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| author | sheaf <sam.derbyshire@gmail.com> | 2021-11-19 10:19:19 +0100 |
|---|---|---|
| committer | Marge Bot <ben+marge-bot@smart-cactus.org> | 2021-11-20 18:13:23 -0500 |
| commit | 742d8b6049c30f3b0cd1704d7a34d865bef41712 (patch) | |
| tree | b22ad862ca4db2e9004d8b4ab4aafbc11bcde0a9 /testsuite/tests/polykinds | |
| parent | bc7e9f038112496c45aeb81d1504e57acb3722c7 (diff) | |
| download | haskell-742d8b6049c30f3b0cd1704d7a34d865bef41712.tar.gz | |
Include "not more specific" info in overlap msg
When instances overlap, we now include additional information
about why we weren't able to select an instance: perhaps
one instance overlapped another but was not strictly more specific,
so we aren't able to directly choose it.
Fixes #20542
Diffstat (limited to 'testsuite/tests/polykinds')
| -rw-r--r-- | testsuite/tests/polykinds/T13393.stderr | 7 |
1 files changed, 3 insertions, 4 deletions
diff --git a/testsuite/tests/polykinds/T13393.stderr b/testsuite/tests/polykinds/T13393.stderr index 759f3408b0..3836059249 100644 --- a/testsuite/tests/polykinds/T13393.stderr +++ b/testsuite/tests/polykinds/T13393.stderr @@ -3,12 +3,11 @@ T13393.hs:61:3: error: • Ambiguous type variable ‘t0’ arising from a use of ‘mapM’ prevents the constraint ‘(Traversable t0)’ from being solved. Probable fix: use a type annotation to specify what ‘t0’ should be. - These potential instances exist: + Potentially matching instances: instance Traversable (Either a) -- Defined in ‘Data.Traversable’ instance Traversable Identity -- Defined in ‘Data.Traversable’ - instance Traversable Maybe -- Defined in ‘Data.Traversable’ - ...plus N others - ...plus N instances involving out-of-scope types + ...plus four others + ...plus 28 instances involving out-of-scope types (use -fprint-potential-instances to see them all) • In a stmt of a 'do' block: mapM putBackLeftOverInputAndReturnOutput undefined |