Change rust build to use the --locked flag

[frederikrothenberger]

This change makes builds fail if the Cargo.lock file is outdated, which prevents future PRs such as #1972.

[nmattia]

Thanks that makes a lot of sense! should it be part of the build script though? we may only want it enabled on CI

[frederikrothenberger]

Thanks that makes a lot of sense! should it be part of the build script though? we may only want it enabled on CI

CI does not call cargo build directly. Should I make it an optional flag on the build script?

[nmattia]

@frederikrothenberger may even be able to get away with an extra step like so:

$ cargo generate-lockfile --locked

[frederikrothenberger]

@frederikrothenberger may even be able to get away with an extra step like so:

$ cargo generate-lockfile --locked

I don't think this does what we want? It fails if dependencies could be updated. What we want is failure if the lock file must be updated, right?

[nmattia]

True, this might work:

$ cargo update --workspace --locked
    Updating crates.io index
    Updating sha2 v0.10.7 -> v0.10.8
error: the lock file /Users/nicolas/internet-identity/Cargo.lock needs to be updated but --locked was passed to prevent this
If you want to try to generate the lock file without accessing the network, remove the --locked flag and use --offline instead.

found here: https://users.rust-lang.org/t/check-if-the-cargo-lock-is-up-to-date-without-building-anything/91048/5

Either way, a separate step testing specifically for this might be clearer & less invasive

[frederikrothenberger]

Superseded by #1979.