Peter Simons

Personally, I am rather unhappy about the current "guessing code" and would love to replace it with a more deterministic solution that chooses the appropriate `src` value based on the...

The problem is https://github.com/NixOS/cabal2nix/blob/a50090673759454fd45038bb4a4cab0831269765/src/Cabal2Nix/Generate.hs#L25. When Cabal files are compiled into a `PackageDescription`, `cabal2nix` must commit to one particular CPU, OS, and compiler version so that all those Cabal conditionals can...

The `hackage2nix` expression at https://github.com/NixOS/nixpkgs/blob/master/pkgs/development/tools/haskell/cabal2nix/hackage2nix.nix#L27-L31 uses the following code: ``` postInstall = '' exe=$out/bin/${pname} mkdir -p $out/share/bash-completion/completions $exe --bash-completion-script $exe >$out/share/bash-completion/completions/${pname} ''; ```

Well, `nix-shell` does neither compile nor install anything -- it just provides an environment in which _you_ can compile and/or install things --, thus the `postInstall` hook is never executed...

Please use any of these flags: ~~~ --enable-library-profiling enable library profiling in the generated build --enable-executable-profiling enable executable profiling in the generated build --enable-profiling enable both library and executable profiling...

I see. Sorry, I misunderstood your request at first.

The `c2hs-0.28.3` test suite still fails when built in NixOS: ~~~ [...] configuring configureFlags: --verbose --prefix=/nix/store/z72s6rgg2v2y6y6c6yknd764pq69r5wr-c2hs-0.28.3 --libdir=$prefix/lib/$compiler --libsubdir=$pkgid --datadir=/nix/store/8gc2dlcw2lk335gqm9n0x9p1d660xkfj-c2hs-0.28.3-data/share/ghc-8.0.2 --docdir=/nix/store/cbk9xxs88wricw6s6bva24nrmykdha8m-c2hs-0.28.3-doc/share/doc --with-gcc=gcc --package-db=/build/package.conf.d --ghc-option=-optl=-Wl,-rpath=/nix/store/z72s6rgg2v2y6y6c6yknd764pq69r5wr-c2hs-0.28.3/lib/ghc-8.0.2/c2hs-0.28.3 --ghc-option=-j4 --disable-split-objs --disable-library-profiling --disable-profiling --enable-shared --disable-coverage --enable-library-vanilla...

@jchia, NixOS compiles this code with GHC 6.4.0.

Unfortunately, it's not easy test these builds with GCC 7.x. It can be done, but it's very build intensive and I don't think I'll have a chance to do it....

For what it's worth, the test suite still fails in c2hs-2.8.3: [...] EDIT: [It turned out](https://github.com/haskell/c2hs/issues/192#issuecomment-388519900) that this failure is unrelated to this issue, so I moved the (large) build...