v1.6.0.20171022

This is a pre-release for testing

Changes since v1.5.1

Major changes:

• Complete overhaul of how snapshots are defined, the packages and
  extra-deps fields, and a number of related items. For full
  details, please see
  the writeup on these changes. PR #3249,
  see the PR description for a number of related issues.
• Upgraded to version 2.0 of the Cabal library.

Behavior changes:

• The --install-ghc flag is now on by default. For example, if you
  run stack build in a directory requiring a GHC that you do not
  currently have, Stack will automatically download and install that
  GHC. You can explicitly set install-ghc: false or pass the flag
  --no-install-ghc to regain the previous behavior.
• stack ghci no longer loads modules grouped by package. This is
  always an improvement for plain ghci - it makes loading faster and
  less noisy. For intero, this has the side-effect that it will no
  longer load multiple packages that depend on TH loading relative
  paths. TH relative paths will still work when loading a single
  package into intero. See
  #3309
• Setting GHC options for a package via ghc-options: in your
  stack.yaml will promote it to a local package, providing for more
  consistency with flags and better reproducibility. See:
  #849
• Options passsed via --ghci-options are now passed to the end of the
  invocation of ghci, instead of the middle. This allows using +RTS
  without an accompanying -RTS.
• When auto-detecting --ghc-build, tinfo6 is now preferred over
  standard if both versions of libtinfo are installed
• Addition of stack build --copy-compiler-tool, to allow tools like
  intero to be installed globally for a particular compiler.
  #2643
• Stack will now try to detect the width of the running terminal
  (only on POSIX for the moment) and use that to better display
  output messages. Work is ongoing, so some messages will not
  be optimal yet. The terminal width can be overriden with the
  new --terminal-width command-line option (this works even on
  non-POSIX).
• Stack will ask before saving hackage credentials to file. This new
  prompt can be avoided by using the save-hackage-creds setting. Please
  see #2159.

Other enhancements:

• The with-hpack configuration option specifies an Hpack executable to use
  instead of the Hpack bundled with Stack. Please
  see #3179.
• It's now possible to skip tests and benchmarks using --skip
  flag
• GitSHA1 is now StaticSHA256 and is implemented using the StaticSize 64 ByteString for improved performance.
  See #3006
• Dependencies via HTTP(S) archives have been generalized to allow
  local file path archives, as well as to support setting a
  cryptographic hash (SHA256) of the contents for better
  reproducibility.
• Allow specifying --git-branch when upgrading
• When running stack upgrade from a file which is different from the
  default executable path (e.g., on POSIX systems,
  ~/.local/bin/stack), it will now additionally copy the new
  executable over the currently running stack executable. If
  permission is denied (such as in /usr/local/bin/stack), the user
  will be prompted to try again using sudo. This is intended to
  assist with the user experience when the PATH environment variable
  has not been properly configured, see
  #3232.
• stack setup for ghcjs will now install alex and happy if
  they are not present. See
  #3109.
• --ghc-options and --ghcjs-boot-options now parse their input, so
  multiple arguments can be passed in one option.
  See #3315
• Added stack ghci --only-main flag, to skip loading / importing
  all but main modules. See the ghci documentation page
  for further info.
• Allow GHC's colored output to show through. GHC colors output
  starting with version 8.2.1, for older GHC this does nothing.
  Sometimes GHC's heuristics would work fine even before this change,
  for example in stack ghci, but this override's GHC's heuristics
  when they're broken by our collecting and processing GHC's output.
• Extended the ghc-options field to support $locals, $targets,
  and $everything. See:
  #3329
• Better error message for case that stack ghci file targets are
  combined with invalid package targets. See:
  #3342
• For profiling now uses -fprof-auto -fprof-cafs instead of
  the deprecated -auto-all -caf-all. See:
  #3360
• Better descriptions are now available for stack upgrade --help. See:
  #3070
• When using Nix, nix-shell now depends always on gcc to prevent build errors
  when using the FFI. As ghc depends on gcc anyway, this doesn't increase the
  dependency footprint.
• --cwd DIR can now be passed to stack exec in order to execute the
  program in a different directory. See:
  #3264

Bug fixes:

• stack hoogle correctly generates Hoogle databases. See:
  #3362
• stack --docker-help is now clearer about --docker implying
  system-ghc: true, rather than both --docker and --no-docker.
• stack haddock now includes package names for all modules in the
  Haddock index page. See:
  #2886
• Fixed an issue where Stack wouldn't detect missing Docker images
  properly with newer Docker versions.
  #3171
• Previously, cabal files with just test-suite could cause build to fail
  (#2862)
• If an invalid snapshot file has been detected (usually due to
  mismatched hashes), Stack will delete the downloaded file and
  recommend either retrying or filing an issue upstream. See
  #3319.
• Modified the flag parser within Stack to match the behavior of
  Cabal's flag parser, which allows multiple sequential dashes. See
  #3345
• Now clears the hackage index cache if it is older than the
  downloaded index. Fixes potential issue if stack was interrupted when
  updating index.
  See #3033
• The Stack install script now respects the -d option.
  See #3366.
• stack script can now handle relative paths to source files.
  See #3372.
• Fixes explanation of why a target is needed by the build plan, when the
  target is an extra dependency from the commandline.
  See #3378.
• Previously, if you delete a yaml file from ~/.stack/build-plan, it would
  trust the etag and not re-download. Fixed in this version.
• Invoking stack --docker in parallel now correctly locks the sqlite database.
  See #3400.
• docs.haskellstack.org RTD documentation search is replaced by the mkdocs
  search. Please see
  #3376.
• stack clean now works with nix. See
  #3468.
• stack build --only-dependencies no longer builds local project packages
  that are depended on. See
  #3476.
• Properly handle relative paths stored in the precompiled cache files. See
  #3431.
• In some cases, Cabal does not realize that it needs to reconfigure, and must
  be told to do so automatically. This would manifest as a "shadowed
  dependency" error message. We now force a reconfigure whenever a dependency is
  built, even if the package ID remained the same. See
  #2781.