Fix #10996 FN memleak suppressed for library function by (void) (#5891)

Author: chrchr-github

lib/checkleakautovar.cpp

@@ -833,15 +833,18 @@ const Token * CheckLeakAutoVar::checkTokenInsideExpression(const Token * const t
             } else {
                 // check if tok is assigned into another variable
                 const Token *rhs = tok;
+                bool isAssignment = false;
                 while (rhs->astParent()) {
-                    if (rhs->astParent()->str() == "=")
+                    if (rhs->astParent()->str() == "=") {
+                        isAssignment = true;
                         break;
+                    }
                     rhs = rhs->astParent();
                 }
                 while (rhs->isCast()) {
                     rhs = rhs->astOperand2() ? rhs->astOperand2() : rhs->astOperand1();
                 }
-                if (rhs->varId() == tok->varId()) {
+                if (rhs->varId() == tok->varId() && isAssignment) {
                     // simple assignment
                     varInfo.erase(tok->varId());
                 } else if (rhs->astParent() && rhs->str() == "(" && !mSettings->library.returnValue(rhs->astOperand1()).empty()) {

test/testleakautovar.cpp

@@ -455,12 +455,19 @@ class TestLeakAutoVar : public TestFixture {
         ASSERT_EQUALS("[test.cpp:3]: (error) Memory leak: p\n", errout.str());
     }
 
-    void assign21() { // #10186
-        check("void f(int **x) {\n"
+    void assign21() {
+        check("void f(int **x) {\n" // #10186
               "    void *p = malloc(10);\n"
               "    *x = (int*)p;\n"
               "}", true);
         ASSERT_EQUALS("", errout.str());
+
+        check("struct S { int i; };\n" // #10996
+              "void f() {\n"
+              "    S* s = new S();\n"
+              "    (void)s;\n"
+              "}", true);
+        ASSERT_EQUALS("[test.cpp:5]: (error) Memory leak: s\n", errout.str());
     }
 
     void assign22() { // #9139