Fix parsing of [$var] (fixes #2309)

src/ShellCheck/ASTLib.hs

@@ -59,10 +59,28 @@ willSplit x =
     T_NormalWord _ l -> any willSplit l
     _ -> False
 
-isGlob T_Extglob {} = True
-isGlob T_Glob {} = True
-isGlob (T_NormalWord _ l) = any isGlob l
-isGlob _ = False
+isGlob t = case t of
+    T_Extglob {} -> True
+    T_Glob {} -> True
+    T_NormalWord _ l -> any isGlob l || hasSplitRange l
+    _ -> False
+  where
+    -- foo[x${var}y] gets parsed as foo,[,x,$var,y],
+    -- so check if there's such an interval
+    hasSplitRange l =
+        let afterBracket = dropWhile (not . isHalfOpenRange) l
+        in any isClosingRange afterBracket
+
+    isHalfOpenRange t =
+        case t of
+            T_Literal _ "[" -> True
+            _ -> False
+
+    isClosingRange t =
+        case t of
+            T_Literal _ str -> ']' `elem` str
+            _ -> False
+
 
 -- Is this shell word a constant?
 isConstant token =

src/ShellCheck/Analytics.hs

@@ -2311,6 +2311,8 @@ prop_checkUnused45= verifyTree checkUnusedAssignments "readonly foo=bar"
 prop_checkUnused46= verifyTree checkUnusedAssignments "readonly foo=(bar)"
 prop_checkUnused47= verifyNotTree checkUnusedAssignments "a=1; alias hello='echo $a'"
 prop_checkUnused48= verifyNotTree checkUnusedAssignments "_a=1"
+prop_checkUnused49= verifyNotTree checkUnusedAssignments "declare -A array; key=a; [[ -v array[$key] ]]"
+
 checkUnusedAssignments params t = execWriter (mapM_ warnFor unused)
   where
     flow = variableFlow params

src/ShellCheck/AnalyzerLib.hs

@@ -497,14 +497,8 @@ getModifiedVariables t =
 
         -- Count [[ -v foo ]] as an "assignment".
         -- This is to prevent [ -v foo ] being unassigned or unused.
-        TC_Unary id _ "-v" token -> do
-            str <- fmap (takeWhile (/= '[')) $ -- Quoted index
-                    flip getLiteralStringExt token $ \x ->
-                case x of
-                    T_Glob _ s -> return s -- Unquoted index
-                    _          -> []
-
-            guard . not . null $ str
+        TC_Unary id _ "-v" token -> maybeToList $ do
+            str <- getVariableForTestDashV token
             return (t, token, str, DataString SourceChecked)
 
         TC_Unary _ _ "-n" token -> markAsChecked t token
@@ -724,6 +718,20 @@ getIndexReferences s = fromMaybe [] $ do
   where
     re = mkRegex "(\\[.*\\])"
 
+-- Given a NormalWord like foo or foo[$bar], get foo.
+-- Primarily used to get references for [[ -v foo[bar] ]]
+getVariableForTestDashV :: Token -> Maybe String
+getVariableForTestDashV t = do
+    str <- takeWhile ('[' /=) <$> getLiteralStringExt toStr t
+    guard $ isVariableName str
+    return str
+  where
+    -- foo[bar] gets parsed with [bar] as a glob, so undo that
+    toStr (T_Glob _ s) = return s
+    -- Turn foo[$x] into foo[\0] so that we can get the constant array name
+    -- in a non-constant expression (while filtering out foo$x[$y])
+    toStr _ = return "\0"
+
 prop_getOffsetReferences1 = getOffsetReferences ":bar" == ["bar"]
 prop_getOffsetReferences2 = getOffsetReferences ":bar:baz" == ["bar", "baz"]
 prop_getOffsetReferences3 = getOffsetReferences "[foo]:bar" == ["bar"]
@@ -782,9 +790,8 @@ getReferencedVariables parents t =
         T_Glob _ s -> return s    -- Also when parsed as globs
         _          -> []
 
-    getIfReference context token = do
-            str@(h:_) <- getLiteralStringExt literalizer token
-            when (isDigit h) $ fail "is a number"
+    getIfReference context token = maybeToList $ do
+            str <- getVariableForTestDashV token
             return (context, token, getBracedReference str)
 
     isArithmeticAssignment t = case getPath parents t of

src/ShellCheck/Checks/Commands.hs

@@ -845,6 +845,9 @@ checkAliasesExpandEarly = CommandCheck (Exactly "alias") (f . arguments)
 
 prop_checkUnsetGlobs1 = verify checkUnsetGlobs "unset foo[1]"
 prop_checkUnsetGlobs2 = verifyNot checkUnsetGlobs "unset foo"
+prop_checkUnsetGlobs3 = verify checkUnsetGlobs "unset foo[$i]"
+prop_checkUnsetGlobs4 = verify checkUnsetGlobs "unset foo[x${i}y]"
+prop_checkUnsetGlobs5 = verifyNot checkUnsetGlobs "unset foo]["
 checkUnsetGlobs = CommandCheck (Exactly "unset") (mapM_ check . arguments)
   where
     check arg =

src/ShellCheck/Parser.hs

@@ -1372,6 +1372,8 @@ prop_readGlob5 = isOk readGlob "[^[:alpha:]1-9]"
 prop_readGlob6 = isOk readGlob "[\\|]"
 prop_readGlob7 = isOk readGlob "[^[]"
 prop_readGlob8 = isOk readGlob "[*?]"
+prop_readGlob9 = isOk readGlob "[!]^]"
+prop_readGlob10 = isOk readGlob "[]]"
 readGlob = readExtglob <|> readSimple <|> readClass <|> readGlobbyLiteral
     where
         readSimple = do
@@ -1379,22 +1381,25 @@ readGlob = readExtglob <|> readSimple <|> readClass <|> readGlobbyLiteral
             c <- oneOf "*?"
             id <- endSpan start
             return $ T_Glob id [c]
-        -- Doesn't handle weird things like [^]a] and [$foo]. fixme?
         readClass = try $ do
             start <- startSpan
             char '['
-            s <- many1 (predefined <|> readNormalLiteralPart "]" <|> globchars)
+            negation <- charToString (oneOf "!^") <|> return ""
+            leadingBracket <- charToString (oneOf "]") <|> return ""
+            s <- many (predefined <|> readNormalLiteralPart "]" <|> globchars)
+            guard $ not (null leadingBracket) || not (null s)
             char ']'
             id <- endSpan start
-            return $ T_Glob id $ "[" ++ concat s ++ "]"
+            return $ T_Glob id $ "[" ++ concat (negation:leadingBracket:s) ++ "]"
           where
-           globchars = fmap return . oneOf $ "!$[" ++ extglobStartChars
+           globchars = charToString $ oneOf $ "![" ++ extglobStartChars
            predefined = do
               try $ string "[:"
               s <- many1 letter
               string ":]"
               return $ "[:" ++ s ++ ":]"
 
+        charToString = fmap return
         readGlobbyLiteral = do
             start <- startSpan
             c <- extglobStart <|> char '['