The hmake parser specifically doesn't depend on layout. A module doing crazy stuff like
module M where import qualified {- " -} N
is perfectly fine, and all it takes to implement is the addition of a `concatMap' over and above the version which expects the whole import on one line. (FWIW, the hmake parser is ~200 lines, of which ~150 lines deals with cpp, ~30 lines deals with comments, and ~20 lines actually reads the imports.)
But the point is you *can* construct valid modules which will confuse hmake (I just did). Our experience with GHC has told us, if nothing else, that the obscure cases always crop up eventually :-)
But ghci already contains a Haskell parser - so it should be much less work.
Agreed, except that you don't want to fully-parse each module twice, nor in general do you want to report all parse errors on the import-gathering pass!
Yes, that is indeed a problem. Cheers, Simon