Peering over cabal's shoulder into dist-newstyle.

[philderbeast]

The tutorial as it stands builds with bazel. If I make it also build with stack and cabal then bazel is seen to peer over cabal's shoulder into dist-newstyle/** and not like what it sees there. No errors are reported about stuff in .stack-work/**;

tutorial> bazel build //...
ERROR: /.../rules_haskell_examples/tutorial/dist-newstyle/build/x86_64-osx/ghc-8.2.2
/tutorial-1.0.0/cache/BUILD:1:1: invalid character: ''
...
ERROR: /.../rules_haskell_examples/tutorial/dist-newstyle/build/x86_64-osx/ghc-8.2.2
/tutorial-1.0.0/cache/BUILD:5:1: name 'lib' is not defined
ERROR: error loading package 'dist-newstyle/build/x86_64-osx/ghc-8.2.2
/tutorial-1.0.0/cache': Package 'dist-newstyle/build/x86_64-osx/ghc-8.2.2
/tutorial-1.0.0/cache' contains errors
INFO: Elapsed time: 0.307s
INFO: 0 processes.
FAILED: Build did NOT complete successfully (1 packages loaded)

[philderbeast]

I have a repo with the reproduction on branch repro/dist-newstyle-10.

tutorial> stack install cabal-install
Copying from /.../.stack/snapshots/x86_64-osx/lts-11.22/8.2.2/bin/cabal to
/Users/pdejoux/dev/src/haskell/rules_haskell_examples/tutorial/__build/cabal

Copied executables to /.../rules_haskell_examples/tutorial/__build:
- cabal
tutorial> stack build
tutorial> __build/cabal new-build all
tutorial> bazel build //...
...
FAILED: Build did NOT complete successfully (1 packages loaded)

[philderbeast]

If I rename dist-newstyle to .dist-newstyle the errors are still reported.

[mboes]

Could this be because of GHC environment files? Cabal generates them by default and GHC picks them up by default. The Cabal maintainers have been asked to stop this but they're adamant. See haskell/cabal#4542

[guibou]

I think that it is due to the BUILD file inside the dist-newstyle. Bazel recursively go into subdirectories and check for BUILD files.

Does it solve the problem to add a .bazelignore file on top of the directory which contains dist-newstyle? You may need bazel 0.17.1 because that's a new feature.

[philderbeast]

@guibou the problem does seem to lie with those BUILD files.

tutorial> bazel build //...
ERROR: /.../dist-newstyle/build/x86_64-osx/ghc-8.2.2/tutorial-1.0.0/cache/BUILD:1:1: invalid character: ''
ERROR: /.../dist-newstyle/build/x86_64-osx/ghc-8.2.2/tutorial-1.0.0/cache/BUILD:1:2: invalid character: ''
...
ERROR: /.../dist-newstyle/build/x86_64-osx/ghc-8.2.2/tutorial-1.0.0/cache/BUILD:4:1: name 'lib' is not defined
ERROR: /.../dist-newstyle/build/x86_64-osx/ghc-8.2.2/tutorial-1.0.0/cache/BUILD:5:1: name 'lib' is not defined
ERROR: error loading package 'dist-newstyle/build/x86_64-osx/ghc-8.2.2/tutorial-1.0.0/cache': 
Package 'dist-newstyle/build/x86_64-osx/ghc-8.2.2/tutorial-1.0.0/cache' contains errors
INFO: Elapsed time: 0.191s
INFO: 0 processes.
FAILED: Build did NOT complete successfully (1 packages loaded)

[philderbeast]

I've added the .bazelignore but am now hitting #11 when building with bazel 0.17.2.

[guibou]

Thank you for theses reports, they are extremely valuable.

I'm closing this bug as resolved because that is not a rules_haskell issue (i.e.: presence of a cabal artefact) and bazel provides a solution in 0.17.2. Discussion will continue on #11 about the too small archive.