From: Jonny Grant <jg@jguk.org>
To: gcc-help <gcc-help@gcc.gnu.org>
Subject: Re: build error --std=c++17 vs --std=c++23 -Wrestrict "may overlap up to 9223372036854775813 bytes at offset -3"
Date: Sun, 12 Feb 2023 00:14:59 +0000 [thread overview]
Message-ID: <89f2f365-6592-9eac-4f90-05ce7477233f@jguk.org> (raw)
In-Reply-To: <681c1224-aec4-9831-26b1-e11fd182dd5c@jguk.org>
I saw there are quite a few similar issues reported.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=Wrestrict
Maybe it is similar to this one
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105651
Jonny
On 11/02/2023 23:38, Jonny Grant wrote:
> Hello
>
> Anyone else seeing an issue when using c++23 ?
> gcc (Ubuntu 12.2.0-3ubuntu1) 12.2.0
>
> The only change is to use --std=c++23
>
> -Wrestrict is enabled by -Wall
>
>
> #include <string>
>
> typedef struct a_bc
> {
> std::string a;
> std::string b;
> } a_t;
>
> void f()
> {
> a_t c;
>
> c.a = " sdfsdf fsdfsdf fdfsfdsdf "; // seems to need this long string to reproduce, down to 8 bytes it didn't
> c.b = "E";
> }
>
>
>
>
>
>
>
>
> $ g++ -O3 --std=c++23 -Wall -c -o gcc_err3 src/gcc_err3.cpp
> In file included from /usr/include/c++/12/string:40,
> from src/gcc_err3.cpp:4:
> In static member function ‘static constexpr std::char_traits<char>::char_type* std::char_traits<char>::copy(char_type*, const char_type*, std::size_t)’,
> inlined from ‘static constexpr void std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::_S_copy(_CharT*, const _CharT*, size_type) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /usr/include/c++/12/bits/basic_string.h:423:21,
> inlined from ‘constexpr std::__cxx11::basic_string<_CharT, _Traits, _Allocator>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::_M_replace(size_type, size_type, const _CharT*, size_type) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /usr/include/c++/12/bits/basic_string.tcc:532:22,
> inlined from ‘constexpr std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::assign(const _CharT*) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /usr/include/c++/12/bits/basic_string.h:1647:19,
> inlined from ‘constexpr std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::operator=(const _CharT*) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /usr/include/c++/12/bits/basic_string.h:815:28,
> inlined from ‘void f(const std::string&, bool, bool)’ at src/gcc_err3.cpp:17:13:
> /usr/include/c++/12/bits/char_traits.h:431:56: warning: ‘void* __builtin_memcpy(void*, const void*, long unsigned int)’ accessing 9223372036854775810 or more bytes at offsets -4611686018427387902 and [-4611686018427387903, 4611686018427387904] may overlap up to 9223372036854775813 bytes at offset -3 [-Wrestrict]
> 431 | return static_cast<char_type*>(__builtin_memcpy(__s1, __s2, __n));
> | ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~
next prev parent reply other threads:[~2023-02-12 0:15 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-11 23:38 Jonny Grant
2023-02-12 0:14 ` Jonny Grant [this message]
2023-02-12 1:33 ` Jonathan Wakely
2023-02-12 11:20 ` Jonny Grant
2023-02-23 14:09 Saifi Khan
2023-02-23 16:32 ` Jonathan Wakely
2023-02-23 17:47 ` Saifi Khan
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