Fixed #3220 (False positive: possible null pointer dereference: 'SwDoc *pDoc = NULL; pDoc->do_something();')

lib/check.h

@@ -104,6 +104,10 @@ public:
         std::cout << errmsg.toXML(true, 1) << std::endl;
     }
 
+    bool inconclusiveFlag() const {
+        return _settings && _settings->inconclusive;
+    }
+
 protected:
     const std::string _name;
     const Tokenizer * const _tokenizer;

lib/checknullpointer.cpp

@@ -184,8 +184,13 @@ bool CheckNullPointer::isPointerDeRef(const Token *tok, bool &unknown)
     if (Token::Match(tok->tokAt(-3), "!!sizeof [;{}=+-/(,] * %var%") && Token::Match(tok->tokAt(-3), "!!decltype [;{}=+-/(,] * %var%"))
         return true;
 
-    if (!Token::simpleMatch(tok->tokAt(-2), "& (") && !Token::Match(tok->tokAt(-2), "sizeof|decltype (") && tok->strAt(-1) != "&"  && tok->strAt(-1) != "&&" && Token::Match(tok->next(), ". %var%"))
+    // read/write member variable
-        return true;
+    if (!Token::simpleMatch(tok->tokAt(-2), "& (") && !Token::Match(tok->tokAt(-2), "sizeof|decltype (") && tok->strAt(-1) != "&"  && tok->strAt(-1) != "&&" && Token::Match(tok->next(), ". %var%")) {
+        if (tok->strAt(3) != "(")
+            return true;
+        unknown = true;
+        return false;
+    }
 
     if (Token::Match(tok->previous(), "[;{}=+-/(,] %var% ["))
         return true;
@@ -299,6 +304,11 @@ void CheckNullPointer::nullPointerAfterLoop()
                 if (CheckNullPointer::isPointerDeRef(tok2, unknown)) {
                     nullPointerError(tok2, varname, tok->linenr(), inconclusive);
                 }
+
+                else if (unknown && _settings->inconclusive) {
+                    nullPointerError(tok2, varname, tok->linenr(), true);
+                }
+
                 break;
             }
         }
@@ -1050,6 +1060,8 @@ private:
                 setnull(checks, tok.varId());
             else if (CheckNullPointer::isPointerDeRef(&tok, unknown))
                 dereference(checks, &tok);
+            else if (unknown && owner->inconclusiveFlag())
+                dereference(checks, &tok);
             else
                 // TODO: Report debug warning that it's unknown if a
                 // pointer is dereferenced

test/testnullpointer.cpp

@@ -87,15 +87,22 @@ private:
         ASSERT_EQUALS("[test.cpp:4]: (error) Possible null pointer dereference: tok - otherwise it is redundant to check if tok is null at line 3\n", errout.str());
 
         // #2681
-        check("void foo(const Token *tok)\n"
+        {
-              "{\n"
+            const char code[] = "void foo(const Token *tok)\n"
-              "    while (tok && tok->str() == \"=\")\n"
+                                "{\n"
-              "        tok = tok->next();\n"
+                                "    while (tok && tok->str() == \"=\")\n"
-              "\n"
+                                "        tok = tok->next();\n"
-              "    if (tok->str() != \";\")\n"
+                                "\n"
-              "        ;\n"
+                                "    if (tok->str() != \";\")\n"
-              "}\n");
+                                "        ;\n"
-        ASSERT_EQUALS("[test.cpp:6]: (error) Possible null pointer dereference: tok - otherwise it is redundant to check if tok is null at line 3\n", errout.str());
+                                "}\n";
+
+            check(code, false);   // inconclusive=false => no error
+            ASSERT_EQUALS("", errout.str());
+
+            check(code, true);    // inconclusive=true => error
+            ASSERT_EQUALS("[test.cpp:6]: (error) Possible null pointer dereference: tok - otherwise it is redundant to check if tok is null at line 3\n", errout.str());
+        }
 
         check("void foo()\n"
               "{\n"
@@ -715,12 +722,21 @@ private:
               "}\n");
         ASSERT_EQUALS("[test.cpp:4]: (error) Null pointer dereference\n", errout.str());
 
-        check("static void foo(int x)\n"
+        {
-              "{\n"
+            const char code[] = "static void foo(int x)\n"
-              "    Foo<int> *abc = 0;\n"
+                                "{\n"
-              "    abc->a();\n"
+                                "    Foo<int> *abc = 0;\n"
-              "}\n");
+                                "    abc->a();\n"
-        ASSERT_EQUALS("[test.cpp:4]: (error) Possible null pointer dereference: abc\n", errout.str());
+                                "}\n";
+
+            // inconclusive=false => no error
+            check(code,false);
+            ASSERT_EQUALS("", errout.str());
+
+            // inconclusive=true => error
+            check(code, true);
+            ASSERT_EQUALS("[test.cpp:4]: (error) Possible null pointer dereference: abc\n", errout.str());
+        }
 
         check("static void foo()\n"
               "{\n"
@@ -899,6 +915,13 @@ private:
               "    int x = &fred->x;\n"
               "}");
         ASSERT_EQUALS("", errout.str());
+
+        // ticket #3220: calling member function
+        check("void f() {\n"
+              "    Fred *fred = NULL;\n"
+              "    fred->do_something();\n"
+              "}");
+        ASSERT_EQUALS("", errout.str());
     }
 
     // Ticket #2350