Fix Windows build to work with ghc 7.10

It was failing at link time, some problem with terminatePID.
Re-implemented that to not use a C wrapper function, which cleared up the
problem. Removed old EvilLinker hack with must have been related to the
same problem.

Note that I have not tested this with older ghc's. In
f11f7520b5 I mention having tried this
approach before, and getting segfaults.. So, who knows. It seems to work
fine with ghc 7.10 at least.

Build/EvilLinker.hs

@@ -95,19 +95,13 @@ parseCollect2 = do
 	path <- manyTill anyChar (try $ string ldcmd)
 	void $ char ' '
 	params <- restOfLine
-	return $ CmdParams (path ++ ldcmd) (skipHack $ escapeDosPaths params) Nothing
+	return $ CmdParams (path ++ ldcmd) (escapeDosPaths params) Nothing
   where
 	ldcmd = "ld.exe"
 	versionline = do
 		void $ string "collect2 version"
 		restOfLine
 
-{- For unknown reasons, asking the linker to link this in fails,
- - with error about multiple definitions of a symbol from the library.
- - This is a horrible hack. -}
-skipHack :: String -> String
-skipHack = replace "dist/build/git-annex/git-annex-tmp/Utility/winprocess.o" ""
-
 {- Input contains something like 
  - c:/program files/haskell platform/foo -LC:/Program Files/Haskell Platform/ -L...
  - and the *right* spaces must be escaped with \

Utility/WinProcess.hs

@@ -11,5 +11,18 @@ module Utility.WinProcess where
 
 import Utility.PID
 
-foreign import ccall unsafe "terminatepid"
-	terminatePID :: PID -> IO ()
+import System.Win32.Process
+import Control.Exception (bracket)
+import Control.Monad
+
+terminatePID :: PID -> IO ()
+terminatePID p = bracket 
+	(openProcess pROCESS_TERMINATE False p)
+	(void . c_closeProcess)
+	(\h -> void $ c_TerminateProcess h 1)
+
+foreign import ccall unsafe "windows.h TerminateProcess"
+	c_TerminateProcess :: ProcessHandle -> Int -> IO Int
+
+foreign import ccall unsafe "windows.h CloseHandle"
+	c_closeProcess :: ProcessHandle -> IO Bool

Utility/winprocess.c

@@ -1,10 +0,0 @@
-#include <windows.h>
-
-void terminatepid (DWORD pid) {
-	HANDLE h;
-	h = OpenProcess(PROCESS_TERMINATE, 0, pid);
-	if (h != NULL) {
-		TerminateProcess(h, 1);
-	}
-	CloseHandle(h);
-}

debian/changelog

@@ -1,3 +1,9 @@
+git-annex (5.20150825) UNRELEASED; urgency=medium
+
+  * Fix Windows build to work with ghc 7.10.
+
+ -- Joey Hess <id@joeyh.name>  Tue, 01 Sep 2015 14:46:18 -0700
+
 git-annex (5.20150824) unstable; urgency=medium
 
   * Sped up downloads of files from ssh remotes, reducing the

git-annex.cabal

@@ -158,7 +158,6 @@ Executable git-annex
 
   if (os(windows))
     Build-Depends: Win32, Win32-extras, unix-compat (>= 0.4.1.3), setenv
-    C-Sources: Utility/winprocess.c
   else
     Build-Depends: unix
     -- Need to list these because they're generated from .hsc files.