From: Jason Merrill <jason@redhat.com>
To: Jakub Jelinek <jakub@redhat.com>,
Richard Biener <richard.guenther@gmail.com>
Cc: Marek Polacek <polacek@redhat.com>,
GCC Patches <gcc-patches@gcc.gnu.org>
Subject: Re: C++ PATCH for c++/65398 (valid constexpr rejected)
Date: Fri, 20 Mar 2015 14:53:00 -0000 [thread overview]
Message-ID: <550C347E.2070801@redhat.com> (raw)
In-Reply-To: <20150319180536.GA1746@tucnak.redhat.com>
On 03/19/2015 02:05 PM, Jakub Jelinek wrote:
> Though, a question is if we do (or, if we don't and should) reject say
> constexpr char s[] = "abc";
> constexpr int j = 4;
> constexpr char c = *(&s[j] - 2);
> because there was out of bound access in there.
I don't see an out-of-bound access in this example; taking the address
of one-past-the-end is OK as long as you don't try to access through it.
> Unfortunately we reject even that (regardless the patch), and yeah, it's
> because of how POINTER_PLUS_EXPR uses sizetype as a type of the second operand.
This seems like something to fix in this patch.
> + tree t = fold_convert_loc (loc, TREE_TYPE (op01),
> + TREE_OPERAND (op00, 1));
> + t = size_binop_loc (loc, PLUS_EXPR, op01, t);
This seems to be assuming that the elements are size 1.
Jason
next prev parent reply other threads:[~2015-03-20 14:53 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-13 14:41 Marek Polacek
2015-03-18 10:08 ` Richard Biener
2015-03-19 18:05 ` Jakub Jelinek
2015-03-19 18:13 ` Marek Polacek
2015-03-19 18:17 ` Jakub Jelinek
2015-03-19 18:33 ` Marek Polacek
2015-03-20 14:53 ` Jason Merrill [this message]
2015-03-20 14:59 ` Jakub Jelinek
2015-03-20 15:03 ` Jason Merrill
2015-03-20 15:11 ` Jakub Jelinek
2015-03-20 15:15 ` Jason Merrill
2015-03-20 15:28 ` Jakub Jelinek
2015-03-20 20:57 ` C++ PATCH for c++/65398 (valid constexpr rejected) (take 2) Marek Polacek
2015-03-20 21:04 ` Jakub Jelinek
2015-03-20 21:10 ` Jason Merrill
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