SC2249: When verbose, warn about missing default case (fixes #997)

src/ShellCheck/Analytics.hs

@@ -172,6 +172,7 @@ nodeChecks = [
     ,checkRedirectionToCommand
     ,checkNullaryExpansionTest
     ,checkDollarQuoteParen
+    ,checkDefaultCase
     ]
 
 
@@ -3202,5 +3203,22 @@ checkDollarQuoteParen params t =
   where
     fix id = fixWith [replaceStart id params 2 "\"$"]
 
+prop_checkDefaultCase1 = verify checkDefaultCase "case $1 in a) true ;; esac"
+prop_checkDefaultCase2 = verify checkDefaultCase "case $1 in ?*?) true ;; *? ) true ;; esac"
+prop_checkDefaultCase3 = verifyNot checkDefaultCase "case $1 in x|*) true ;; esac"
+prop_checkDefaultCase4 = verifyNot checkDefaultCase "case $1 in **) true ;; esac"
+checkDefaultCase _ t =
+    case t of
+        T_CaseExpression id _ list ->
+            unless (any canMatchAny list) $
+                verbose id 2249 "Consider adding a default *) case, even if it just exits with error."
+        _ -> return ()
+  where
+    canMatchAny (_, list, _) = any canMatchAny' list
+    -- hlint objects to 'pattern' as a variable name
+    canMatchAny' pat = fromMaybe False $ do
+        pg <- wordToExactPseudoGlob pat
+        return $ pseudoGlobIsSuperSetof pg [PGMany]
+
 return []
 runTests =  $( [| $(forAllProperties) (quickCheckWithResult (stdArgs { maxSuccess = 1 }) ) |])

src/ShellCheck/AnalyzerLib.hs

@@ -154,6 +154,7 @@ warn  id code str = addComment $ makeComment WarningC id code str
 err   id code str = addComment $ makeComment ErrorC id code str
 info  id code str = addComment $ makeComment InfoC id code str
 style id code str = addComment $ makeComment StyleC id code str
+verbose id code str = addComment $ makeComment VerboseC id code str
 
 warnWithFix :: MonadWriter [TokenComment] m => Id -> Code -> String -> Fix -> m ()
 warnWithFix  = addCommentWithFix WarningC