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author | John Wiegley <johnw@newartisans.com> | 2015-07-30 15:08:28 +0200 |
---|---|---|
committer | Ben Gamari <ben@smart-cactus.org> | 2015-07-30 17:05:35 +0200 |
commit | 4f80ec0ee438800d95673a4898e69371957fed09 (patch) | |
tree | 47b00b465f2e700aed1e50333c8e0f74e3a754e1 /testsuite/tests/generics | |
parent | 26315ed282db2eb1977872bbcb0b298f32b38e99 (diff) | |
download | haskell-4f80ec0ee438800d95673a4898e69371957fed09.tar.gz |
Improve error message for newtypes and deriving clauses
Summary:
Change the error message generated when a deriving clause related to a newtype
fails to always suggested trying GeneralizedNewtypeDeriving, even in
situations where it may not work. Fixes #9600.
Test Plan: testsuite/deriving/should_fail/9600.hs
Reviewers: austin, bgamari, simonpj
Rebased-by: bgamari
Reviewed By: simonpj
Subscribers: bgamari, hvr, simonmar, carter
Differential Revision: https://phabricator.haskell.org/D216
GHC Trac Issues: #9600
Diffstat (limited to 'testsuite/tests/generics')
-rw-r--r-- | testsuite/tests/generics/T5462No1.stderr | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/testsuite/tests/generics/T5462No1.stderr b/testsuite/tests/generics/T5462No1.stderr index 87ef888461..7c1aec8d79 100644 --- a/testsuite/tests/generics/T5462No1.stderr +++ b/testsuite/tests/generics/T5462No1.stderr @@ -1,20 +1,20 @@ [1 of 2] Compiling GFunctor ( GFunctor/GFunctor.hs, out_T5462No1/GFunctor.o ) [2 of 2] Compiling T5462No1 ( T5462No1.hs, out_T5462No1/T5462No1.o ) -T5462No1.hs:24:42: +T5462No1.hs:24:42: error: Can't make a derived instance of ‘GFunctor F’: - ‘GFunctor’ is not a derivable class + ‘GFunctor’ is not a standard derivable class (Eq, Show, etc.) Try GeneralizedNewtypeDeriving for GHC's newtype-deriving extension In the newtype declaration for ‘F’ -T5462No1.hs:26:23: +T5462No1.hs:26:23: error: Can't make a derived instance of ‘C1 G’: - ‘C1’ is not a derivable class + ‘C1’ is not a standard derivable class (Eq, Show, etc.) Try enabling DeriveAnyClass In the data declaration for ‘G’ -T5462No1.hs:27:23: +T5462No1.hs:27:23: error: Can't make a derived instance of ‘C2 H’: - ‘C2’ is not a derivable class + ‘C2’ is not a standard derivable class (Eq, Show, etc.) Try enabling DeriveAnyClass In the data declaration for ‘H’ |