Fil-Qt: A Qt Base build with Fil-C experience

(git.qt.io)

35 points | by pjmlp 2 days ago

5 comments

  • wewewedxfgdf 18 minutes ago
    I believe much more in making C/C++ safer than using something as complex as Rust.

    SafER is better than deeply complex and unable to be understood except by Rust experts.

    • vlovich123 8 minutes ago
      I don’t know what you mean by SafER but it’s important to remember that Fil-C sacrifices a lot of performance for that safety which detracts the reasons you’d be running that software as otherwise C was a bad language for them. Sometimes this won’t matter but there are places fil-c won’t be able to go that Rust can - embedded and OS kernel come to mind. Other places would be things like browsers or games. Rust gives you the safety without giving up the ability to do performance.

      Also, I could be wrong but I believe any assembly linked into Fil-C bypassed the safety guarantees which would be something to keep in mind (not a big deal generally, but a source of hidden implicit unsafe).

    • timschmidt 12 minutes ago
      In my experience (20+ years with C/C++, and about 4 years with Rust), Rust is significantly less complex than C++, while being similarly capable. The extra syntax that throws off so many C++ devs is almost exclusively about data types and lifetimes, which I find very useful for understanding my own code and others', and which I wish I had in C++.
    • bfrog 12 minutes ago
      If you can’t understand ownership I’m baffled how you believe you can write well behaved C or C++.

      Rust at least embeds this information in the API with checks. C and C++ are doc comments at best.

  • dayli 44 minutes ago
    Interesting to see Fil‑C used with a large framework like Qt. The fact that it compiles with minimal changes says a lot about the compatibility layer and the InvisiCaps approach.
  • rubymamis 2 days ago
    This is awesome. Would love to see if it catches some of the Qt bugs I found but haven't been resolved yet[1].

    [1] https://qt-project.atlassian.net/browse/QTBUG-122658

    • cristianadam 2 days ago
      I only tried to get Qt Base up and running. But Qt Declarative will be next, after Qt Base.
      • rubymamis 2 days ago
        That would be awesome (:
    • yjftsjthsd-h 1 hour ago
      Depends in which sense you want it to "catch" the bugs. As this readme notes/quotes,

      > All memory safety errors are caught as Fil-C panics.

      If your problem is a memory-based bug causing a crash, I think this would just... catch the memory-based bug and crash. Like, it'd crash more reliably. On the other hand, if you want to find and debug the problem, that might be a good thing.

      • dafelst 1 hour ago
        Sure, if the memory error is an immediately crashing one like a null per deref, but if is (for example) a memory corruption (e.g. an out of bounds write or a write-after-free) then this would be super helpful in exposing where those are happening at the source.
      • wat10000 41 minutes ago
        That’s what “catch” means here. As in, catch it in the act. Tools that make bugs crash more reliably and closer to the source of the problem are extremely valuable.
  • rowanG077 1 hour ago
    I thought the point of Fil-C was to be a drop in safe replacement of C. This project existing implies it isn't. What's going on?
    • loeg 26 minutes ago
      It isn't entirely drop-in for all programs.
    • meibo 1 hour ago
      It's not done yet.
      • g-mork 52 minutes ago
        Sure fooled me. I follow his Twitter account and there isn't much he hasn't got building with it at this point. UX comes later. Amazing it's the random work of one person
        • vlovich123 4 minutes ago
          I don’t think so much is fil-c itself, but from the looks of the diff it’s a new platform essentially. That can require porting existing software generally which you can read from the posted diff
    • wat10000 36 minutes ago
      Most large C code bases aren’t really written in C. They’re written in an almost-C that includes certain extensions and undefined behavior. In this case, it uses inline assembly (an extension) and manipulating pointers as integers (undefined behavior).