#6804 segmentation fault (invalid code) in Token::getValueTokenDeadPointer. Fix null pointer access

TestGarbage: Increase coverage by running all code snippets as C as well as C++ code. (inspired by #6800)

lib/token.cpp

@@ -1436,6 +1436,8 @@ const Token *Token::getValueTokenDeadPointer() const
         const Variable * const var = vartok->variable();
         if (var->isStatic() || var->isReference())
             continue;
+		if (!var->scope())
+			return nullptr; // #6804
         if (var->scope()->type == Scope::eUnion && var->scope()->nestedIn == this->scope())
             continue;
         // variable must be in same function (not in subfunction)

test/testgarbage.cpp

@@ -134,6 +134,7 @@ private:
         TEST_CASE(garbageCode92);
         TEST_CASE(garbageCode93);
         TEST_CASE(garbageCode94);
+		TEST_CASE(garbageCode95);
 
         TEST_CASE(garbageValueFlow);
         TEST_CASE(garbageSymbolDatabase);
@@ -141,7 +142,20 @@ private:
         TEST_CASE(templateSimplifierCrashes);
     }
 
-    std::string checkCode(const char code[], const char filename[] = "test.cpp") {
+	std::string checkCode(const char code[], const std::string filename = "test.cpp") {
+		// double the tests - run each example as C as well as C++
+		const std::string alternatefilename = (filename=="test.c") ? "test.cpp" : "test.c";
+		// run alternate check first. It should only ensure stability
+		try {
+			checkCodeInternal(code, alternatefilename);
+		}
+		catch(InternalError& ) {
+		}
+
+		return checkCodeInternal(code, filename);
+	}
+
+    std::string checkCodeInternal(const char code[], const std::string& filename) {
         errout.str("");
 
         Settings settings;
@@ -156,7 +170,7 @@ private:
         // tokenize..
         Tokenizer tokenizer(&settings, this);
         std::istringstream istr(code);
-        tokenizer.tokenize(istr, filename);
+		tokenizer.tokenize(istr, filename.c_str());
 
         // call all "runChecks" in all registered Check classes
         for (std::list<Check *>::const_iterator it = Check::instances().begin(); it != Check::instances().end(); ++it) {
@@ -734,6 +748,10 @@ private:
         ASSERT_THROW(checkCode("typedef long __m256i __attribute__ ( ( ( ) ) )[ ; ( ) { } typedef __m256i __attribute__ ( ( ( ) ) ) < ] ( ) { ; }"), InternalError);
     }
 
+    void garbageCode95() { // #6804
+        checkCode("{ } x x ; { } h h [ ] ( ) ( ) { struct x ( x ) ; int __attribute__ ( ) f ( ) { h - > first = & x ; struct x * n = h - > first ; ( ) n > } }");	 // do not crash
+    }
+
     void garbageValueFlow() {
         // #6089
         const char* code = "{} int foo(struct, x1, struct x2, x3, int, x5, x6, x7)\n"