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    SubjectRe: [PATCH 16/16] fix handling of integer constant expressions
    Date
    >> Here are three independently invalid non-ICEs that sparse doesn't
    >> diagnose.
    >>
    >> extern int f(void);
    >> enum { cast_to_ptr = (int) (void *) 0 };
    >> enum { cast_to_float = (int) (double) 1 };
    >
    > Those two *really* shouldn't fail. I don't care if the C standard says
    > so,
    > that is *fine*.

    GCC doesn't guarantee you this, either.

    > In particular, "offsetof()" should be portably able to basically be the
    > standard #define, which involves an integer cast from a constant
    > pointer.
    > That had *better* be a valid constant integer expression, because it's
    > very useful.

    Yes it's useful. That's why GCC gives you __builtin_offsetof()
    for this purpose.

    > And I think standards can go screw themselves, and you can make it an
    > error with some "--standard-pedantic" switch or similar.
    >
    > Standards are just random pieces of paper, for crying out loud! They
    > have
    > zero relevance in the end.

    Sure, as long as you don't care about compatibility across
    compilers, what matters is what the compilers you _do_ use
    actually implement. And note that GCC doesn't guarantee
    you much over what the C standard does. Almost everything
    it allows extra is just an implementation side effect.


    Segher

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