Uncaught recursive type definition with cargo check

[asdfish]

Problem

cargo check does not catch a case of recursive type definitions

Steps

1. Put the following in main.rs

#[derive(Clone, Debug)]
enum Expr {
    Literal(i32),
    Add([Box<Expr>; 2]),
}

fn eval_literal(expr: &i32, cont: impl FnOnce(&i32)) {
    cont(expr);
}
fn eval_add([left, right]: &[Box<Expr>; 2], cont: impl FnOnce(&i32)) {
    eval_expr(left, move |left| {
        eval_expr(right, move |right| cont(&(left + right)))
    })
}

fn eval_expr(expr: &Expr, cont: impl FnOnce(&i32)) {
    match expr {
        Expr::Literal(expr) => eval_literal(expr, cont),
        Expr::Add(expr) => eval_add(expr, cont),
    }
}

fn main() {
    eval_expr(
        &Expr::Add([
            Box::new(Expr::Literal(1)),
            Box::new(Expr::Add([
                Box::new(Expr::Literal(1)),
                Box::new(Expr::Literal(2)),
            ])),
        ]),
        |result| {
            println!("{}", result);
        },
    );
}

Output

cargo build

error: reached the recursion limit while instantiating `eval_expr::<{closure@src\main.rs:11:21: 11:32}>`
  --> src\main.rs:11:5
   |
11 | /     eval_expr(left, move |left| {
12 | |         eval_expr(right, move |right| cont(&(left + right)))
13 | |     })
   | |______^
   |
note: `eval_expr` defined here
  --> src\main.rs:16:1
   |
16 | fn eval_expr(expr: &Expr, cont: impl FnOnce(&i32)) {

cargo check

    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.02s

Possible Solution(s)

No response

Version

[ehuss]

Thanks for the report! This is a known issue called "post-monomorphization error". cargo check does not do monomoprhization, and so any errors that show up then are not reported.

Closing as a duplicate of rust-lang/rust#99682
Also note that https://rust-lang.github.io/rfcs/3477-cargo-check-lang-policy.html sets a policy that we acknowledge not everything will not catch everything.