diff --git a/lib/symboldatabase.cpp b/lib/symboldatabase.cpp
index 3fa719fda..9fd9396fe 100644
--- a/lib/symboldatabase.cpp
+++ b/lib/symboldatabase.cpp
@@ -1876,13 +1876,13 @@ Function::Function(const Tokenizer *mTokenizer, const Token *tok, const Scope *s
     }
 }
 
-bool Function::argsMatch(const Scope *scope, const Token *first, const Token *second, const std::string &path, unsigned int path_length)
+bool Function::argsMatch(const Scope *scope, const Token *first, const Token *second, const std::string &path, nonneg int path_length)
 {
     const bool isCPP = scope->check->isCPP();
     if (!isCPP) // C does not support overloads
         return true;
 
-    unsigned int arg_path_length = path_length;
+    int arg_path_length = path_length;
 
     while (first->str() == second->str() &&
            first->isLong() == second->isLong() &&
@@ -3269,7 +3269,7 @@ const Function * Function::getOverriddenFunctionRecursive(const ::Type* baseType
     return nullptr;
 }
 
-const Variable* Function::getArgumentVar(std::size_t num) const
+const Variable* Function::getArgumentVar(nonneg int num) const
 {
     for (std::list<Variable>::const_iterator i = argumentList.begin(); i != argumentList.end(); ++i) {
         if (i->index() == num)
@@ -3990,7 +3990,7 @@ bool Scope::hasInlineOrLambdaFunction() const
     return false;
 }
 
-void Scope::findFunctionInBase(const std::string & name, size_t args, std::vector<const Function *> & matches) const
+void Scope::findFunctionInBase(const std::string & name, nonneg int args, std::vector<const Function *> & matches) const
 {
     if (isClassOrStruct() && definedType && !definedType->derivedFrom.empty()) {
         const std::vector<Type::BaseInfo> &derivedFrom = definedType->derivedFrom;
@@ -4793,7 +4793,7 @@ const Scope * SymbolDatabase::findNamespace(const Token * tok, const Scope * sco
 
 //---------------------------------------------------------------------------
 
-Function * SymbolDatabase::findFunctionInScope(const Token *func, const Scope *ns, const std::string & path, unsigned int path_length)
+Function * SymbolDatabase::findFunctionInScope(const Token *func, const Scope *ns, const std::string & path, nonneg int path_length)
 {
     const Function * function = nullptr;
     const bool destructor = func->strAt(-1) == "~";
@@ -4860,9 +4860,9 @@ bool SymbolDatabase::isReservedName(const std::string& iName) const
         return c_keywords.find(iName) != c_keywords.cend();
 }
 
-unsigned int SymbolDatabase::sizeOfType(const Token *type) const
+nonneg int SymbolDatabase::sizeOfType(const Token *type) const
 {
-    unsigned int size = mTokenizer->sizeOfType(type);
+    int size = mTokenizer->sizeOfType(type);
 
     if (size == 0 && type->type() && type->type()->isEnumType() && type->type()->classScope) {
         size = mSettings->sizeof_int;
diff --git a/lib/symboldatabase.h b/lib/symboldatabase.h
index d86c25574..46af0a690 100644
--- a/lib/symboldatabase.h
+++ b/lib/symboldatabase.h
@@ -221,7 +221,7 @@ class CPPCHECKLIB Variable {
 
 public:
     Variable(const Token *name_, const Token *start_, const Token *end_,
-             std::size_t index_, AccessControl access_, const Type *type_,
+             nonneg int index_, AccessControl access_, const Type *type_,
              const Scope *scope_, const Settings* settings)
         : mNameToken(name_),
           mTypeStartToken(start_),
@@ -294,7 +294,7 @@ public:
      * Get declaration ID (varId used for variable in its declaration).
      * @return declaration ID
      */
-    unsigned int declarationId() const {
+    nonneg int declarationId() const {
         // name may not exist for function arguments
         if (mNameToken)
             return mNameToken->varId();
@@ -306,7 +306,7 @@ public:
      * Get index of variable in declared order.
      * @return variable index
      */
-    std::size_t index() const {
+    nonneg int index() const {
         return mIndex;
     }
 
@@ -520,7 +520,7 @@ public:
      * Get array dimension length.
      * @return length of dimension
      */
-    MathLib::bigint dimension(std::size_t index_) const {
+    MathLib::bigint dimension(nonneg int index_) const {
         return mDimensions[index_].num;
     }
 
@@ -528,7 +528,7 @@ public:
      * Get array dimension known.
      * @return length of dimension known
      */
-    bool dimensionKnown(std::size_t index_) const {
+    bool dimensionKnown(nonneg int index_) const {
         return mDimensions[index_].known;
     }
 
@@ -638,7 +638,7 @@ private:
     const Token *mTypeEndToken;
 
     /** @brief order declared */
-    std::size_t mIndex;
+    nonneg int mIndex;
 
     /** @brief what section is this variable declared in? */
     AccessControl mAccess;  // public/protected/private
@@ -715,14 +715,14 @@ public:
         return tokenDef->str();
     }
 
-    std::size_t argCount() const {
+    nonneg int argCount() const {
         return argumentList.size();
     }
-    std::size_t minArgCount() const {
+    nonneg int minArgCount() const {
         return argumentList.size() - initArgCount;
     }
-    const Variable* getArgumentVar(std::size_t num) const;
-    unsigned int initializedArgCount() const {
+    const Variable* getArgumentVar(nonneg int num) const;
+    nonneg int initializedArgCount() const {
         return initArgCount;
     }
     void addArguments(const SymbolDatabase *symbolDatabase, const Scope *scope);
@@ -850,13 +850,13 @@ public:
     const Scope *functionScope;       ///< scope of function body
     const Scope* nestedIn;            ///< Scope the function is declared in
     std::list<Variable> argumentList; ///< argument list
-    unsigned int initArgCount;        ///< number of args with default values
+    nonneg int initArgCount;        ///< number of args with default values
     Type type;                        ///< constructor, destructor, ...
     AccessControl access;             ///< public/protected/private
     const Token *noexceptArg;         ///< noexcept token
     const Token *throwArg;            ///< throw token
 
-    static bool argsMatch(const Scope *scope, const Token *first, const Token *second, const std::string &path, unsigned int path_length);
+    static bool argsMatch(const Scope *scope, const Token *first, const Token *second, const std::string &path, nonneg int path_length);
 
     static bool returnsReference(const Function *function);
 
@@ -964,8 +964,8 @@ public:
     std::list<Variable> varlist;
     const Scope *nestedIn;
     std::list<Scope *> nestedList;
-    unsigned int numConstructors;
-    unsigned int numCopyOrMoveConstructors;
+    nonneg int numConstructors;
+    nonneg int numCopyOrMoveConstructors;
     std::list<UsingInfo> usingList;
     ScopeType type;
     Type* definedType;
@@ -982,7 +982,7 @@ public:
     std::vector<Enumerator> enumeratorList;
 
     const Enumerator * findEnumerator(const std::string & name) const {
-        for (std::size_t i = 0, end = enumeratorList.size(); i < end; ++i) {
+        for (int i = 0, end = enumeratorList.size(); i < end; ++i) {
             if (enumeratorList[i].name->str() == name)
                 return &enumeratorList[i];
         }
@@ -1107,7 +1107,7 @@ private:
      */
     bool isVariableDeclaration(const Token* const tok, const Token*& vartok, const Token*& typetok) const;
 
-    void findFunctionInBase(const std::string & name, size_t args, std::vector<const Function *> & matches) const;
+    void findFunctionInBase(const std::string & name, nonneg int args, std::vector<const Function *> & matches) const;
 };
 
 
@@ -1116,9 +1116,9 @@ class CPPCHECKLIB ValueType {
 public:
     enum Sign { UNKNOWN_SIGN, SIGNED, UNSIGNED } sign;
     enum Type { UNKNOWN_TYPE, NONSTD, RECORD, CONTAINER, ITERATOR, VOID, BOOL, CHAR, SHORT, WCHAR_T, INT, LONG, LONGLONG, UNKNOWN_INT, FLOAT, DOUBLE, LONGDOUBLE } type;
-    unsigned int bits;                    ///< bitfield bitcount
-    unsigned int pointer;                 ///< 0=>not pointer, 1=>*, 2=>**, 3=>***, etc
-    unsigned int constness;               ///< bit 0=data, bit 1=*, bit 2=**
+    nonneg int bits;                    ///< bitfield bitcount
+    nonneg int pointer;                 ///< 0=>not pointer, 1=>*, 2=>**, 3=>***, etc
+    nonneg int constness;               ///< bit 0=data, bit 1=*, bit 2=**
     const Scope *typeScope;               ///< if the type definition is seen this point out the type scope
     const ::Type *smartPointerType;       ///< Smart pointer type
     const Library::Container *container;  ///< If the type is a container defined in a cfg file, this is the used container
@@ -1127,9 +1127,9 @@ public:
 
     ValueType() : sign(UNKNOWN_SIGN), type(UNKNOWN_TYPE), bits(0), pointer(0U), constness(0U), typeScope(nullptr), smartPointerType(nullptr), container(nullptr), containerTypeToken(nullptr) {}
     ValueType(const ValueType &vt) : sign(vt.sign), type(vt.type), bits(vt.bits), pointer(vt.pointer), constness(vt.constness), typeScope(vt.typeScope), smartPointerType(vt.smartPointerType), container(vt.container), containerTypeToken(vt.containerTypeToken), originalTypeName(vt.originalTypeName) {}
-    ValueType(enum Sign s, enum Type t, unsigned int p) : sign(s), type(t), bits(0), pointer(p), constness(0U), typeScope(nullptr), smartPointerType(nullptr), container(nullptr), containerTypeToken(nullptr) {}
-    ValueType(enum Sign s, enum Type t, unsigned int p, unsigned int c) : sign(s), type(t), bits(0), pointer(p), constness(c), typeScope(nullptr), smartPointerType(nullptr), container(nullptr), containerTypeToken(nullptr) {}
-    ValueType(enum Sign s, enum Type t, unsigned int p, unsigned int c, const std::string &otn) : sign(s), type(t), bits(0), pointer(p), constness(c), typeScope(nullptr), smartPointerType(nullptr), container(nullptr), containerTypeToken(nullptr), originalTypeName(otn) {}
+    ValueType(enum Sign s, enum Type t, nonneg int p) : sign(s), type(t), bits(0), pointer(p), constness(0U), typeScope(nullptr), smartPointerType(nullptr), container(nullptr), containerTypeToken(nullptr) {}
+    ValueType(enum Sign s, enum Type t, nonneg int p, nonneg int c) : sign(s), type(t), bits(0), pointer(p), constness(c), typeScope(nullptr), smartPointerType(nullptr), container(nullptr), containerTypeToken(nullptr) {}
+    ValueType(enum Sign s, enum Type t, nonneg int p, nonneg int c, const std::string &otn) : sign(s), type(t), bits(0), pointer(p), constness(c), typeScope(nullptr), smartPointerType(nullptr), container(nullptr), containerTypeToken(nullptr), originalTypeName(otn) {}
     ValueType &operator=(const ValueType &other) = delete;
 
     static ValueType parseDecl(const Token *type, const Settings *settings);
@@ -1202,7 +1202,7 @@ public:
         return const_cast<Scope *>(this->findScope(tok, const_cast<const Scope *>(startScope)));
     }
 
-    const Variable *getVariableFromVarId(std::size_t varId) const {
+    const Variable *getVariableFromVarId(nonneg int varId) const {
         return mVariableList.at(varId);
     }
 
@@ -1240,7 +1240,7 @@ public:
      * @param type Token which will contain e.g. "int", "*", or string.
      * @return sizeof for given type, or 0 if it can't be calculated.
      */
-    unsigned int sizeOfType(const Token *type) const;
+    nonneg int sizeOfType(const Token *type) const;
 
     /** Set array dimensions when valueflow analysis is completed */
     void setArrayDimensionsUsingValueFlow();
@@ -1272,7 +1272,7 @@ private:
     bool isFunction(const Token *tok, const Scope* outerScope, const Token **funcStart, const Token **argStart, const Token** declEnd) const;
     const Type *findTypeInNested(const Token *startTok, const Scope *startScope) const;
     const Scope *findNamespace(const Token * tok, const Scope * scope) const;
-    Function *findFunctionInScope(const Token *func, const Scope *ns, const std::string & path, unsigned int path_length);
+    Function *findFunctionInScope(const Token *func, const Scope *ns, const std::string & path, nonneg int path_length);
     const Type *findVariableTypeInBase(const Scope *scope, const Token *typeTok) const;
 
     typedef std::map<unsigned int, unsigned int> MemberIdMap;