Crash trying to print value from external crate

[xasmx]

Trying to print a value for a type defined in an external crate is crashing rusti:

$ cargo run -- -L testi/target/debug/
Running target/debug/rusti -L testi/target/debug/
rusti=> extern crate testi;
rusti=> use testi::Foo;
rusti=> Foo
LLVM ERROR: Program used external function '__ZN21Foo...std..fmt..Debug3fmt20h8530f8b2d5755ad6iaaE' which could not be resolved!
An unknown error occurred

To learn more, run the command again with --verbose.
$

Environment:

• OS X Yosemite 10.10.3
• rustc 1.5.0-nightly (6e5a32547 2015-09-19)
• cargo 0.6.0-nightly (de11b58 2015-09-16)
• rusti commit 842564d

Both rusti and the testi crate compiled clean with this version.

External crate:
$ cat testi/Cargo.toml
[package]
name = "testi"
version = "0.0.1"

---

$ cat testi/src/lib.rs

[derive(Debug)]

pub struct Foo;

[murarth]

The issue here is that rusti needs both an rlib and a dylib build available for any crate it wants to load, but it doesn't check that both of these exist before trying to run the code that depends on them. Therefore, LLVM's linker encounters a missing symbol and aborts.

To build both rlib and dylib for a project, you can either add crate-type = ["rlib", "dylib"] to the [lib] section of your Cargo.toml or run cargo rustc -- --crate-type=rlib,dylib to build the project.

Keep this issue open, though. I definitely want to improve the error message for this case.

Edit: Implementing an error message for this will be problematic because some core crates (core, libc, collections, etc.) don't have dylib versions installed. I don't have any idea how rusti could differentiate between core crates and user-supplied crates for this check.