Entry 22
A config section the binary had never heard of
Filescrates/cairns-core/src/config.rscrates/cairns/src/serve.rs
[[link]] from 21 worked here and did nothing on someone else's machine,
with no error either way. Two causes, and only one of them is interesting.
The dull one: a Homebrew tap is a git clone, and it is as old as the last
brew update. brew upgrade cairns against a stale tap reinstalls the version
the tap knows about. Mine did exactly that while I was reproducing the
report - I installed "0.5.0" and got 0.4.1.
The one that matters
A cairns that predates [[link]] reads a config containing it, ignores the
section entirely, and prints ok.
$ cairns --version
cairns 0.4.1
$ cairns check
ok
That is serde's default: unknown fields are skipped. It is the right default for an entry's front matter, where 1 deliberately passes unknown keys through so a project can carry its own metadata. It is the wrong default for configuration, because configuration is instructions - a key the program does not recognise is an instruction it is not following, and silence is the worst possible answer.
Every config struct now refuses what it does not recognise:
cairns.toml: TOML parse error at line 59, column 3
unknown field `lnik`, expected one of `spec_version`, `project`, `paths`,
`site`, `index`, `check`, `docs`, `area`, `publish`, `link`
which catches a typo and, from here on, catches a config written for a newer cairns than the one running. It cannot fix 0.4.1 - that binary will go on ignoring things quietly - so the first symptom of being too old is still the one that was reported. From v0.5.1 the failure is loud.
spec_version was supposed to cover this and did not, because the rule says
additive changes do not bump it. That rule is right for the entry format, where
a new optional field genuinely does no harm to an old reader. For config it is
wrong, and the fix is the one above rather than a version bump on every added
section.
Serve prints its version now
Twice today I have been confused by a cairns serve still running the binary
it was started with. It says which version it is at startup.