2 files changed, 40 insertions, 0 deletions
diff --git a/tests/ui/nll/user-annotations/region-error-ice-109072.rs b/tests/ui/nll/user-annotations/region-error-ice-109072.rs
new file mode 100644
index 00000000000..3f2ad3ccbf5
--- /dev/null
+++ b/tests/ui/nll/user-annotations/region-error-ice-109072.rs
@@ -0,0 +1,14 @@
+// Regression test for #109072.
+// Check that we don't ICE when canonicalizing user annotation.
+
+trait Lt<'a> {
+    type T;
+}
+
+impl Lt<'missing> for () { //~ ERROR undeclared lifetime
+    type T = &'missing (); //~ ERROR undeclared lifetime
+}
+
+fn main() {
+    let _: <() as Lt<'_>>::T = &();
+}
diff --git a/tests/ui/nll/user-annotations/region-error-ice-109072.stderr b/tests/ui/nll/user-annotations/region-error-ice-109072.stderr
new file mode 100644
index 00000000000..d90971bed25
--- /dev/null
+++ b/tests/ui/nll/user-annotations/region-error-ice-109072.stderr
@@ -0,0 +1,26 @@
+error[E0261]: use of undeclared lifetime name `'missing`
+  --> $DIR/region-error-ice-109072.rs:8:9
+   |
+LL | impl Lt<'missing> for () {
+   |     -   ^^^^^^^^ undeclared lifetime
+   |     |
+   |     help: consider introducing lifetime `'missing` here: `<'missing>`
+
+error[E0261]: use of undeclared lifetime name `'missing`
+  --> $DIR/region-error-ice-109072.rs:9:15
+   |
+LL |     type T = &'missing ();
+   |               ^^^^^^^^ undeclared lifetime
+   |
+help: consider introducing lifetime `'missing` here
+   |
+LL |     type T<'missing> = &'missing ();
+   |           ++++++++++
+help: consider introducing lifetime `'missing` here
+   |
+LL | impl<'missing> Lt<'missing> for () {
+   |     ++++++++++
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0261`.