decent-toml-rs-alternative (cargo): A fork of the toml-rs crate (by Alex Crichton) that does not depend on serde. It is much less powerful, less documented, and not well-tested yet, but it is fast to compile and does what I want for my own use case. It might grow into a very capable crate at some point. Pair it with the decent-serde-toml-derive-alternative crate to derive the (de)serialization implementation for your own types, and thus avoid syn, quote, and serde entirely.
Keywords: parser|toml