1 files changed, 88 insertions, 0 deletions
diff --git a/src/test/ui/polymorphization/generators.rs b/src/test/ui/polymorphization/generators.rs
new file mode 100644
index 00000000000..dd7c3497de2
--- /dev/null
+++ b/src/test/ui/polymorphization/generators.rs
@@ -0,0 +1,88 @@
+// build-fail
+// compile-flags: -Zpolymorphize-errors
+#![feature(const_generics, generators, generator_trait)]
+//~^ WARN the feature `const_generics` is incomplete
+
+use std::marker::Unpin;
+use std::ops::{Generator, GeneratorState};
+use std::pin::Pin;
+
+enum YieldOrReturn<Y, R> {
+    Yield(Y),
+    Return(R),
+}
+
+fn finish<T, Y, R>(mut t: T) -> Vec<YieldOrReturn<Y, R>>
+where
+    T: Generator<(), Yield = Y, Return = R> + Unpin,
+{
+    let mut results = Vec::new();
+    loop {
+        match Pin::new(&mut t).resume(()) {
+            GeneratorState::Yielded(yielded) => results.push(YieldOrReturn::Yield(yielded)),
+            GeneratorState::Complete(returned) => {
+                results.push(YieldOrReturn::Return(returned));
+                return results;
+            }
+        }
+    }
+}
+
+// This test checks that the polymorphization analysis functions on generators.
+
+pub fn unused_type<T>() -> impl Generator<(), Yield = u32, Return = u32> + Unpin {
+    //~^ ERROR item has unused generic parameters
+    || {
+        //~^ ERROR item has unused generic parameters
+        yield 1;
+        2
+    }
+}
+
+pub fn used_type_in_yield<Y: Default>() -> impl Generator<(), Yield = Y, Return = u32> + Unpin {
+    || {
+        yield Y::default();
+        2
+    }
+}
+
+pub fn used_type_in_return<R: Default>() -> impl Generator<(), Yield = u32, Return = R> + Unpin {
+    || {
+        yield 3;
+        R::default()
+    }
+}
+
+pub fn unused_const<const T: u32>() -> impl Generator<(), Yield = u32, Return = u32> + Unpin {
+    //~^ ERROR item has unused generic parameters
+    || {
+        //~^ ERROR item has unused generic parameters
+        yield 1;
+        2
+    }
+}
+
+pub fn used_const_in_yield<const Y: u32>() -> impl Generator<(), Yield = u32, Return = u32> + Unpin
+{
+    || {
+        yield Y;
+        2
+    }
+}
+
+pub fn used_const_in_return<const R: u32>() -> impl Generator<(), Yield = u32, Return = u32> + Unpin
+{
+    || {
+        yield 4;
+        R
+    }
+}
+
+fn main() {
+    finish(unused_type::<u32>());
+    finish(used_type_in_yield::<u32>());
+    finish(used_type_in_return::<u32>());
+    finish(unused_const::<1u32>());
+    finish(used_const_in_yield::<1u32>());
+    finish(used_const_in_return::<1u32>());
+}