From d4fdf6e7542941ab8d5b0d43f9c5bc0b278f638d Mon Sep 17 00:00:00 2001
From: Yuki Okushi <huyuumi.dev@gmail.com>
Date: Thu, 1 Oct 2020 14:10:44 +0900
Subject: [PATCH] Add a regression test for issue-74244

---
 .../ui/type-alias-impl-trait/issue-74244.rs   | 20 +++++++++++++++++++
 .../type-alias-impl-trait/issue-74244.stderr  |  9 +++++++++
 2 files changed, 29 insertions(+)
 create mode 100644 src/test/ui/type-alias-impl-trait/issue-74244.rs
 create mode 100644 src/test/ui/type-alias-impl-trait/issue-74244.stderr

diff --git a/src/test/ui/type-alias-impl-trait/issue-74244.rs b/src/test/ui/type-alias-impl-trait/issue-74244.rs
new file mode 100644
index 000000000000..bb4104b3d251
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-74244.rs
@@ -0,0 +1,20 @@
+#![feature(type_alias_impl_trait)]
+
+trait Allocator {
+    type Buffer;
+}
+
+struct DefaultAllocator;
+
+impl<T> Allocator for DefaultAllocator {
+    //~^ ERROR: the type parameter `T` is not constrained
+    type Buffer = ();
+}
+
+type A = impl Fn(<DefaultAllocator as Allocator>::Buffer);
+
+fn foo() -> A {
+    |_| ()
+}
+
+fn main() {}
diff --git a/src/test/ui/type-alias-impl-trait/issue-74244.stderr b/src/test/ui/type-alias-impl-trait/issue-74244.stderr
new file mode 100644
index 000000000000..ff6bacd277e1
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-74244.stderr
@@ -0,0 +1,9 @@
+error[E0207]: the type parameter `T` is not constrained by the impl trait, self type, or predicates
+  --> $DIR/issue-74244.rs:9:6
+   |
+LL | impl<T> Allocator for DefaultAllocator {
+   |      ^ unconstrained type parameter
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0207`.