Fixed ticket #3550 (false positive: (error) Memory pointed to by 'pxpm' is freed twice)

lib/checkother.cpp

@@ -2514,8 +2514,17 @@ void CheckOther::checkDoubleFree()
             closeDirVariables.clear();
         }
 
+
         // If a variable is passed to a function, remove it from the set of previously freed variables
-        else if (Token::Match(tok, "%var% (") && !Token::Match(tok, "printf|sprintf|snprintf|fprintf")) {
+        else if (Token::Match(tok, "%var% (") && !Token::Match(tok, "printf|sprintf|snprintf|fprintf|if|while")) {
+
+            // If this is a new function definition, clear all variables
+            if (Token::Match(tok->next()->link(), ") {")) {
+                freedVariables.clear();
+                closeDirVariables.clear();
+            }
+            // If it is a function call, then clear those variables in its argument list
+            else if (Token::Match(tok->next()->link(), ") ;")) {
                 for (const Token* tok2 = tok->tokAt(2); tok2 != tok->linkAt(1); tok2 = tok2->next()) {
                     if (Token::Match(tok2, "%var%")) {
                         unsigned int var = tok2->varId();
@@ -2526,6 +2535,7 @@ void CheckOther::checkDoubleFree()
                     }
                 }
             }
+        }
 
         // If a pointer is assigned a new value, remove it from the set of previously freed variables
         else if (Token::Match(tok, "%var% =")) {

lib/checkother.h

@@ -329,6 +329,7 @@ public:
         c.sizeofForStrncmpError(0);
         c.sizeofForNumericParameterError(0);
         c.coutCerrMisusageError(0, "cout");
+        c.doubleFreeError(0, "varname");
 
         // style/warning
         c.cstyleCastError(0);

test/testother.cpp

@@ -4679,6 +4679,18 @@ private:
             "  delete[] p;\n"
             "}");
         ASSERT_EQUALS("[test.cpp:4]: (error) Memory pointed to by 'p' is freed twice.\n", errout.str());
+
+        check(
+            "~LineMarker() {"
+            "  delete pxpm;"
+            "}"
+            "LineMarker &operator=(const LineMarker &) {"
+            "  delete pxpm;"
+            "  pxpm = NULL;"
+            "  return *this;"
+            "}"
+        );
+        ASSERT_EQUALS("", errout.str());
     }
 
     void coutCerrMisusage() {