The German community did a voting for a "technical wish list". "Source search" made it into the top 20 wishes. See [[w:de:WP:Umfragen/Technische_Wünsche/Suche#Wünsche]].
I had the chance to talk with one of the current CirrusSearch developers and we think it should be fairly easy to implement this: In addition to the current field (which contains the visible text only) we could add a second field that contains the plain, untransformed wiki text. I suggest a keyword "insource:..." to allow searching this field. This could be very powerful in combination with the existing "hastemplate:...".
- This will roughly double the size of the index. Is this worth it?
- Stemming should be disabled on this field, if that's possible. And it probably needs a few more tweaks.
- Searching for special characters can't work, right?
- Can this still work if we switch to Parsoid some day? It should, right?