Fixed #2641 (False positive: Possible null pointer dereference (global pointer, function call))

lib/checknullpointer.cpp

@@ -448,6 +448,15 @@ void CheckNullPointer::nullPointerStructByDeRefAndChec()
             else if (indentlevel2 == 0 && tok2->str() == "return")
                 break;
 
+            // Function call: If the pointer is a global variable it
+            // might be changed by the call.
+            // TODO: false negatives if the pointer is local.
+            else if (Token::Match(tok2, "[;{}] %var% (") &&
+                     Token::simpleMatch(tok2->tokAt(2)->link(), ") ;"))
+            {
+                break;
+            }
+
             // Check if pointer is null.
             // TODO: false negatives for "if (!p || .."
             else if (Token::Match(tok2, "if ( !| %varid% )|&&", varid1))

test/testnullpointer.cpp

@@ -326,6 +326,15 @@ private:
               "        ;\n"
               "}\n");
         ASSERT_EQUALS("", errout.str());
+
+        // #2641 - global pointer, function call
+        check("ABC *abc;\n"
+              "void f() {\n"
+              "    abc->a = 0;\n"
+              "    do_stuff();\n"
+              "    if (abc) { }\n"
+              "}");
+        ASSERT_EQUALS("",errout.str());
     }
 
     // Dereferencing a pointer and then checking if it is null