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    SubjectRe: [PATCH -mm] sys_semctl gcc 4.1 warning fix
    On Thu, May 11, 2006 at 10:40:33PM +0200, Adrian Bunk wrote:
    > We could turn of this kind of warnings that generate these kind of false
    > positives globally with -Wno-uninitialized until a future gcc version
    > might be better at avoiding false positives.
    > But there's one problem, this turns off two kinds of warnings:
    > - 'foo' may be used uninitialized in this function
    > - 'foo' is used uninitialized in this function
    > The first kind of warnings is the one generating the false positives
    > while the second kind are warnings we do not want to lose, but AFAIK
    > there's no way to only turn off the first kind.
    > Perhaps asking the gcc developers for separate options for these two
    > kinds of warnings in gcc 4.2 and then turning off the first kind is
    > the way to go?

    Folks, let's look at it that way:
    * warnings are tools to locate broken places in the tree.
    * we have two signals ("is unused" and "may be unused"), say
    A(location, verision) and B(location, version).
    * A has fairly high S/N ratio.
    * B has very large noise component, but it's only weakly dependent
    on the verision.

    The question is how to get useful information out of those.
    * solution 1: introduce C(location, version) and filter A and B
    with it, to kill noise in B.
    * solution 2: ignore B, either by gcc modification or simply filtering
    it with grep.
    * solution 3: subtract the signals for consequent versions.

    IMO it's obvious that combining outputs of (2) and (3) gives the best S/N.
    The reason why (1) is bad is that it kills high-S/N channel in the areas
    with high noise on low-S/N channel *and* that filtered-out areas will
    remain filtered out in the next versions. IOW, it's a clear loss.
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      Last update: 2006-05-11 23:16    [W:0.020 / U:7.004 seconds]
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