info: error out when file matching options used on non-directory

When file matching options are specified when getting info of
something other than a directory, they won't have any effect, so error out
to avoid confusion.

This commit was sponsored by mo on Patreon.

CHANGELOG

@@ -1,3 +1,11 @@
+git-annex (7.20190820) UNRELEASED; urgency=medium
+
+  * info: When file matching options are specified when getting
+    info of something other than a directory, they won't have any effect,
+    so error out to avoid confusion.
+
+ -- Joey Hess <id@joeyh.name>  Sat, 24 Aug 2019 12:54:35 -0400
+
 git-annex (7.20190819) upstream; urgency=medium
 
   * New git-lfs special remote, which can be used to store data on any git-lfs

Command/Info.hs

@@ -132,6 +132,7 @@ start o ps = do
 
 globalInfo :: InfoOptions -> Annex ()
 globalInfo o = do
+	disallowMatchingOptions
 	u <- getUUID
 	whenM ((==) DeadTrusted <$> lookupTrust u) $
 		earlyWarning "Warning: This repository is currently marked as dead."
@@ -144,6 +145,7 @@ itemInfo :: InfoOptions -> String -> Annex ()
 itemInfo o p = ifM (isdir p)
 	( dirInfo o p
 	, do
+		disallowMatchingOptions
 		v <- Remote.byName' p
 		case v of
 			Right r -> remoteInfo o r
@@ -164,6 +166,10 @@ noInfo s = do
 	showNote $ "not a directory or an annexed file or a treeish or a remote or a uuid"
 	showEndFail
 
+disallowMatchingOptions :: Annex ()
+disallowMatchingOptions = whenM Limit.limited $
+	giveup "File matching options can only be used when getting info on a directory."
+
 dirInfo :: InfoOptions -> FilePath -> Annex ()
 dirInfo o dir = showCustom (unwords ["info", dir]) $ do
 	stats <- selStats