2 files changed, 4 insertions, 14 deletions
diff --git a/compiler/rustc_const_eval/src/transform/check_consts/check.rs b/compiler/rustc_const_eval/src/transform/check_consts/check.rs
index e203c79030d..625f57b872b 100644
--- a/compiler/rustc_const_eval/src/transform/check_consts/check.rs
+++ b/compiler/rustc_const_eval/src/transform/check_consts/check.rs
@@ -222,7 +222,7 @@ impl<'mir, 'tcx> Checker<'mir, 'tcx> {
 
         // `async` functions cannot be `const fn`. This is checked during AST lowering, so there's
         // no need to emit duplicate errors here.
-        if is_async_fn(self.ccx) || body.generator.is_some() {
+        if self.ccx.is_async() || body.generator.is_some() {
             tcx.sess.delay_span_bug(body.span, "`async` functions cannot be `const fn`");
             return;
         }
@@ -1056,12 +1056,8 @@ fn is_int_bool_or_char(ty: Ty<'_>) -> bool {
     ty.is_bool() || ty.is_integral() || ty.is_char()
 }
 
-fn is_async_fn(ccx: &ConstCx<'_, '_>) -> bool {
-    ccx.fn_sig().map_or(false, |sig| sig.header.asyncness == hir::IsAsync::Async)
-}
-
 fn emit_unstable_in_stable_error(ccx: &ConstCx<'_, '_>, span: Span, gate: Symbol) {
-    let attr_span = ccx.fn_sig().map_or(ccx.body.span, |sig| sig.span.shrink_to_lo());
+    let attr_span = ccx.tcx.def_span(ccx.def_id()).shrink_to_lo();
 
     ccx.tcx
         .sess
diff --git a/compiler/rustc_const_eval/src/transform/check_consts/mod.rs b/compiler/rustc_const_eval/src/transform/check_consts/mod.rs
index b026bb2bad6..25ba97ee605 100644
--- a/compiler/rustc_const_eval/src/transform/check_consts/mod.rs
+++ b/compiler/rustc_const_eval/src/transform/check_consts/mod.rs
@@ -61,14 +61,8 @@ impl<'mir, 'tcx> ConstCx<'mir, 'tcx> {
             && is_const_stable_const_fn(self.tcx, self.def_id().to_def_id())
     }
 
-    /// Returns the function signature of the item being const-checked if it is a `fn` or `const fn`.
-    pub fn fn_sig(&self) -> Option<&'tcx hir::FnSig<'tcx>> {
-        // Get this from the HIR map instead of a query to avoid cycle errors.
-        //
-        // FIXME: Is this still an issue?
-        let hir_map = self.tcx.hir();
-        let hir_id = hir_map.local_def_id_to_hir_id(self.def_id());
-        hir_map.fn_sig_by_hir_id(hir_id)
+    fn is_async(&self) -> bool {
+        self.tcx.asyncness(self.def_id()) == hir::IsAsync::Async
     }
 }