`is(symbol == module)` puts a red underline squiggle under `module`, however this is a valid expression.
Comment #1 by r.sagitario — 2020-03-10T07:26:59Z
This is a rather recent addition to the language (including `package`). It is supported by the dmd based engine, but DParser won't keep up with all changes.
I can add it to the parser of that engine, though, but not in semantics.
Comment #2 by turkeyman — 2020-03-10T07:30:54Z
Oh whoops, I didn't realise I wasn't using the DMD engine.
I just re-installed on my work PC, and it's not the default.