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.

5 files changed, 17 insertions, 17 deletions

diff --git a/CmdLine/Action.hs b/CmdLine/Action.hs
index 7d9dce574..27621e445 100644
--- a/CmdLine/Action.hs
+++ b/CmdLine/Action.hs
@@ -38,7 +38,7 @@ performCommandAction Command { cmdcheck = c, cmdname = name } seek cont = do
 	showerrcount =<< Annex.getState Annex.errcounter
   where
 	showerrcount 0 = noop
-	showerrcount cnt = error $ name ++ ": " ++ show cnt ++ " failed"
+	showerrcount cnt = giveup $ name ++ ": " ++ show cnt ++ " failed"
 
 {- Runs one of the actions needed to perform a command.
  - Individual actions can fail without stopping the whole command,
diff --git a/CmdLine/Batch.hs b/CmdLine/Batch.hs
index cca93b0b3..627c1df10 100644
--- a/CmdLine/Batch.hs
+++ b/CmdLine/Batch.hs
@@ -56,7 +56,7 @@ batchInput parser a = do
 			either parseerr a (parser v)
 			batchInput parser a
   where
-	parseerr s = error $ "Batch input parse failure: " ++ s
+	parseerr s = giveup $ "Batch input parse failure: " ++ s
 
 -- Runs a CommandStart in batch mode.
 --
diff --git a/CmdLine/GitAnnexShell.hs b/CmdLine/GitAnnexShell.hs
index 599d12fec..70c86ec2f 100644
--- a/CmdLine/GitAnnexShell.hs
+++ b/CmdLine/GitAnnexShell.hs
@@ -71,7 +71,7 @@ globalOptions =
 		check Nothing = unexpected expected "uninitialized repository"
 		check (Just u) = unexpectedUUID expected u
 	unexpectedUUID expected u = unexpected expected $ "UUID " ++ fromUUID u
-	unexpected expected s = error $
+	unexpected expected s = giveup $
 		"expected repository UUID " ++ expected ++ " but found " ++ s
 
 run :: [String] -> IO ()
@@ -109,7 +109,7 @@ builtin cmd dir params = do
 		Git.Config.read r
 			`catchIO` \_ -> do
 				hn <- fromMaybe "unknown" <$> getHostname
-				error $ "failed to read git config of git repository in " ++ hn ++ " on " ++ dir ++ "; perhaps this repository is not set up correctly or has moved"
+				giveup $ "failed to read git config of git repository in " ++ hn ++ " on " ++ dir ++ "; perhaps this repository is not set up correctly or has moved"
 
 external :: [String] -> IO ()
 external params = do
@@ -120,7 +120,7 @@ external params = do
 	checkDirectory lastparam
 	checkNotLimited
 	unlessM (boolSystem "git-shell" $ map Param $ "-c":params') $
-		error "git-shell failed"
+		giveup "git-shell failed"
 
 {- Split the input list into 3 groups separated with a double dash --.
  - Parameters between two -- markers are field settings, in the form:
@@ -150,6 +150,6 @@ checkField (field, val)
 	| otherwise = False
 
 failure :: IO ()
-failure = error $ "bad parameters\n\n" ++ usage h cmds
+failure = giveup $ "bad parameters\n\n" ++ usage h cmds
   where
 	h = "git-annex-shell [-c] command [parameters ...] [option ...]"
diff --git a/CmdLine/GitAnnexShell/Checks.hs b/CmdLine/GitAnnexShell/Checks.hs
index 63d2e594f..47bc11a76 100644
--- a/CmdLine/GitAnnexShell/Checks.hs
+++ b/CmdLine/GitAnnexShell/Checks.hs
@@ -26,7 +26,7 @@ checkEnv var = do
 	case v of
 		Nothing -> noop
 		Just "" -> noop
-		Just _ -> error $ "Action blocked by " ++ var
+		Just _ -> giveup $ "Action blocked by " ++ var
 
 checkDirectory :: Maybe FilePath -> IO ()
 checkDirectory mdir = do
@@ -44,7 +44,7 @@ checkDirectory mdir = do
 					then noop
 					else req d' (Just dir')
   where
-	req d mdir' = error $ unwords 
+	req d mdir' = giveup $ unwords 
 		[ "Only allowed to access"
 		, d
 		, maybe "and could not determine directory from command line" ("not " ++) mdir'
@@ -64,4 +64,4 @@ gitAnnexShellCheck :: Command -> Command
 gitAnnexShellCheck = addCheck okforshell . dontCheck repoExists
   where
 	okforshell = unlessM (isInitialized <||> isJust . gcryptId <$> Annex.getGitConfig) $
-		error "Not a git-annex or gcrypt repository."
+		giveup "Not a git-annex or gcrypt repository."
diff --git a/CmdLine/Seek.hs b/CmdLine/Seek.hs
index 5d20ad0db..7fc64c528 100644
--- a/CmdLine/Seek.hs
+++ b/CmdLine/Seek.hs
@@ -40,7 +40,7 @@ withFilesInGitNonRecursive :: String -> (FilePath -> CommandStart) -> CmdParams
 withFilesInGitNonRecursive needforce a params = ifM (Annex.getState Annex.force)
 	( withFilesInGit a params
 	, if null params
-		then error needforce
+		then giveup needforce
 		else seekActions $ prepFiltered a (getfiles [] params)
 	)
   where
@@ -54,7 +54,7 @@ withFilesInGitNonRecursive needforce a params = ifM (Annex.getState Annex.force)
 			[] -> do
 				void $ liftIO $ cleanup
 				getfiles c ps
-			_ -> error needforce
+			_ -> giveup needforce
 
 withFilesNotInGit :: Bool -> (FilePath -> CommandStart) -> CmdParams -> CommandSeek
 withFilesNotInGit skipdotfiles a params
@@ -117,7 +117,7 @@ withPairs a params = seekActions $ return $ map a $ pairs [] params
   where
 	pairs c [] = reverse c
 	pairs c (x:y:xs) = pairs ((x,y):c) xs
-	pairs _ _ = error "expected pairs"
+	pairs _ _ = giveup "expected pairs"
 
 withFilesToBeCommitted :: (FilePath -> CommandStart) -> CmdParams -> CommandSeek
 withFilesToBeCommitted a params = seekActions $ prepFiltered a $
@@ -152,11 +152,11 @@ withFilesMaybeModified a params = seekActions $
 withKeys :: (Key -> CommandStart) -> CmdParams -> CommandSeek
 withKeys a params = seekActions $ return $ map (a . parse) params
   where
-	parse p = fromMaybe (error "bad key") $ file2key p
+	parse p = fromMaybe (giveup "bad key") $ file2key p
 
 withNothing :: CommandStart -> CmdParams -> CommandSeek
 withNothing a [] = seekActions $ return [a]
-withNothing _ _ = error "This command takes no parameters."
+withNothing _ _ = giveup "This command takes no parameters."
 
 {- Handles the --all, --branch, --unused, --failed, --key, and
  - --incomplete options, which specify particular keys to run an
@@ -191,7 +191,7 @@ withKeyOptions'
 withKeyOptions' ko auto mkkeyaction fallbackaction params = do
 	bare <- fromRepo Git.repoIsLocalBare
 	when (auto && bare) $
-		error "Cannot use --auto in a bare repository"
+		giveup "Cannot use --auto in a bare repository"
 	case (null params, ko) of
 		(True, Nothing)
 			| bare -> noauto $ runkeyaction loggedKeys
@@ -203,10 +203,10 @@ withKeyOptions' ko auto mkkeyaction fallbackaction params = do
 		(True, Just (WantSpecificKey k)) -> noauto $ runkeyaction (return [k])
 		(True, Just WantIncompleteKeys) -> noauto $ runkeyaction incompletekeys
 		(True, Just (WantBranchKeys bs)) -> noauto $ runbranchkeys bs
-		(False, Just _) -> error "Can only specify one of file names, --all, --branch, --unused, --failed, --key, or --incomplete"
+		(False, Just _) -> giveup "Can only specify one of file names, --all, --branch, --unused, --failed, --key, or --incomplete"
   where
 	noauto a
-		| auto = error "Cannot use --auto with --all or --branch or --unused or --key or --incomplete"
+		| auto = giveup "Cannot use --auto with --all or --branch or --unused or --key or --incomplete"
 		| otherwise = a
 	incompletekeys = staleKeysPrune gitAnnexTmpObjectDir True
 	runkeyaction getks = do