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    SubjectRe: [PATCH 7/7] asm-generic: suppress sparse warning in ioctl.h
    On Fri, Apr 04, 2008 at 02:19:51AM +0100, Al Viro wrote:
    > * no functions returning variably-modified type.

    Note: *pointer* to function returning a variably-modified type is possible,
    is variably-modified itself and as such can appear only in function and
    the same "compiler will consider VLA compatible with any array that has
    as compatible element, but if the size doesn't match it's on your head"
    applies. IOW,

    int a[2][2] = {{1, 2}, {3, 4}};

    int (*f(void))[2] /* return a pointer to two-element array of int */
    return &a[0];

    int h(int n)
    /* pointer to function that returns a pointer to n-element VLA of int */
    int (*(*p)(void))[n];
    /* OK if n is 2, undefined otherwise */
    p = f;
    return p()[1][1];

    is fine and h(2) will give you 4, but if you ever do e.g. h(1), you are in
    nasal daemon country. In reality h(1) will _probably_ give a[1][0], but
    compiler has every right to silently produce a binary that'll wipe your disk
    or do the same itself...

     \ /
      Last update: 2008-04-04 04:03    [W:0.027 / U:121.336 seconds]
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