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POOverride -Werror when installing from Cabal
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  1. POOverride -Werror when installing from Cabal
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    copied!<p>I'm trying to install the <a href="http://hackage.haskell.org/package/nano-hmac-0.2.0" rel="noreferrer">nano-hmac-0.2.0</a> package (a dependency of a package I want) from Hackage using Cabal and GHC 6.12.1, but it fails with the following error:</p> <pre><code>Data/Digest/OpenSSL/HMAC.hsc:1:0: Warning: Module `Prelude' is deprecated: You are using the old package `base' version 3.x. Future GHC versions will not support base version 3.x. You should update your code to use the new base version 4.x. &lt;no location info&gt;: Failing due to -Werror. </code></pre> <p>Sure enough, the package's .cabal file has the following line in it:</p> <pre><code> ghc-options: -Wall -Werror -O2 -fvia-C </code></pre> <p>I'd like to be able to override the <code>-Werror</code> option so I can install the package without manually modifying the .cabal file, but can't find a way that will work. In particular, I tried passing <code>--ghc-options</code> to Cabal to stick a <code>-Wwarn</code> in GHC's argument list, like this:</p> <pre><code>$ cabal install nano-hmac-0.2.0 -v2 --ghc-options='-Wwarn' </code></pre> <p>This doesn't do what I want, though; the verbose output verifies that <code>-Wwarn</code> is getting added to the beginning of GHC's argument list, but the <code>-Werror</code> from the .cabal file appears later and seems to override it:</p> <pre><code>/usr/bin/ghc -Wwarn --make -package-name nano-hmac-0.2.0 -hide-all-packages -fbuilding-cabal-package -i -idist/build -i. -idist/build/autogen -Idist/build/autogen -Idist/build -optP-include -optPdist/build/autogen/cabal_macros.h -odir dist/build -hidir dist/build -stubdir dist/build -package-id base-3.0.3.2-0092f5a086872e0cdaf979254933cd43 -package-id bytestring-0.9.1.5-125aff5b9d19ec30231ae2684b8c8577 -O -Wall -Werror -O2 -fvia-C -XForeignFunctionInterface -XBangPatterns -XCPP Data.Digest.OpenSSL.HMAC </code></pre> <p>I also tried passing <code>--constraint='base &gt;= 4'</code> to Cabal to force it to use a more recent version of base and avoid the warning entirely, but I get the same failure, and I still see the following in the verbose output:</p> <pre><code>Dependency base ==3.0.3.2: using base-3.0.3.2 </code></pre> <p>Is there a way to get rid of or override the <code>-Werror</code> coming from the .cabal file via the Cabal command line, or am I stuck modifying the .cabal file myself?</p>
 

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