bail in collect_trait_impl_trait_tys if signatures reference errors

src/test/ui/async-await/in-trait/bad-signatures.rs

@@ -0,0 +1,16 @@
+// edition:2021
+
+#![feature(async_fn_in_trait)]
+//~^ WARN the feature `async_fn_in_trait` is incomplete
+
+trait MyTrait {
+    async fn bar(&abc self);
+    //~^ ERROR expected identifier, found keyword `self`
+    //~| ERROR expected one of `:`, `@`, or `|`, found keyword `self`
+}
+
+impl MyTrait for () {
+    async fn bar(&self) {}
+}
+
+fn main() {}