configuration to disable automatic merge conflict resolution

* Added annex.resolvemerge configuration, which can be set to false to
  disable the usual automatic merge conflict resolution done by git-annex
  sync and the assistant.
* sync: Added --no-resolvemerge option.

Note that disabling merge conflict resolution is probably not a good idea
in a direct mode repo or adjusted branch. Since updates to both are done
outside the usual work tree, if it fails the tree is not left in a
conflicted state, and it would be hard to manually resolve the conflict.
Still, made annex.resolvemerge be supported in those cases for consistency.

This commit was sponsored by Riku Voipio.

Annex/AdjustedBranch.hs

@@ -318,8 +318,8 @@ findAdjustingCommit (AdjBranch b) = go =<< catCommit b
 {- Update the currently checked out adjusted branch, merging the provided
  - branch into it. Note that the provided branch should be a non-adjusted
  - branch. -}
-updateAdjustedBranch :: Branch -> (OrigBranch, Adjustment) -> [Git.Merge.MergeConfig] -> Git.Branch.CommitMode -> Annex Bool
+updateAdjustedBranch :: Branch -> (OrigBranch, Adjustment) -> [Git.Merge.MergeConfig] -> Annex Bool -> Git.Branch.CommitMode -> Annex Bool
-updateAdjustedBranch tomerge (origbranch, adj) mergeconfig commitmode = catchBoolIO $
+updateAdjustedBranch tomerge (origbranch, adj) mergeconfig canresolvemerge commitmode = catchBoolIO $
 	join $ preventCommits go
   where
 	adjbranch@(AdjBranch currbranch) = originalToAdjusted origbranch adj
@@ -417,7 +417,7 @@ updateAdjustedBranch tomerge (origbranch, adj) mergeconfig commitmode = catchBoo
 		-- this commit will be a fast-forward.
 		adjmergecommitff <- commitAdjustedTree' adjtree (BasisBranch mergecommit) [currbranch]
 		showAction "Merging into adjusted branch"
-		ifM (autoMergeFrom adjmergecommitff (Just currbranch) mergeconfig commitmode)
+		ifM (autoMergeFrom adjmergecommitff (Just currbranch) mergeconfig canresolvemerge commitmode)
 			( reparent adjtree adjmergecommit =<< getcurrentcommit
 			, return False
 			)

Annex/AutoMerge.hs

@@ -43,18 +43,18 @@ import qualified Data.ByteString.Lazy as L
  - Callers should use Git.Branch.changed first, to make sure that
  - there are changes from the current branch to the branch being merged in.
  -}
-autoMergeFrom :: Git.Ref -> Maybe Git.Ref -> [Git.Merge.MergeConfig] -> Git.Branch.CommitMode -> Annex Bool
+autoMergeFrom :: Git.Ref -> Maybe Git.Ref -> [Git.Merge.MergeConfig] -> Annex Bool -> Git.Branch.CommitMode -> Annex Bool
-autoMergeFrom branch currbranch mergeconfig commitmode = do
+autoMergeFrom branch currbranch mergeconfig canresolvemerge commitmode = do
 	showOutput
 	case currbranch of
 		Nothing -> go Nothing
 		Just b -> go =<< inRepo (Git.Ref.sha b)
   where
 	go old = ifM isDirect
-		( mergeDirect currbranch old branch (resolveMerge old branch False) mergeconfig commitmode
+		( mergeDirect currbranch old branch resolvemerge mergeconfig commitmode
 		, do
 			r <- inRepo (Git.Merge.merge branch mergeconfig commitmode)
-				<||> (resolveMerge old branch False <&&> commitResolvedMerge commitmode)
+				<||> (resolvemerge <&&> commitResolvedMerge commitmode)
 			-- Merging can cause new associated files to appear
 			-- and the smudge filter will add them to the database.
 			-- To ensure that this process sees those changes,
@@ -62,6 +62,11 @@ autoMergeFrom branch currbranch mergeconfig commitmode = do
 			Database.Keys.closeDb
 			return r
 		)
+	  where
+		resolvemerge = ifM canresolvemerge
+			( resolveMerge old branch False
+			, return False 
+			)
 
 {- Resolves a conflicted merge. It's important that any conflicts be
  - resolved in a way that itself avoids later merge conflicts, since

Assistant/Sync.hs

@@ -211,7 +211,8 @@ manualPull currentbranch remotes = do
 		else return Nothing
 	haddiverged <- liftAnnex Annex.Branch.forceUpdate
 	forM_ normalremotes $ \r ->
-		liftAnnex $ Command.Sync.mergeRemote r currentbranch Command.Sync.mergeConfig
+		liftAnnex $ Command.Sync.mergeRemote r
+			currentbranch Command.Sync.mergeConfig def
 	return (catMaybes failed, haddiverged)
   where
 	wantpull gc = remoteAnnexPull gc

Assistant/Threads/Merger.hs

@@ -78,6 +78,7 @@ onChange file
 					]
 				void $ liftAnnex $ Command.Sync.merge
 					currbranch Command.Sync.mergeConfig
+					def
 					Git.Branch.AutomaticCommit
 					changedbranch
 	mergecurrent _ = noop

CHANGELOG

@@ -12,6 +12,10 @@ git-annex (6.20170520) UNRELEASED; urgency=medium
   * metadata: When setting metadata of a file that did not exist,
     no error message was displayed, unlike getting metadata and most other
     git-annex commands. Fixed this oversight.
+  * Added annex.resolvemerge configuration, which can be set to false to 
+    disable the usual automatic merge conflict resolution done by git-annex
+    sync and the assistant.
+  * sync: Added --no-resolvemerge option.
 
  -- Joey Hess <id@joeyh.name>  Wed, 24 May 2017 14:03:40 -0400
 

Command/Merge.hs

@@ -33,4 +33,4 @@ mergeBranch = do
 mergeSynced :: CommandStart
 mergeSynced = do
 	prepMerge
-	mergeLocal mergeConfig =<< join getCurrBranch
+	mergeLocal mergeConfig def =<< join getCurrBranch

Command/PostReceive.hs

@@ -48,4 +48,4 @@ fixPostReceiveHookEnv = do
 updateInsteadEmulation :: CommandStart
 updateInsteadEmulation = do
 	prepMerge
-	mergeLocal mergeConfig =<< join getCurrBranch
+	mergeLocal mergeConfig def =<< join getCurrBranch

Command/Sync.hs

@@ -76,8 +76,14 @@ data SyncOptions  = SyncOptions
 	, noContentOption :: Bool
 	, contentOfOption :: [FilePath]
 	, keyOptions :: Maybe KeyOptions
+	, resolveMergeOverride :: ResolveMergeOverride
 	}
 
+newtype ResolveMergeOverride = ResolveMergeOverride Bool
+
+instance Default ResolveMergeOverride where
+	def = ResolveMergeOverride False
+
 optParser :: CmdParamsDesc -> Parser SyncOptions
 optParser desc = SyncOptions
 	<$> (many $ argument str
@@ -117,6 +123,9 @@ optParser desc = SyncOptions
 		<> metavar paramPath
 		))
 	<*> optional parseAllOption
+	<*> (ResolveMergeOverride <$> invertableSwitch "resolvemerge" True
+		( help "do not automatically resolve merge conflicts"
+		))
 
 -- Since prepMerge changes the working directory, FilePath options
 -- have to be adjusted.
@@ -132,6 +141,7 @@ instance DeferredParseClass SyncOptions where
 		<*> pure (noContentOption v)
 		<*> liftIO (mapM absPath (contentOfOption v))
 		<*> pure (keyOptions v)
+		<*> pure (resolveMergeOverride v)
 
 seek :: SyncOptions -> CommandSeek
 seek o = allowConcurrentOutput $ do
@@ -150,7 +160,7 @@ seek o = allowConcurrentOutput $ do
 	-- These actions cannot be run concurrently.
 	mapM_ includeCommandAction $ concat
 		[ [ commit o ]
-		, [ withbranch (mergeLocal mergeConfig) ]
+		, [ withbranch (mergeLocal mergeConfig (resolveMergeOverride o)) ]
 		, map (withbranch . pullRemote o mergeConfig) gitremotes
 		,  [ mergeAnnex ]
 		]
@@ -219,11 +229,14 @@ mergeConfig =
 	, Git.Merge.MergeUnrelatedHistories
 	]
 
-merge :: CurrBranch -> [Git.Merge.MergeConfig] -> Git.Branch.CommitMode -> Git.Branch -> Annex Bool
+merge :: CurrBranch -> [Git.Merge.MergeConfig] -> ResolveMergeOverride -> Git.Branch.CommitMode -> Git.Branch -> Annex Bool
-merge (Just b, Just adj) mergeconfig commitmode tomerge =
+merge currbranch mergeconfig resolvemergeoverride commitmode tomerge = case currbranch of
-	updateAdjustedBranch tomerge (b, adj) mergeconfig commitmode
+	(Just b, Just adj) -> updateAdjustedBranch tomerge (b, adj) mergeconfig canresolvemerge commitmode
-merge (b, _) mergeconfig commitmode tomerge =
+	(b, _) -> autoMergeFrom tomerge b mergeconfig canresolvemerge commitmode
-	autoMergeFrom tomerge b mergeconfig commitmode
+  where
+	canresolvemerge = case resolvemergeoverride of
+		ResolveMergeOverride True -> getGitConfigVal annexResolveMerge
+		ResolveMergeOverride False -> return False
 
 syncBranch :: Git.Branch -> Git.Branch
 syncBranch = Git.Ref.underBase "refs/heads/synced" . fromDirectBranch . fromAdjustedBranch
@@ -296,15 +309,15 @@ commitStaged commitmode commitmessage = do
 	void $ inRepo $ Git.Branch.commit commitmode False commitmessage branch parents
 	return True
 
-mergeLocal :: [Git.Merge.MergeConfig] -> CurrBranch -> CommandStart
+mergeLocal :: [Git.Merge.MergeConfig] -> ResolveMergeOverride -> CurrBranch -> CommandStart
-mergeLocal mergeconfig currbranch@(Just _, _) =
+mergeLocal mergeconfig resolvemergeoverride currbranch@(Just _, _) =
 	go =<< needMerge currbranch
   where
 	go Nothing = stop
 	go (Just syncbranch) = do
 		showStart "merge" $ Git.Ref.describe syncbranch
-		next $ next $ merge currbranch mergeconfig Git.Branch.ManualCommit syncbranch
+		next $ next $ merge currbranch mergeconfig resolvemergeoverride Git.Branch.ManualCommit syncbranch
-mergeLocal _ (Nothing, madj) = do
+mergeLocal _ _ (Nothing, madj) = do
 	b <- inRepo Git.Branch.currentUnsafe
 	ifM (isJust <$> needMerge (b, madj))
 		( do
@@ -365,7 +378,7 @@ pullRemote o mergeconfig remote branch = stopUnless (pure $ pullOption o && want
 	next $ do
 		showOutput
 		stopUnless fetch $
-			next $ mergeRemote remote branch mergeconfig
+			next $ mergeRemote remote branch mergeconfig (resolveMergeOverride o)
   where
 	fetch = inRepoWithSshOptionsTo (Remote.repo remote) (Remote.gitconfig remote) $
 		Git.Command.runBool
@@ -377,8 +390,8 @@ pullRemote o mergeconfig remote branch = stopUnless (pure $ pullOption o && want
  - were committed (or pushed changes, if this is a bare remote),
  - while the synced/master may have changes that some
  - other remote synced to this remote. So, merge them both. -}
-mergeRemote :: Remote -> CurrBranch -> [Git.Merge.MergeConfig] -> CommandCleanup
+mergeRemote :: Remote -> CurrBranch -> [Git.Merge.MergeConfig] -> ResolveMergeOverride -> CommandCleanup
-mergeRemote remote currbranch mergeconfig = ifM isBareRepo
+mergeRemote remote currbranch mergeconfig resolvemergeoverride = ifM isBareRepo
 	( return True
 	, case currbranch of
 		(Nothing, _) -> do
@@ -390,7 +403,7 @@ mergeRemote remote currbranch mergeconfig = ifM isBareRepo
 	)
   where
 	mergelisted getlist = and <$> 
-		(mapM (merge currbranch mergeconfig Git.Branch.ManualCommit . remoteBranch remote) =<< getlist)
+		(mapM (merge currbranch mergeconfig resolvemergeoverride Git.Branch.ManualCommit . remoteBranch remote) =<< getlist)
 	tomerge = filterM (changed remote)
 	branchlist Nothing = []
 	branchlist (Just branch) = [branch, syncBranch branch]

Types/GitConfig.hs

@@ -58,6 +58,7 @@ data GitConfig = GitConfig
 	, annexHttpHeaders :: [String]
 	, annexHttpHeadersCommand :: Maybe String
 	, annexAutoCommit :: Configurable Bool
+	, annexResolveMerge :: Configurable Bool
 	, annexSyncContent :: Configurable Bool
 	, annexDebug :: Bool
 	, annexWebOptions :: [String]
@@ -115,6 +116,8 @@ extractGitConfig r = GitConfig
 	, annexHttpHeadersCommand = getmaybe (annex "http-headers-command")
 	, annexAutoCommit = configurable True $ 
 		getmaybebool (annex "autocommit")
+	, annexResolveMerge = configurable True $ 
+		getmaybebool (annex "resolvemerge")
 	, annexSyncContent = configurable False $ 
 		getmaybebool (annex "synccontent")
 	, annexDebug = getbool (annex "debug") False

doc/forum/controlling_how___34__git_annex_sync__34___resolves_conflicts/comment_2_c091e5a668b15aca7b2faa955beab403._comment

@@ -0,0 +1,8 @@
+[[!comment format=mdwn
+ username="joey"
+ subject="""comment 2"""
+ date="2017-06-01T16:16:44Z"
+ content="""
+I've implemented the annex.automerge configuration setting, for the next
+release. There's also a `git annex sync --no-resolvemerge`
+"""]]

doc/git-annex-config.mdwn

@@ -32,6 +32,12 @@ These settings can be overridden on a per-repository basis using
   Set to false to prevent the git-annex assistant and git-annex sync
   from automatically committing changes to files in the repository.
 
+* `annex.resolvemerge`
+
+  Set to false to prevent merge conflicts being automatically resolved
+  by the git-annex assitant, git-annex sync, git-annex merge, 
+  and the git-annex post-receive hook.
+
 * `annex.synccontent`
 
   Set to true to make git-annex sync default to syncing content.

doc/git-annex-merge.mdwn

@@ -12,6 +12,9 @@ This performs the same merging (and merge conflict resolution)
 that is done by the sync command, but without pushing or pulling any
 data.
 
+When annex.resolvemerge is set to false, merge conflict resolution
+will not be done.
+
 # SEE ALSO
 
 [[git-annex]](1)

doc/git-annex-sync.mdwn

@@ -21,11 +21,6 @@ worry about the details, you can use sync.
 The content of annexed objects is not synced by default, but the --content
 option (see below) can make that also be synchronized.
 
-Merge conflicts are automatically handled by sync. When two conflicting
-versions of a file have been committed, both will be added to the tree,
-under different filenames. For example, file "foo" would be replaced
-with "foo.somekey" and "foo.otherkey".
-
 Note that syncing with a remote will not normally update the remote's working
 tree with changes made to the local repository. (Unless it's configured
 with receive.denyCurrentBranch=updateInstead.) However, those changes
@@ -114,6 +109,18 @@ by running "git annex sync" on the remote.
   less efficient. When --content is synced, the files are processed
   in parallel as well.
 
+* `--resolvemerge`, `--no-resolvemerge`
+
+  By default, merge conflicts are automatically handled by sync. When two
+  conflicting versions of a file have been committed, both will be added 
+  to the tree, under different filenames. For example, file "foo" 
+  would be replaced with "foo.variant-A" and "foo.variant-B". (See
+  [[git-annex-resolvemerge]](1) for details.)
+
+  Use `--no-resolvemerge` to disable this automatic merge conflict
+  resolution. It can also be disabled by setting annex.resolvemerge
+  to false.
+
 # SEE ALSO
 
 [[git-annex]](1)

doc/git-annex.mdwn

@@ -1040,6 +1040,15 @@ Here are all the supported configuration settings.
   To configure the behavior in all clones of the repository,
   this can be set in [[git-annex-config]].
 
+* `annex.resolvemerge`
+
+  Set to false to prevent merge conflicts being automatically resolved
+  by the git-annex assitant, git-annex sync, git-annex merge,
+  and the git-annex post-receive hook.
+
+  To configure the behavior in all clones of the repository,
+  this can be set in [[git-annex-config]].
+
 * `annex.synccontent`
 
   Set to true to make git-annex sync default to syncing content.