git-annex.cabal: Deal with breaking changes in Cabal 2.0

https://github.com/haskell/cabal/issues/4655

This means that when a module is conditionally imported via ifdef
depending on the OS or build flags, the cabal file has to mirror the
same logic there to only list the module then.

Since there are lots of OS's and lots of combinations of build flags
here, it's rather difficult to know if the cabal file has been completelty
correctly updated to match the source code.

So I am very unhappy with needing to update things in two places. I've
only tested this on linux with most build flags enables; this will
probably need significant time and testing to catch every cabal file
tweak that this change to Cabal requires. And it will be a continual
source of compile failures going forward when the code is modified and
the cabal file not also updated.

DRY DRY DRY, I repeat myself, but: DRY! Sigh..

(Also, had to remove all Build.* that are standalone programs from the
Other-Modules list, because since cabal passes those modules to ghc when
building git-annex, it complains that they use module Main. Those
modules are only used when building with the Makefile anyway, so this
change shouldn't break anything.)

This commit was sponsored by Thomas Hochstein on Patreon.

CHANGELOG

@@ -39,6 +39,7 @@ git-annex (6.20170521) UNRELEASED; urgency=medium
   * Fix the external special remotes git-annex-remote-ipfs, 
     git-annex-remote-torrent and the example.sh template to correctly
     support filenames with spaces.
+  * git-annex.cabal: Deal with breaking changes in Cabal 2.0.
 
  -- Joey Hess <id@joeyh.name>  Sat, 17 Jun 2017 13:02:24 -0400
 

doc/bugs/Cannot_build_with_GHC_8.2.1.mdwn

@@ -48,3 +48,4 @@ Dependency tree exhaustively searched.
 ### Have you had any luck using git-annex before? (Sometimes we get tired of reading bug reports all day and a lil' positive end note does wonders)
 Yes :)
 
+> [[fixed|done]] --[[Joey]]

doc/bugs/Cannot_build_with_GHC_8.2.1/comment_6_e948c8fcf34559808726aaa0d5f5f020._comment

@@ -0,0 +1,14 @@
+[[!comment format=mdwn
+ username="joey"
+ subject="""comment 6"""
+ date="2017-08-18T15:02:42Z"
+ content="""
+I've updated the cabal file, it should build now. Although unfortunately
+the breaking changes to cabal are such that it might still fail to build
+with some OS's and some combinations of build flags, where it used to build
+before. I only tested on Linux with stack (modified for resolver:
+nightly-2017-08-17)
+
+As to the quickcheck failures, I think that's the same problem I already
+fixed in [[!commit da8e84efe997fcbfcf489bc4fa9cc835ed131d3a]].
+"""]]

git-annex.cabal

@@ -409,30 +409,31 @@ Executable git-annex
     CPP-Options: -DWITH_ASSISTANT
 
   if flag(Assistant)
-    if os(linux)
+    if os(linux) || flag(Android)
       Build-Depends: hinotify
       CPP-Options: -DWITH_INOTIFY
+      Other-Modules: Utility.DirWatcher.INotify
     else
       if os(darwin)
         Build-Depends: hfsevents
         CPP-Options: -DWITH_FSEVENTS
+        Other-Modules: Utility.DirWatcher.FSEvents
       else
         if os(windows)
           Build-Depends: Win32-notify
           CPP-Options: -DWITH_WIN32NOTIFY
+          Other-Modules: Utility.DirWatcher.Win32Notify
         else
           if (! os(solaris) && ! os(linux))
-            if flag(Android)
-              Build-Depends: hinotify
-              CPP-Options: -DWITH_INOTIFY
-            else
-              CPP-Options: -DWITH_KQUEUE
-              C-Sources: Utility/libkqueue.c
+            CPP-Options: -DWITH_KQUEUE
+            C-Sources: Utility/libkqueue.c
+            Other-Modules: Utility.DirWatcher.Kqueue
 
   if flag(Dbus)
     if (os(linux))
       Build-Depends: dbus (>= 0.10.7), fdo-notify (>= 0.3)
       CPP-Options: -DWITH_DBUS -DWITH_DESKTOP_NOTIFY -DWITH_DBUS_NOTIFICATIONS
+      Other-Modules: Utility.DBus
 
   if flag(Android)
     Build-Depends: data-endian
@@ -481,6 +482,7 @@ Executable git-annex
   if flag(Benchmark)
     Build-Depends: criterion, deepseq
     CPP-Options: -DWITH_BENCHMARK
+    Other-Modules: Command.Benchmark
 
   Other-Modules:
     Annex
@@ -651,20 +653,10 @@ Executable git-annex
     Backend.URL
     Backend.Utilities
     Backend.WORM
-    Build.BuildVersion
     Build.BundledPrograms
     Build.Configure
     Build.DesktopFile
-    Build.DistributionUpdate
-    Build.EvilLinker
-    Build.EvilSplicer
-    Build.InstallDesktopFile
-    Build.LinuxMkLibs
-    Build.MakeMans
     Build.Mans
-    Build.NullSoftInstaller
-    Build.OSXMkLibs
-    Build.Standalone
     Build.TestConfig
     Build.Version
     BuildInfo
@@ -687,7 +679,6 @@ Executable git-annex
     Command.AddUrl
     Command.Adjust
     Command.Assistant
-    Command.Benchmark
     Command.CalcKey
     Command.CheckPresentKey
     Command.Commit
@@ -984,16 +975,11 @@ Executable git-annex
     Utility.Bloom
     Utility.CoProcess
     Utility.CopyFile
-    Utility.DBus
     Utility.Daemon
     Utility.Data
     Utility.DataUnits
     Utility.DirWatcher
-    Utility.DirWatcher.FSEvents
-    Utility.DirWatcher.INotify
-    Utility.DirWatcher.Kqueue
     Utility.DirWatcher.Types
-    Utility.DirWatcher.Win32Notify
     Utility.Directory
     Utility.DiskFree
     Utility.Dot
@@ -1016,14 +1002,10 @@ Executable git-annex
     Utility.LockFile
     Utility.LockFile.LockStatus
     Utility.LockFile.PidLock
-    Utility.LockFile.Posix
-    Utility.LockFile.Windows
     Utility.LockPool
     Utility.LockPool.LockHandle
     Utility.LockPool.PidLock
-    Utility.LockPool.Posix
     Utility.LockPool.STM
-    Utility.LockPool.Windows
     Utility.LogFile
     Utility.Lsof
     Utility.MagicWormhole
@@ -1070,5 +1052,14 @@ Executable git-annex
     Utility.UserInfo
     Utility.Verifiable
     Utility.WebApp
-    Utility.WinProcess
     Utility.Yesod
+
+  if (os(windows))
+    Other-Modules:
+      Utility.LockFile.Windows
+      Utility.LockPool.Windows
+      Utility.WinProcess
+  else
+    Other-Modules:
+      Utility.LockFile.Posix
+      Utility.LockPool.Posix