5 files changed, 46 insertions, 0 deletions
diff --git a/tests/ui/feature-gates/feature-gate-unboxed-closures-manual-impls.stderr b/tests/ui/feature-gates/feature-gate-unboxed-closures-manual-impls.stderr
index f647380ef9b..b1613f638d3 100644
--- a/tests/ui/feature-gates/feature-gate-unboxed-closures-manual-impls.stderr
+++ b/tests/ui/feature-gates/feature-gate-unboxed-closures-manual-impls.stderr
@@ -64,6 +64,12 @@ error[E0229]: associated type bindings are not allowed here
    |
 LL | impl FnOnce() for Foo1 {
    |      ^^^^^^^^ associated type not allowed here
+   |
+help: parenthesized trait syntax expands to `FnOnce<(), Output=()>`
+  --> $DIR/feature-gate-unboxed-closures-manual-impls.rs:16:6
+   |
+LL | impl FnOnce() for Foo1 {
+   |      ^^^^^^^^
 
 error[E0658]: the precise format of `Fn`-family traits' type parameters is subject to change
   --> $DIR/feature-gate-unboxed-closures-manual-impls.rs:23:6
diff --git a/tests/ui/fn/issue-39259.rs b/tests/ui/fn/issue-39259.rs
new file mode 100644
index 00000000000..5872f1007b0
--- /dev/null
+++ b/tests/ui/fn/issue-39259.rs
@@ -0,0 +1,13 @@
+#![feature(fn_traits)]
+#![feature(unboxed_closures)]
+
+struct S;
+
+impl Fn(u32) -> u32 for S {
+//~^ ERROR associated type bindings are not allowed here [E0229]
+    fn call(&self) -> u32 {
+        5
+    }
+}
+
+fn main() {}
diff --git a/tests/ui/fn/issue-39259.stderr b/tests/ui/fn/issue-39259.stderr
new file mode 100644
index 00000000000..b656b76bfe4
--- /dev/null
+++ b/tests/ui/fn/issue-39259.stderr
@@ -0,0 +1,15 @@
+error[E0229]: associated type bindings are not allowed here
+  --> $DIR/issue-39259.rs:6:17
+   |
+LL | impl Fn(u32) -> u32 for S {
+   |                 ^^^ associated type not allowed here
+   |
+help: parenthesized trait syntax expands to `Fn<(u32,), Output=u32>`
+  --> $DIR/issue-39259.rs:6:6
+   |
+LL | impl Fn(u32) -> u32 for S {
+   |      ^^^^^^^^^^^^^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0229`.
diff --git a/tests/ui/lifetimes/issue-95023.stderr b/tests/ui/lifetimes/issue-95023.stderr
index 35c3797c77a..5b93eff8614 100644
--- a/tests/ui/lifetimes/issue-95023.stderr
+++ b/tests/ui/lifetimes/issue-95023.stderr
@@ -25,6 +25,12 @@ error[E0229]: associated type bindings are not allowed here
    |
 LL | impl Fn(&isize) for Error {
    |      ^^^^^^^^^^ associated type not allowed here
+   |
+help: parenthesized trait syntax expands to `Fn<(&isize,), Output=()>`
+  --> $DIR/issue-95023.rs:3:6
+   |
+LL | impl Fn(&isize) for Error {
+   |      ^^^^^^^^^^
 
 error[E0220]: associated type `B` not found for `Self`
   --> $DIR/issue-95023.rs:6:44
diff --git a/tests/ui/traits/issue-87558.stderr b/tests/ui/traits/issue-87558.stderr
index 494274d8c30..b647f9794bd 100644
--- a/tests/ui/traits/issue-87558.stderr
+++ b/tests/ui/traits/issue-87558.stderr
@@ -17,6 +17,12 @@ error[E0229]: associated type bindings are not allowed here
    |
 LL | impl Fn(&isize) for Error {
    |      ^^^^^^^^^^ associated type not allowed here
+   |
+help: parenthesized trait syntax expands to `Fn<(&isize,), Output=()>`
+  --> $DIR/issue-87558.rs:3:6
+   |
+LL | impl Fn(&isize) for Error {
+   |      ^^^^^^^^^^
 
 error: aborting due to 3 previous errors