Add the interleaved-output option/config value #3225

[snoyberg]

• Fixes Add flag to print GHC output to stdout #3225
• Fixes Report progress on STDOUT/STDERR during compilation of individual modules #3508

Note: Documentation fixes for https://docs.haskellstack.org/en/stable/ should target the "stable" branch, not master.

Please include the following checklist in your PR:

• Any changes that could be relevant to users have been recorded in the ChangeLog.md
• The documentation has been updated, if necessary.

Please also shortly describe how you tested your change. Bonus points for added tests!

Manual experimentation only, sorry.

[snoyberg]

Note that there are some subtle UX choices to be made in withOutputType, such as:

• Do we dump output from non-local packages? Currently, YES
• If we're just building a single package, do we still prefix output? Currently, YES

These are easy changes to make in the code, it's really a design issue. And I'd rather get the design right the first time around, so bikeshed away.

[mgsloan]

LGTM! 👍 👍

To me it seems consistent to dump output for non-local and single packages with this flag set. It would be good to have a way of suppressing such output for non-project packages, though, since the user does not have direct control over resolving errors / what is included in the output.

[nh2]

Looks good to me and works well!

I've also tested the following:

• .stack-work/install/x86_64-linux/lts-11.6/8.2.2/bin/stack --stack-root $PWD/tmpstackroot --work-dir tmpworkdir build lens --interleaved-output
• equivalent stack install
• running with 2>&1
• redirecting with tee and 2>outfile

[nh2]

I have observed it to dump to stderr instead of stdout.

[nh2]

Do we dump output from non-local packages? Currently, YES
If we're just building a single package, do we still prefix output? Currently, YES

These look like good choices to me.

[nh2]

I think you also want to update

https://github.com/commercialhaskell/stack/blob/b532cc8dc9bea7ad07aa26a608d7f877fffe75db/doc/build_command.md#build-output

the section that still says

By default, when building multiple target packages, the output from these will end up in a log file instead of on the console unless it contains errors or warnings, to avoid problems of interleaved output and decrease console noise.

For example with

Alternatively, you can pass `--interleaved-output` to see output of all packages being built scroll by in a streaming fashion.

[snoyberg]

Good catches @nh2, I think 4e6b247 should address both points. Holler if not, otherwise we can merge this once CI passes.

[buggymcbugfix]

Why does adding interleaved-output: true to my stack.yaml not work?