From 246f7465b35f827d200eba25a1c27fddd18d7962 Mon Sep 17 00:00:00 2001
From: Luv-Ray <zhuoxun.yang777@outlook.com>
Date: Sat, 23 Mar 2024 23:33:43 +0800
Subject: [PATCH] Add test in `higher-ranked`

---
 .../structually-relate-aliases.rs             | 17 ++++++++++++
 .../structually-relate-aliases.stderr         | 27 +++++++++++++++++++
 2 files changed, 44 insertions(+)
 create mode 100644 tests/ui/higher-ranked/structually-relate-aliases.rs
 create mode 100644 tests/ui/higher-ranked/structually-relate-aliases.stderr

diff --git a/tests/ui/higher-ranked/structually-relate-aliases.rs b/tests/ui/higher-ranked/structually-relate-aliases.rs
new file mode 100644
index 00000000000..8df24702811
--- /dev/null
+++ b/tests/ui/higher-ranked/structually-relate-aliases.rs
@@ -0,0 +1,17 @@
+// regression test for issue #121649.
+
+trait ToUnit<'a> {
+    type Unit;
+}
+
+trait Overlap<T> {}
+
+type Assoc<'a, T> = <T as ToUnit<'a>>::Unit;
+
+impl<T> Overlap<T> for T {}
+
+impl<T> Overlap<for<'a> fn(&'a (), Assoc<'a, T>)> for T {}
+//~^ ERROR 13:17: 13:49: the trait bound `for<'a> T: ToUnit<'a>` is not satisfied [E0277]
+//~| ERROR 13:36: 13:48: the trait bound `for<'a> T: ToUnit<'a>` is not satisfied [E0277]
+
+fn main() {}
diff --git a/tests/ui/higher-ranked/structually-relate-aliases.stderr b/tests/ui/higher-ranked/structually-relate-aliases.stderr
new file mode 100644
index 00000000000..59fab52b221
--- /dev/null
+++ b/tests/ui/higher-ranked/structually-relate-aliases.stderr
@@ -0,0 +1,27 @@
+WARN rustc_infer::infer::relate::generalize may incompletely handle alias type: AliasTy { args: [?1t, '^0.Named(DefId(0:15 ~ structually_relate_aliases[de75]::{impl#1}::'a), "'a")], def_id: DefId(0:5 ~ structually_relate_aliases[de75]::ToUnit::Unit) }
+WARN rustc_infer::infer::relate::generalize may incompletely handle alias type: AliasTy { args: [?1t, !2_0.Named(DefId(0:15 ~ structually_relate_aliases[de75]::{impl#1}::'a), "'a")], def_id: DefId(0:5 ~ structually_relate_aliases[de75]::ToUnit::Unit) }
+error[E0277]: the trait bound `for<'a> T: ToUnit<'a>` is not satisfied
+  --> $DIR/structually-relate-aliases.rs:13:36
+   |
+LL | impl<T> Overlap<for<'a> fn(&'a (), Assoc<'a, T>)> for T {}
+   |                                    ^^^^^^^^^^^^ the trait `for<'a> ToUnit<'a>` is not implemented for `T`
+   |
+help: consider restricting type parameter `T`
+   |
+LL | impl<T: for<'a> ToUnit<'a>> Overlap<for<'a> fn(&'a (), Assoc<'a, T>)> for T {}
+   |       ++++++++++++++++++++
+
+error[E0277]: the trait bound `for<'a> T: ToUnit<'a>` is not satisfied
+  --> $DIR/structually-relate-aliases.rs:13:17
+   |
+LL | impl<T> Overlap<for<'a> fn(&'a (), Assoc<'a, T>)> for T {}
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `for<'a> ToUnit<'a>` is not implemented for `T`
+   |
+help: consider restricting type parameter `T`
+   |
+LL | impl<T: for<'a> ToUnit<'a>> Overlap<for<'a> fn(&'a (), Assoc<'a, T>)> for T {}
+   |       ++++++++++++++++++++
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0277`.