Do not rebuild when no files changed

[blyxxyz]

We were asking cargo to rebuild if assets/xhs or assets/xhs.1.gz changed. Those are dead symlinks, so cargo always errors and assumes they changed.

That caused a lot of unnecessary rebuilds. I found the problem by running with CARGO_LOG=cargo::core::compiler::fingerprint=info.

Asking cargo to watch only the files we actually care about fixes it.

[ducaale]

How often XH_FEATURES will be updated with this change?

PS: I will not have access to my computer for more than a week. Until then, I won't be able to properly review your PRs 😔.

[blyxxyz]

How often XH_FEATURES will be updated with this change?

It keeps working, I think cargo keeps track of each set of features separately.

PS: I will not have access to my computer for more than a week. Until then, I won't be able to properly review your PRs 😔.

Thank you for the heads-up!

[ducaale]

Since XH_FEATURES is updated in build.rs which should only be rerun whenever a change in syntax files is detected, I was worried about the possibility of XH_FEATURES ending up with a stale value. But it turns out cargo will always execute build.rs whenever a different set of features is passed to it (verified it by printing inside build.rs and using cargo's -vv flag).

$ cargo run -- --version
   Compiling xh v0.14.0 (/home/ducaale/xh)
    Finished dev [unoptimized + debuginfo] target(s) in 25.03s
     Running `target/debug/xh --version`
xh 0.14.0
-native-tls
$ cargo run --features=native-tls -- --version
   Compiling xh v0.14.0 (/home/ducaale/xh)
    Finished dev [unoptimized + debuginfo] target(s) in 25.39s
     Running `target/debug/xh --version`
xh 0.14.0
+native-tls

Approved!