Cannot do cabal 3.0 build for 8.6.5

[jarcane]

Trying to install cabal-hie-8.6.5 gives me the following error instead:

Warning: Failed to build documentation for haddock-api-2.22.0 (which is
required by test:wrapper-test from haskell-ide-engine-0.9.0.0, test:unit-test
from haskell-ide-engine-0.9.0.0 and others).
# stack (for cabal-hie-8.6.5)
# cabal (for cabal-hie-8.6.5)
cabal: unrecognized 'new-install' option
`--symlink-bindir=/home/annaia/.local/bin'
Error when running Shake build system:
  at src/Development/Shake/Internal/Args.hs:81:69-79:
* Depends on: cabal-hie-8.6.5
* Raised the exception:
user error (Development.Shake.command_, system command failed
Command: cabal new-install --write-ghc-environment-files=never --symlink-bindir=/home/annaia/.local/bin exe:hie --overwrite-policy=always
Exit code: 1
Stderr:
cabal: unrecognized 'new-install' option
`--symlink-bindir=/home/annaia/.local/bin'
)

I have ghc-8.6.5 and cabal 3.0 installed locally so I'm presuming this is because somehow the stack temp cabal isn't the right version?

Anyway to fix this or is there something I'm missing?

[nponeccop]

Apparently cabal 3 doesn't recognize the new-build option:

cabal: unrecognized 'new-install' option

This can be fixed by several means:

• Installing the right cabal-install privately and using it in install.hs
• Warning the user from install.hs that cabal-install is too new
• Supporting cabal 3 builds

A short term solution is to put cabal-install 2.x into PATH. Note that projects built with cabal 3 won't work with HIE either, so there's no reason to trying to build it with cabal 3 because it will break later.

[lukel97]

Does cabal 3.0 support cabal v2-build?

[fendor]

Is that already the release that drops the old-style builds?
cc @power-fungus

[alanz]

Has cabal 3.0 been released yet?

[nponeccop]

Has cabal 3.0 been released yet?

No. However:

• We do build against GHC-nightly
• We'll need to support it when it's out
• Having a version check is a good idea to prevent breakage. We do check stack for example.

[alanz]

@nponeccop we build against stackage nightly, not ghc nightly.

And we have a number of dependencies, that are intricately tied to the environment. So I would not expect a new cabal to just work, without updates to cabal-helper and ghc-mod at the very least.

[nponeccop]

@nponeccop we build against stackage nightly, not ghc nightly.
oh, my bad. I saw ghc-nightly in .circleci and thought it's against GHC HEAD built by someone else (which is not a bad idea)

[alanz]

I think this should be closed, as wontfix?

[fendor]

I think this should be addressed soonish. Would be the fix to just use cabal v2-build, to ensure backwards and forwards compatibility?

[mpickering]

I think using v2-build is an easy way to fix this?

[fendor]

Actually, the problem seems to be:

cabal: unrecognized 'new-install' option `--symlink-bindir=/home/annaia/.local/bin'

Which seems to be replaced by --installdir

[fendor]

This problem is becoming more urgent. The fix, per se, is simple, just check for the version string, before using v2-install.
However, the question arises what version range we aim to support.