From b166e65184147564cfd444caefb019d3251ed03c Mon Sep 17 00:00:00 2001
From: Andrew Zhogin <andrew.zhogin@gmail.com>
Date: Sun, 11 May 2025 02:21:56 +0700
Subject: [PATCH] Async drop fix for async_drop_in_place<T> layout calculated
 for unspecified T

---
 compiler/rustc_middle/src/ty/mod.rs           |  3 +++
 .../async-await/async-drop/open-drop-error.rs | 21 +++++++++++++++++++
 2 files changed, 24 insertions(+)
 create mode 100644 tests/ui/async-await/async-drop/open-drop-error.rs

diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index 2d69a1c2b553e..dda0faa3afedd 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -1924,6 +1924,9 @@ impl<'tcx> TyCtxt<'tcx> {
         def_id: DefId,
         args: GenericArgsRef<'tcx>,
     ) -> Option<&'tcx CoroutineLayout<'tcx>> {
+        if args[0].has_placeholders() || args[0].has_non_region_param() {
+            return None;
+        }
         let instance = InstanceKind::AsyncDropGlue(def_id, Ty::new_coroutine(self, def_id, args));
         self.mir_shims(instance).coroutine_layout_raw()
     }
diff --git a/tests/ui/async-await/async-drop/open-drop-error.rs b/tests/ui/async-await/async-drop/open-drop-error.rs
new file mode 100644
index 0000000000000..1d97eee521094
--- /dev/null
+++ b/tests/ui/async-await/async-drop/open-drop-error.rs
@@ -0,0 +1,21 @@
+//@ compile-flags: -Zmir-enable-passes=+DataflowConstProp
+//@ edition: 2021
+//@ build-pass
+#![feature(async_drop)]
+#![allow(incomplete_features)]
+
+use std::mem::ManuallyDrop;
+use std::{
+    future::async_drop_in_place,
+    pin::{pin, Pin},
+};
+fn main() {
+    a(b)
+}
+fn b() {}
+fn a<C>(d: C) {
+    let e = pin!(ManuallyDrop::new(d));
+    let f = unsafe { Pin::map_unchecked_mut(e, |g| &mut **g) };
+    let h = unsafe { async_drop_in_place(f.get_unchecked_mut()) };
+    h;
+}