[darcs-users] upcoming darcs 2.8.4: ghc 7.6 support

[Benjamin Franksen]

Ganesh Sittampalam wrote:
> It seems pressure is growing for darcs 2.8 to support GHC 7.6 - a few
> people have asked about it on IRC and at least one distro has patched
> things themselves.
> 
> I've pushed the patches to the 2.8 repo
> (http://darcs.net/releases/branch-2.8/). The changes aren't entirely
> trivial, but I'm reasonably confident they work.

I had a problem building the 2.8 branch with ghc-6.12.3. The build (cabal 
install -f-library) chose haskeline-0.6.4.7 which fails to install with 
ghc-6.12.3:

[...]
[18 of 27] Compiling System.Console.Haskeline.Backend.Terminfo ( 
System/Console/Haskeline/Backend/Terminfo.hs, 
dist/build/System/Console/Haskeline/Backend/Terminfo.o )

System/Console/Haskeline/Backend/Terminfo.hs:200:9:
    Inferred type is less polymorphic than expected
      Quantified type variable `m' escapes
    In the expression: Writer.tell
    In the definition of `output': output = Writer.tell
cabal: Error: some packages failed to install:
darcs-2.8.3 depends on haskeline-0.6.4.7 which failed to install.
haskeline-0.6.4.7 failed during the building phase.

The build succeeds if I make this change:

franksen at aragon:~/ctl/tools/darcs/branch-2.8-issue2199 > darcs whatsnew
hunk ./darcs.cabal 630
+  if impl(ghc<7.4)
+    build-depends:    haskeline    <= 0.6.3.2
+

(this is in the executable section, something similar will be needed for the 
library part)

haskeline-0.6.3.2 is the latest version on hackage that claims to have been 
successfully built with ghc-6.12.3. I have not checked building with later 
versions.

Cheers
-- 
Ben Franksen
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