[Bug c++/21135] [4.0/4.1 Regression] &a[-2] ICE at the top level

["kenner at vlsi1 dot ultra dot nyu dot edu" <gcc-bugzilla at gcc dot gnu dot org>]

------- Additional Comments From kenner at vlsi1 dot ultra dot nyu dot edu  2005-05-30 18:36 -------
Subject: Re:   [4.0/4.1 Regression] &a[-2] ICE at the top level

    The difference in the handling of these two expressions is that
    get_inner_reference sets the "offset" out-parameter for &a[-2], but
    not for a[2].  That's at odds with its documentation, which says that
    offset is only set if the offset is not a constant.

Is this because the value doesn't fit in some type?  I don't understand
why it's doing that.

    Furthermore, the out-parameter "bitpos" is signed, which suggests that
    negative values should be acceptable.

I think this is just consistency: bitpos is signed all over the place.
But, actually, I think there are some cases where the are negative bit
positions: the object a thin pointer in Ada points to comes to mind.

    Changing get_inner_reference to use ssizetype and sbitsizetype
    throughout fixes the problems -- but I'm not sure if that's 100%
    correct.

Nor am I, but I can't offhand think of anything it would breajk.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21135