2 files changed, 48 insertions, 0 deletions
diff --git a/tests/ui/traits/new-solver/assembly/assemble-normalizing-self-ty-impl-ambiguity.rs b/tests/ui/traits/new-solver/assembly/assemble-normalizing-self-ty-impl-ambiguity.rs
new file mode 100644
index 00000000000..727ce84ba35
--- /dev/null
+++ b/tests/ui/traits/new-solver/assembly/assemble-normalizing-self-ty-impl-ambiguity.rs
@@ -0,0 +1,25 @@
+// compile-flags: -Ztrait-solver=next
+
+// Checks that we do not get ambiguity by considering an impl
+// multiple times if we're able to normalize the self type.
+trait Trait<'a> {}
+
+impl<'a, T: 'a> Trait<'a> for T {}
+
+fn impls_trait<'a, T: Trait<'a>>() {}
+
+trait Id {
+    type Assoc;
+}
+impl<T> Id for T {
+    type Assoc = T;
+}
+
+fn call<T>() {
+    impls_trait::<<T as Id>::Assoc>();
+}
+
+fn main() {
+    call::<()>();
+    impls_trait::<<<() as Id>::Assoc as Id>::Assoc>();
+}
diff --git a/tests/ui/traits/new-solver/assembly/assemble-normalizing-self-ty-impl-ambiguity.stderr b/tests/ui/traits/new-solver/assembly/assemble-normalizing-self-ty-impl-ambiguity.stderr
new file mode 100644
index 00000000000..91b635b35eb
--- /dev/null
+++ b/tests/ui/traits/new-solver/assembly/assemble-normalizing-self-ty-impl-ambiguity.stderr
@@ -0,0 +1,23 @@
+error[E0283]: type annotations needed: cannot satisfy `<T as Id>::Assoc: Trait<'_>`
+  --> $DIR/assemble-normalizing-self-ty-impl-ambiguity.rs:19:5
+   |
+LL |     impls_trait::<<T as Id>::Assoc>();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: cannot satisfy `<T as Id>::Assoc: Trait<'_>`
+note: required by a bound in `impls_trait`
+  --> $DIR/assemble-normalizing-self-ty-impl-ambiguity.rs:9:23
+   |
+LL | fn impls_trait<'a, T: Trait<'a>>() {}
+   |                       ^^^^^^^^^ required by this bound in `impls_trait`
+
+error[E0282]: type annotations needed
+  --> $DIR/assemble-normalizing-self-ty-impl-ambiguity.rs:24:5
+   |
+LL |     impls_trait::<<<() as Id>::Assoc as Id>::Assoc>();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot infer type of the type parameter `T` declared on the function `impls_trait`
+
+error: aborting due to 2 previous errors
+
+Some errors have detailed explanations: E0282, E0283.
+For more information about an error, try `rustc --explain E0282`.