Ben Gamari authored 5 years ago and Marge Bot committed 5 years ago

Previously we would hackily evaluate a textual code snippet to compute
actions to disable I/O buffering and flush the stdout/stderr handles.
This broke in a number of ways (#15336, #16563).

Instead we now ship a module (`GHC.GHCi.Helpers`) with `base` containing
the needed actions. We can then easily refer to these via `Orig` names.

TcSimplify.decideQuantification was doing the Wrong Thing when
"growing" the type variables to quantify over. We were trying to do
this on a tyvar set where we'd split off the dependent type varaibles;
and we just got it wrong.  A kind variable wasn't being generalised
properly, with confusing knock on consequences.

All this led to Trac #13371 and Trac #13393.

This commit tidies it all up:

* The type TcDepVars is renamed as CandidateQTvs;
  and splitDepVarsOfType to candidateQTyVarsOfType

* The code in TcSimplify.decideQuantification is simpler.
  It no longer does the tricky "grow" stuff over TcDepVars.
  Instead it use ordinary VarSets (thereby eliminating the
  nasty growThetaTyVarsDSet) and uses that to filter the
  result of candidateQTyVarsOfType.

* I documented that candidateQTyVarsOfType returns the type
  variables in a good order in which to quantify, and rewrote
  it to use an accumulator pattern, so that we would predicatably
  get left-to-right ordering.

In doing all this I also made UniqDFM behave a little more nicely:

* When inserting an element that is there already, keep the old tag,
  while still overwriting with the new value.

* This means that when doing udfmToList we get back elements in the
  order they were originally inserted, rather than in reverse order.

It's not a big deal, but in a subsequent commit I use it to improve
the order of type variables in inferred types.

All this led to a lot of error message wibbles:
 - changing the order of quantified variables
 - changing the order in which instances are listed in GHCi
 - changing the tidying of variables in typechecker erors

There's a submodule update for 'array' because one of its tests
has an error-message change.

I may not have associated all of them with the correct commit.

Rationale in the comment.
Also updates submodule array with test output changes.

GHC Trac: #4012

Ben Gamari authored 9 years ago and Ben Gamari committed 9 years ago

Commit 547c5971 modifies the
pretty-printer to render names from a set of core packages (`base`,
`ghc-prim`, `template-haskell`) as unqualified. The idea here was that
many of these names typically are not in scope but are well-known by the
user and therefore qualification merely introduces noise.

This, however, is a very large hammer and potentially breaks any
consumer who relies on parsing GHC output (hence #11208). This commit
partially reverts this change, now only printing `Constraint` (which
appears quite often in errors) as unqualified.

Fixes #11208.

Updates tests in `array` submodule.

Test Plan: validate

Reviewers: hvr, thomie, austin

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D1619

GHC Trac Issues: #11208

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>