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.

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Resolving dependencies...
Starting     edit-distance-linear-0.2.0.1
Building     edit-distance-linear-0.2.0.1
Failed to install edit-distance-linear-0.2.0.1
Build log ( /home/builder/.cabal/logs/ghc-8.6.3/edit-distance-linear-0.2.0.1-IoyxOOsyf4k5MgXMPnGhBz.log ):
cabal: Entering directory '/tmp/cabal-tmp-12809/edit-distance-linear-0.2.0.1'
Configuring edit-distance-linear-0.2.0.1...
Preprocessing library for edit-distance-linear-0.2.0.1..
Building library for edit-distance-linear-0.2.0.1..

<no location info>: error:
    Warning: Couldn't figure out LLVM version!
             Make sure you have installed LLVM 6.0
[1 of 2] Compiling Paths_edit_distance_linear ( dist/build/autogen/Paths_edit_distance_linear.hs, dist/build/Paths_edit_distance_linear.o )

<no location info>: error:
    Warning: Couldn't figure out LLVM version!
             Make sure you have installed LLVM 6.0
ghc: could not execute: opt
cabal: Leaving directory '/tmp/cabal-tmp-12809/edit-distance-linear-0.2.0.1'
cabal: Error: some packages failed to install:
edit-distance-linear-0.2.0.1-IoyxOOsyf4k5MgXMPnGhBz failed during the building
phase. The exception was:
ExitFailure 1