pub fn migrate_file(input: &str) -> Result<Option<String>, Error>Expand description
Pure migration from any supported version’s TOML string into the current
schema version’s TOML string. Returns Ok(None) when the input is already
at CURRENT_SCHEMA_VERSION.
Comments and decoration on keys whose dotted path survives the migration
are preserved via toml_edit::DocumentMut reconciliation (sync_table).
Keys that are renamed, removed, or restructured lose their comments — the
.backup file written by migrate_file_in_place retains the original
for manual recovery.