commit f9ccb2543d3387e42f20ea52900609af9bc2a922 Author: Isis Lovecruft isis@torproject.org Date: Wed Mar 14 20:59:16 2018 +0000
doc: Document our current rough-draft policy on Rust dependencies.
* FIXES #25310: https://bugs.torproject.org/25310 --- doc/HACKING/CodingStandardsRust.md | 16 ++++++++++++++++ 1 file changed, 16 insertions(+)
diff --git a/doc/HACKING/CodingStandardsRust.md b/doc/HACKING/CodingStandardsRust.md index ad8cd9d04..915d37e00 100644 --- a/doc/HACKING/CodingStandardsRust.md +++ b/doc/HACKING/CodingStandardsRust.md @@ -61,6 +61,22 @@ In general, we use modules from only the Rust standard library whenever possible. We will review including external crates on a case-by-case basis.
+If a crate only contains traits meant for compatibility between Rust +crates, such as [the digest crate](https://crates.io/crates/digest) or +[the failure crate](https://crates.io/crates/failure), it is very likely +permissible to add it as a dependency. However, a brief review should +be conducted as to the usefulness of implementing external traits +(i.e. how widespread is the usage, how many other crates either +implement the traits or have trait bounds based upon them), as well as +the stability of the traits (i.e. if the trait is going to change, we'll +potentially have to re-do all our implementations of it). + +For large external libraries, especially which implement features which +would be labour-intensive to reproduce/maintain ourselves, such as +cryptographic or mathematical/statistics libraries, only crates which +have stabilised to 1.0.0 should be considered, however, again, we may +make exceptions on a case-by-case basis. + Currently, Tor requires that you use the latest stable Rust version. At some point in the future, we will freeze on a given stable Rust version, to ensure backward compatibility with stable distributions that ship it.