[GHC] #9846: GHC --make should also look for .hi, not only for .hs

[GHC]

#9846: GHC --make should also look for .hi, not only for .hs
-------------------------------------+-------------------------------------
       Reporter:  larsrh             |                   Owner:
           Type:  feature request    |                  Status:  new
       Priority:  normal             |               Milestone:  ⊥
      Component:  Compiler           |                 Version:
       Keywords:                     |        Operating System:
   Architecture:  Unknown/Multiple   |  Unknown/Multiple
     Difficulty:  Unknown            |         Type of failure:
     Blocked By:                     |  None/Unknown
Related Tickets:                     |               Test Case:
                                     |                Blocking:
                                     |  Differential Revisions:
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 Currently, `ghc --make` will only consider .hs source files from the
 include path.

 Example (assuming `Library` can't be resolved from the package database):

 `A.hs`
 {{{#!hs
 module A where

 import B
 import Library
 }}}

 `B.hs`
 {{{#!hs
 module B where
 }}}

 Compiling these files with `ghc --make -Idir A.hs B.hs` will succeed only
 if GHC finds a `Library.hs` file.

 In a thread on [https://www.haskell.org/pipermail/glasgow-haskell-
 users/2014-November/025476.html glasgow-haskell-users], Simon proposed
 relaxing this constraint; namely: In `--make` mode, when encountering an
 import `X`, GHC will try the following in order:

 1. resolve the import from a package
 2. search the include path for `X.hs` or `X.lhs`
 3. search the include path for `X.hi`

 It already does 1 and 2, and this proposal would add 3.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9846>
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