Debugging - Wasmtime

# Debugging

You can also browse this source code online and clone the wasmtime repository to run the example locally.

This example shows off how to set up a module for dynamic runtime debugging via a native debugger like GDB or LLDB.

## `main.rs`

    //! Example of enabling debuginfo for wasm code which allows interactive
    //! debugging of the wasm code. When using recent versions of LLDB
    //! you can debug this executable and set breakpoints in wasm code and look at
    //! the rust source code as input.

    // To execute this example you'll need to run two commands:
    //
    //      cargo build -p example-fib-debug-wasm --target wasm32-unknown-unknown
    //      cargo run --example fib-debug

    use wasmtime::*;

    fn main() -> Result<()> {
        // Load our previously compiled wasm file (built previously with Cargo) and
        // also ensure that we generate debuginfo so this executable can be
        // debugged in GDB.
        let engine = Engine::new(
            Config::new()
                .debug_info(true)
                .cranelift_opt_level(OptLevel::None),
        )?;
        let mut store = Store::new(&engine, ());
        let module = Module::from_file(&engine, "target/wasm32-unknown-unknown/debug/fib.wasm")?;
        let instance = Instance::new(&mut store, &module, &[])?;

        // Invoke `fib` export
        let fib = instance.get_typed_func::<i32, i32>(&mut store, "fib")?;
        println!("fib(6) = {}", fib.call(&mut store, 6)?);
        Ok(())
    }