Refs #13031 Fix FN resourceLeak with cast (danmar#7973)

Author: chrchr-github

lib/checkmemoryleak.cpp

@@ -744,8 +744,15 @@ bool CheckMemoryLeakStructMember::isMalloc(const Variable *variable) const
     for (const Token *tok2 = variable->nameToken(); tok2 && tok2 != variable->scope()->bodyEnd; tok2 = tok2->next()) {
         if (Token::Match(tok2, "= %varid% [;=]", declarationId))
             return false;
-        if (Token::Match(tok2, "%varid% = %name% (", declarationId) && mSettings->library.getAllocFuncInfo(tok2->tokAt(2)))
-            alloc = true;
+        if (Token::Match(tok2, "%varid% =", declarationId)) {
+            const Token* tok3 = tok2->tokAt(1)->astOperand2();
+            while (tok3 && tok3->isCast())
+                tok3 = tok3->astOperand2() ? tok3->astOperand2() : tok3->astOperand1();
+            if ((tok3 && Token::Match(tok3->tokAt(-1), "%name% (") && mSettings->library.getAllocFuncInfo(tok3->tokAt(-1))) ||
+                (Token::simpleMatch(tok3, "new") && tok3->isCpp())) {
+                alloc = true;
+            }
+        }
     }
     return alloc;
 }

test/testmemleak.cpp

@@ -1673,6 +1673,7 @@ class TestMemleakStructMember : public TestFixture {
         TEST_CASE(assign2);
         TEST_CASE(assign3);
         TEST_CASE(assign4); // #11019
+        TEST_CASE(assign5);
 
         // Failed allocation
         TEST_CASE(failedAllocation);
@@ -1919,6 +1920,29 @@ class TestMemleakStructMember : public TestFixture {
         ASSERT_EQUALS("", errout_str());
     }
 
+    void assign5() {
+        check("struct S { int fd; };\n"
+              "void f() {\n"
+              "    struct S* s = (struct S*)malloc(sizeof(struct S));\n"
+              "    s->fd = open(\"abc\", O_RDWR | O_NOCTTY);\n"
+              "    free(s);\n"
+              "}\n"
+              "void g() {\n"
+              "    struct S* s = static_cast<struct S*>(malloc(sizeof(struct S)));\n"
+              "    s->fd = open(\"abc\", O_RDWR | O_NOCTTY);\n"
+              "    free(s);\n"
+              "}\n"
+              "void h() {\n"
+              "    S* s = new S;\n"
+              "    s->fd = open(\"abc\", O_RDWR | O_NOCTTY);\n"
+              "    delete s;\n"
+              "}\n");
+        ASSERT_EQUALS("[test.cpp:5:5]: (error) Resource leak: s.fd [resourceLeak]\n"
+                      "[test.cpp:10:5]: (error) Resource leak: s.fd [resourceLeak]\n"
+                      "[test.cpp:16:1]: (error) Resource leak: s.fd [resourceLeak]\n",
+                      errout_str());
+    }
+
     void failedAllocation() {
         check("static struct ABC * foo()\n"
               "{\n"