> You don't
Great. Very obvious.
As much as it pains me to say so, this is probably fine for configuration languages so long as they’re backwards compatible. Eg toml is used by rust’s cargo tool. Cargo can just say “hey Cargo.toml is parsed in toml version 1.1 format”.
How does your IDE and linter learn that?
In fairness it's probably not too bad as long as everyone actually migrates to the newest version eventually... But that isn't guaranteed - look at YAML. Or even JSONC. VSCode has a hard-coded lists of which `.json` files are actually JSONC. Gross.
TOML went through some substantial changes in the past with 0.4, 0.5, and 1.0. As I mentioned in my other comment[1], it's not ideal, but it is what it is.
I wouldn't be surprised if 1.1 would be the last version. Maybe there will be a 1.2 to clarify some things, but I wouldn't expect any further major changes.
[1]: https://news.ycombinator.com/item?id=36020654