Revert breaking commit: https://github.com/matklad/once_cell/commit/8e47e43a49aa3b818837ad5f9b70da104b0755fa

--- .home/.cargo/macports/once_cell-1.14.0/src/lib.rs	2006-07-24 09:21:28.000000000 +0800
+++ .home/.cargo/macports/once_cell-1.14.0/src/lib.rs	2026-01-05 06:43:16.000000000 +0800
@@ -348,9 +348,11 @@
         cell::{Cell, UnsafeCell},
         fmt, hint, mem,
         ops::{Deref, DerefMut},
-        panic::{RefUnwindSafe, UnwindSafe},
     };
 
+    #[cfg(feature = "std")]
+    use std::panic::{RefUnwindSafe, UnwindSafe};
+
     /// A cell which can be written to only once. It is not thread safe.
     ///
     /// Unlike [`std::cell::RefCell`], a `OnceCell` provides simple `&`
@@ -380,7 +382,9 @@
     // `&unsync::OnceCell` to sneak a `T` through `catch_unwind`,
     // by initializing the cell in closure and extracting the value in the
     // `Drop`.
+    #[cfg(feature = "std")]
     impl<T: RefUnwindSafe + UnwindSafe> RefUnwindSafe for OnceCell<T> {}
+    #[cfg(feature = "std")]
     impl<T: UnwindSafe> UnwindSafe for OnceCell<T> {}
 
     impl<T> Default for OnceCell<T> {
@@ -676,6 +680,7 @@
         init: Cell<Option<F>>,
     }
 
+    #[cfg(feature = "std")]
     impl<T, F: RefUnwindSafe> RefUnwindSafe for Lazy<T, F> where OnceCell<T>: RefUnwindSafe {}
 
     impl<T: fmt::Debug, F> fmt::Debug for Lazy<T, F> {
@@ -1220,6 +1225,7 @@
     unsafe impl<T, F: Send> Sync for Lazy<T, F> where OnceCell<T>: Sync {}
     // auto-derived `Send` impl is OK.
 
+    #[cfg(feature = "std")]
     impl<T, F: RefUnwindSafe> RefUnwindSafe for Lazy<T, F> where OnceCell<T>: RefUnwindSafe {}
 
     impl<T, F> Lazy<T, F> {
