Rust: Unable to resolve breakpoints when debugging a unit test in a lib target

[mchernyavsky]

Environment

• Operating system: macOS Mojave 10.14.4
• Rust toolchain: nightly-x86_64-apple-darwin
• Rustc version: 1.35.0-nightly (96d700f1b 2019-04-10)

Problem description

On macOS, when you build tests (with cargo test --no-run) in a lib target, and right after that run LLDB on the test binary, the debugger unable to resolve breakpoints.

Steps to reproduce:

Example project:

• Cargo.toml:

[package]
name = "sandbox"
version = "0.1.0"
edition = "2018"

• src/main.rs:

fn main() {}

#[test]
fn test() { assert_eq!(2 + 2, 5) }

• src/lib.rs:

#[test]
fn test() { assert_eq!(2 + 2, 4) }

Test script (bash):

• test.sh:

#!/usr/bin/env bash
rm -rf target
EXE="$(cargo test --no-run --message-format=json --lib test 2>/dev/null | jq -r '.executable')"
sleep "$1"
lldb "$EXE" <<< "b test"

• Delay 1 second before running the LLDB:

> ./test.sh 1
(lldb) target create "/Users/mikhail.chernyavsky/Workspace/rust-sandbox/target/debug/sandbox-5d25a79faaa6e465"
Current executable set to '/Users/mikhail.chernyavsky/Workspace/rust-sandbox/target/debug/sandbox-5d25a79faaa6e465' (x86_64).
(lldb) b test
Breakpoint 1: no locations (pending).
WARNING:  Unable to resolve breakpoint to any actual locations.

• Delay 2 seconds before running the LLDB:

> ./test.sh 2
(lldb) target create "/Users/mikhail.chernyavsky/Workspace/rust-sandbox/target/debug/sandbox-5d25a79faaa6e465"
Current executable set to '/Users/mikhail.chernyavsky/Workspace/rust-sandbox/target/debug/sandbox-5d25a79faaa6e465' (x86_64).
(lldb) b test
Breakpoint 1: where = sandbox-5d25a79faaa6e465`sandbox::test::h95a153b117ba44e2 + 11 at lib.rs:2:23, address = 0x00000001000017bb

P.S.

I also noticed that the *.dSYM file is not listed in the filenames field:

> cargo test --no-run --message-format=json --lib test 2>/dev/null | jq -r '.filenames'
[
  "/Users/mikhail.chernyavsky/Workspace/rust-sandbox/target/debug/sandbox-5d25a79faaa6e465"
]

For example, build unit tests in bin target:

> cargo test --no-run --message-format=json --bin sandbox 2>/dev/null | jq -r '.filenames'
[
  "/Users/mikhail.chernyavsky/Workspace/rust-sandbox/target/debug/deps/libsandbox-006b5c7138cbbb04.rlib"
]
[
  "/Users/mikhail.chernyavsky/Workspace/rust-sandbox/target/debug/sandbox-94b9126e8bd84c57",
  "/Users/mikhail.chernyavsky/Workspace/rust-sandbox/target/debug/sandbox-94b9126e8bd84c57.dSYM"
]

[stepan-romankov]

Any plans for this? Still doesn't work in 1.39

[jiegec]

I think this issue should be moved to cargo. This is how dSYM uplifting works for binaries:

https://github.com/rust-lang/cargo/issues/4490

https://github.com/rust-lang/cargo/blob/e618d47a1765ca18d1601d4cf891a55a34d23aed/src/cargo/core/compiler/build_context/target_info.rs#L260-L269

[kwhrtsk]

I tried to make a simple workaround to avoid this problem with VSCode (CodeLLDB).

https://github.com/kwhrtsk/rust-lldb-workaround

Any other workarounds?

[jiegec]

This should be fixed by rust-lang/cargo#7965

[tamerh]

After upgrading the Rust seems I am still having this problem