Is normal string the only string that can be const/static?

help
1

Heya,

I can do

fn main() {
    const ABC1: &str = "abc";
    static ABC2: String = String::new();
}

but it seems that other strings can't be defined.

fn main() {
    const ABC3: &OsStr = OsStr::new("abc");
    const ABC4: OsString = OsString::new();
    const ABC5: &Path = Path::new("abc");
    const ABC6: PathBuf = PathBuf::new();
}

Or could you please advise some workaround?

Thank you.

2

If there is no const fn method to construct an object, then it can't be stored in a constant. But it can be stored in a static variable using OnceLock.

2 Likes
3

Also if you're doing this inside main, let works fine for most things.

1 Like
4

I wanted to do that in a root of a module. I'll most likely just use a normal string and then OsStr::new(CONSSTRING) when needed.

Thank you.

5

OsStr::new and Path::new take an AsRef and traits can’t yet be used in const :confused:

OsString::new and PathBuf::new could presumably be const, but there aren’t many uses for an empty string that you cannot modify.

6

Won't work for const, but if static, LazyLock is an option:

use std::sync::LazyLock;

static STRING: LazyLock<OsStr> = LazyLock::new(|| OsStr::new("abc"));