From 9a7bb0ef249258aacf144d04f5d437ba70533128 Mon Sep 17 00:00:00 2001
From: Niko Matsakis <niko@alum.mit.edu>
Date: Thu, 18 Oct 2018 15:48:48 -0400
Subject: [PATCH] normalize the self-type that we extract from impl

---
 .../borrow_check/nll/type_check/mod.rs        |  1 +
 .../nll/user-annotations/normalize-self-ty.rs | 25 +++++++++++++++++++
 2 files changed, 26 insertions(+)
 create mode 100644 src/test/ui/nll/user-annotations/normalize-self-ty.rs

diff --git a/src/librustc_mir/borrow_check/nll/type_check/mod.rs b/src/librustc_mir/borrow_check/nll/type_check/mod.rs
index 6783083c9584..7737fcc765d8 100644
--- a/src/librustc_mir/borrow_check/nll/type_check/mod.rs
+++ b/src/librustc_mir/borrow_check/nll/type_check/mod.rs
@@ -1019,6 +1019,7 @@ impl<'a, 'gcx, 'tcx> TypeChecker<'a, 'gcx, 'tcx> {
                 {
                     let impl_self_ty = tcx.type_of(impl_def_id);
                     let impl_self_ty = impl_self_ty.subst(tcx, &substs);
+                    let impl_self_ty = self.normalize(impl_self_ty, locations);
 
                     // There may be type variables in `substs` and hence
                     // in `impl_self_ty`, but they should all have been
diff --git a/src/test/ui/nll/user-annotations/normalize-self-ty.rs b/src/test/ui/nll/user-annotations/normalize-self-ty.rs
new file mode 100644
index 000000000000..d97cc88dd9af
--- /dev/null
+++ b/src/test/ui/nll/user-annotations/normalize-self-ty.rs
@@ -0,0 +1,25 @@
+// Regression test for #55183: check a case where the self type from
+// the inherent impl requires normalization to be equal to the
+// user-provided type.
+//
+// run-pass
+
+#![feature(nll)]
+
+trait Mirror {
+    type Me;
+}
+
+impl<T> Mirror for T {
+    type Me = T;
+}
+
+struct Foo<A, B>(A, B);
+
+impl<A> Foo<A, <A as Mirror>::Me> {
+    fn m(b: A) { }
+}
+
+fn main() {
+    <Foo<&'static u32, &u32>>::m(&22);
+}