MonadFail proposal, phase 1

This implements phase 1 of the MonadFail proposal (MFP, #10751).

- MonadFail warnings are all issued as desired, tunable with two new flags
- GHC was *not* made warning-free with `-fwarn-missing-monadfail-warnings`
  (but it's disabled by default right now)

Credits/thanks to
- Franz Thoma, whose help was crucial to implementing this
- My employer TNG Technology Consulting GmbH for partially funding us
  for this work

Reviewers: goldfire, austin, #core_libraries_committee, hvr, bgamari, fmthoma

Reviewed By: hvr, bgamari, fmthoma

Subscribers: thomie

Projects: #ghc

Differential Revision: https://phabricator.haskell.org/D1248

GHC Trac Issues: #10751

1 files changed, 3 insertions, 1 deletions

diff --git a/testsuite/tests/driver/T4437.hs b/testsuite/tests/driver/T4437.hs
index f76dc34354..d3bee2a61a 100644
--- a/testsuite/tests/driver/T4437.hs
+++ b/testsuite/tests/driver/T4437.hs
@@ -33,7 +33,9 @@ expectedGhcOnlyExtensions :: [String]
 expectedGhcOnlyExtensions = ["RelaxedLayout",
                              "AlternativeLayoutRule",
                              "AlternativeLayoutRuleTransitional",
-                             "OverloadedLabels"]
+                             "OverloadedLabels",
+                             "Strict",
+                             "MonadFailDesugaring"]
 
 expectedCabalOnlyExtensions :: [String]
 expectedCabalOnlyExtensions = ["Generics",