One issue, maybe? Is getLinterConfigurationOptions() not actually required to use thsoe options in .arclint? I'd expect an exception if you try to specify them without overriding it.

I don't quite understand your comment. How are options passed from .arclint to the linters? I'm not sure myself.

I don't quite understand your comment. How are options passed from .arclint to the linters? I'm not sure myself.

ArcanistConfigurationDrivenLintEngine loads the configuration engine near the top of buildLinters(), near line 27:

It does a top-level typecheck for the file format (basically, it should contain a map of linter specifications):

PhutilTypeSpec::checkMap(
  $config,
  array(
    'linters' => 'map<string, map<string, wild>>',
    'debug'   => 'optional bool',
  ));

Then it goes through linters and typechecks each one of those, by calling getLinterConfigurationOptions(). This is implemented by:

• ArcanistLinter (adds severity, severity.rules)
• ArcanistExternalLinter (adds bin, flags, interpreter)
• optionally the concrete linter class itself, to add more flags

Then the actual typecheck happens, near line 57, which checks type, include and exclude:

PhutilTypeSpec::checkMap(
  $spec,
  array(
    'type' => 'string',
    'include' => 'optional string | list<string>',
    'exclude' => 'optional string | list<string>',
  ) + $more);

So the expectation is that if you have a .arclint file and add arbitrary configuration to a linter section, you'll get an exception when you run lint if you didn't actually specify that the config keys are known (some day, this should be a little prettier):

$ arc lint --rev HEAD^
Exception
Got unexpected parameters: quack
(Run with --trace for a full exception trace.)

So to add options strict-math and strict-units, I'd expect you to need something like (I namespaced the option names here):

public function getLinterConfigurationOptions() {
  return parent::getLinterConfigurationOptions() + array(
    'lessc.strict-math' => 'optional bool',
    'lessc.strict-units' => 'optional bool',
  );
}

...otherwise, you'll get that exception if you specify these in .arclint and run lint.