Add a FIXME note about what's missing

src/test/ui/inline-const/const-match-pat-lifetime-err.rs

@@ -0,0 +1,34 @@
+// ignore-test
+
+#![allow(incomplete_features)]
+#![feature(const_mut_refs)]
+#![feature(inline_const)]
+
+use std::marker::PhantomData;
+
+#[derive(PartialEq, Eq)]
+pub struct InvariantRef<'a, T: ?Sized>(&'a T, PhantomData<&'a mut &'a T>);
+
+impl<'a, T: ?Sized> InvariantRef<'a, T> {
+    pub const fn new(r: &'a T) -> Self {
+        InvariantRef(r, PhantomData)
+    }
+}
+
+impl<'a> InvariantRef<'a, ()> {
+    pub const NEW: Self = InvariantRef::new(&());
+}
+
+fn match_invariant_ref<'a>() {
+    let y = ();
+    match InvariantRef::new(&y) {
+    //~^ ERROR `y` does not live long enough [E0597]
+        // FIXME(nbdd0121): This should give the same error as `InvariantRef::<'a>::NEW` (without
+        // const block)
+        const { InvariantRef::<'a>::NEW } => (),
+    }
+}
+
+fn main() {
+    match_invariant_ref();
+}