alt Hacker News> the build failed at the linker stage
> The compiler did its job fine
> Where CCC Succeeds Correctness: Compiled every C file in the kernel (0 errors)
I don't think that follows. It's entirely possible that the compiler produced garbage assembly for a bunch of the kernel code that would make it totally not work even if it did link. (The SQLite code passing its self tests doesn't convince me otherwise, because the Linux kernel uses way more advanced/low-level/uncommon features than SQLite does.)
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Yeah I saw a post on LinkedIn (can't find it again sorry) where they found that CCC compiles C by mostly just ignoring errors. `const` is a nop. It doesn't care if you redefine variables with different types, use a string where an `int` is expected, etc.
Whenever I've done optimisation (e.g. genetic algorithms / simulated annealing) before you always have to be super careful about your objective function because the optimisation will always come up with some sneaky lazy way to satisfy it that you didn't think of. I guess this is similar - their objective was to compile valid C code and pass some tests. They totally forgot about not compiling invalid code.
I agree. Lack of errors is not an indicator of correct compilation. Piping something to /dev/null won't provide any errors either & so there is nothing we can conclude from it. The fact that it compiles SQLite correctly does provide some evidence that their compiler at least implements enough of the C semantics involved in SQLite.