1 files changed, 67 insertions, 0 deletions
diff --git a/tests/ui/polymorphization/const_parameters/closures.rs b/tests/ui/polymorphization/const_parameters/closures.rs
new file mode 100644
index 00000000000..2f41beeb969
--- /dev/null
+++ b/tests/ui/polymorphization/const_parameters/closures.rs
@@ -0,0 +1,67 @@
+// build-fail
+// compile-flags:-Zpolymorphize=on
+#![feature(generic_const_exprs, rustc_attrs)]
+//~^ WARN the feature `generic_const_exprs` is incomplete
+
+// This test checks that the polymorphization analysis correctly detects unused const
+// parameters in closures.
+
+// Function doesn't have any generic parameters to be unused.
+#[rustc_polymorphize_error]
+pub fn no_parameters() {
+    let _ = || {};
+}
+
+// Function has an unused generic parameter in parent and closure.
+#[rustc_polymorphize_error]
+pub fn unused<const T: usize>() -> usize {
+    //~^ ERROR item has unused generic parameters
+    let add_one = |x: usize| x + 1;
+    //~^ ERROR item has unused generic parameters
+    add_one(3)
+}
+
+// Function has an unused generic parameter in closure, but not in parent.
+#[rustc_polymorphize_error]
+pub fn used_parent<const T: usize>() -> usize {
+    let x: usize = T;
+    let add_one = |x: usize| x + 1;
+    //~^ ERROR item has unused generic parameters
+    x + add_one(3)
+}
+
+// Function uses generic parameter in value of a binding in closure.
+#[rustc_polymorphize_error]
+pub fn used_binding<const T: usize>() -> usize {
+    let x = || {
+        let y: usize = T;
+        y
+    };
+
+    x()
+}
+
+// Closure uses a value as an upvar, which used the generic parameter.
+#[rustc_polymorphize_error]
+pub fn unused_upvar<const T: usize>() -> usize {
+    let x: usize = T;
+    let y = || x;
+    //~^ ERROR item has unused generic parameters
+    y()
+}
+
+// Closure uses generic parameter in substitutions to another function.
+#[rustc_polymorphize_error]
+pub fn used_substs<const T: usize>() -> usize {
+    let x = || unused::<T>();
+    x()
+}
+
+fn main() {
+    no_parameters();
+    let _ = unused::<1>();
+    let _ = used_parent::<1>();
+    let _ = used_binding::<1>();
+    let _ = unused_upvar::<1>();
+    let _ = used_substs::<1>();
+}