Hi I am trying to write criterion benchmarks for the pretty library. Unfortunately, building the benchmark executable fails at some point during the development with the following error message: ---8<--- <command line>: cannot satisfy -package-id pretty-1.1.1.1-inplace: pretty-1.1.1.1-inplace is shadowed by package pretty-1.1.1.1-7bd0114e9691fca3d3447fc0133701cf --->8--- I don't understand the cause of the error, let alone what I am supposed to do next. Any help is much appreciated. Here are the steps that lead to the above quoted error. Sorry, if this is not the smallest counter example possible. As I said, I hardly understand what is going on. (the two patch files mentioned are attached to this email, virthualenv is version 0.2.1) ---8<--- git clone https://github.com/haskell/pretty.git cd pretty git apply /tmp/0001-hello-world-setup.patch export PATH=/opt/ghc-7.4.2/install/bin:/opt/haskell-platform-2012.4.0.0/install/bin:$PATH ~/.cabal/bin/virthualenv source .virthualenv/bin/activate cabal configure --user cabal build cabal install cabal install criterion cabal configure --user --enable-benchmarks cabal build git apply /tmp/0002-replaced-example-with-real-benchmark.patch cabal install language-c cabal configure --user --enable-benchmarks cabal build # error --->8--- So the first build of the benchmark executable works, but the second one "suddenly" fails. Executing "cabal build -v" next yields ---8<--- $ cabal build -v creating dist/build creating dist/build/autogen Building pretty-1.1.1.1... Preprocessing library pretty-1.1.1.1... Building library... creating dist/build /opt/ghc-7.4.2/install/bin/ghc --make -package-name pretty-1.1.1.1 -hide-all-packages -fbuilding-cabal-package -package-conf /home/alex/tmp/pretty/.virthualenv/ghc_pkg_db -i -idist/build -isrc -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-4.5.1.0-66f22db3dfcd87541c9c7e50e7095d26 -O -Wall -fwarn-tabs -XHaskell98 -XCPP -XBangPatterns Text.PrettyPrint Text.PrettyPrint.HughesPJ Linking... /usr/bin/ar -r dist/build/libHSpretty-1.1.1.1.a dist/build/Text/PrettyPrint.o dist/build/Text/PrettyPrint/HughesPJ.o /usr/bin/ar: creating dist/build/libHSpretty-1.1.1.1.a /usr/bin/ld -x --hash-size=31 --reduce-memory-overheads -r -o dist/build/HSpretty-1.1.1.1.o dist/build/Text/PrettyPrint.o dist/build/Text/PrettyPrint/HughesPJ.o Registering pretty-1.1.1.1... /opt/ghc-7.4.2/install/bin/ghc-pkg update - --global --user --package-conf=/home/alex/tmp/pretty/.virthualenv/ghc_pkg_db --package-conf=dist/package.conf.inplace Preprocessing benchmark 'bench-pretty' for pretty-1.1.1.1... Building benchmark bench-pretty... creating dist/build/bench-pretty creating dist/build/bench-pretty/bench-pretty-tmp /opt/ghc-7.4.2/install/bin/ghc --make -o dist/build/bench-pretty/bench-pretty -hide-all-packages -fbuilding-cabal-package -package-conf /home/alex/tmp/pretty/.virthualenv/ghc_pkg_db -package-conf dist/package.conf.inplace -i -idist/build/bench-pretty/bench-pretty-tmp -ibench -idist/build/autogen -Idist/build/autogen -Idist/build/bench-pretty/bench-pretty-tmp -optP-include -optPdist/build/autogen/cabal_macros.h -odir dist/build/bench-pretty/bench-pretty-tmp -hidir dist/build/bench-pretty/bench-pretty-tmp -stubdir dist/build/bench-pretty/bench-pretty-tmp -package-id base-4.5.1.0-66f22db3dfcd87541c9c7e50e7095d26 -package-id criterion-0.6.2.1-5ae981935ea0c9773e0df464b5922b27 -package-id language-c-0.4.2-fe58279e43af097994ce7b7010785c69 -package-id pretty-1.1.1.1-inplace -O -O -XHaskell98 bench/Bench.hs <command line>: cannot satisfy -package-id pretty-1.1.1.1-inplace: pretty-1.1.1.1-inplace is shadowed by package pretty-1.1.1.1-7bd0114e9691fca3d3447fc0133701cf (use -v for more information) --->8--- What does this mean? What am I doing wrong? How can I fix this? Greetings, Alex