How can I create source maps?

[PiNotEqual3]

From what I read about it, I need to add -sass-debug-info but I am not sure.

See https://github.com/less/less.js/pull/1038

Or maybe --source-map --source-map-basepath?

node_modules/less/bin/lessc --source-map --source-map-basepath="`pwd`"/web --source-map-rootpath=/ --strict-imports web/assets/site/css/bootstrap/bootstrap-full.less web/assets/site/css/bootstrap/bootstrap-full.css

See https://github.com/less/less.js/issues/1050

Mainly I need to define custom parameters for lessc

[Remo]

lessy doesn't use lessc, but rather lessphp, which unfortunately doesn't support source maps https://github.com/leafo/lessphp/issues/531 unless someone adds sourcemap support, you'll be out of luck. you could add support for lessc to lessy, but I'm not sure such a dependency is the way to go..