[GHC] #16202: Hadrian install script doesn't update location of haddockHTMLs and haddockInterfaces

[GHC]

#16202: Hadrian install script doesn't update location of haddockHTMLs and
haddockInterfaces
-------------------------------------+-------------------------------------
           Reporter:  harpocrates    |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Build System   |           Version:  8.6.3
  (Hadrian)                          |
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  Installing GHC
  Unknown/Multiple                   |  failed
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
-------------------------------------+-------------------------------------
 This is to track part two of the plan here:
 https://gitlab.haskell.org/ghc/ghc/merge_requests/50#note_1808.

 When installing a bindist, the make system runs `ghc-cabal` to reconfigure
 packages and regenerate the package DB. Hadrian, on the other hand, seems
 to just be copying the package DB as is to its install location. This is
 mostly OK since most paths only need to be relative to package root.
 However, it breaks down for the `haddock-interfaces` and `haddock-html`
 fields, (esp. since documentation can be installed in a completely
 different location).

 The following interaction demonstrates the problem. Note how `ghc-pkg` is
 pointing us to a directory that doesn't even exist!

 {{{
 $ ./hadrian/build.sh -c -j binary-dist
 $ mv _build/bindist/ghc-8.7.20190117-x86_64-apple-darwin.tar.xz
 /Users/alec/scratch
 $ cd /Users/alec/scratch
 $ tar xpvf ghc-8.7.20190117-x86_64-apple-darwin.tar.xz
 $ ./configure --prefix=/Users/alec/scratch && make install
 $ ./bin/ghc-pkg field base haddock-html
 haddock-html: /Users/alec/scratch/lib/../../docs/html/libraries/base
 $ ls /Users/alec/scratch/lib/../../docs/html/libraries/base
 ls: /Users/alec/scratch/lib/../../docs/html/libraries/base: No such file
 or directory
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16202>
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