Make `bisect` the default search strategy about cargo-msrv HOT 2 CLOSED

Hi @danieleades, thanks for your question.

I think there are two reasons at the moment why it isn't the default:

1. The bisect implementation has not been battle tested and aside from my own use, I've received no feedback on how well the implementation performs. On the flip side, having it as the default may very well generate such feedback.
2. At the time of implementation there were some issues regarding different versions of Cargo.lock files. Older Cargo versions did not support newer lock files. When using bisection, this issue becomes much more prominent, as we would now install much older toolchains, while currently, most often the MSRV is a much more recent version of Rust which has support for the newer lock file. This issue can be alleviated by running cargo msrv with the --ignore-lockfile flag, but it also changes the behaviour since we now run a toolchain against unfrozen dependency versions.

However, a binary search can significantly reduce the time necessary to determine the MSRV, especially when you also reduce the search space further by setting --minimum <version> (e.g. 1.31.0 for Rust edition 2018), so it's definitely a worth to think about, and to start a conversation about.

What would be the primary reason(s) for you to have --bisect as the default?

#45 (comment)

from cargo-msrv.

i'm using 'bisect' to find the msrv on new projects. it's significantly faster than the linear search.

I'm also using the 2018 edition as a minimum. perhaps the edition set in cargo.toml should be respected as a minimum? or at least, the editions could be used as aliases with the --min argument. That's a different issue of course.

from cargo-msrv.