Thread

1. JoshTriplett · 1789746575 · focus · HN ↗

   > When both conditions are met, the loop body is replaced with a call to std::this_thread::yield().

   Insert screaming here.

   An infinite loop, with no library calls whatsoever, gets a system call inserted. That's a horrible surprise waiting to happen.

   The entire concept of the "forward progress guarantee" is broken. An infinite loop should compile to an infinite loop. Nothing more, nothing less.

   1. ibobev · 1789749755 · focus · HN ↗

      > An infinite loop should compile to an infinite loop.

      I think that a compiler option should control this. It can be a nice optimization, but the programmer should be able to opt out.

      1. WalterBright · 1789769724 · focus · HN ↗

         Every flag that changes the semantics of the code bifurcates the language into two languages.

         1. ibobev · 1789777034 · focus · HN ↗

            If we accept this definition, C++ already seems to be many different languages. At my job, I'm currently fighting floating-point determinism issues across different build configurations, compilers, CPUs, operating systems, and standard library and libm implementations so that snapshot tests pass with the same hashes on all platforms. I can confirm that this is a complete nightmare.

            1. WalterBright · 1789782032 · focus · HN ↗

               Yup. I tried hard to not allow D's behaviors to be changed based on a compiler switch. Yes, we have switches to enable certain features, but not silent behavior changes.

               It's not perfect, but the forest of such switches in C compilers motivated D to not have them.

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