Invoking TH in another module triggers error about unknown _closure symbol

[leftaroundabout]

With GHC-HEAD (ghc-8.3.20170622) and haddock-ghc-HEAD 7cecbd9, I get

Resolving dependencies...
Configuring dumb-cas-0.1.0.0...
Preprocessing library for dumb-cas-0.1.0.0..
Running Haddock on library for dumb-cas-0.1.0.0..
Warning: The documentation for the following packages are not installed. No
links will be generated to these packages: array-0.5.1.2, base-4.10.0.0,
containers-0.5.10.2, deepseq-1.4.3.0, ghc-boot-th-8.3, ghc-prim-0.5.0.0,
integer-gmp-1.0.0.1, pretty-1.1.3.3, template-haskell-2.12.0.0
Haddock coverage:
   0% (  0 /  2) in 'CAS.Dumb.Util.These'
  Missing documentation for:
    Module header
    tuc (CAS/Dumb/Util/These.hs:3)
   0% (  0 /  4) in 'CAS.Dumb.Tree'
  Missing documentation for:
    Module header
    CAS (CAS/Dumb/Tree.hs:5)
    Ept (CAS/Dumb/Tree.hs:6)
    mp (CAS/Dumb/Tree.hs:8)
   0% (  0 /  2) in 'CAS.Dumb.Symbols.PatternGenerator'
  Missing documentation for:
    Module header
    templateFoo (CAS/Dumb/Symbols/PatternGenerator.hs:7)
haddock-2.17.3: /tmp/ghc18584_0/ghc_4.o: unknown symbol `dumbzmcaszm0zi1zi0zi0zm1ivh3qQbBmg3Azz8f9IvUmT_CASziDumbziUtilziThese_tuc_closure'

When trying to get the documentation for
https://github.com/leftaroundabout/dumb-cas/tree/haddock-bug/example-reduce/CAS/Dumb

module CAS.Dumb.Tree where
import CAS.Dumb.Util.These
mp :: Maybe (Int, ())
mp = tuc

module CAS.Dumb.Util.These where
tuc :: t (k, a)
tuc = undefined

{-# LANGUAGE TemplateHaskell       #-}
module CAS.Dumb.Symbols.ASCII () where
import CAS.Dumb.Tree
import CAS.Dumb.Symbols.PatternGenerator
type EP g = Bool
templateFoo ''EP ['A'..'Z']

module CAS.Dumb.Symbols.PatternGenerator where
import CAS.Dumb.Tree
import Language.Haskell.TH
templateFoo :: Name -> [Char] -> DecsQ
templateFoo _ _ = return []

The problem seems to be specific to this particular imports topology.

Issue does not occur with haddock-2.16.1 on ghc-7.10.2. I have not checked any versions of GHC or haddock in between.

[alexbiehl]

@leftaroundabout Thanks for the report! This is certainly a duplicate of #640. Now ghc/ghc@d55bea1 should have fixed this. Pinging @duog, maybe he knows what is going on.

[leftaroundabout]

Unfortunately the problem remains also with ghc-8.3.20170706.

$ haddock-2.17.3 --ghc-version
8.3.20170706
$ cabal haddock --with-haddock haddock-2.17.3
Resolving dependencies...
Configuring dumb-cas-0.1.0.0...
Preprocessing library for dumb-cas-0.1.0.0..
Running Haddock on library for dumb-cas-0.1.0.0..
Warning: The documentation for the following packages are not installed. No
links will be generated to these packages: array-0.5.1.2, base-4.10.0.0,
containers-0.5.10.2, deepseq-1.4.3.0, ghc-boot-th-8.3, ghc-prim-0.5.0.0,
integer-gmp-1.0.0.1, pretty-1.1.3.3, template-haskell-2.12.0.0
Haddock coverage:
   0% (  0 /  2) in 'CAS.Dumb.Util.These'
  Missing documentation for:
    Module header
    tuc (CAS/Dumb/Util/These.hs:3)
   0% (  0 /  2) in 'CAS.Dumb.Tree'
  Missing documentation for:
    Module header
    mp (CAS/Dumb/Tree.hs:5)
   0% (  0 /  2) in 'CAS.Dumb.Symbols.PatternGenerator'
  Missing documentation for:
    Module header
    templateFoo (CAS/Dumb/Symbols/PatternGenerator.hs:7)
haddock-2.17.3: /tmp/ghc27181_0/ghc_4.o: unknown symbol `dumbzmcaszm0zi1zi0zi0zm1ivh3qQbBmg3Azz8f9IvUmT_CASziDumbziUtilziThese_tuc_closure'

[duog]

Thanks for the reproduction @leftaroundabout, do you mind if I add this to ghc as a test case?

I'll try to fix this in the next couple of days, in the meantime you could perhaps workaround by enabling TemplateHaskell in every module. You could do this by passing -optghc=-XTemplateHaskell to haddock.

[duog]

I believe I've fixed this: patch

[alexbiehl]

@leftaroundabout please try again with current GHC HEAD, duogs patch has landed.

[leftaroundabout]

Yes! I've run straight into the next issue, but this one is solved...

[leftaroundabout]

Thanks for the quick fix, @duog.