Multiple target "categories" in config.toml

help
1

Let's say I have the following config.toml:

[build]
jobs = 17 # 2N+1 where 2 is number of cores
incremental = true
# May need to run `cargo install sccache`
rustc-wrapper = "sccache"

[profile.release]
opt-level = 3 # All optimizations!
debug = 0 # No debug info
strip = "symbols"
lto = "fat"

I can then build this with cargo build --release.
I'm aware I could also add a target entry to build, e.g.

[build]
jobs = 17 # 2N+1 where 2 is number of cores
incremental = true
# May need to run `cargo install sccache`
rustc-wrapper = "sccache" # Might need to change to full path for windows
target = ["foo", "bar"]

However, I'd like to have certain targets only build for release builds. How I thought I could do this would be something like:

[build]
jobs = 17 # 2N+1 where 2 is number of cores
incremental = true
# May need to run `cargo install sccache`
rustc-wrapper = "sccache" # Might need to change to full path for windows
[build.release] # Set different build options for release?
jobs = 17
rustc-wrapper = "sccache"
target = [  "aarch64-apple-darwin", "aarch64-pc-windows-gnullvm"]

Similar to how you have profile and profile.release. This does not work however.
Is there a way to achieve what I'm seeking in the config.toml file? I'm aware I could probably use something like a makefile, but I'd prefer not to if there is a more elegant inbuilt way.

2

On a design level, keep in mind that the following are equivalent:

[build]
jobs = 17 # 2N+1 where 2 is number of cores
incremental = true
# May need to run `cargo install sccache`
rustc-wrapper = "sccache" # Might need to change to full path for windows
[build.release] # Set different build options for release?
jobs = 17
rustc-wrapper = "sccache"
target = [  "aarch64-apple-darwin", "aarch64-pc-windows-gnullvm"]

[build]
jobs = 17 # 2N+1 where 2 is number of cores
incremental = true
# May need to run `cargo install sccache`
rustc-wrapper = "sccache" # Might need to change to full path for windows
# Set different build options for release?
release = {
  jobs = 17,
  rustc-wrapper = "sccache",
  target = [  "aarch64-apple-darwin", "aarch64-pc-windows-gnullvm"],
}

and users are allowed to name profiles with whatever they want, including having a jobs profile.

(use of multi-line inline tables like that is supported in the TOML 1.1 spec which will be supported in Cargo once feat(toml): TOML 1.1 parse support by epage · Pull Request #16415 · rust-lang/cargo · GitHub is merged)

3

Not that I know of. If anyone does want to explore this design space, the initial focus should be on the use case then on potential options for resolving that use case.