Recognize wait -p as assigning a variable (fixes #2179)

src/ShellCheck/ASTLib.hs

@@ -228,6 +228,39 @@ getOpts (gnu, arbitraryLongOpts) string longopts args = process args
 
     listToArgs = map (\x -> ("", (x, x)))
 
+
+-- Generic getOpts that doesn't rely on a format string, but may also be inaccurate.
+-- This provides a best guess interpretation instead of failing when new options are added.
+--
+--    "--" is treated as end of arguments
+--    "--anything[=foo]" is treated as a long option without argument
+--    "-any" is treated as -a -n -y, with the next arg as an option to -y unless it starts with -
+--    anything else is an argument
+getGenericOpts :: [Token] -> [(String, (Token, Token))]
+getGenericOpts = process
+  where
+    process (token:rest) =
+        case getLiteralStringDef "\0" token of
+            "--" -> map (\c -> ("", (c,c))) rest
+            '-':'-':word -> (takeWhile (`notElem` "\0=") word, (token, token)) : process rest
+            '-':optString ->
+                let opts = takeWhile (/= '\0') optString
+                in
+                    case rest of
+                        next:_ | "-" `isPrefixOf` getLiteralStringDef "\0" next  ->
+                            map (\c -> ([c], (token, token))) opts ++ process rest
+                        next:remainder ->
+                            case reverse opts of
+                                last:initial ->
+                                    map (\c -> ([c], (token, token))) (reverse initial)
+                                        ++ [([last], (token, next))]
+                                        ++ process remainder
+                                [] -> process remainder
+                        [] -> map (\c -> ([c], (token, token))) opts
+            _ -> ("", (token, token)) : process rest
+    process [] = []
+
+
 -- Is this an expansion of multiple items of an array?
 isArrayExpansion (T_DollarBraced _ _ l) =
     let string = concat $ oversimplify l in