repr_transparent_external_private_fields: treat `rustc_pub_transparent` types as local

compiler/rustc_hir_analysis/src/check/check.rs

@@ -1259,7 +1259,8 @@ pub(super) fn check_transparent<'tcx>(tcx: TyCtxt<'tcx>, adt: ty::AdtDef<'tcx>)
                 ty::Tuple(list) => list.iter().try_for_each(|t| check_non_exhaustive(tcx, t)),
                 ty::Array(ty, _) => check_non_exhaustive(tcx, *ty),
                 ty::Adt(def, args) => {
-                    if !def.did().is_local() {
+                    if !def.did().is_local() && !tcx.has_attr(def.did(), sym::rustc_pub_transparent)
+                    {
                         let non_exhaustive = def.is_variant_list_non_exhaustive()
                             || def
                                 .variants()

tests/ui/repr/repr-transparent-non-exhaustive-transparent-in-prose.rs

@@ -0,0 +1,25 @@
+//@ check-pass
+
+#![feature(sync_unsafe_cell)]
+#![allow(unused)]
+#![deny(repr_transparent_external_private_fields)]
+
+// https://github.com/rust-lang/rust/issues/129470
+
+struct ZST;
+
+#[repr(transparent)]
+struct TransparentWithManuallyDropZST {
+    value: i32,
+    md: std::mem::ManuallyDrop<ZST>,
+    mu: std::mem::MaybeUninit<ZST>,
+    p: std::pin::Pin<ZST>,
+    pd: std::marker::PhantomData<ZST>,
+    pp: std::marker::PhantomPinned,
+    c: std::cell::Cell<ZST>,
+    uc: std::cell::UnsafeCell<ZST>,
+    suc: std::cell::SyncUnsafeCell<ZST>,
+    zst: ZST,
+}
+
+fn main() {}