remove redundant wrapping of return types of allow_internal_unstable(…

…) and rustc_allow_const_fn_unstable()

compiler/rustc_attr/src/builtin.rs

@@ -1035,15 +1035,15 @@ pub fn find_transparency(
 pub fn allow_internal_unstable<'a>(
     sess: &'a Session,
     attrs: &'a [Attribute],
-) -> Option<impl Iterator<Item = Symbol> + 'a> {
-    Some(allow_unstable(sess, attrs, sym::allow_internal_unstable))
+) -> impl Iterator<Item = Symbol> + 'a {
+    allow_unstable(sess, attrs, sym::allow_internal_unstable)
 }
 
 pub fn rustc_allow_const_fn_unstable<'a>(
     sess: &'a Session,
     attrs: &'a [Attribute],
-) -> Option<impl Iterator<Item = Symbol> + 'a> {
-    Some(allow_unstable(sess, attrs, sym::rustc_allow_const_fn_unstable))
+) -> impl Iterator<Item = Symbol> + 'a {
+    allow_unstable(sess, attrs, sym::rustc_allow_const_fn_unstable)
 }
 
 fn allow_unstable<'a>(

compiler/rustc_expand/src/base.rs

@@ -756,8 +756,8 @@ impl SyntaxExtension {
         name: Symbol,
         attrs: &[ast::Attribute],
     ) -> SyntaxExtension {
-        let allow_internal_unstable = attr::allow_internal_unstable(sess, &attrs)
-            .map(|features| features.collect::<Vec<Symbol>>().into());
+        let allow_internal_unstable =
+            Some(attr::allow_internal_unstable(sess, &attrs).collect::<Vec<Symbol>>().into());
 
         let mut local_inner_macros = false;
         if let Some(macro_export) = sess.find_by_name(attrs, sym::macro_export) {

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

@@ -85,8 +85,7 @@ pub fn rustc_allow_const_fn_unstable(
     feature_gate: Symbol,
 ) -> bool {
     let attrs = tcx.get_attrs(def_id);
-    attr::rustc_allow_const_fn_unstable(&tcx.sess, attrs)
-        .map_or(false, |mut features| features.any(|name| name == feature_gate))
+    attr::rustc_allow_const_fn_unstable(&tcx.sess, attrs).any(|name| name == feature_gate)
 }
 
 // Returns `true` if the given `const fn` is "const-stable".

compiler/rustc_passes/src/check_const.rs

@@ -106,7 +106,7 @@ impl<'tcx> CheckConstVisitor<'tcx> {
             // However, we cannot allow stable `const fn`s to use unstable features without an explicit
             // opt-in via `rustc_allow_const_fn_unstable`.
             attr::rustc_allow_const_fn_unstable(&tcx.sess, &tcx.get_attrs(def_id))
-                .map_or(false, |mut features| features.any(|name| name == feature_gate))
+                .any(|name| name == feature_gate)
         };
 
         match required_gates {