Regression: no output during build step for Cabal scripts in 3.8

[georgefst]

I don't see anything about this in the changelog.

Main.hs:

{- cabal:
build-depends: base
-}

module Main where

main = putStrLn "done"

$ cabal-3.6.2.0 run Main.hs
Resolving dependencies...
Build profile: -w ghc-9.2.3 -O1
In order, the following will be built (use -v for more details):
 - fake-package-0 (exe:script) (first run)
Configuring executable 'script' for fake-package-0..
Preprocessing executable 'script' for fake-package-0..
Building executable 'script' for fake-package-0..
[1 of 1] Compiling Main             ( Main.hs, /tmp/cabal-repl.-223388/dist-newstyle/build/x86_64-linux/ghc-9.2.3/fake-package-0/x/script/build/script/script-tmp/Main.o )
Linking /tmp/cabal-repl.-223388/dist-newstyle/build/x86_64-linux/ghc-9.2.3/fake-package-0/x/script/build/script/script ...
done

$ cabal-3.8.1.0 run Main.hs
done

This is great when nothing needs to be rebuilt (an impossible scenario before 3.8, as nothing was cached). And we do see some output if building fails. But I'd argue that it's very confusing not to see any during a successful build either. At least in the case where significant building of dependencies is necessary, it's impossible to know whether the script is hanging at run time, or useful work is being done.

It seems to me that the ideal behaviour would be for any output from the build step to go to stderr by default, perhaps with flags to alter behaviour.

[jneira]

hi, do you see the expected behaviour with -v or -v2?
I think the build output was removed by default as it interfered with the output of the script itself, making its use more difficult

[georgefst]

Ah, thanks. -v1 is enough to see the output.

I'm not sure what the best UX is here. I feel like it would be less surprising if the build output were printed by default, with a message about how to disable it. But we'd want the ability to specify -v0 for Cabal from within the script, and AFAIK this isn't currently possible.

[georgefst]

It seems to me that the ideal behaviour would be for any output from the build step to go to stderr by default, perhaps with flags to alter behaviour.

#7790 would be a big step in the right direction.

[ulysses4ever]

Just 2c: I think it's fine for cabal run to not print anything by default, and if you're interested in what happens at the build stage, you should rather use cabal build. Switching from stdout to stderr, albeit a noble goal, is neither close (for boring technical reasons, especially the test suite) nor strictly speaking related to this discussion whether we want any output at all.

[georgefst]

I admittedly am not sure I'm familiar with your "boring technical reasons", but I think not printing anything would be (and in the case of scripts, is) pretty poor UX. A user wants to know what's going on when a process doesn't respond instantly.