Fix #13031 FP resourceLeak with struct (#7982)

Author: chrchr-github

lib/checkmemoryleak.cpp

@@ -858,8 +858,14 @@ void CheckMemoryLeakStructMember::checkStructVariable(const Variable* const vari
             // This struct member is allocated.. check that it is deallocated
             int indentlevel3 = indentlevel2;
             for (const Token *tok3 = tok2; tok3; tok3 = tok3->next()) {
-                if (tok3->str() == "{")
+                if (tok3->str() == "{") {
+                    if (tok3->scope()->type == ScopeType::eIf && tok3 == tok3->scope()->bodyStart) { // bailout: member checked in if condition
+                        const Token* const condBeg = tok3->scope()->classDef->tokAt(1);
+                        if (Token::findmatch(condBeg, ". %varid%", condBeg->link(), assignToks.first->varId()))
+                            break;
+                    }
                     ++indentlevel3;
+                }
 
                 else if (tok3->str() == "}") {
                     if (indentlevel3 == 0) {

test/testmemleak.cpp

@@ -1941,6 +1941,18 @@ class TestMemleakStructMember : public TestFixture {
                       "[test.cpp:10:5]: (error) Resource leak: s.fd [resourceLeak]\n"
                       "[test.cpp:16:1]: (error) Resource leak: s.fd [resourceLeak]\n",
                       errout_str());
+
+        check("struct S { int fd; };\n" // #13031
+              "void f() {\n"
+              "    struct S* s = malloc(sizeof(struct S));\n"
+              "    s->fd = open(\"abc\", O_RDWR | O_NOCTTY);\n"
+              "    if (s->fd < 0) {\n"
+              "        free(s);\n"
+              "        return NULL;\n"
+              "    }\n"
+              "    return s;\n"
+              "}\n");
+        ASSERT_EQUALS("", errout_str());
     }
 
     void failedAllocation() {