[commit: ghc] master: Add RubbishLit for absent bindings of UnliftedRep (448b77b)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/448b77b93b369745e9bfbc8b46a5b87bb73dd379/ghc

>---------------------------------------------------------------

commit 448b77b93b369745e9bfbc8b46a5b87bb73dd379
Author: Sebastian Graf <sebastian.graf at kit.edu>
Date:   Sun Oct 14 20:32:40 2018 +0200

    Add RubbishLit for absent bindings of UnliftedRep
    
    Summary:
    Trac #9279 reminded us that the worker wrapper transformation copes
    really badly with absent unlifted boxed bindings.
    
    As `Note [Absent errors]` in WwLib.hs points out, we can't just use
    `absentError` for unlifted bindings because there is no bottom to hide
    the error in.
    So instead, we synthesise a new `RubbishLit` of type
    `forall (a :: TYPE 'UnliftedRep). a`, which code-gen may subsitute for
    any boxed value. We choose `()`, so that there is a good chance that
    the program crashes instead instead of leading to corrupt data, should
    absence analysis have been too optimistic (#11126).
    
    Reviewers: simonpj, hvr, goldfire, bgamari, simonmar
    
    Reviewed By: simonpj
    
    Subscribers: osa1, rwbarton, carter
    
    GHC Trac Issues: #15627, #9279, #4306, #11126
    
    Differential Revision: https://phabricator.haskell.org/D5153


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448b77b93b369745e9bfbc8b46a5b87bb73dd379
 compiler/basicTypes/Literal.hs                     |  87 +++++-
 compiler/codeGen/StgCmmUtils.hs                    |   1 +
 compiler/coreSyn/CoreUtils.hs                      |  11 +-
 compiler/ghci/ByteCodeAsm.hs                       |   4 +
 compiler/ghci/ByteCodeGen.hs                       |   1 +
 compiler/prelude/TysPrim.hs                        |  13 +
 compiler/prelude/TysWiredIn.hs                     |   2 +-
 compiler/stgSyn/CoreToStg.hs                       |  10 +-
 compiler/stranal/WwLib.hs                          |  36 ++-
 testsuite/tests/stranal/should_compile/T15627.hs   |  19 ++
 .../tests/stranal/should_compile/T15627.stderr     | 338 +++++++++++++++++++++
 testsuite/tests/stranal/should_compile/all.T       |   6 +
 12 files changed, 508 insertions(+), 20 deletions(-)

Diff suppressed because of size. To see it, use:

    git diff-tree --root --patch-with-stat --no-color --find-copies-harder --ignore-space-at-eol --cc 448b77b93b369745e9bfbc8b46a5b87bb73dd379