Avoid backtraces on expected failures when built with ghc 8; only use backtraces for unexpected errors.

ghc 8 added backtraces on uncaught errors. This is great, but git-annex was
using error in many places for a error message targeted at the user, in
some known problem case. A backtrace only confuses such a message, so omit it.

Notably, commands like git annex drop that failed due to eg, numcopies,
used to use error, so had a backtrace.

This commit was sponsored by Ethan Aubin.

6 files changed, 11 insertions, 11 deletions

diff --git a/Annex/AdjustedBranch.hs b/Annex/AdjustedBranch.hs
index 4caf637c7..72c07a5bc 100644
--- a/Annex/AdjustedBranch.hs
+++ b/Annex/AdjustedBranch.hs
@@ -596,7 +596,7 @@ checkAdjustedClone = ifM isBareRepo
 				aps <- fmap commitParent <$> findAdjustingCommit (AdjBranch currbranch)
 				case aps of
 					Just [p] -> setBasisBranch basis p
-					_ -> error $ "Unable to clean up from clone of adjusted branch; perhaps you should check out " ++ Git.Ref.describe origbranch
+					_ -> giveup $ "Unable to clean up from clone of adjusted branch; perhaps you should check out " ++ Git.Ref.describe origbranch
 			ifM versionSupportsUnlockedPointers
 				( return InAdjustedClone
 				, return NeedUpgradeForAdjustedClone
@@ -610,6 +610,6 @@ isGitVersionSupported = not <$> Git.Version.older "2.2.0"
 checkVersionSupported :: Annex ()
 checkVersionSupported = do
 	unlessM versionSupportsAdjustedBranch $
-		error "Adjusted branches are only supported in v6 or newer repositories."
+		giveup "Adjusted branches are only supported in v6 or newer repositories."
 	unlessM (liftIO isGitVersionSupported) $
-		error "Your version of git is too old; upgrade it to 2.2.0 or newer to use adjusted branches."
+		giveup "Your version of git is too old; upgrade it to 2.2.0 or newer to use adjusted branches."
diff --git a/Annex/Branch.hs b/Annex/Branch.hs
index a426c76d8..9663311d5 100644
--- a/Annex/Branch.hs
+++ b/Annex/Branch.hs
@@ -225,7 +225,7 @@ getHistorical date file =
 	-- This check avoids some ugly error messages when the reflog
 	-- is empty.
 	ifM (null <$> inRepo (Git.RefLog.get' [Param (fromRef fullname), Param "-n1"]))
-		( error ("No reflog for " ++ fromRef fullname)
+		( giveup ("No reflog for " ++ fromRef fullname)
 		, getRef (Git.Ref.dateRef fullname date) file
 		)
 
@@ -574,7 +574,7 @@ checkBranchDifferences ref = do
 		<$> catFile ref differenceLog
 	mydiffs <- annexDifferences <$> Annex.getGitConfig
 	when (theirdiffs /= mydiffs) $
-		error "Remote repository is tuned in incompatable way; cannot be merged with local repository."
+		giveup "Remote repository is tuned in incompatable way; cannot be merged with local repository."
 
 ignoreRefs :: [Git.Sha] -> Annex ()
 ignoreRefs rs = do
diff --git a/Annex/Content.hs b/Annex/Content.hs
index cb96a0068..e879e4eeb 100644
--- a/Annex/Content.hs
+++ b/Annex/Content.hs
@@ -268,8 +268,8 @@ lockContentUsing locker key a = do
 		(unlock lockfile)
 		(const a)
   where
-	alreadylocked = error "content is locked"
-	failedtolock e = error $ "failed to lock content: " ++ show e
+	alreadylocked = giveup "content is locked"
+	failedtolock e = giveup $ "failed to lock content: " ++ show e
 
 	lock contentfile lockfile =
 		(maybe alreadylocked return 
diff --git a/Annex/FileMatcher.hs b/Annex/FileMatcher.hs
index fa46e64b1..654c5a960 100644
--- a/Annex/FileMatcher.hs
+++ b/Annex/FileMatcher.hs
@@ -165,7 +165,7 @@ largeFilesMatcher = go =<< annexLargeFiles <$> Annex.getGitConfig
 	mkmatcher expr = do
 		parser <- mkLargeFilesParser
 		either badexpr return $ parsedToMatcher $ parser expr
-	badexpr e = error $ "bad annex.largefiles configuration: " ++ e
+	badexpr e = giveup $ "bad annex.largefiles configuration: " ++ e
 
 simply :: MatchFiles Annex -> ParseResult
 simply = Right . Operation
diff --git a/Annex/Init.hs b/Annex/Init.hs
index 5aff4cf39..8a208fe2b 100644
--- a/Annex/Init.hs
+++ b/Annex/Init.hs
@@ -129,7 +129,7 @@ ensureInitialized = getVersion >>= maybe needsinit checkUpgrade
   where
 	needsinit = ifM Annex.Branch.hasSibling
 			( initialize Nothing Nothing
-			, error "First run: git-annex init"
+			, giveup "First run: git-annex init"
 			)
 
 {- Checks if a repository is initialized. Does not check version for ugrade. -}
diff --git a/Annex/View.hs b/Annex/View.hs
index 7d2b43e60..d865c8f78 100644
--- a/Annex/View.hs
+++ b/Annex/View.hs
@@ -110,7 +110,7 @@ refineView origview = checksize . calc Unchanged origview
 			in (view', Narrowing)
 	
 	checksize r@(v, _)
-		| viewTooLarge v = error $ "View is too large (" ++ show (visibleViewSize v) ++ " levels of subdirectories)"
+		| viewTooLarge v = giveup $ "View is too large (" ++ show (visibleViewSize v) ++ " levels of subdirectories)"
 		| otherwise = r
 
 updateViewComponent :: ViewComponent -> MetaField -> ViewFilter -> Writer [ViewChange] ViewComponent
@@ -424,4 +424,4 @@ genViewBranch view = withViewIndex $ do
 	return branch
 
 withCurrentView :: (View -> Annex a) -> Annex a
-withCurrentView a = maybe (error "Not in a view.") a =<< currentView
+withCurrentView a = maybe (giveup "Not in a view.") a =<< currentView