Resolving dependencies...
Configuring mtl-2.2.1...
Building mtl-2.2.1...
Installed mtl-2.2.1
Configuring regex-base-0.93.2...
Building regex-base-0.93.2...
Installed regex-base-0.93.2
Configuring regex-tre-0.91...
Building regex-tre-0.91...
Failed to install regex-tre-0.91
Build log ( /home/builder/.cabal/logs/regex-tre-0.91.log ):
cabal: Entering directory '/tmp/cabal-tmp-31428/regex-tre-0.91'
[1 of 1] Compiling Main             ( /tmp/cabal-tmp-31428/regex-tre-0.91/dist/setup/setup.hs, /tmp/cabal-tmp-31428/regex-tre-0.91/dist/setup/Main.o )
Linking /tmp/cabal-tmp-31428/regex-tre-0.91/dist/setup/setup ...
regex-tre needs to compile against the libtre libary from http://laurikari.net/tre/
You might also need to edit the end of the regex-tre.cabal file to point at
the directories where libtre 'include' and 'lib' have been installed.

Configuring regex-tre-0.91...
Warning: No 'build-type' specified. If you do not need a custom Setup.hs or
./configure script then use 'build-type: Simple'.
regex-tre needs to compile against the libtre libary from http://laurikari.net/tre/
You might also need to edit the end of the regex-tre.cabal file to point at
the directories where libtre 'include' and 'lib' have been installed.

Building regex-tre-0.91...
Preprocessing library regex-tre-0.91...

Text/Regex/TRE/Wrap.hsc:1:16: warning:
    -fglasgow-exts is deprecated: Use individual extensions instead

Text/Regex/TRE/Wrap.hsc:1:16: warning:
    -fffi is deprecated: use -XForeignFunctionInterface or pragma {-# LANGUAGE ForeignFunctionInterface #-} instead

<no location info>: error: 
Failing due to -Werror.
cabal: Leaving directory '/tmp/cabal-tmp-31428/regex-tre-0.91'
cabal: Error: some packages failed to install:
regex-tre-0.91 failed during the building phase. The exception was:
ExitFailure 1