Function cargo::util::toml::validate_profiles

fn validate_profiles(
    profiles: &TomlProfiles,
    cli_unstable: &CliUnstable,
    features: &Features,
    warnings: &mut Vec<String>,
) -> CargoResult<()>

Checks syntax validity and unstable feature gate for each profile.

It’s a bit unfortunate both -Z flags and cargo-features are required, because profiles can now be set in either Cargo.toml or config.toml.