Fixed #1439 (false positive: memory leak when using realloc)

lib/tokenize.cpp

@@ -2945,6 +2945,36 @@ bool Tokenizer::simplifyTokenList()
     simplifyLogicalOperators();
     simplifyCasts();
 
+    // simplify "x=realloc(y,0);" => "free(y); x=0;"..
+    for (Token *tok = _tokens; tok; tok = tok->next())
+    {
+        if (Token::Match(tok, "; %var% = realloc ( %var% , 0 ) ;"))
+        {
+            const std::string varname(tok->next()->str());
+            const unsigned int varid(tok->next()->varId());
+
+            // Delete the "%var% ="
+            tok->deleteNext();
+            tok->deleteNext();
+
+            // Change function name "realloc" to "free"
+            tok->next()->str("free");
+
+            // delete the ", 0"
+            Token::eraseTokens(tok->tokAt(3), tok->tokAt(6));
+
+            // goto the ";"
+            tok = tok->tokAt(5);
+
+            // insert "var=0;"
+            tok->insertToken(";");
+            tok->insertToken("0");
+            tok->insertToken("=");
+            tok->insertToken(varname);
+            tok->next()->varId(varid);
+        }
+    }
+
     // Simplify simple calculations..
     while (simplifyCalculations())
         ;

test/testsimplifytokens.cpp

@@ -211,6 +211,9 @@ private:
 
         // Tokenizer::simplifyReference
         TEST_CASE(simplifyReference);
+
+        // x = realloc(y,0);  =>  free(y);x=0;
+        TEST_CASE(simplifyRealloc);
     }
 
     std::string tok(const char code[], bool simplify = true)
@@ -3993,6 +3996,12 @@ private:
         ASSERT_EQUALS("void f ( ) { int a ; a ++ ; }",
                       tok("void f() { int a; int &b = a; b++; }"));
     }
+
+    void simplifyRealloc()
+    {
+        ASSERT_EQUALS("; free ( p ) ; p = 0 ;",
+                      tok("; p = realloc(p,0);"));
+    }
 };
 
 REGISTER_TEST(TestSimplifyTokens)