Migrating from 0.6

0.7 is one breaking change and two behaviours worth knowing about. Most programs recompile without an edit.

Format is #[non_exhaustive]

The one change that can stop a build. A match over Format outside the crate now needs a wildcard arm:

match format {
    Format::Json => read_json(),
    Format::Toml => read_toml(),
    Format::Yaml => read_yaml(),
    other => return Err(MyError::Unsupported(other.feature())),
}

Why once, now: 0.7 adds Ini and Properties, and adding a variant to an exhaustive enum is breaking whether or not the attribute is there. Marking it non_exhaustive in the same release means the next format — and there will be one — is additive. Format::feature() names the cargo feature for any variant, so a wildcard arm can always say something useful.

If you never match on Format — most callers pass it, not inspect it — nothing changes.

The diagnostics have a runtime seam

The stderr lines ([dynamic-config] …: reloaded in 3ms) are unchanged by default, byte for byte. What is new: set_log_sink routes them anywhere at runtime, set_log_level quiets them, and a log feature forwards them to the log crate. The tracing feature still outranks everything when compiled in.

The language bindings change behaviour here: the Python wheel now delivers these lines through logging from the first import (see that package's changelog), and the Node addon gains an opt-in setLogger.

New formats, if you want them

dynamic-config = { version = "0.7", features = ["ini", "properties"] }

config.ini and config.properties then resolve, discover and watch like any other source. Neither can be a save target — the error says why. The dialect of each is specified in Formats.