• Matthías Páll Gissurarson's avatar
    Fix errors caused by invalid candidates leaking from hole fits · 22c951e6
    Matthías Páll Gissurarson authored
    This is a one line fix (and a note) that fixes four tickets, #15007,
     #15321 and #15202, #15314
    
    The issue was that errors caused by illegal candidates (according to GHC
    stage or being internal names) were leaking to the user, causing
    bewildering error messages. If a candidate causes the type checker to
    error, it is not a valid hole fit, and should be discarded.
    
    As mentioned in #15321, this can cause a pattern of omissions, which
    might be hard to discover. A better approach would be to gather the
    error messages, and ask users to report them as GHC bugs. This will be
    implemented in a subsequent change.
    
    Reviewers: bgamari, simonpj
    
    Reviewed By: simonpj
    
    Subscribers: simonpj, rwbarton, thomie, carter
    
    GHC Trac Issues: #15007, #15321, #15202, #15314
    
    Differential Revision: https://phabricator.haskell.org/D4909
    
    (cherry picked from commit 39de4e3d)
    22c951e6
TcHoleErrors.hs 42.9 KB