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Unix Co-Creator Brian Kernighan on Rust, Distros and NixOS (thenewstack.io)
submitted 1 year ago by to c/programming@programming.dev
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[–] 15 points 1 year ago (6 children)

In my limited experience the speed a rust complied executable runs is highly dependent on compiler options. By default (from what I remember), rust includes a ton of debug info in the resulting program. With the correct compiler flags you can strip all that out and programs run very close to c speeds.

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  • [–] 16 points 1 year ago (4 children)

    The default for cargo is debug builds why that would surprise anyone as being slower is beyond me, —release isn’t that much extra to type or alias. Do people not learn how their tools work any longer? This isn’t that far off from c/c++ where you set cflags etc to fit the final binaries purpose.

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  • [–] 4 points 1 year ago (2 children)

    Tbf this mistake comes up so often I do wonder if cargo should have defaulted to release builds. It seems to be what beginners expect.

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  • [–] 4 points 1 year ago (1 child)

    Gcc, clang, msvc, and all the other compilers also don’t optimize by default. It’s very normal and very expected for the default build to not include optimizations

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  • [–] 1 point 1 year ago

    Sure but you don't normally run GCC or Clang directly; you make, and that normally does optimise. I think a closer example is CMake which doesn't enable release mode by default.

    MSVC is usually run from Visual Studio which makes it obvious which mode is being used so the default doesn't matter so much.

    As for "all the other compilers", Go optimises by default. It does seem to be the exception though...

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  • [–] 6 points 1 year ago

    Yeah, cargo build produces a debug build and cargo build --release is for actually distributing to users. (It doesn't add the debug symbols, but also spends more time optimizing.)

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