

compiler/rustc_metadata/src/rmeta/decoder.rs

@@ -1254,14 +1254,6 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
         }
     }
 
-    fn is_foreign_item(self, id: DefIndex) -> bool {
-        if let Some(parent) = self.def_key(id).parent {
-            matches!(self.def_kind(parent), DefKind::ForeignMod)
-        } else {
-            false
-        }
-    }
-
     #[inline]
     fn def_key(self, index: DefIndex) -> DefKey {
         *self

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

@@ -280,7 +280,6 @@ provide! { tcx, def_id, other, cdata,
     }
     associated_item => { cdata.get_associated_item(def_id.index, tcx.sess) }
     inherent_impls => { cdata.get_inherent_implementations_for_type(tcx, 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)) }
     is_mir_available => { cdata.is_item_mir_available(def_id.index) }
     is_ctfe_mir_available => { cdata.is_ctfe_mir_available(def_id.index) }

compiler/rustc_middle/src/hir/mod.rs

@@ -10,6 +10,7 @@ use crate::query::Providers;
 use crate::ty::{EarlyBinder, ImplSubject, TyCtxt};
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::sync::{par_for_each_in, DynSend, DynSync};
+use rustc_hir::def::DefKind;
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::*;
 use rustc_query_system::ich::StableHashingContext;
@@ -110,6 +111,12 @@ impl<'tcx> TyCtxt<'tcx> {
             None => self.type_of(def_id).map_bound(ImplSubject::Inherent),
         }
     }
+
+    /// Returns `true` if this is a foreign item (i.e., linked via `extern { ... }`).
+    pub fn is_foreign_item(self, def_id: impl Into<DefId>) -> bool {
+        self.opt_parent(def_id.into())
+            .map_or(false, |parent| matches!(self.def_kind(parent), DefKind::ForeignMod))
+    }
 }
 
 pub fn provide(providers: &mut Providers) {

compiler/rustc_middle/src/query/mod.rs

@@ -726,12 +726,6 @@ rustc_queries! {
         desc { |tcx| "checking if item is promotable: `{}`", tcx.def_path_str(key) }
     }
 
-    /// Returns `true` if this is a foreign item (i.e., linked via `extern { ... }`).
-    query is_foreign_item(key: DefId) -> bool {
-        desc { |tcx| "checking if `{}` is a foreign item", tcx.def_path_str(key) }
-        separate_provide_extern
-    }
-
     /// Returns `Some(generator_kind)` if the node pointed to by `def_id` is a generator.
     query generator_kind(def_id: DefId) -> Option<hir::GeneratorKind> {
         desc { |tcx| "looking up generator kind of `{}`", tcx.def_path_str(def_id) }