Bad error message `No hackage.haskell.org repository` for legacy `remote-repo` entry in the cabal configuration

[andreasabel]

It would be good if the help texts contained some example uses.
I fail to discover how to invoke cabal-plan to get my license report.

This is what I tried:

$ cabal install -f license-report cabal-plan
...

$ cabal-plan --version
cabal-plan 0.7.2.0

$ cabal-plan license-report --help
Usage: cabal-plan license-report [--licensedir DIR] PATTERN
  Generate license report for a component

Available options:
  --licensedir DIR         Write per-package license documents to folder
  PATTERN                  Pattern to match.
  -h,--help                Show this help text

$ cabal-plan license-report Agda:exe:agda
cabal-plan: user error (No hackage.haskell.org repository)

$ ping hackage.haskell.org
PING ...: 56 data bytes
64 bytes from ... icmp_seq=0 ttl=60 time=15.678 ms

In particular, I do not understand the error No hackage.haskell.org repository and how to address it.

[andreasabel]

After some research, looking at the source code of cabal-plan(passing the safety pig ;-)), I could fix the problem by replacing in my .cabal/config

remote-repo: hackage.haskell.org:http://hackage.haskell.org/packages/archive

with

repository hackage.haskell.org
  url: http://hackage.haskell.org/

However, according to https://cabal.readthedocs.io/en/latest/installing-packages.html#legacy-repositories this is just expanding a synonym:

  remote-repo: hackage.haskell.org:http://hackage.haskell.org/packages/archive

This is just syntactic sugar for

  repository hackage.haskell.org
    url: http://hackage.haskell.org/packages/archive

although, in (and only in) the specific case of Hackage, the URL http://hackage.haskell.org/packages/archive will be silently translated to http://hackage.haskell.org/.

[nomeata]

JFTR: I just ran into this as well

[sellout]

I just ran into this, and wanted to make the workaround/fix more explicit in case anyone else still has an ancient .cabal/config around.

Basically, the remote-repo field in Cabal config files is “legacy” (read: obsolete and not well supported). To fix it, rewrite any

remote-repo: {{repository}}:{{url}}

to

repository {{repository}}
  url: {{url}}

Since providing a better error message here would basically entail parsing remote-repo anyway, it seems like it’s no harder to just support the legacy syntax. I.e., I feel like this issue should be closed, and instead, it would be nice if Cabal itself warned on legacy syntax.