Error when generator trait is not found

2 files changed, 23 insertions, 0 deletions

diff --git a/src/test/ui/lang-item-missing-generator.rs b/src/test/ui/lang-item-missing-generator.rs
new file mode 100644
index 00000000000..0c329542928
--- /dev/null
+++ b/src/test/ui/lang-item-missing-generator.rs
@@ -0,0 +1,19 @@
+// error-pattern: requires `generator` lang_item
+#![feature(no_core, lang_items, unboxed_closures)]
+#![no_core]
+
+#[lang = "sized"] pub trait Sized { }
+
+#[lang = "fn_once"]
+#[rustc_paren_sugar]
+pub trait FnOnce<Args> {
+    type Output;
+
+    extern "rust-call" fn call_once(self, args: Args) -> Self::Output;
+}
+
+pub fn abc() -> impl FnOnce(f32) {
+    |_| {}
+}
+
+fn main() {}
diff --git a/src/test/ui/lang-item-missing-generator.stderr b/src/test/ui/lang-item-missing-generator.stderr
new file mode 100644
index 00000000000..d0cc4b81be6
--- /dev/null
+++ b/src/test/ui/lang-item-missing-generator.stderr
@@ -0,0 +1,4 @@
+error: requires `generator` lang_item
+
+error: aborting due to previous error
+