[GHC] #15483: ghc -M requires -dep-suffix for no good reason

[GHC]

#15483: ghc -M requires -dep-suffix for no good reason
-------------------------------------+-------------------------------------
           Reporter:  ulysses4ever   |             Owner:  (none)
               Type:  feature        |            Status:  new
  request                            |
           Priority:  normal         |         Milestone:  8.6.1
          Component:  Driver         |           Version:  8.4.3
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 Doing
 {{{
 ghc -M Foo.hs
 }}}
 gives
 {{{
 You must specify at least one -dep-suffix
 }}}
 I went to the documentation and noticed
 ([https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/separate_compilation.html
 #makefile-dependencies 7.8.12]) an example:
 {{{
 depend :
         ghc -dep-suffix '' -M $(HC_OPTS) $(SRCS)
 }}}
 So, empty suffix is fine. Why not default to empty string then?

 I found a commit which introduced the requirement
 ([https://github.com/ghc/ghc/commit/af072fc35d8dbe7962e62700da052593e999c0ef
 af072fc]): it says, it fixed #7381, and this doesn't seem to do anything
 with `dep-suffix` in particular. So, maybe there is no good reason to
 require that.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15483>
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