Cannot open shared library when debugging with CodeLLDB - visual-studio-code

Question

I am working on a proof-of-concept app, written in Rust, with the end goal being to produce a shared library (.dll/.so) callable via C ABI from a number of other languages (C++, C#, etc). I have two simple components; poc is a Rust console app, which references poclib which exposes some simple functions. The app itself builds and runs fine so far, but I am stuck on how to debug it in VSCode using CodeLLDB.
I have a top level "workspace" like this:
[workspace]
members = [
"poc",
"poclib"
]
poc/cargo.toml looks like this:
[package]
name = "poc"
version = "0.1.0"
edition = "2018"
[dependencies.poclib]
path = "../poclib"
[dependencies]
And poclib/cargo.toml looks like this:
[package]
name = "poclib"
version = "0.1.0"
edition = "2018"
[lib]
crate_type = ["cdylib"]
[dependencies]
unicode-segmentation = "1.7.1"
My launch.json looks like this:
{
"version": "0.2.0",
"configurations": [
{
"type": "lldb",
"request": "launch",
"name": "Debug executable 'poc'",
"cargo": {
"args": [
"build",
"--bin=poc",
"--package=poc"
],
"filter": {
"name": "poc",
"kind": "bin"
}
},
"args": [ ],
"cwd": "${workspaceFolder}"
}
]
}
When I try to launch and debug in VSCode with the CodeLLDB extension installed, the app builds but then raises an error: /home/username/src/rustpoc/target/debug/poc: error while loading shared libraries: libpoclib.so: cannot open shared object file: No such file or directory. If I just do cargo run instead, it builds and runs fine, and I can verify that libpoclib.so is being built and placed in the ./target/debug folder.
If I comment out the crate_type option in the poclib/cargo.toml, it launches fine and I can hit breakpoints, but the shared library is no longer created.
I've tried adding an LD_LIBRARY_PATH setting to the launch.json, like this:
"env": {
"LD_LIBRARY_PATH": "${workspaceFolder}/target/debug"
},
That doesn't fix anything, but it does change the error message - with that setting I get /home/username/src/rustpoc/target/debug/poc: error while loading shared libraries: libstd-0a9489cf400f65e4.so: cannot open shared object file: No such file or directory
How can I enable debugging Rust in VSCode while still producing shared libraries?

Answer 1

I don't understand why it worked at all initially, but the solution was to fix the crate_type option so that I'm producing both C ABI libraries and native Rust libraries.
crate_type = ["cdylib","lib"]
With that setting the build output contains both a libpoclib.so for use from C, and a libpoclib.rlib which the poc binary can link statically against, and LLDB debugging works as expected.