Warning: The install command is a part of the legacy v1 style of cabal usage.

Please switch to using either the new project style and the new-install
command or the legacy v1-install alias as new-style projects will become the
default in the next version of cabal-install. Please file a bug if you cannot
replicate a working v1- use case with the new-style commands.

For more information, see: https://wiki.haskell.org/Cabal/NewBuild

Resolving dependencies...
Starting     Diff-0.4.0
Starting     colour-2.3.5
Starting     transformers-compat-0.6.5
Starting     base-compat-0.10.5
Building     Diff-0.4.0
Building     colour-2.3.5
Building     transformers-compat-0.6.5
Building     base-compat-0.10.5
Completed    Diff-0.4.0
Starting     unix-compat-0.5.2
Building     unix-compat-0.5.2
Completed    transformers-compat-0.6.5
Completed    unix-compat-0.5.2
Completed    base-compat-0.10.5
Completed    colour-2.3.5
Starting     ansi-terminal-0.10.2
Building     ansi-terminal-0.10.2
Completed    ansi-terminal-0.10.2
Starting     ansi-wl-pprint-0.6.9
Building     ansi-wl-pprint-0.6.9
Completed    ansi-wl-pprint-0.6.9
Starting     optparse-applicative-0.14.3.0
Building     optparse-applicative-0.14.3.0
Completed    optparse-applicative-0.14.3.0
Starting     git-mediate-1.0.6
Building     git-mediate-1.0.6
Failed to install git-mediate-1.0.6
Build log ( /home/builder/.cabal/logs/ghc-8.6.3/git-mediate-1.0.6-Bri7UHwery34gTB1n5nPde.log ):
cabal: Entering directory '/tmp/cabal-tmp-22187/git-mediate-1.0.6'
Configuring git-mediate-1.0.6...
Preprocessing executable 'git-mediate' for git-mediate-1.0.6..
Building executable 'git-mediate' for git-mediate-1.0.6..
[ 1 of 10] Compiling Conflict         ( src/Conflict.hs, dist/build/git-mediate/git-mediate-tmp/Conflict.o )
[ 2 of 10] Compiling PPDiff           ( src/PPDiff.hs, dist/build/git-mediate/git-mediate-tmp/PPDiff.o )

src/PPDiff.hs:16:11: error:
    Not in scope: data constructor ‘First’
    Perhaps you want to add ‘First’ to the import list in the import of
    ‘Data.Algorithm.Diff’ (src/PPDiff.hs:6:1-37).
   |
16 | ppDiff c (First x)  = wrap c Red   $ '-':x
   |           ^^^^^

src/PPDiff.hs:17:11: error:
    Not in scope: data constructor ‘Second’
    Perhaps you want to add ‘Second’ to the import list
    in the import of ‘Data.Algorithm.Diff’ (src/PPDiff.hs:6:1-37).
   |
17 | ppDiff c (Second x) = wrap c Green $ '+':x
   |           ^^^^^^

src/PPDiff.hs:18:11: error:
    Not in scope: data constructor ‘Both’
    Perhaps you want to add ‘Both’ to the import list in the import of
    ‘Data.Algorithm.Diff’ (src/PPDiff.hs:6:1-37).
   |
18 | ppDiff _ (Both x _) =                ' ':x
   |           ^^^^
cabal: Leaving directory '/tmp/cabal-tmp-22187/git-mediate-1.0.6'
cabal: Error: some packages failed to install:
git-mediate-1.0.6-Bri7UHwery34gTB1n5nPde failed during the building phase. The
exception was:
ExitFailure 1