[GHC] #14793: some executables in the binary distribution are not versioned

[GHC]

#14793: some executables in the binary distribution are not versioned
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           Reporter:  dmwit          |             Owner:  (none)
               Type:  feature        |            Status:  new
  request                            |
           Priority:  normal         |         Milestone:
          Component:  Build System   |           Version:  8.2.2
           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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 GHC is generally quite careful to play nicely when you install multiple
 versions, in particular by putting a version number somewhere in the
 filepath for almost every installed file. Then a few top-level non-
 versioned symlinks are made to (versioned) executables. Consequently,
 build tools with enough knowledge of the GHC versioning infrastructure can
 select an older or newer GHC to build things with by ignoring the top-
 level symlinks and explicitly selecting the versioned executable names.

 There are a few exceptions where this is not possible: hsc2hs, hp2ps, and
 hpc. These executables are *overwritten* on each installation, so it is
 not possible to select "the one that goes with the currently chosen
 compiler".

 I'd like to request that these begin being installed with the same scheme
 as other GHC executables: with an appended dash and version number,
 together with a non-versioned symlink.

 I don't know to what extent this matters for hp2ps and hpc; perhaps these
 change infrequently enough that it doesn't matter too much. But hsc2hs at
 least bakes some GHC version knowledge in; it has at least a default
 template that it #include's that defines some C macros, and this template
 changes occasionally. There is a command-line option to specify a template
 filepath explicitly, but it would be nice if build tools could reliably
 choose a version of hsc2hs that has the right defaults, so that using the
 command-line flag is a special case for special circumstances.

 (For some context: I have just finished hunting down an issue related to
 exactly this. I installed an older GHC to test that some code was
 backwards-compatible. All of a sudden, existing builds, still using the
 new compiler, started failing, because hsc2hs was now using an outdated
 template that did not define all the necessary macros.)

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14793>
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