2fd8614f5d units: Add additional must_use (Tobin C. Harding)
79a229b391 units: Add pedantic lint return_self_not_must_use (Tobin C. Harding)
Pull request description:
Enable return_self_must_use and also run the linter locally with must_use_candidate.
Add must_use attribute as required excluding obvious functions (conversion, getters, etc).
Done as part of https://github.com/rust-bitcoin/rust-bitcoin/issues/3185
ACKs for top commit:
apoelstra:
ACK 2fd8614f5d091377f179440b04ec71f4853fd187; successfully ran local tests; nice! will one-ACK merge
Tree-SHA512: 90868846d6877830ca2b6931e8b94208434acc5a7b21808a32e2e1568c0ad33185644b931cae500e6619b8b4f19c39bce6922502d9233173722ef0e6455edba6