• Edward Z. Yang's avatar
    Error early when you register with too old a version of Cabal. · d80caca1
    Edward Z. Yang authored
    
    
    On the GHC 8.0 RCs, multiple users reported a very strange error
    whereby GHC would complain that the symbols names recorded in interface
    files did not match the expected name.  The reason for this is
    that they were using an old version of Cabal which chose symbol
    names differently from the installed package ID ('id' field) which
    the package was to be installed with; GHC 8.0 now mandates that
    these coincides.
    
    This change adds a test to ghc-pkg to make sure that 'id' and 'key'
    (which is how Cabal previously reported what the symbol name
    was supposed to be) match; if they don't match or key is missing,
    we assume that the Cabal was too old.
    
    Bikeshed points:
    
        - Should we offer more information about how to upgrade
          Cabal correctly (i.e. specify a version?)
    
        - Should we allow for a missing 'key'?  If we allow for
          'key' to be missing, we lose the ability to detect
          Cabal from GHC 7.8 or earlier being used.  If we
          require it to be specified, then it will not be possible
          for Cabal to deprecate the (unused) field and remove it
          without having BC for 8.0.
    Signed-off-by: default avatarEdward Z. Yang <ezyang@cs.stanford.edu>
    
    Test Plan: validate
    
    Reviewers: austin, bgamari, hvr
    
    Reviewed By: hvr
    
    Subscribers: bergmark, thomie
    
    Differential Revision: https://phabricator.haskell.org/D1892
    
    GHC Trac Issues: #11558
    d80caca1
Makefile 3.62 KB