diff --git a/lib/symboldatabase.cpp b/lib/symboldatabase.cpp
index 51c5f33da..ca7b39f23 100644
--- a/lib/symboldatabase.cpp
+++ b/lib/symboldatabase.cpp
@@ -1430,11 +1430,19 @@ void SymbolDatabase::validate() const
     const std::size_t functions = functionScopes.size();
     for (std::size_t i = 0; i < functions; ++i) {
         const Scope* scope = functionScopes[i];
-        if (scope->isExecutable()) {
-            const Function* function = scope->function;
-            if (!function) {
-                cppcheckError(nullptr);
+        const Function* function = scope->function;
+        if (scope->isExecutable() && !function) {
+        if (_settings->debugwarnings)
+            {
+                const std::list<const Token*> callstack(1, scope->classDef);
+                const std::string msg = std::string("executable scope '") + scope->classDef->str() + "' with unknown function";
+                const ErrorLogger::ErrorMessage errmsg(callstack, &_tokenizer->list, Severity::debug,
+                                                       "symbolDatabaseWarning",
+                                                       msg,
+                                                       false);
+                _errorLogger->reportErr(errmsg);
             }
+
         }
     }
 }
@@ -1687,7 +1695,7 @@ bool Function::argsMatch(const Scope *scope, const Token *first, const Token *se
 
 Function* SymbolDatabase::addGlobalFunction(Scope*& scope, const Token*& tok, const Token *argStart, const Token* funcStart)
 {
-    Function* function = 0;
+    Function* function = nullptr;
     for (std::multimap<std::string, const Function *>::iterator i = scope->functionMap.find(tok->str()); i != scope->functionMap.end() && i->first == tok->str(); ++i) {
         if (Function::argsMatch(scope, i->second->argDef->next(), argStart->next(), "", 0)) {
             function = const_cast<Function *>(i->second);
@@ -1709,7 +1717,7 @@ Function* SymbolDatabase::addGlobalFunction(Scope*& scope, const Token*& tok, co
         function->functionScope = scope;
         return function;
     }
-    return 0;
+    return nullptr;
 }
 
 Function* SymbolDatabase::addGlobalFunctionDecl(Scope*& scope, const Token *tok, const Token *argStart, const Token* funcStart)
@@ -2000,7 +2008,6 @@ const Token *Type::initBaseInfo(const Token *tok, const Token *tok1)
                 base.isVirtual = true;
                 tok2 = tok2->next();
             }
-
             if (!tok2)
                 return nullptr;
 
@@ -2061,7 +2068,7 @@ const Function* Type::getFunction(const std::string& funcName) const
 
     for (std::size_t i = 0; i < derivedFrom.size(); i++) {
         if (derivedFrom[i].type) {
-            const Function* func = derivedFrom[i].type->getFunction(funcName);
+            const Function* const func = derivedFrom[i].type->getFunction(funcName);
             if (func)
                 return func;
         }
diff --git a/lib/tokenize.cpp b/lib/tokenize.cpp
index c576659f1..2b2436fce 100644
--- a/lib/tokenize.cpp
+++ b/lib/tokenize.cpp
@@ -7540,10 +7540,10 @@ void Tokenizer::simplifyEnum()
                     continue;
                 }
 
-                Token * enumName = 0;
-                Token * enumValue = 0;
-                Token * enumValueStart = 0;
-                Token * enumValueEnd = 0;
+                Token * enumName = nullptr;
+                Token * enumValue = nullptr;
+                Token * enumValueStart = nullptr;
+                Token * enumValueEnd = nullptr;
 
                 if (Token::Match(tok1->previous(), ",|{ %type%")) {
                     if (Token::Match(tok1->next(), ",|}")) {
@@ -7811,7 +7811,7 @@ void Tokenizer::simplifyEnum()
 
                 tempTok->insertToken(";");
                 tempTok = tempTok->next();
-                if (typeTokenStart == 0)
+                if (typeTokenStart == nullptr)
                     tempTok->insertToken("int");
                 else {
                     Token *tempTok1 = typeTokenStart;
@@ -9840,9 +9840,7 @@ void Tokenizer::createSymbolDatabase()
 {
     if (!_symbolDatabase)
         _symbolDatabase = new SymbolDatabase(this, _settings, _errorLogger);
-    if (_settings->debug) {
-        //_symbolDatabase->validate();
-    }
+    _symbolDatabase->validate();
 }
 
 void Tokenizer::deleteSymbolDatabase()
diff --git a/test/testconstructors.cpp b/test/testconstructors.cpp
index a55cdf22b..ddba1633c 100644
--- a/test/testconstructors.cpp
+++ b/test/testconstructors.cpp
@@ -2519,7 +2519,7 @@ private:
               "    float g;\n"
               "public:\n"
               "    Fred() : f{0, true} { }\n"
-              "    float get() const\n"
+              "    float get() const;\n"
               "};\n"
               "float Fred::get() const { return g; }");
         ASSERT_EQUALS("[test.cpp:9]: (warning) Member variable 'Fred::g' is not initialized in the constructor.\n", errout.str());
diff --git a/test/testother.cpp b/test/testother.cpp
index f4c38037d..bfb8ae651 100644
--- a/test/testother.cpp
+++ b/test/testother.cpp
@@ -4992,7 +4992,7 @@ private:
         check("class C {\n"
               "    int x;\n"
               "    void g() { return x*x; }\n"
-              "    void f();\n"
+              "    void f(Foo z);\n"
               "};\n"
               "\n"
               "void C::f(Foo z) {\n"
diff --git a/test/testsymboldatabase.cpp b/test/testsymboldatabase.cpp
index d815d7dfa..db4a2c1e0 100644
--- a/test/testsymboldatabase.cpp
+++ b/test/testsymboldatabase.cpp
@@ -1598,7 +1598,7 @@ private:
         check("testing::testing()\n"
               "{\n"
               "}");
-        ASSERT_EQUALS("", errout.str());
+        ASSERT_EQUALS("[test.cpp:1]: (debug) executable scope 'testing' with unknown function\n", errout.str());
     }
 
     void symboldatabase5() {