process cycles as soon as they are detected

We used to wait for the recursion limit, but that might well be too
long!

src/test/compile-fail/issue-32326.rs

@@ -0,0 +1,20 @@
+// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// Regression test for #32326. We ran out of memory because we
+// attempted to expand this case up to the recursion limit, and 2^N is
+// too big.
+
+enum Expr { //~ ERROR E0072
+    Plus(Expr, Expr),
+    Literal(i64),
+}
+
+fn main() { }

src/test/compile-fail/sized-cycle-note.rs

@@ -20,11 +20,11 @@ struct Baz { q: Option<Foo> }
 
 struct Foo { q: Option<Baz> }
 //~^ ERROR recursive type `Foo` has infinite size
-//~| type `Foo` is embedded within `std::option::Option<Foo>`...
-//~| ...which in turn is embedded within `std::option::Option<Foo>`...
-//~| ...which in turn is embedded within `Baz`...
-//~| ...which in turn is embedded within `std::option::Option<Baz>`...
-//~| ...which in turn is embedded within `Foo`, completing the cycle.
+//~| NOTE type `Foo` is embedded within `std::option::Option<Foo>`...
+//~| NOTE ...which in turn is embedded within `std::option::Option<Foo>`...
+//~| NOTE ...which in turn is embedded within `Baz`...
+//~| NOTE ...which in turn is embedded within `std::option::Option<Baz>`...
+//~| NOTE ...which in turn is embedded within `Foo`, completing the cycle.
 
 impl Foo { fn bar(&self) {} }