Agreed, though by "parsing" I meant to include easy steps like cfg checks. In fact, cfg checks should probably be done at the same time as parsing and disabled items should be discarded as soon as possible---though I don't know whether that is already done in the current compiler, or whether it's beneficial or even possible at all.
We do some parsing "underneath" disabled cfg checks, in order to support user-friendliness features like "that function you tried to call doesn't exist, but if you enabled feature xyz then it would". But we do discard cfg-protected items before doing any subsequent heavier operations.
