Cargo config: Rustflags are concatenated in non-deterministic order

[Systemcluster]

According to the Cargo Docs, defining rustflags in multiple target configurations concatenates them:

If several cfg and $triple targets are candidates, then the rustflags are concatenated.

However this happens in a non-deterministic order:

Using this sample .cargo/config file

[target.'cfg(target_arch="x86_64")']
rustflags = [
	"-Ctarget-cpu=x86-64",
	"-Ctarget-feature=+crt-static"
]
[target.'cfg(debug_assertions)']
rustflags = [
	"-Ctarget-cpu=native",
	"-Ctarget-feature=-crt-static",
]

and this main.rs:

#![feature(target_feature, cfg_target_feature)]

#[cfg(target_feature="crt-static")]
fn foo() -> &'static str {"yes"}
#[cfg(not(target_feature="crt-static"))]
fn foo() -> &'static str {"no"}

fn main() {
	println!("Feature enabled? {}", foo());
}

results in a different output each compilation.

PS C:\Snip> cargo run
   Compiling testproj v0.0.1-dev (file:///Snip)    
    Finished dev [unoptimized + debuginfo] target(s) in 0.57 secs
     Running `target\debug\testproj.exe`
Feature enabled? no

# <modify and save main.rs>
PS C:\Snip> cargo run
   Compiling testproj v0.0.1-dev (file:///Snip)
    Finished dev [unoptimized + debuginfo] target(s) in 0.64 secs
     Running `target\debug\testproj.exe`
Feature enabled? yes

Resolving the concatenation deterministically would surely be desirable.

I would propose resolving them in the order of appearance in the config file, and with project-local configs having precedence over those higher in the directory hierarchy.