[commit: ghc] ghc-8.6: Suppress -Winaccessible-code in derived code (8bed140)

[git at git.haskell.org]

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

On branch  : ghc-8.6
Link       : http://ghc.haskell.org/trac/ghc/changeset/8bed140099f8ab78e3e728fd2e50dd73d7210e84/ghc

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

commit 8bed140099f8ab78e3e728fd2e50dd73d7210e84
Author: Ryan Scott <ryan.gl.scott at gmail.com>
Date:   Tue Jul 24 14:40:42 2018 +0200

    Suppress -Winaccessible-code in derived code
    
    Summary:
    It's rather unfortunate that derived code can produce inaccessible
    code warnings (as demonstrated in #8128, #8740, and #15398), since
    the programmer has no control over the generated code. This patch
    aims to suppress `-Winaccessible-code` in all derived code. It
    accomplishes this by doing the following:
    
    * Generalize the `ic_env :: TcLclEnv` field of `Implication` to
      be of type `Env TcGblEnc TcLclEnv` instead. This way, it also
      captures `DynFlags`, which record the flag state at the time
      the `Implication` was created.
    * When typechecking derived code, turn off `-Winaccessible-code`.
      This way, any insoluble given `Implication`s that are created when
      typechecking this derived code will remember that
      `-Winaccessible-code` was disabled.
    * During error reporting, consult the `DynFlags` of an
      `Implication` before making the decision to report an inaccessible
      code warning.
    
    Test Plan: make test TEST="T8128 T8740 T15398"
    
    Reviewers: simonpj, bgamari
    
    Reviewed By: simonpj
    
    Subscribers: monoidal, rwbarton, thomie, carter
    
    GHC Trac Issues: #8128, #8740, #15398
    
    Differential Revision: https://phabricator.haskell.org/D4993
    
    (cherry picked from commit 44a7b9baa45c4ab939c7d996519b5e3de3e13c5a)


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

8bed140099f8ab78e3e728fd2e50dd73d7210e84
 compiler/typecheck/TcErrors.hs                     | 33 +++++----
 compiler/typecheck/TcInstDcls.hs                   | 84 ++++++++++++++++++----
 compiler/typecheck/TcRnTypes.hs                    | 66 +++++++++++------
 compiler/typecheck/TcSMonad.hs                     | 34 +++++----
 compiler/typecheck/TcSimplify.hs                   | 39 +++++-----
 compiler/typecheck/TcUnify.hs                      | 38 +++++-----
 testsuite/tests/deriving/should_compile/T15398.hs  | 20 ++++++
 .../tests/deriving/should_compile/T8128.stderr     | 14 ----
 .../tests/deriving/should_compile/T8740.stderr     | 18 -----
 testsuite/tests/deriving/should_compile/all.T      |  1 +
 10 files changed, 209 insertions(+), 138 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 8bed140099f8ab78e3e728fd2e50dd73d7210e84