Do not report cycle error when inferring return type for suggestion

4 files changed, 52 insertions, 0 deletions

diff --git a/src/test/ui/suggestions/return-cycle-2.rs b/src/test/ui/suggestions/return-cycle-2.rs
new file mode 100644
index 00000000000..d6d24be1b8d
--- /dev/null
+++ b/src/test/ui/suggestions/return-cycle-2.rs
@@ -0,0 +1,14 @@
+use std::marker::PhantomData;
+
+struct Token<T>(PhantomData<T>);
+
+impl<T> Token<T> {
+    fn as_ref(_: i32, _: i32) -> _ {
+        //~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
+        //~| NOTE not allowed in type signatures
+        //~| HELP replace with the correct return type
+        Token(PhantomData::<&T>)
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/suggestions/return-cycle-2.stderr b/src/test/ui/suggestions/return-cycle-2.stderr
new file mode 100644
index 00000000000..3a1a0f7f4f5
--- /dev/null
+++ b/src/test/ui/suggestions/return-cycle-2.stderr
@@ -0,0 +1,12 @@
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/return-cycle-2.rs:6:34
+   |
+LL |     fn as_ref(_: i32, _: i32) -> _ {
+   |                                  ^
+   |                                  |
+   |                                  not allowed in type signatures
+   |                                  help: replace with the correct return type: `Token<&'static T>`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0121`.
diff --git a/src/test/ui/suggestions/return-cycle.rs b/src/test/ui/suggestions/return-cycle.rs
new file mode 100644
index 00000000000..60b80e35a20
--- /dev/null
+++ b/src/test/ui/suggestions/return-cycle.rs
@@ -0,0 +1,14 @@
+use std::marker::PhantomData;
+
+struct Token<T>(PhantomData<T>);
+
+impl<T> Token<T> {
+    fn new() -> _ {
+        //~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
+        //~| NOTE not allowed in type signatures
+        //~| HELP replace with the correct return type
+        Token(PhantomData::<()>)
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/suggestions/return-cycle.stderr b/src/test/ui/suggestions/return-cycle.stderr
new file mode 100644
index 00000000000..63fa9e04087
--- /dev/null
+++ b/src/test/ui/suggestions/return-cycle.stderr
@@ -0,0 +1,12 @@
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
+  --> $DIR/return-cycle.rs:6:17
+   |
+LL |     fn new() -> _ {
+   |                 ^
+   |                 |
+   |                 not allowed in type signatures
+   |                 help: replace with the correct return type: `Token<()>`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0121`.