Re-make MaybeLazy::default lazy

compiler/rustc_target/src/spec/maybe_lazy.rs

@@ -6,6 +6,7 @@ use std::ops::Deref;
 use std::sync::LazyLock;
 
 enum MaybeLazyInner<T: 'static + ToOwned + ?Sized, F> {
+    LazyStaticFn(LazyLock<T::Owned>),
     Lazy(LazyLock<T::Owned, F>),
     Cow(Cow<'static, T>),
 }
@@ -60,6 +61,7 @@ impl<T: 'static + ?Sized + ToOwned<Owned: Clone>, F: FnOnce() -> T::Owned> Clone
     fn clone(&self) -> Self {
         MaybeLazy {
             inner: MaybeLazyInner::Cow(match &self.inner {
+                MaybeLazyInner::LazyStaticFn(f) => Cow::Owned((*f).to_owned()),
                 MaybeLazyInner::Lazy(f) => Cow::Owned((*f).to_owned()),
                 MaybeLazyInner::Cow(c) => c.clone(),
             }),
@@ -72,7 +74,7 @@ impl<T: 'static + ?Sized + ToOwned<Owned: Default>, F: FnOnce() -> T::Owned> Def
 {
     #[inline]
     fn default() -> MaybeLazy<T, F> {
-        MaybeLazy::owned(T::Owned::default())
+        MaybeLazy { inner: MaybeLazyInner::LazyStaticFn(LazyLock::new(T::Owned::default)) }
     }
 }
 
@@ -85,6 +87,7 @@ impl<T: 'static + ?Sized + ToOwned<Owned: Borrow<T>>, F: FnOnce() -> T::Owned> D
     #[inline]
     fn deref(&self) -> &T {
         match &self.inner {
+            MaybeLazyInner::LazyStaticFn(f) => (&**f).borrow(),
             MaybeLazyInner::Lazy(f) => (&**f).borrow(),
             MaybeLazyInner::Cow(c) => &*c,
         }