allow `cargo --profile debug` for simpler Makefiles

[lolbinarycat]

Problem

cargo is great for simple projects, but for more complex (eg. multi-language) projects, it is often desirable to use cargo in addition to a more general build system, such as make.

however, the way cargo outputs build directories is often difficult to configure via make, usually resulting in people writing their makefiles in a way that only works with --release

Proposed Solution

if this was implemented, configuring builds would be as simple as:

profile = debug
bin = target/$(profile)/myprogram

$(bin): src/main.rs Cargo.toml
	cargo build --profile $(profile)

and then you could call either make profile=release or make profile=debug

Notes

this already works fine for profile=release, but it throws an error when you try to build it with less optimizations:

cargo build --profile debug
error: profile name `debug` is reserved
To configure the default development profile, use the name `dev` as in [profile.dev]
See https://doc.rust-lang.org/cargo/reference/profiles.html for more on configuring profiles.

[epage]

If I understand, you are wanting debug to be an alias for dev so the profile name can be used for the directory name.

Likely another option is to define your own profile in a config and have it inherit dev.

#6790 would be another option for this.

[lolbinarycat]

i just want an elegant way to use rust in makefiles, as far as i can tell, there really isn't one right now

[soloturn]

custom profiles and out-flag is not good enough in case you do not like adapting rust flags?
https://stackoverflow.com/questions/38803760/how-to-get-a-release-build-with-debugging-information-when-using-cargo

cargo build --profile=myprofile --out myprofile

@epage how can one use this in a project repository? or is this a personal setting?

[epage]

@soloturn sorry for the delayed repsonse. April was busy and I've still not caught up to it.

I'm not entirely sure about the nature of your question. Your link doesn't seem too relevant to the conversation here. This is about being able to predict the location of final artifacts which gets more difficult for dev profile because it outputs to the debug directory.

[epage]

As for this issue, we talked about it in the Cargo team meeting and are concerned that making them alias each other could get in the way of some other debug/dev profile work we are considering, see https://blog.rust-lang.org/inside-rust/2024/12/13/this-development-cycle-in-cargo-1.84.html#improving-the-built-in-profiles

As such, determining what to do with this issue is blocked until we know whether we want to do that and whether one blocks the other.

As I mentioned earlier, ways around this are

• A custom profile that inherits dev, making the directory predictable
• Using the unstable --artifact-dir option to specify a custom location to write to
• (future possibility) update the artifact-dir template to make the profile name consistent (and always specify the target), see Redefine CARGO_TARGET_DIR to be only an artifacts directory #14125 (comment)