Respect `config.toml`

[winstxnhdw]

I have the following configuration

[build]
rustflags = ["-C", "target-cpu=native"]

But cargo codspeed build doesn't seem to respect this config. I have to manually add the flag.

RUSTFLAGS="-C target-cpu=native" cargo codspeed build

[GuillaumeLagrange]

Hello!
Unfurtunately, this is a limitation of cargo that we highlight here: https://codspeed.io/docs/benchmarks/rust/index#cargo-codspeed

As of today, we do not support build.rustflags in cargo config.

However, you can use [target.'cfg(all())'] instead of [build] as a workaround which does the same and is compatible.

-[build]
+[target.'cfg(all())']
rustflags = ["--cfg", "your_feature_flag"]

Until rust-lang/cargo#5376 is solved, there's not much more than we can do!

If cargo config get gets stabilized, we'll be able to circumvent the issue, but in the meantime we do not want to re-implement cargo config parsing in cargo codspeed for something that already has a workaround