Fixed #4237 (False positive: (error) Memory Leak: data (references and pointer aliases))

lib/tokenize.cpp

@@ -6017,6 +6017,32 @@ bool Tokenizer::simplifyKnownVariables()
                 tok = tok->previous();
                 goback = false;
             }
+            // Reference to variable
+            if (Token::Match(tok, "%type%|* & %var% = %var% ;")) {
+                Token *start = tok->previous();
+                while (Token::Match(start,"%type%|*|&"))
+                    start = start->previous();
+                if (!Token::Match(start,"[;{}]"))
+                    continue;
+                const Token *reftok = tok->tokAt(2);
+                const Token *vartok = reftok->tokAt(2);
+                int level = 0;
+                for (Token *tok2 = tok->tokAt(6); tok2; tok2 = tok2->next()) {
+                    if (tok2->str() == "{") {
+                        ++level;
+                    } else if (tok2->str() == "}") {
+                        if (level <= 0)
+                            break;
+                        --level;
+                    } else if (tok2->varId() == reftok->varId()) {
+                        tok2->str(vartok->str());
+                        tok2->varId(vartok->varId());
+                    }
+                }
+                Token::eraseTokens(start, tok->tokAt(6));
+                tok = start;
+            }
+
             if (tok->isName() && (Token::Match(tok, "static| const| static| %type% const| %var% = %any% ;") ||
                                   Token::Match(tok, "static| const| static| %type% const| %var% ( %any% ) ;"))) {
                 bool isconst = false;

test/testmemleak.cpp

@@ -517,9 +517,6 @@ private:
         // use reference
         ASSERT_EQUALS(";;callfunc&use;", getcode("struct AB *ab; f(&ab);", "ab"));
 
-        // reference
-        ASSERT_EQUALS(";", getcode("char *p; char * & ref = p; p = malloc(10);", "p"));
-
         // return..
         ASSERT_EQUALS(";;return;", getcode("char *s; return;", "s"));
         ASSERT_EQUALS(";;returnuse;", getcode("char *s; return s;", "s"));

test/testtokenize.cpp

@@ -175,6 +175,7 @@ private:
         TEST_CASE(simplifyKnownVariables50);    // #4066 sprintf changes
         TEST_CASE(simplifyKnownVariables51);    // #4409 hang
         TEST_CASE(simplifyKnownVariables52);    // #4728 "= x %cop%"
+        TEST_CASE(simplifyKnownVariables53);    // references
         TEST_CASE(simplifyKnownVariablesIfEq1); // if (a==5) => a is 5 in the block
         TEST_CASE(simplifyKnownVariablesIfEq2); // if (a==5) { buf[a++] = 0; }
         TEST_CASE(simplifyKnownVariablesBailOutAssign1);
@@ -2722,6 +2723,11 @@ private:
         ASSERT_EQUALS("void f ( ) { }", tokenizeAndStringify("void f() { Foo *p = 0; bool b = (p && (p->type() == 1)); }", true));
     }
 
+    void simplifyKnownVariables53() { // references
+        ASSERT_EQUALS("void f ( ) { int x ; x = abc ( ) ; }", tokenizeAndStringify("void f() { int x; int &ref=x; ref=abc(); }", true));
+        ASSERT_EQUALS("void f ( ) { int * p ; p = abc ( ) ; }", tokenizeAndStringify("void f() { int *p; int *&ref=p; ref=abc(); }", true));
+    }
+
     void simplifyKnownVariablesIfEq1() {
         const char code[] = "void f(int x) {\n"
                             "    if (x==5) {\n"