User-config `builddir` option is ignored

[mixphix]

Describe the bug
The cabal user-config setting builddir has no effect on the location of the output files. The command line option --builddir= works as expected.

To Reproduce
Steps to reproduce the behavior:

$ cabal --version
cabal-install version 3.10.1.0
compiled using version 3.10.1.0 of the Cabal library

$ cabal user-config diff
+ builddir: /Users/mbrown/.cabal/dist/build

$ cabal build
...

$ ls
...
dist-newstyle/
...

Expected behavior
The artifacts should not have shown up in the project directory, but rather in the directory specified in the config file.

System information

• Operating system: macOS Ventura
• ghc-9.2.7

Additional context
Persists after removing the build folder, with quotes around the file path, with environment variables...

[mixphix]

I was trying to find a way to (globally) prevent Cabal's build artifacts from syncing to iCloud, by appending .nosync to its output folder. The workaround is to make a shell function that passes this option in every time — yikes!

[ulysses4ever]

Thank you for the report! This is not supported, and it's not easy to support as discussed in #5271. There should be a warning, of course, and that's reported (although for project files) in #7941.