handle unnamed bitfields of size zero

Author: ludviggunne

addons/cppcheckdata.py

@@ -166,7 +166,7 @@ class ValueType:
     Attributes:
         type             nonstd/pod/record/smart-pointer/container/iterator/void/bool/char/short/wchar_t/int/long/long long/unknown int/float/double/long double
         sign             signed/unsigned
-        bits
+        bits             >= 0 for bit-fields, otherwise -1
         pointer
         constness
         reference
@@ -178,7 +178,7 @@ class ValueType:
 
     type = None
     sign = None
-    bits = 0
+    bits = -1
     constness = 0
     pointer = 0
     typeScopeId = None
@@ -188,7 +188,7 @@ class ValueType:
     def __init__(self, element):
         self.type = element.get('valueType-type')
         self.sign = element.get('valueType-sign')
-        self.bits = int(element.get('valueType-bits', 0))
+        self.bits = int(element.get('valueType-bits', -1))
         self.pointer = int(element.get('valueType-pointer', 0))
         self.constness = int(element.get('valueType-constness', 0))
         self.reference = element.get('valueType-reference')

addons/misra.py

@@ -2017,7 +2017,7 @@ def misra_6_1(self, data):
         for token in data.tokenlist:
             if not token.valueType:
                 continue
-            if token.valueType.bits == 0:
+            if token.valueType.bits == -1:
                 continue
             if not token.variable:
                 continue

lib/symboldatabase.cpp

@@ -8110,7 +8110,7 @@ std::string ValueType::dump() const
         break;
     }
 
-    if (bits > 0) {
+    if (bits >= 0) {
         ret += " valueType-bits=\"";
         ret += std::to_string(bits);
         ret += '\"';

lib/symboldatabase.h

@@ -1236,7 +1236,7 @@ class CPPCHECKLIB ValueType {
         DOUBLE,
         LONGDOUBLE
     } type = UNKNOWN_TYPE;
-    nonneg int bits{};                         ///< bitfield bitcount
+    int bits{};                                ///< bitfield bitcount
     nonneg int pointer{};                      ///< 0=>not pointer, 1=>*, 2=>**, 3=>***, etc
     nonneg int constness{};                    ///< bit 0=data, bit 1=*, bit 2=**
     nonneg int volatileness{};                 ///< bit 0=data, bit 1=*, bit 2=**

lib/token.h

@@ -82,7 +82,7 @@ struct TokenImpl {
     nonneg int mIndex{};
 
     /** Bitfield bit count. */
-    unsigned char mBits{};
+    char mBits = -1;
 
     // AST..
     Token* mAstOperand1{};
@@ -751,9 +751,9 @@ class CPPCHECKLIB Token {
 
     // cppcheck-suppress unusedFunction
     bool isBitfield() const {
-        return mImpl->mBits > 0;
+        return mImpl->mBits >= 0;
     }
-    unsigned char bits() const {
+    char bits() const {
         return mImpl->mBits;
     }
     const std::set<TemplateSimplifier::TokenAndName*>* templateSimplifierPointers() const {

lib/tokenize.cpp

@@ -10015,7 +10015,7 @@ void Tokenizer::simplifyBitfields()
             !Token::simpleMatch(tok->tokAt(2), "default :")) {
             Token *tok1 = typeTok->next();
             if (Token::Match(tok1, "%name% : %num% [;=]"))
-                tok1->setBits(static_cast<unsigned char>(MathLib::toBigNumber(tok1->tokAt(2))));
+                tok1->setBits(static_cast<char>(MathLib::toBigNumber(tok1->tokAt(2))));
             if (tok1 && tok1->tokAt(2) &&
                 (Token::Match(tok1->tokAt(2), "%bool%|%num%") ||
                  !Token::Match(tok1->tokAt(2), "public|protected|private| %type% ::|<|,|{|;"))) {
@@ -10041,9 +10041,9 @@ void Tokenizer::simplifyBitfields()
             Token *newTok = typeTok->insertToken(name);
             newTok->isAnonymousBitfield(true);
             if (newTok->tokAt(2)->isBoolean())
-                newTok->setBits(static_cast<unsigned char>(newTok->strAt(2) == "true"));
+                newTok->setBits(static_cast<char>(newTok->strAt(2) == "true"));
             else
-                newTok->setBits(static_cast<unsigned char>(MathLib::toBigNumber(newTok->tokAt(2))));
+                newTok->setBits(static_cast<char>(MathLib::toBigNumber(newTok->tokAt(2))));
             newTok->deleteNext(2);
         }
 

lib/valueflow.cpp

@@ -440,7 +440,7 @@ static Result accumulateStructMembers(const Scope* scope, F f, ValueFlow::Accura
     for (const Variable& var : scope->varlist) {
         if (var.isStatic())
             continue;
-        const size_t bits = var.nameToken() ? var.nameToken()->bits() : 0;
+        const char bits = var.nameToken() ? var.nameToken()->bits() : -1;
         if (const ValueType* vt = var.valueType()) {
             if (vt->type == ValueType::Type::RECORD && vt->typeScope == scope)
                 return {0, false};
@@ -455,7 +455,7 @@ static Result accumulateStructMembers(const Scope* scope, F f, ValueFlow::Accura
             else
                 total = f(total, *vt, dim, bits);
         }
-        if (accuracy == ValueFlow::Accuracy::ExactOrZero && total == 0 && bits == 0)
+        if (accuracy == ValueFlow::Accuracy::ExactOrZero && total == 0 && bits == -1)
             return {0, false};
     }
     return {total, true};
@@ -537,10 +537,17 @@ size_t ValueFlow::getSizeOf(const ValueType &vt, const Settings &settings, Accur
     if (vt.type == ValueType::Type::RECORD && vt.typeScope) {
         size_t currentBitCount = 0;
         size_t currentBitfieldAlloc = 0;
-        auto accHelper = [&](size_t total, const ValueType& vt2, size_t dim, size_t bits) -> size_t {
+        auto accHelper = [&](size_t total, const ValueType& vt2, size_t dim, char bits) -> size_t {
             const size_t charBit = settings.platform.char_bit;
             size_t n = ValueFlow::getSizeOf(vt2, settings,accuracy, ++maxRecursion);
             size_t a = getAlignOf(vt2, settings, accuracy);
+            if (bits == 0) {
+                if (currentBitfieldAlloc == 0) {
+                    bits = n * charBit;
+                } else {
+                    bits = currentBitfieldAlloc * charBit - currentBitCount;
+                }
+            }
             if (bits > 0) {
                 size_t ret = total;
                 if (currentBitfieldAlloc == 0) {