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    SubjectRe: [00/02] add BUILD_BUG_DECL assertion (for 3.4??)
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    On Sun, 2012-04-08 at 16:38 -0600, Jim Cromie wrote:

    > this patch (0001) adds new bug.h macro, BUILD_BUG_DECL(name, cond),
    > which unlike other *BUG* assertions is usable at file scope. Its
    > primary purpose is to enforce identical sizes of 2 separate arrays,
    > which but for considerations of packing/padding/section, would be
    > together in a struct.
    >
    > const char const *names[] = { "bart", "lisa", "homer", "marge" };
    > int a[] = {1,2,3,4};
    > int b[] = {1,2,3,5};
    > long d[] = {1,2};
    >
    > BUILD_BUG_DECL(foo, ARRAY_SIZE(a) != ARRAY_SIZE(b));
    > BUILD_BUG_DECL(buz, sizeof(a) != sizeof(b)); // good
    > BUILD_BUG_DECL(a, sizeof(a) != sizeof(d)); // ok on x32, error x64
    > BUILD_BUG_DECL(b, ARRAY_SIZE(a) != ARRAY_SIZE(names)); // good
    >
    > macro expands as:
    > static __attribute__ ((__section__(".init.data"))) struct {
    > int BUILD_BUG_DECL_buz[1 - 2*!!(sizeof(a) != sizeof(b))];
    > } BUILD_BUG_DECL_buz[0] __attribute__((unused));
    >

    If possible, it might be better to wrap the
    declarations themselves in a macro that ensures
    the sizes are the same.

    Something like:

    declare_same_size_arrays(
    typeof array1[] = {...},
    typeof array2[] = {...}
    );




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