How to declare a const String in stable Rust? [duplicate]

问题

This question already has answers here:

What are the differences between Rust's `String` and `str`? (8 answers)

Trying to declare a String const results in expected type, found “my string” (1 answer)

Closed 2 years ago.

I am trying to declare a const String in stable Rust but it does not let me declare it:

const CONSTANT_VALUE: String = String::from("constant value");

fn main() {
    println!("{}", TARGET_PORT_KEY);     
}

It is saying that:

Calls in constants are limited to tuple structs and tuple variants

I do not want to declare my string as literal and call to_string() on literal all the time.

What is the correct way to declare a constant String value?

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来源：https://stackoverflow.com/questions/53932824/how-to-declare-a-const-string-in-stable-rust