From 2db0492e6264d22629ed75b60f8c0dcebc451966 Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Mon, 12 Sep 2022 04:20:26 +0000
Subject: [PATCH] Normalize closure signature after construction

---
 compiler/rustc_typeck/src/check/closure.rs |  3 ++
 src/test/ui/closures/issue-101696.rs       | 36 ++++++++++++++++++++++
 2 files changed, 39 insertions(+)
 create mode 100644 src/test/ui/closures/issue-101696.rs

diff --git a/compiler/rustc_typeck/src/check/closure.rs b/compiler/rustc_typeck/src/check/closure.rs
index 55cbaf71e7c..893227d3e7d 100644
--- a/compiler/rustc_typeck/src/check/closure.rs
+++ b/compiler/rustc_typeck/src/check/closure.rs
@@ -624,6 +624,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             ),
             bound_vars,
         );
+        // Astconv can't normalize inputs or outputs with escaping bound vars,
+        // so normalize them here, after we've wrapped them in a binder.
+        let result = self.normalize_associated_types_in(self.tcx.hir().span(hir_id), result);
 
         let c_result = self.inh.infcx.canonicalize_response(result);
         self.typeck_results.borrow_mut().user_provided_sigs.insert(expr_def_id, c_result);
diff --git a/src/test/ui/closures/issue-101696.rs b/src/test/ui/closures/issue-101696.rs
new file mode 100644
index 00000000000..0a358bd1643
--- /dev/null
+++ b/src/test/ui/closures/issue-101696.rs
@@ -0,0 +1,36 @@
+// check-pass
+
+use std::marker::PhantomData;
+
+#[derive(Default)]
+struct MyType<'a> {
+    field: usize,
+    _phantom: PhantomData<&'a ()>,
+}
+
+#[derive(Default)]
+struct MyTypeVariant<'a> {
+    field: usize,
+    _phantom: PhantomData<&'a ()>,
+}
+
+trait AsVariantTrait {
+    type Type;
+}
+
+impl<'a> AsVariantTrait for MyType<'a> {
+    type Type = MyTypeVariant<'a>;
+}
+
+type Variant<G> = <G as AsVariantTrait>::Type;
+
+fn foo<T: Default, F: FnOnce(T)>(f: F) {
+    let input = T::default();
+    f(input);
+}
+
+fn main() {
+    foo(|a: <MyType as AsVariantTrait>::Type| {
+        a.field;
+    });
+}