Lints

khora check runs twelve lints alongside type checking. They are part of the compiler rather than a separate tool, so the editor underlines what the command line reports and there is no second configuration to keep in step.

The lints

Name	Default	What it finds
dangling-expression	warn	A statement that computes something and does nothing with it.
discarded-result	warn	A statement that produces a Result and drops it on the floor.
inconsistent-constructor	warn	A constructor whose name disagrees with what it takes — new, empty, root and of follow a rule std keeps.
misplaced-main	warn	A main in a file that is not an entry point.
reference-cycle	warn	A cycle that reference counting cannot collect.
undocumented-export	allow	A pub item nobody described in one line.
unknown-allow	warn	A // @klint allow naming something that is not a lint.
unreachable-code	warn	A statement that cannot run, because the one before it left the block.
unused-binding	warn	A binding nothing reads — locals, parameters, and the names a pattern binds.
unused-capability	warn	A capability a signature asks for that its body cannot be using.
unused-import	warn	An imported name the file never mentions.
useless-allow	allow	A // @klint allow that suppressed nothing.

Levels

[lints]
unused-import = "deny"
undocumented-export = "warn"
unreachable-code = "allow"

Level	Effect
allow	Not reported.
warn	Reported; khora check still succeeds.
deny	Reported as an error; khora check and khora build fail.

The table form carries an option alongside the level, for a lint that takes one:

[lints]
some-lint = { level = "warn", max = 15 }

No shipped lint takes an option yet. The manifest accepts the form so that adding one does not need a manifest change.

In a workspace, [workspace.lints] sets the defaults a member inherits with lints.workspace = true.

Naming a lint that does not exist is a warning, and the message lists the ones that do — a typo would otherwise configure nothing and say nothing, which is the worst direction for a setting to fail in, because a setting you have written down is one you have stopped thinking about. It is a warning rather than an error because a manifest may be older or newer than the toolchain reading it.

The two that are off

undocumented-export is off for the reason Rust’s missing_docs is: a young package gets forty warnings on its first build, and the answer to forty warnings is not forty doc comments. Switch it on when a package decides its surface is a promise. This repository sets it to deny, because khora doc regenerates the reference from /// comments and the gate fails on a stale page — so a documented export cannot drift, and nothing else checked that an export was documented at all.

useless-allow is off because it fires on exactly the lines somebody is already editing to satisfy a new lint, so turning it on while lints are still being added produces churn in the files under the most pressure. Turn it on once they have settled; a stale suppression hides the next finding on that line.

Suppressing one line

// @klint allow unused-binding
let width = measure(shape);

The pragma applies to the line that follows it. unknown-allow is what makes it safe to have: a misspelled lint name in a comment would otherwise suppress nothing and say nothing, and the reader would believe the line was handled.

Prefer the naming escape where one exists. A binding whose name starts with _ is deliberately unused, and _ alone binds nothing — both are quieter than a pragma and neither goes stale.

The receiver of a trait method is the exception. self is part of the signature: it cannot be deleted, and renaming it to _self is refused with error: the receiver of `tag` is `?` here, but `Codec` declares `A. A trait method that ignores its receiver — common in a witness trait — takes the pragma:

impl Codec for IntCodec {
  // @klint allow unused-binding
  fn encode(self, value: Int) -> String { Int::to_string(value) }
}

Where they run

• khora check and khora build, against the manifest nearest the file.
• The language server, at the same levels, so the editor and the command line agree.

There is no khora lint. A separate command is a second thing to run and a second answer to disagree with the first.