Kas Ob.

@Clément Try this non blocking refined code with leakage : unit uTCPPortCheckNonBlocking; interface uses Windows, Winsock2; function WSAInitialize(MajorVersion, MinorVerion: Integer): Boolean; function WSADeInitialize: Boolean; function CheckTCPPortNB(const IP: string; Port: Integer; out TimeMS: Integer): Boolean; var CHECKPOINT_TIMEOUT_MS: integer = 1000; implementation function CheckTCPPortNB(const IP: string; Port: Integer; out TimeMS: Integer): Boolean; var s: TSocket; Addr: TSockAddrIn; SAddr: TSockAddr absolute Addr; QPF, QPC1: Int64; NonBlockMode: DWORD; Res: Integer; FDW, FDE: fd_set; TimeVal: TTimeVal; function GetElapsedTime: Integer; var QPC2: Int64; begin QueryPerformanceCounter(QPC2); Result := (QPC2 - QPC1) div (QPF div 1000); end; begin Result := False; TimeMS := 0; s := socket(AF_INET, SOCK_STREAM, IPPROTO_TCP); if s = INVALID_SOCKET then Exit; NonBlockMode := 1; ioctlsocket(s, Integer(FIONBIO), NonBlockMode); Addr.sin_family := AF_INET; Addr.sin_addr.S_addr := inet_addr(PAnsiChar(AnsiString(IP))); Addr.sin_port := htons(Port); QueryPerformanceFrequency(QPF); QueryPerformanceCounter(QPC1); Res := connect(s, SAddr, SizeOf(SAddr)); if (Res = SOCKET_ERROR) and (WSAGetLastError = WSAEWOULDBLOCK) then begin TimeVal.tv_sec := 0; // 1 sec = 1000000 usec TimeVal.tv_usec := 1000; // 1 ms = 1000 usec repeat FDW.fd_count := 1; FDW.fd_array[0] := s; FDE.fd_count := 1; FDE.fd_array[0] := s; TimeMS := GetElapsedTime; Res := select(1, nil, @FDW, @FDE, @TimeVal); until (Res > 0) or (TimeMS >= CHECKPOINT_TIMEOUT_MS); end; Result := (FDW.fd_count = 1) and (FDE.fd_count = 0); TimeMS := GetElapsedTime; if s <> INVALID_SOCKET then closesocket(s); end; function WSAInitialize(MajorVersion, MinorVerion: Integer): Boolean; var WSA: TWsaData; begin Result := WSAStartup(MakeWord(MajorVersion, MinorVerion), WSA) = 0; if Result then begin Result := (Byte(WSA.wVersion shr 8) = MinorVerion) and (Byte(WSA.wVersion) = MajorVersion); if not Result then begin Result := False; WSADeInitialize; end; end; end; function WSADeInitialize: Boolean; begin Result := WSACleanup = 0; end; initialization WSAInitialize(2, 2); finalization //WSADeInitialize; end. the result and that is clean WireShark view, don't you think ? also the timing is very close the ICMP ping, adjust CHECKPOINT_TIMEOUT_MS, in the above code it is 1 sec. Now to the real question because i still don't understand you are you trying to achieve, see, i will put my logic circulating in my brain, and please either correct me ( show me what i am missing ) or try be convinced with different approach. Trying to utilize TCP as ping somehow, is the point is to keep the connection alive then this will not help at all you need to 1) Use the same TCP connection you are trying to keep alive, meaning adding specific protocol Ping/Pong between you Client/Server (explained earlier), or you don't need to keep a connection alive you need to check server availability on specific port, then fine, you need to 2) A simple Connect and like (1) or, connect and then disconnect like the samples above, but in this case you don't need to send anything or wait to receive, so sending zero length data is like calling for undefined behavior or unknown consequences, like as i mentioned firewalls interactions or in this case if PERM_SACK is always there and signaling the peer (server) is it OK to selectively send ACK, then server after connect and ACK the connection it might hold on ACK after that zero length data packet, because it is within its right, keep it as much as 300ms may be, while answering your packet with another zero packet hence your client received an answer but didn't receive ACK for the send, this will cause confusion. 3) you don't want to just detect listening port ( aka open port and port scan style), you want to check the server logic part is answering requests then simple connect and disconnect is not suitable and you need to 4) Connect and send something not zero length to avoid (2) then we returned to (1) or (2) again because of (3) This loop that is bugging me. Anyway the code in this post is working fine and it is non blocking and will detect running server on specific TCP port, if you want to send and receive then the change is minimal: Repeat the select loop twice, the first to check readiness for write, the same loop above, then perform send, then another loop but for read instead of write, you need FDR just like FDW without FDW, you can use the same variable, after that you perform recv then close, do not call shutdown, and to be perfect then another loop after recv to check for read same as the first loop, and that it is. Hope that helps.

Thank you for pointing this. Yup, you are right there as i can't remember trying this on blocking connect and it seems Windows still doesn't support TCP_USER_TIMEOUT even it was RFCed since 2009 https://datatracker.ietf.org/doc/html/rfc5482 Thank you again. SACK can be disabled per socket, that i am sure of, and you can test it, but from what i can see PERM_SACK is always globally available either disabled or enabled, PERM_SACK does allow the peer to use and utilize SACK.

@Clément Try this please: unit uTCPPortCheckBlocking; interface uses Windows, Winsock2; function WSAInitialize(MajorVersion, MinorVerion: Integer): Boolean; function WSADeInitialize: Boolean; function CheckTCPPortBlocking(const IP: string; Port: Integer; out TimeMS: Integer): Boolean; implementation function CheckTCPPortBlocking(const IP: string; Port: Integer; out TimeMS: Integer): Boolean; var s: TSocket; Addr: TSockAddrIn; SAddr: TSockAddr absolute Addr; QPC1, QPC2, QPF: Int64; begin Result := False; s := socket(AF_INET, SOCK_STREAM, IPPROTO_TCP); if s = INVALID_SOCKET then Exit; Addr.sin_family := AF_INET; Addr.sin_addr.S_addr := inet_addr(PAnsiChar(AnsiString(IP))); Addr.sin_port := htons(Port); QueryPerformanceFrequency(QPF); QueryPerformanceCounter(QPC1); Result := connect(s, SAddr, SizeOf(SAddr)) <> SOCKET_ERROR; QueryPerformanceCounter(QPC2); TimeMS := (QPC2 - QPC1) div (QPF div 1000); if Result then closesocket(s); end; function WSAInitialize(MajorVersion, MinorVerion: Integer): Boolean; var WSA: TWsaData; begin Result := WSAStartup(MakeWord(MajorVersion, MinorVerion), WSA) = 0; if Result then begin Result := (Byte(WSA.wVersion shr 8) = MinorVerion) and (Byte(WSA.wVersion) = MajorVersion); if not Result then begin Result := False; WSADeInitialize; end; end; end; function WSADeInitialize: Boolean; begin Result := WSACleanup = 0; end; initialization WSAInitialize(2, 2); finalization //WSADeInitialize; end. This is blocking mode, and you can reduce the timeout before connect to 1 second, And i really angry now as i can't disable SACK for connect !, i not only sure it was disabled for connect but i had to enforce enabling it with my 5 years old project when i needed to deep analyze FileZilla SSH fast behavior and replicate it with my code, back then i found SACK played huge role in achieving stable 8MB/s of file downloading over 100mbps connection between Ukraine and France with RTC and SecureBlackBox. But now with my current Windows (10.0.19045.4291) it is enabled and can't be disabled as i can see, back then my Windows 10 was version 17something. Anyway: the code above is simple stupid but will do the will perform fast without the need to send or perform recv it will detect if remote port is listening and i think this is what you are looking for. This is my result with google IP var PortScanRes: Boolean; Time: Integer; begin PortScanRes := CheckTCPPortBlocking('142.251.36.46', 80, Time); Memo1.Lines.Add(BoolToStr(PortScanRes, True) + ' ' + IntToStr(Time));

No, you are not ! I cannot compile your code, but have to point that SACK (Selective Acknowledgements) is enabled and this option might solve your problem Disable delayed ACK like Remy suggestion https://stackoverflow.com/questions/55034112/c-disable-delayed-ack-on-windows But away from that, i highly recommend to use Select before any read or receive or even close, select is your best friend and guidance for these ACK, select will trigger sending pending ACKs. Now to the real cause : you have to know this very important fact about shutdown( , SD_SEND ): It will send FIN and wait for ACK but will with high probability prevent sending any further traffic even ACK !!!!, this behavior with ACK has being changed over many Windows versions and it is different from OS to OS. Also your Wireshark capture is is only for the client, this is half useful, you will get the better picture by capture the traffic in both side, so the ACK was an acknowledgment for what exactly ? notice the failed one and retransmitted is the the ACK with SEQ=1 so the failed to sent is the FIN not the ACK, the packet before the last one.

Also, i would love to see if there a change in timing in your result with TCP_NODELAY.

I do understand, and it will work. Just handle an error after that send to exit the loop, and i want to add this fact: The TCP peer that does close the socket will trigger TIME_WAIT on the remote side, TIME_WAIT is absolutely harmless and in fact it is a good thing, just don't panic if like in this case on server side you see them accumulate.

Hi @Clément , Well, i couldn't let it go, as that loop is stuck in my head and it need fixing. Firstly and as a rule of thumb in this era always disable Nagle algorithm TCP_NODELAY, even if Windows says it will be disabled by default https://learn.microsoft.com/en-us/windows/win32/api/winsock/nf-winsock-setsockopt Secondly : That "While not done do " loop is confusing, what is the point of it ? it is acting as blocking or non blocking ? I mean what will happen if Send retuned an error? then you are spiking the CPU for 200ms with that Sleep(0) over erroneous/broken socket, also it is acting as blocking, then the logic sense is to replace it with more reliable approach. And here the suggestions : 1) Don't Send a zero length TCP (or UDP) packet !, yes it works for now, but trust me there is many firewalls with different flavors and smells, and they will block that as DoS, and it is rightfully they do. 2) Is your 0 length for saving traffic ? if so, then its make less sense, the the packet header for IPv4 and the TCP is over 44 bytes and most likely will be 56 bytes, so send something, if you are checking your own server then send the current time (current tick) and let the server returned it, thus you will have the round trip measured in ms, in my projects i do have similar ping but i do define the protocol as (2+1)*4 then (3+1)*4 bytes, client send its time and the last received server time, the server will add its current time and last received client time and return it, hence both will have live delay, specially for the server it can map the clients latencies. (+1 is for the ping and pong header and its option) 3) Why creating the socket each and every time, create once and reuse it, i always use the same one for the real data traffic, if you are pinging a HTTP server then perform a small request and let the server response with minimal response. 4) Before sending it always better to check for readiness for write, aka writability, so in your code above you can perform select() then and only then perform the send.

Have a look at this HeapMM https://github.com/maximmasiutin/FastCodeBenchmark/blob/master/MMv1_BV113/HeapMM.pas This is more than sufficient for your need case, only you must understand that the way you will use the DLL is similar to the way you intended to use the separated process, in other words : be careful ! there is no memory sharing for managed types ! So no string or arrays passing (among other managed types) between your exe and that dll ! Last thing, there is this directive in that HeapMM {$DEFINE USE_PROCESS_HEAP} This should be disabled {.$DEFINE USE_PROCESS_HEAP} By disabling it, the dll will be using its own heap and will free it so if it does leaks memory it will be erased on unloading the library. Also note this: if you are going to run multiple scripts concurrently then this will the DLL approach will be challenging, so either let them run and every now and then unload the library (FreeLibrary), or you can copy the DLL with different names and loading them separately, just food for thoughts. ps: understanding how memory manager works is nice to know, the the heap one is the most minimalistic form for a memory manager.

Yes, this is the only way, also you can make it a DLL, only make sure to not use a shared memory memory manager with the exe. Use the OS heap API as local memory manager.

No, will not. Because : 1) for 32 bit : it will stay on 32 bit and will not hit the signed not signed range anyway, hence it will still working. 2) for 64 bit: well same as above ! Now back to this in whole You are hitting different village here, what are you talking about or referring to, are stuff belongs to runtime pointer operation, at run time calculated : 1) These bug are exposed by FastMM with high memory allocation, there is a setting in FastMM4Options.inc called AlwaysAllocateTopDown, this will catch or at least help in catching such bugs. 2) No matter what your code is doing with pointers the code will stay at its place and it is where the image had being loaded, (not talking about runtime generated code like JIT or any), we are talking about default a process started by executing an exe, and we assuming the compiler is doing right job, the EIP will not leave the designated as execution pages when the image had being loaded by the OS, now if we moved these pages up by address, meaning we pushed the loading address 100mb or $F000000, will it fail ? if there is relocation table then it will not fail, if there is no relocation table, then the OS will revert to the default which most likely $400000 and call it a day. ASLR merely load the image at different places as i said, and here i want to list what it does exactly for last time 1) Load the executable binary/image at random address, in the old days it was always the same and it comes form the PE. 2) Make the stack allocation at random, without it and like the old age, the stack like for the main thread was always at the same address, this is very observable even now with a debugged process, the stack position between two runs, and that because (3) : 3) Make memory allocation at random, this is second most important change as a process calls VirtualAlloc at beginning of its start without ASLR enabled most likely will have the same address, ASLR will prevent that. Now, in both case id a DLL does support ASLR or not it will comply with relocation table to be loadable, duh, and this is most of the ASLR critical point, the rest is : it does expect a memory allocation or a position at the stack to be the same every time, i never saw a Delphi generated code have that, hence all Delphi DLLs are ASLR ready ! , and they will work fine. For EXE it might be different but only for the image loading addresses, but it will also be ready for the randomization of the stack and allocations. This is a nice article about ASLR when it failed to be ASLR https://insights.sei.cmu.edu/blog/when-aslr-is-not-really-aslr-the-case-of-incorrect-assumptions-and-bad-defaults/

Well, this need some explanation. 1) ASLR has nothing to do with code, well written or bad one. 2) ASLR is merely randomization of system allocation memory for this process, so no address can be guessed per execution. 3) Badly written code can violate ASLR, but this is not bad code, it is code that runs out side the control of the compiler, aka override it with fixed address, such code will fail, ASLR in fact being made for this case, now if the code of the executable is abusing the addressing scheme then it will fail, beyond that, only malicious and blindly (or remotely) injected code will fail to run as intended, because there is known addresses before hand. 4) Windows executables should support ASLR by simply have right and well defined relocation table in PE. 5) By default all DLLs should and must be ASLR compatible because by definition and form the beginning of Windows OS and its API, the DLL loading address can't be known before hand, and can't be fixed, yet for many years and many versions, Windows loaded specific DLLs to the same addresses. 6) for EXE to support ASLR it must have Relocation Table https://0xrick.github.io/win-internals/pe7/ without it it will fail if ASLR is enforced by the OS, this is historical problem as for long time the loading address for EXE on windows was $400000 by default so many linker ( and compiler) didn't follow the rules and generated right relocation table, or even worse, there is many tools to minimize your EXE size that does strip that table rendering the EXE not ASLR compatible. 7) to my knowledge Delphi generated binaries relocation table was correct and right and was there, and should be a problem unless there is regression somewhere. Again ASLR compatibility is Linker responsibility, but yet the compiler could generate code that confuses the linker and make it fail to build right relocation table. ps: Relocation table in short words, it is a table that the system will parse and patch (change addresses) after (and while) loading the PE image sections into the memory based on the relative addresses in that table to the addresses that OS picked, and that before giving the new process the execution in case of EXE, and while blocking LoadLibrary and before calling DllMain.

Yes, right on the point. This is very confusing, as there is anonymous methods and there is anonymous procedure/function. These are different things, methods are aware of self and it is a must to have, while the latter don't have self.

I think i can pin point it ! Just remembered another situation when the project wasn't using specific 3rd party library library, namely AlphaSkins and acPng dcu kept popping in compiled while it wasn't referenced in that project, the project wasn't even using AlphaSkins but the standard VCL TImage, this happen on my IDE and my PC not the client (owner of the source), i solved it by simply disabling or removing that package form the IDE when working on that project.

I witnessed such behavior, in few times was not a pas unit but in dcu file referring to some ghost unit that i don't have reference in the code. And it was a removed referenced unit after refactoring, so searching for the name of needed unit will return no result, while the dcu still having the reference. Try to rename the folders with your DCU's, also when it dcu tracking then Process Monitor will show some extra information about this.

Rename that unit, then build.

As i said because it failed so many times to guarantee better and safer code practice, as we read so many times, so is it the best?, yeah it is,.. is it suggest to continue to be used in most critical software ? here comes the answer : NO , so is there better solution ? Yes and they calling to skip it to something better and more safer, not ... again not because it can't deliver, but there is a problem with the human factor and they gave up on fixing it. Don't take my opinion on the subject, and think about this : Can all the big companies wrong as they call to drop the language and switch to something else ? And please remember that : what ever you might suggest or even imagine, is already had been done and tried with C/C++ and still failed again and again. Rust doesn't have that much of unique as language except key features which limit the developer to design as he might imagine or wish, and involve the compiler even more, for Delphi (though) this might trigger many here, smart pointer will be wrong direction and will not solve anything, not just because Embarcadero might fail to deliver, or waste of time and resources, but because with all the libraries in C/C++ and still failing, so why repeat the tested and expect different result, please don't take this as debate for now about this subject, it is what one can deduce from what is happening now. Delphi will be many folds safer with removing or limiting the memory handling by code and give that to the compiler, same as Rust, if there is no shuffling then we don't need smart pointer or stupid ones, it is so simple, will this hinder our coding design, may be it will, but most likely it only need more code, though i doubt it will be longer than it is now, in all cases it will ensure better design and structure, a hardened and sound one. Imagine one directive at the top of the unit Delphi file that make all the variables and fields initialized and compiler and compile time managed, the compiler will stop you until fix them all, breaking zero backward code (legacy), and ensure the future is brighter and better, and the transition will be easier with compiler error and warning, and no smart pointers with stupid code that trying to retrieve few milliseconds in performance while different approach could be faster at the root.

Fair and with in your right, but let me ask you a simple question When you last time saw Delphi/Pascal code where a function had one letter name like f or g ?... Yesterday i watched this I believe i pasted the link as Stefan put it in the German forum The talk is great and very valuable, and if anyone is not familiar with lecture then know that this dude wrote C++ specification for breakfast, and here it comes write the guide lines for safety, yet when i watched it i saw that he himself with his examples violate a rule that always use expressive naming, and yes there was f and g, this comes from math, and the obsession of C++ developer with math to look cool, everyone looks to Bjarne and his talks and books, yet the beginners will scratch these examples in their brains forever with one letter function as name. Look at this "New Rules" titled in 2020 https://devblogs.microsoft.com/cppblog/new-safety-rules-in-c-core-check/ I think every C and C++ compiler out there does warn about default for a switch, yet that blog post deemed it a must to remind everyone with it, in Rust the code will not compile and C and C++ and in %90 no one will see it because there 458648567 another warning, some of these warnings makes sense but most of them don't, C and C++ are cursed with arrogance and stubbornness and its culture is beyond control, (my opinion) Rollo62 all what i am saying is even with all of this power of C++, it fails be the best language for long term security and safety, they (the most invested companies and teams and i trust they have better insight and view on this subject ) said C/C++ will not cut it and Rust it is. they decided to burn the tower and throw the power tools for better language, that (again) doesn't bring any thing new, on the contrary only remove the ability to use many C++ features, and evidently they see it as success story.

One more thing, if it was easy to define and put finger on memory safety issues in C++, then trust me, no one would have discussed memory safety at this scope and this range of popularity. Each projects and each company has its own strict guide lines for safety and integrity of code, yet it is so clear that they are still short and still fail. In movies they say the villain should be masterful without any mistakes every time, while the good detective need to be lucky once. With security this rule is reversed the good guy should not make a simple mistake in thousands of code, and the villain need to be lucky to found one mistake. Delphi/Pascal is easier to produce memory safe code and executables.

Its not that only. See, we the Delphi programmers used to do things in specific way, this out of the structure of the language of Pascal and by tradition or best practices, it goes like (as example ) automatically without thinking to put try..finally then call free, C++ there is none like this, but i am not saying C++ is incapable of, on contrary it can do more things because it is more powerful, but C++ developers doesn't have the discipline of Pascal's, this is exactly why all these big companies with their top tier developer keep doing or falling with the same traps again and again. When these big companies suggest to switch to different language like Rust not out of powerful of Rust or the lack of the tools in C++, on the contrary they reached to a conclusion that too much power is simply harmful, more limited tools are better fit and more secure. When you say Delphi is not memory safe, yes it is, just like any other language, yet the guide lines for Pascal and Delphi are way simpler and clearer than C++ to produce memory safe code (either bugs or vulnerability) , Rust is similar, its guide lines are harder to break as they incorporated within the language syntax itself. In Delphi if you leave the Overflow Check at on all the time, then you really had to be making big mistakes to breach memory safety for something like accessing index memory or handling managed types, these managed types specially arrays and strings are managed by the compiler in very nice way, in C++ there is hundreds of implementation of such arrays and strings, and they all will depends on some implementation, yet while they are completely safe at the same type coming form the same library, they are useless when it comes to interact with different library or the OS or whatever and here comes the problems of casting and unsafe converting.

Also SHA3, SHA512 are faster by at least %50 than SHA256.

If C++ compiler allocated all vars upfront and didn't use PUSH/POP inside any scope of code then they will be closer.

As Lajos said, if they are only cache and will not be needed after a restart or to be shared with different process, then put them in system temp folder and don't share writing, as for hashing 44Mb is nothing to worry about, but you can build a table to hash parts like every 64kb this way you will check that part when you read (need) it.

About this ! I am sorry but will try again with different method to explain why few users here is missing the right angel to look at this. So: 1) The memory safety in all these articles and publication are not about what you think is, though few of them miss name the problem or miss use the term in wrong places, this is the problem when there is no clear definition. 2) The most memory safe language is JavaScript, I honestly believe that, as stupid as it sound, BUT you must understand what are we describing here, see, it is near impossible to write JS code and take over a PC, can you ? and the question is not that, to be exact can you escalate memory failure within JS code to execute out of bound code aka hijack the execution ? NOPE, you can't ! JS is almost always runs in a special VM with interpreter, so you need to escalate a memory violation to escape that VM which in %99 run inside isolated process of browser then hijack the execution there, then escape the host browser process itself, then trigger malicious execution in the host that runs the browser, .... JS is memory safe for this subject, which is escalating memory triggered violation by malicious data (again data) to execute managed or unmanaged code (malicious or whatsoever aka DDoS) 3) I am mathematician by education, and i tend to an abstract(s) everywhere, this helps me, so lets look at this but from different perspective, one said he can compare potatoes and grapes, may be farmers and cooks will lose their shit, while i am fine with it, it is his build, abstract, math realm ... call it what ever you want, and let him call it as he wish, he managed to compare potatoes and grapes, and without understanding this scale we can't argue with rightness not we can call it fallacy, he might be comparing the percent of water or Zinc ... in both, or something not very usual like the shade of color in comparison HTML color names then sorts these names then put the grape or the potato in a scale of it, You know what we don't care about this abstract we care about different thing, there is a scale so we can use it, When all these companies shouting about memory safety, well they have the best developer and programmers in the world, i mean literally the best end there, and their code with be reviewed many times, and these companies like Apple, Google, Microsoft, Oracle, IBM ...they don't cheap out on bugs and security, i am sure they tried everything they could, and now they are throwing the towel, no matter how good and experienced their developers, they again and again do the same mistakes and same wrong doing, causing security bug and CVE, these cost money and reputation, remember these CVE are fixed and patched by the same experienced top shelf programmers, yet again they doomed to repeat the same. This also goes for open source software like Linux and Mozilla, literally the memory safety induced breach is there and no one can see it, and nor AI. Anyway, they are throwing the towel now and switch to prevent the developer from doing smart stuff, and limit their lanes, Rust is very strict and fit those needs, and that why all of these as C++ is way too much powerful and the developers tend grab it and start swing, the approach of investing in the developers them self, looks like failed or didn't yield the required result, so switching to different approach like changing the tooling. Again memory safety is not from powerful language as powerfulness is irrelevant here, but from consequences of using that language to handle data in the memory. 4) They all managed to have a scale to compare Rust and C/C++ in memory safety (again within the context explained above), then we can use the same scale for Delphi. 5) C++ is way more powerful than Rust, and there is nothing can't be done with C++ that Rust has, yet we are talking about different problem the ignoring the human factor, the one that made all these companies give up on their developers, and all these 3 letters agencies recommend, they all saw stuff and shit. back to this It is not !, but wait what are we talking about ? is memory-safe in your phrase is the same as my above or in the articles ? the same perspective ? It is not !, yet it is safer than C++, just because we are limited with stack usage, and our variables allocated before hand.

This subject is relatively fresh Yet searching for "PEM" or "JWK" result in nothing. DDG can find them though

I mentioned or to be exact dreamed about more evolved Pascal enhancement, mentioned it here at once as i recall, but really can't remember any comments or any discussions. So will write it here as it is relevant for memory safety. My suggestion is to introduce new modifier(s) to managed (and non managed) variables, this include classes/objects, the new main modifier is "Auto", example procedure Test(aFileName: string); var SList: TStringList; auto; // the compiler will ensure calling the default constructor and destructor begin //SList := TStringList.Create; // should stop the compiler with specific Error, you are not allowed to create an auto SList.LoadFromFile(aFileName); //SList.Free // should stop the compiler with specific Error, you are not allowed to destreuct/free an auto end There is also similar modifier like "init/create" and "free" these will only their part and the compiler will ensure you can't abuse the memory layout or use after free. This also can be applied to fields in TObject/Class, the compiler will put the default constructor and destructor in their right position and will stop compiling when the code is trying to call constructor and destructor. But one could say using "auto" for the fields in classes will make initializing slower, no it will not as sooner or later it will initialized or used (except other usage, will follow down), will this cause degradation in performance?, no, not really, after all there is a price for pay. Another modifier which i can argue will be very helpful, is "delayed" or "onuse".., this one is for places when you don't know if that class will be needed or not, so the compiler will not auto create it !, but will initialize it to 0 (nil), and will check against that nil on every first usage with in the current scope then call the constructor in-place, guaranteeing its readiness, while will enforce calling the destructor in every scope it mentioned (referenced) but again if it is nil then nothing to do. With "delayed" modifier there is a performance hit for sure but it is merely "if assigned(x)" and as i mentioned above at the first usage in the current scope, so when in doubt i will leave to the compiler but when i am sure i will need that delayed to be ready for lets say a loop, then i can call specific function on it or just touch it in any code so the following code will not have to have the check for creation, of course if such delayed var is used in a loop then the compiler will put the constructor before entering the loop (at the loop limit preparing code) Also to mention how clean the code will become not just eliminating user after free or use non initialized. as for compiler: Delphi compiler is already equipped and has the ability to do that so minimal adjusting is needed, it does the same with all managed types (strings, arrays..) for the suggested modifiers above it will be close to this Currently the compiler does the same with strings and arrays as seen here ( though this is my XE8 so not sure about the latest versions) for combining the suggested "delayed" with the above the compiler could check for referencing one to another and adjust or rearrange the creation and destruction order. Anyway, this i this another short by me to reach a discussion about this enhancement or call it evolution, also this is the right evolution toward more memory safety. There is also can be a suggestion for different modifier "secure" "mute" (or something), with this one the compiler will allow any assigning to referencing (or double referencing), in other words and as example, X is a class, no code such Y := X is allowed, you need X (the object in X) you have to use it where is it which is X, This will ensure specific design and will limit pointer miss using, you want to load a bunch of the like of that X in an array then either declare them there with in the array and use them there, or, custom and precise steps should be done as guarantee to the compiler that this is well thought of, otherwise we need to write better code and design the structure better, another example ; X is secure object and it is a field in the non secure Z, the compiler will not allow to use X out side the scope of this current scope and/or outside the Z, meaning, the compiler will not allow passing X as parameter to a procedure, but will allow Z, X and its value is not allowed to be used in any direct assigning ":=", still we have the ability to introduce assign as operator that will ship or duplicate X fields, but not X itself or its pointer, that pointer should not be reached or allowed to be accessed by the compiler, and when i say compiler i mean the new language constraints for these suggestions.