[GHC] #8174: GHC should not load packages for TH if they are not used

[GHC]

#8174: GHC should not load packages for TH if they are not used
-------------------------+-------------------------------------------------
       Reporter:  nh2    |             Owner:
           Type:  bug    |            Status:  new
       Priority:         |         Milestone:  7.8.1
  normal                 |           Version:  7.6.3
      Component:         |  Operating System:  Unknown/Multiple
  Compiler               |   Type of failure:  Compile-time performance bug
       Keywords:         |         Test Case:
   Architecture:         |          Blocking:
  Unknown/Multiple       |
     Difficulty:         |
  Unknown                |
     Blocked By:         |
Related Tickets:         |
-------------------------+-------------------------------------------------
 https://github.com/nh2/ghc-bug-th-loading

 When you call

 {{{
 ghc --make -package mypackage
 }}}

 on a module that uses TH, you will see

 {{{
 Loading package mypackage-1.2.3.4 ... linking ... done.
 }}}

 even if no code uses it. This slows down builds, especially cabal ones.

 GHCI does this better and only loads what is needed.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8174>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler