A feature was requested so that compiledb can automatically be include with all targets, primarily for the purpose of ninja, so that the compiledb target does not need to always be specified at the command line when specifying targets.

This may be something like --auto-compiledb. One possible way to easily accomplish this (although some may consider it hacky) is to add the compiledb target on to the COMMAND_LINE_TARGETS global that scons uses to record targets requested at the command line.