Use helper function for searching allow_internal_unstable

compiler/rustc_mir/src/transform/check_consts/mod.rs

@@ -4,10 +4,12 @@
 //! has interior mutability or needs to be dropped, as well as the visitor that emits errors when
 //! it finds operations that are invalid in a certain context.
 
+use rustc_attr as attr;
 use rustc_hir as hir;
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_middle::mir;
 use rustc_middle::ty::{self, TyCtxt};
+use rustc_span::Symbol;
 
 pub use self::qualifs::Qualif;
 
@@ -55,3 +57,9 @@ impl ConstCx<'mir, 'tcx> {
 pub fn is_lang_panic_fn(tcx: TyCtxt<'tcx>, def_id: DefId) -> bool {
     Some(def_id) == tcx.lang_items().panic_fn() || Some(def_id) == tcx.lang_items().begin_panic_fn()
 }
+
+pub fn allow_internal_unstable(tcx: TyCtxt<'tcx>, def_id: DefId, feature_gate: Symbol) -> bool {
+    let attrs = tcx.get_attrs(def_id);
+    attr::allow_internal_unstable(&tcx.sess, attrs)
+        .map_or(false, |mut features| features.any(|name| name == feature_gate))
+}

compiler/rustc_mir/src/transform/qualify_min_const_fn.rs

@@ -1,4 +1,3 @@
-use rustc_attr as attr;
 use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
 use rustc_middle::mir::*;
@@ -344,8 +343,7 @@ fn feature_allowed(tcx: TyCtxt<'tcx>, def_id: DefId, feature_gate: Symbol) -> bo
 
     // However, we cannot allow stable `const fn`s to use unstable features without an explicit
     // opt-in via `allow_internal_unstable`.
-    attr::allow_internal_unstable(&tcx.sess, &tcx.get_attrs(def_id))
-        .map_or(false, |mut features| features.any(|name| name == feature_gate))
+    super::check_consts::allow_internal_unstable(tcx, def_id, feature_gate)
 }
 
 /// Returns `true` if the given library feature gate is allowed within the function with the given `DefId`.
@@ -364,8 +362,7 @@ pub fn lib_feature_allowed(tcx: TyCtxt<'tcx>, def_id: DefId, feature_gate: Symbo
 
     // However, we cannot allow stable `const fn`s to use unstable features without an explicit
     // opt-in via `allow_internal_unstable`.
-    attr::allow_internal_unstable(&tcx.sess, &tcx.get_attrs(def_id))
-        .map_or(false, |mut features| features.any(|name| name == feature_gate))
+    super::check_consts::allow_internal_unstable(tcx, def_id, feature_gate)
 }
 
 fn check_terminator(