Fixed #2647 (False positive: Possible null pointer dereference (member function call))

lib/checknullpointer.cpp

@@ -418,6 +418,16 @@ void CheckNullPointer::nullPointerStructByDeRefAndChec()
         if (var && (var->isLocal() || var->isArgument()))
             isLocal = true;
 
+        // member function may or may not nullify the pointer if it's global (#2647)
+        if (!isLocal)
+        {
+            const Token *tok2 = tok1;
+            while (Token::Match(tok2, "%var% ."))
+                tok2 = tok2->tokAt(2);
+            if (Token::Match(tok2,"%var% ("))
+                continue;
+        }
+
         // count { and } using tok2
         unsigned int indentlevel2 = 0;
         for (const Token *tok2 = tok1->tokAt(3); tok2; tok2 = tok2->next())

test/testnullpointer.cpp

@@ -336,6 +336,13 @@ private:
               "}");
         ASSERT_EQUALS("",errout.str());
 
+        check("Fred *fred;\n"
+              "void f() {\n"
+              "    fred->foo();\n"
+              "    if (fred) { }\n"
+              "}");
+        ASSERT_EQUALS("",errout.str());
+
         // #2641 - local pointer, function call
         check("void f() {\n"
               "    ABC *abc;\n"