Interpreter crashes with with stack overflow in rustc

[stevecheckoway]

I'm trying to make an example showing the struct update format similar to https://rust-book.cs.brown.edu/ch05-01-defining-structs.html#creating-instances-from-other-instances-with-struct-update-syntax but rustc is overflowing its stack.

struct Course {
    department: String,
    number: i32,
    section: i32,
    instructor: String,
}

fn new_course(department: &str, number: i32) -> Course {
    Course {
        department: department.to_string(),
        number, // No need to write number: number
        section: 1,
        instructor: String::from("Staff"),
    }
}

fn main() {
    let cs241 = new_course("CSCI", 241);
    let cs241_2 = Course {
        instructor: String::from("Stephen Checkoway"),
        section: 2,
        ..cs241
    };
}

stderr:

thread 'rustc' has overflowed its stack


fatal runtime error: stack overflow


error: could not compile `aquascope_tmp_proj` (bin "aquascope_tmp_proj")

Caused by:
  process didn't exit successfully: `/usr/local/cargo/bin/aquascope-driver /usr/local/rustup/toolchains/nightly-2023-08-25-x86_64-unknown-linux-musl/bin/rustc --crate-name aquascope_tmp_proj --edition=2021 src/main.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts,future-incompat --crate-type bin --emit=dep-info,metadata -C embed-bitcode=no -C debuginfo=2 -C metadata=eac331abf253eb57 -C extra-filename=-eac331abf253eb57 --out-dir /app/aquascope_tmp_proj/target/plugin-nightly-2023-08-25/debug/deps -C incremental=/app/aquascope_tmp_proj/target/plugin-nightly-2023-08-25/debug/incremental -L dependency=/app/aquascope_tmp_proj/target/plugin-nightly-2023-08-25/debug/deps -C target-feature=-crt-static` (signal: 6, SIGABRT: process abort signal)

[willcrichton]

Hi @stevecheckoway, thanks for the report. You're running into two unimplemented features:

1. Support for &'static strings (Add support for &'static data to the interpreter #75)
2. Support for references to unnamed data (Add support for references to unnamed data #119)

(Obviously the stack overflow is not great DX for making you aware of these things ^^)

These are things we intend to implement, time-permitting. For now, you can make your program work by avoiding both limitations if you rewrite:

let cs241 = new_course("CSCI", 241);

To:

let department = String::from("CSCI");
let cs241 = new_course(&department, 241);

This generates a working diagram:

[stevecheckoway]

Ah great. Thanks for explaining that this is a known limitation.

And thank you for this great tool!