GitLab

Summary:
Previously, GHC would look for instances of wired-in packages in the
in-memory package database and null out the version number.  This was
necessary when the sourcePackageId was used to determine the linker
symbols; however, we now use a package key, so only that needs to be
updated.

Long-term, we can remove this hack by ensuring that Cabal actually records
the proper package key in the database.  This will also fix an unrelated
hack elsewhere.

Keeping version numbers means that wired in packages get rendered differently
when output by GHC.  This is the source of all the test-case output changes.
Signed-off-by: Edward Z. Yang <ezyang@cs.stanford.edu>

Test Plan: validate

Reviewers: hvr, austin

Subscribers: simonmar, ezyang, carter

Differential Revision: https://phabricator.haskell.org/D170

* Deprecate -XOverlappingInstances

* Update test suite.  Several tests even had entirely unnecessary
  uses of -XOverlappingInstances

* Update user manual with a careful description of the instance
  resolution story

* Fix an outright bug in the handling of duplidate instances in GHCi,
  which are meant to silently overwrite the earlier duplicate. The
  logic was right for family instances but was both more complicated,
  and plain wrong, for class instances.  (If you are interested, the
  bug was that we were eliminating the duplicate from the InstEnv, but
  not from the [ClsInst] held in tcg_insts.)  Test is ghci044a.

Now that we're in development mode, Applicative will soon be a
superclass of Monad in HEAD. So let's go ahead and deprecate the
-fno-warn-amp flag, remove the checks, and tweak a few tests
Signed-off-by: Austin Seipp <austin@well-typed.com>

This matches GCC's choice of Unicode quotation marks (i.e. U+2018 and U+2019)
and therefore looks more familiar on the console. This addresses #2507.
Signed-off-by: Herbert Valerio Riedel <hvr@gnu.org>

(this is related to #3647)

The perf tests can probably be rechecked and tightened a little; I fixed
them with AMP the other day but some changes since then have made them
wibble perhaps.
Signed-off-by: Austin Seipp <austin@well-typed.com>

Most of these tests were written by Nicolas Frisby.