clashi doesn't load plugins correctly

[leonschoorl]

clashi should load and use our typechecker plugins automatically, but:

Clash.Prelude> pack (1 :: Index 3)

<interactive>:3:1: error:
    • No instance for (KnownNat (CLog 2 3))

(This should be solved by the combination of GHC.TypeLits.Extra.Solver and GHC.TypeLits.KnownNat.Solver)

Also clashi seems to ignore the -fplugin option:

$ cabal run -- clashi  -fplugin=PluginMissing
Clashi, version 0.9999 (using clash-lib, version 0.9999):
http://www.clash-lang.org/  :? for help
Clash.Prelude>

But do the same with ghci and it will try to load the plugin and error out:

$ ghci  -fplugin=PluginMissing
GHCi, version 8.6.5: http://www.haskell.org/ghc/  :? for help
<command line>: Could not find module ‘PluginMissing’
Use -v to see a list of the files searched for.

[leonschoorl]

I think clashi is ignoring plugins in its interactive session, and only uses them in the session used on files.
Because if we give clashi an input file it will complain about the MissingPlugin:

$ cabal run -- clashi  -fplugin=PluginMissing Pack.hs
...
Could not find module ‘PluginMissing’
Use -v to see a list of the files searched for.

[leonschoorl]

This is only an problem with GHC-8.6.
We're missing https://gitlab.haskell.org/ghc/ghc/commit/599eaada382d04722219bfc319bde94591be3fb1