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diff --git a/tests/ui/on-unimplemented/sum.stderr b/tests/ui/on-unimplemented/sum.stderr
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+++ b/tests/ui/on-unimplemented/sum.stderr
@@ -0,0 +1,43 @@
+error[E0277]: a value of type `i32` cannot be made by summing an iterator over elements of type `&()`
+  --> $DIR/sum.rs:4:25
+   |
+LL |     vec![(), ()].iter().sum::<i32>();
+   |                         ^^^ value of type `i32` cannot be made by summing a `std::iter::Iterator<Item=&()>`
+   |
+   = help: the trait `Sum<&()>` is not implemented for `i32`
+   = help: the following other types implement trait `Sum<A>`:
+             <i32 as Sum<&'a i32>>
+             <i32 as Sum>
+note: the method call chain might not have had the expected associated types
+  --> $DIR/sum.rs:4:18
+   |
+LL |     vec![(), ()].iter().sum::<i32>();
+   |     ------------ ^^^^^^ `Iterator::Item` is `&()` here
+   |     |
+   |     this expression has type `Vec<()>`
+note: required by a bound in `std::iter::Iterator::sum`
+  --> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL
+
+error[E0277]: a value of type `i32` cannot be made by multiplying all elements of type `&()` from an iterator
+  --> $DIR/sum.rs:7:25
+   |
+LL |     vec![(), ()].iter().product::<i32>();
+   |                         ^^^^^^^ value of type `i32` cannot be made by multiplying all elements from a `std::iter::Iterator<Item=&()>`
+   |
+   = help: the trait `Product<&()>` is not implemented for `i32`
+   = help: the following other types implement trait `Product<A>`:
+             <i32 as Product<&'a i32>>
+             <i32 as Product>
+note: the method call chain might not have had the expected associated types
+  --> $DIR/sum.rs:7:18
+   |
+LL |     vec![(), ()].iter().product::<i32>();
+   |     ------------ ^^^^^^ `Iterator::Item` is `&()` here
+   |     |
+   |     this expression has type `Vec<()>`
+note: required by a bound in `std::iter::Iterator::product`
+  --> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0277`.