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    SubjectRe: sparse segfaults


    On Mon, 22 Nov 2004, Mitchell Blank Jr wrote:
    >
    > When I want to do that I just use:
    >
    > #define MAX_SOMETHING (max_of_something + 0)

    Yes, I think I've done that too, and that works. My point is that the
    silly comma-expression should _also_ work, and I don't see any _valid_ use
    of the comma-expression as an lvalue.

    I suspect (but don't have any real argument to back that up) is that the
    gcc "extended lvalues" fell out as a side effect from how gcc ended up
    doing some random semantic tree parsing, and it wasn't really "designed"
    per se, as much as just a random implementation detail. Then somebody
    noticed it, and said "cool" and documented it.

    That's actually in my opinion a really good way to occasionally find a
    more generic form of something - the act of noticing that an algorithm
    just happens to give unintentional side effects that can actually be
    mis-used. So I don't think that it's a bad way per se to add features,
    especially as they then are often free (or even "negative cost", since
    _not_ adding the feature would entail having to add a check against it).

    And for all I know, many of the _good_ gcc features ended up being done
    that way too.

    But I think the (unintentional) downsides of these features are bigger
    than the advantages.

    Linus
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