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    Subjectsparse -Wptr-subtraction-blows: still needed?

    Sparse has a warning -Wptr-subtraction-blows (off by default) which generates
    a warning for any pointer subtractions. This warning relates to GCC
    shortcomings observed in 2005; the original log message:

    > commit 6889bd0f84939675c743229d6fe623513b95e057
    > Author: Linus Torvalds <torvalds@ppc970.osdl.org>
    > Date: Fri Jan 7 15:06:24 2005 -0700
    >
    > Add option "-Wptr-subtraction-blows" to warn about expensive
    > pointer subtractions.
    >
    > Not only does it generate bad code (that can often be rewritten
    > to not do that), it also causes gcc to go into horrible contortions,
    > and Al Viro reports that it can make a factor of 2.5 difference in
    > kernel build times to have just a few of these in common header
    > file inline functions.

    Does this still apply? Do current versions of GCC still have this problem?
    If not, can the option and warning go away?

    - Josh Triplett

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