The help text for many of the scons flags is confusing. The help text for --use-system-mongo-c at least seems straightforward:

--use-system-mongo-c=[on|off|auto]

I'm clearly meant to write either --use-system-mongo-c=on or --use-system-mongo-c=off or --use-system-mongo-c=auto. Simple enough. But the help text for --use-system-icu is baffling:

--use-system-icu=USE-SYSTEM-ICU

Is this telling me to write literally --use-system-icu=USE-SYSTEM-ICU? Or am I supposed to use just --use-system-icu? Or am I meant to infer that USE-SYSTEM-ICU should be replaced with on, off, or auto?

I can probably experiment to figure out what I need to use, but it would be better if the help text were clearer.