[GHC] #13541: Make it easier to use the gold linker

[GHC]

#13541: Make it easier to use the gold linker
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        Reporter:  bgamari           |                Owner:  (none)
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #13810            |  Differential Rev(s):  Phab:D3449
       Wiki Page:                    |
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Comment (by bgamari):

 The diff doesn't touch the runtime linker-detection logic. It also doesn't
 provide a way for the user to override the linker choice, but this could
 be fixed.

 However, I do wish we could drop the runtime probing at some point.
 Currently we start `gcc -v` and `ld -v` on every single GHC compilation.
 On platforms like Windows this can really add up. Even on Linux, where
 process spawning is relatively fast, it's probably 5 to 10 milliseconds
 per execution.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13541#comment:21>
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