Mention DerivingStrategies in the warning when DAC and GND are both enabled
authorChaitanya Koparkar <ckoparkar@gmail.com>
Mon, 14 Jan 2019 19:36:29 +0000 (14:36 -0500)
committerMarge Bot <ben+marge-bot@smart-cactus.org>
Sun, 20 Jan 2019 10:24:59 +0000 (05:24 -0500)
commit800d77e882f24066a7f6d818b2606ad8a0e79e02
tree6e7d9b4673499c1cb29214641571f27e8c32a2e8
parentb137ab75ab269e043e0783e41ac704d1be5570c6
Mention DerivingStrategies in the warning when DAC and GND are both enabled

Summary:

When DeriveAnyClass and GeneralizedNewtypeDeriving are both enabled,
GHC prints out a warning that specifies the strategy it used to
derive a class. This patch updates the warning to mention that users
may pick a particular strategy by using DerivingStrategies.

Test plan: make test TEST=T16179
compiler/typecheck/TcDeriv.hs
testsuite/tests/deriving/should_compile/T16179.hs [new file with mode: 0644]
testsuite/tests/deriving/should_compile/T16179.stderr [new file with mode: 0644]
testsuite/tests/deriving/should_compile/all.T