Improve 'let' parsing, trigger unused var for ((a=1))

ShellCheck/AST.hs

@@ -34,6 +34,7 @@ data CaseType = CaseBreak | CaseFallThrough | CaseContinue deriving (Show, Eq)
 
 data Token =
     TA_Binary Id String Token Token
+    | TA_Assignment Id String Token Token
     | TA_Expansion Id [Token]
     | TA_Index Id Token
     | TA_Sequence Id [Token]
@@ -250,6 +251,7 @@ analyze f g i =
     delve (TC_Noary id typ token) = d1 token $ TC_Noary id typ
 
     delve (TA_Binary id op t1 t2) = d2 t1 t2 $ TA_Binary id op
+    delve (TA_Assignment id op t1 t2) = d2 t1 t2 $ TA_Assignment id op
     delve (TA_Unary id op t1) = d1 t1 $ TA_Unary id op
     delve (TA_Sequence id l) = dl l $ TA_Sequence id
     delve (TA_Trinary id t1 t2 t3) = do
@@ -344,6 +346,7 @@ getId t = case t of
         TC_Unary id _ _ _  -> id
         TC_Noary id _ _  -> id
         TA_Binary id _ _ _  -> id
+        TA_Assignment id _ _ _  -> id
         TA_Unary id _ _  -> id
         TA_Sequence id _  -> id
         TA_Trinary id _ _ _  -> id

ShellCheck/Analytics.hs

@@ -2054,6 +2054,9 @@ prop_checkUnused26= verifyNotTree checkUnusedAssignments "declare -F foo"
 prop_checkUnused27= verifyTree checkUnusedAssignments "var=3; [ var -eq 3 ]"
 prop_checkUnused28= verifyNotTree checkUnusedAssignments "var=3; [[ var -eq 3 ]]"
 prop_checkUnused29= verifyNotTree checkUnusedAssignments "var=(a b); declare -p var"
+prop_checkUnused30= verifyTree checkUnusedAssignments "let a=1"
+prop_checkUnused31= verifyTree checkUnusedAssignments "let 'a=1'"
+prop_checkUnused32= verifyTree checkUnusedAssignments "let a=b=c; echo $a"
 checkUnusedAssignments params t = execWriter (mapM_ warnFor unused)
   where
     flow = variableFlow params
@@ -2742,7 +2745,7 @@ checkLoopVariableReassignment params token =
             T_ForIn _ s _ _ -> return s
             T_ForArithmetic _
                 (TA_Sequence _
-                    [TA_Binary _ "="
+                    [TA_Assignment _ "="
                         (TA_Expansion _ [T_Literal _ var]) _])
                             _ _ _ -> return var
             _ -> fail "not loop"

ShellCheck/AnalyzerLib.hs

@@ -40,8 +40,6 @@ import qualified Data.Map as Map
 import Test.QuickCheck.All (forAllProperties)
 import Test.QuickCheck.Test (quickCheckWithResult, stdArgs, maxSuccess)
 
-import Debug.Trace
-
 type Analysis = ReaderT Parameters (Writer [TokenComment]) ()
 
 
@@ -272,7 +270,7 @@ getVariableFlow shell parents t =
     assignFirst _ = False
 
     setRead t =
-        let read    = getReferencedVariables t
+        let read    = getReferencedVariables parents t
         in mapM_ (\v -> modify (Reference v:)) read
 
     setWritten t =
@@ -331,7 +329,7 @@ getModifiedVariables t =
         TA_Unary _ "|++" var -> maybeToList $ do
             name <- getLiteralString var
             return (t, t, name, DataString $ SourceFrom [t])
-        TA_Binary _ op lhs rhs -> maybeToList $ do
+        TA_Assignment _ op lhs rhs -> maybeToList $ do
             guard $ op `elem` ["=", "*=", "/=", "%=", "+=", "-=", "<<=", ">>=", "&=", "^=", "|="]
             name <- getLiteralString lhs
             return (t, t, name, DataString $ SourceFrom [rhs])
@@ -476,12 +474,15 @@ getIndexReferences s = fromMaybe [] $ do
   where
     re = mkRegex "(\\[.*\\])"
 
-getReferencedVariables t =
+getReferencedVariables parents t =
     case t of
         T_DollarBraced id l -> let str = bracedString t in
             (t, t, getBracedReference str) :
                 map (\x -> (l, l, x)) (getIndexReferences str)
-        TA_Expansion id _ -> getIfReference t t
+        TA_Expansion id _ ->
+            if isArithmeticAssignment t
+            then []
+            else getIfReference t t
         T_Assignment id mode str _ word ->
             [(t, t, str) | mode == Append] ++ specialReferences str t word
 
@@ -518,6 +519,10 @@ getReferencedVariables t =
 
     isDereferencing = (`elem` ["-eq", "-ne", "-lt", "-le", "-gt", "-ge"])
 
+    isArithmeticAssignment t = case getPath parents t of
+        this: TA_Assignment _ "=" _ _ :_ -> True
+        _ -> False
+
 dataTypeFrom defaultType v = (case v of T_Array {} -> DataArray; _ -> defaultType) $ SourceFrom [v]
 
 

ShellCheck/Parser.hs

@@ -708,7 +708,9 @@ readArithmeticContents =
         l <- readAssignment `sepBy` (char ',' >> spacing)
         return $ TA_Sequence id l
 
-    readAssignment = readTrinary `splitBy` ["=", "*=", "/=", "%=", "+=", "-=", "<<=", ">>=", "&=", "^=", "|="]
+    readAssignment = chainr1 readTrinary readAssignmentOp
+    readAssignmentOp = readComboOp ["=", "*=", "/=", "%=", "+=", "-=", "<<=", ">>=", "&=", "^=", "|="] TA_Assignment
+
     readTrinary = do
         x <- readLogicalOr
         do
@@ -2214,13 +2216,29 @@ readTimeSuffix = do
         lookAhead $ char '-'
         readCmdWord
 
--- Fixme: this is a hack that doesn't handle let '++c' or let a\>b
+-- Fixme: this is a hack that doesn't handle let c='4'"5" or let a\>b
+readLetSuffix :: Monad m => SCParser m [Token]
 readLetSuffix = many1 (readIoRedirect <|> try readLetExpression <|> readCmdWord)
   where
+    readLetExpression :: Monad m => SCParser m Token
     readLetExpression = do
         startPos <- getPosition
         expression <- readStringForParser readCmdWord
-        subParse startPos readArithmeticContents expression
+        let (unQuoted, newPos) = kludgeAwayQuotes expression startPos
+        subParse newPos readArithmeticContents unQuoted
+
+    kludgeAwayQuotes :: String -> SourcePos -> (String, SourcePos)
+    kludgeAwayQuotes s p =
+        case s of
+            first:rest@(_:_) ->
+                let (last:backwards) = reverse rest
+                    middle = reverse backwards
+                in
+                    if first `elem` "'\"" && first == last
+                    then (middle, updatePosChar p first)
+                    else (s, p)
+            x -> (s, p)
+
 
 -- bash allows a=(b), ksh allows $a=(b). dash allows neither. Let's warn.
 readEvalSuffix = many1 (readIoRedirect <|> readCmdWord <|> evalFallback)