Source: haskell-vector Version: 0.11.0.0-7 Severity: serious I can reproduce this on amd64:
https://buildd.debian.org/status/fetch.php?pkg=haskell-vector&arch=armhf&ver=0.11.0.0-7%2Bb1&stamp=1499645095&raw=0 ... [1 of 6] Compiling Utilities ( tests/Utilities.hs, dist-ghc/build/vector-tests-O0/vector-tests-O0-tmp/Utilities.o ) tests/Utilities.hs:54:10: error: Duplicate instance declarations: instance Arbitrary a => Arbitrary (Identity a) -- Defined at tests/Utilities.hs:54:10 instance [safe] Arbitrary a => Arbitrary (Identity a) -- Defined in `Test.QuickCheck.Arbitrary' tests/Utilities.hs:57:10: error: Duplicate instance declarations: instance CoArbitrary a => CoArbitrary (Identity a) -- Defined at tests/Utilities.hs:57:10 instance [safe] CoArbitrary a => CoArbitrary (Identity a) -- Defined in `Test.QuickCheck.Arbitrary' /usr/share/cdbs/1/class/hlibrary.mk:147: recipe for target 'build-ghc-stamp' failed make: *** [build-ghc-stamp] Error 1
