diff --git a/tests/ui/const-generics/mgca/unconstrained-type-params.rs b/tests/ui/const-generics/mgca/unconstrained-type-params.rs
new file mode 100644
index 0000000000000..7b9688f53818f
--- /dev/null
+++ b/tests/ui/const-generics/mgca/unconstrained-type-params.rs
@@ -0,0 +1,12 @@
+//! Regression test for https://github.com/rust-lang/rust/issues/146906
+
+#![feature(min_generic_const_args)]
+
+trait Trait {}
+
+impl Trait for [(); N] {}
+//~^ ERROR mismatched types
+
+fn N(f: impl FnOnce(f64) -> f64 + Trait) {}
+
+fn main() {}
diff --git a/tests/ui/const-generics/mgca/unconstrained-type-params.stderr b/tests/ui/const-generics/mgca/unconstrained-type-params.stderr
new file mode 100644
index 0000000000000..da3f64aedb15b
--- /dev/null
+++ b/tests/ui/const-generics/mgca/unconstrained-type-params.stderr
@@ -0,0 +1,13 @@
+error[E0308]: mismatched types
+  --> $DIR/unconstrained-type-params.rs:7:21
+   |
+LL | impl Trait for [(); N] {}
+   |                     ^ expected `usize`, found fn item
+   |
+   = note: expected type `usize`
+           found fn item `fn(_) {N::<_>}`
+   = note: array length can only be `usize`
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0308`.