generic const items: polymorphically recursive consts lead to compiler stack overflow

[fmease]

I expected the following code to lead to an error (overflow, const eval, or cycle):

#![feature(generic_const_items)]

const RECUR<T>: () = RECUR::<(T,)>;

fn main() {}

Instead, the memory & CPU usage of the compiler quickly grew until the OOM killer terminated the process (I presume this to be a stack overflow turned into an OOM situation due to the use of ensure_sufficient_stack somewhere which causes stacks to be allocated on the heap).

Debug builds of the compiler crash immediately with a segmentation fault.
Running rustc with GDB yields (which merely looks like a symptom):

Thread 2 "rustc" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7fffe8bff6c0 (LWP 433325)]
rustc_middle::ty::print::pretty::PrettyPrinter::pretty_print_type<rustc_middle::ty::print::pretty::FmtPrinter> (self=..., ty=...) at compiler/rustc_middle/src/ty/print/pretty.rs:909
909             ty::Slice(ty) => p!("[", print(ty), "]"),

(14,000 line backtrace not included in this issue ^^)

Corresponding UI test: tests/ui/generic-const-items/recursive.rs (known-bug, ignore-test).

Meta

rustc -Vv

rustc 1.73.0-nightly (04abc370b 2023-07-28)
binary: rustc
commit-hash: 04abc370b9f3855b28172b65a7f7d5a433f41412
commit-date: 2023-07-28
host: x86_64-unknown-linux-gnu
release: 1.73.0-nightly
LLVM version: 16.0.5

@rustbot label C-bug T-compiler I-crash requires-incomplete-features F-generic_const_items
@rustbot claim

[theemathas]

Reproduction of the issue on stable:

struct Thing<T>(T);

impl<T> Thing<T> {
    const X: usize = Thing::<Option<T>>::X;
}

fn main() {
    println!("{}", Thing::<i32>::X);
}