Compilation won't work with cargo versions below 1.77

[Oneliness]

for some reason, I have to use rust version below 1.77, and I got this error message

error: unsupported output in build script of `v4l2r v0.0.4`: `cargo::rerun-if-env-changed=V4L2R_VIDEODEV2_H_PATH`
Found a `cargo::key=value` build directive which is reserved for future use.
Either change the directive to `cargo:key=value` syntax (note the single `:`) or upgrade your version of Rust.
See https://doc.rust-lang.org/cargo/reference/build-scripts.html#outputs-of-the-build-script for more information about build script outputs.

changing double colon in build.rs to single solved the problem.

Perhaps consider handling this scenario in the build.rs file?

[Gnurou]

I've been trying to understand the difference between the cargo:: and cargo: notations, but couldn't find anything meaningful. The latest cargo documentation only mentions cargo::. Do you happen to know what the differences are?