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    SubjectRe: gcc fixed size char array initialization bug - known?
    On Fri, Aug 03, 2007 at 12:51:16AM +0200, Guennadi Liakhovetski wrote:
    > On Fri, 3 Aug 2007, Stefan Richter wrote:
    > > Guennadi Liakhovetski wrote:
    > > > with
    > > >
    > > > char c[4] = "012345";
    > > >
    > > > the compiler warns, but actually allocates a 6-byte long array...
    > >
    > > Off-topic here, but: sizeof c / sizeof *c == 4.
    > Don't think it is OT here - kernel depends on gcc. And, what I meant, is,
    > that gcc places all 7 (sorry, not 6 as I said above) characters in the
    > .rodata section of the compiled object file. Of course, it doesn't mean,
    > that c is 7 characters long.

    So gcc does that kind of recovery, after having warned you. Makes sense,
    as long as it's for ordinary variables (and not, say it, struct fields) -
    you get less likely runtime breakage on the undefined behaviour (e.g.
    passing c to string functions). So gcc has generated some padding between
    the global variables, that's all.

    It doesn't change the fact that use of c[4] or strlen(c) or strcpy(..., c)
    means nasal demon country for you.

    Now, if gcc does that for similar situation with struct fields, you'd have
    a cause to complain.
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      Last update: 2007-08-03 01:11    [W:0.020 / U:17.600 seconds]
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