cargo bench --no-run uses release profile

[joliss]

I have the following snippet in my Cargo.toml:

[profile.bench]
debug = true # for profiling

However, when I run cargo bench --no-run, the binary that is placed in
target/release/benches-* does not seem to contain debug information.

Only when I add the following snippet do I get debug information:

[profile.release]
debug = true

[alexcrichton]

cc @matklad, more oddness with profiles!

[anderejd]

@joliss Thank you!! My blood pressure were approaching rage quit levels here right before finding this 😆

~~~I'm on stable Rust 1.29.1 in combination with [Criterion](https://github.com/japaric/criterion.rs).~~~

~~~Removing `--no-run` and having at least one criterion benchmark execute normally before trying to launch the benchmark executable from dtrace does provide a workaround.~~~

EDIT: It turned out to be a script failure unrelated to cargo.

[ehuss]

@alexcrichton I hadn't really thought of it, but it does seem surprising that dependencies use dev/release profiles even when benching/testing. Is that really intended?

@anderejd I'm surprised that --no-run makes any difference, as all that does is avoid running the executable. Can you provide a sample project and a list of steps to run dtrace to exhibit the lack of stack information?

[anderejd]

@ehuss It seems like I was mistaken. It was a silent failure of my dtrace script that produced empty output, nothing related to cargo. Sorry for the noise.

[alexcrichton]

@ehuss I believe that was done historically to ensure that cargo build followed by cargo test didn't recompile everything, although the way of using entirely different profiles was probably a big enough hack that it wasn't really that necessary at the time and is a bit too codified now :(

[LightAndLight]

This is the closest thing I could find to my current problem.

Running cargo bench with

[profile.bench]
debug = true

produces bench binaries without debug symbols.

Running cargo bench with

[profile.release]
debug = true

produces bench binaries with debug symbols.

I'm using perf record -g to observe the (lack) of debug symbols.