Release 0.8

[0.8] - 2019-01-28

• The minimum supported Bazel version is now v0.21.

Added

• haskell_register_toolchains, haskell_register_ghc_bindists and
  haskell_register_ghc_nixpkgs to register multiple toolchains for
  multiple platforms at once. Toolchains from binary distributions can
  now coexist with toolchains from Nixpkgs, even on the same platform.
  On nixpkgs you need to provide a toolchain. See
  the README for instructions.
  See #597
  and #610.
• Instructions on how to reference a local checkout of rules_haskell.
• rules_haskell is forward-compatible with the next breaking changes
  in bazel versions, via the --all_incompatible_changes flag.
  See #613.

Removed

• The generate_so attribute of haskell_binary and haskell_test
  has been completely superseded by linkstatic in the last release
  and became a no-op, so it is removed.
• The main_file attribute of haskell_binary and haskell_test
  had been deprecated because it was a no-op, so it is removed.
• The prebuilt_dependencies attribute of all haskell rules
  had been deprecated two versions ago and is removed.
  Use haskell_import instead (see docs for usage).
• The extra_binaries field is now no longer supported.

Changed

• ghc_bindist now requires a target argument. Use
  haskell_register_ghc_nixpkgs to call ghc_bindist once per known
  target.
  See #610.
• ghc_bindist now registers itself as a toolchain. We no longer
  require a separate toolchain definition and registration in addition
  to ghc_bindist.
  See #610.
• c2hs support is now provided in a separate toolchain called
  c2hs_toolchain, rather than an optional extra to the
  haskell_toolchain.
  See #590.
• Rename bindist arch names so they are the same as in
  rules_go/nodejs.

Fixed

• Prevent duplicate installs of bazel_skylib
  See #536.
• Test suite now executes all binaries, various runtime errors were
  uncovered.
  See #551.
• Repl targets that have indirect cc_library dependencies.
  See #576.
• linkstatic for haskell binaries that have an indirect dependency
  on a prebuilt haskell package.
  See #569.
• … and an indirect dependency on a C library.
  See #567.
• Prefer linking agains static C libraries with linkstatic.
  See #587.
• Haddock flags take precedence over GHC compiler flags.
  See #572.
• User-defined GHC flags now override default flags.
  See #607.
• Dynamic transitive C(++) libraries work.
  See #627.