Workaround restrict error in GCC 12

[TingPing]

bd1249c

Workaround restrict error in GCC 12
https://bugs.webkit.org/show_bug.cgi?id=272309

Reviewed by Darin Adler.

In GCC 12.3.0:

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:431:21,
    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>::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.h:2179:19,
    inlined from ‘constexpr std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::insert(size_type, const _CharT*) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /usr/include/c++/12/bits/basic_string.h:1936:22,
    inlined from ‘std::ostream& WTF::operator<<(std::ostream&, Int128Impl)’ at /host/home/tingping/Projects/WebKit/Source/WTF/wtf/Int128.cpp:268:17:
/usr/include/c++/12/bits/char_traits.h:435:56: error: ‘void* __builtin_memcpy(void*, const void*, long unsigned int)’ accessing 9223372036854775810 or more bytes at offsets [2, 9223372036854775807] and 1 may overlap up to 9223372036854775813 bytes at offset -3 [-Werror=restrict]
  435 |         return static_cast<char_type*>(__builtin_memcpy(__s1, __s2, __n));
      |                                        ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~

* Source/WTF/wtf/Int128.cpp:
(WTF::operator<<):

Canonical link: https://commits.webkit.org/277203@main

9fd1a25

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
❌ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 wincairo
	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe
	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 wpe-skia
✅ 🛠 🧪 jsc	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
✅ 🛠 🧪 jsc-arm64	✅ 🛠 tv	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 tv-sim		✅ 🧪 api-gtk
✅ 🛠 🧪 merge	✅ 🛠 watch		✅ 🛠 jsc-armv7
	✅ 🛠 watch-sim		✅ 🧪 jsc-armv7-tests

[webkit-early-warning-system]

EWS run on current version of this PR (hash 9fd1a25)

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
❌ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 wincairo
	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe
	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 wpe-skia
✅ 🛠 🧪 jsc	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
✅ 🛠 🧪 jsc-arm64	✅ 🛠 tv	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 tv-sim		✅ 🧪 api-gtk
✅ 🛠 🧪 merge	✅ 🛠 watch		✅ 🛠 jsc-armv7
	✅ 🛠 watch-sim		✅ 🧪 jsc-armv7-tests

[TingPing]

Style check failure is because that function already used wrong indentation, this leaves the style as it was.

[darinadler]

Is this GCC 12 warning correct, or a bug? If it’s a bug, do you have a link to the GCC bug report?

This doesn’t seem like a great fix, especially unconditionally on all platforms without any comment. But on the other hand, pretty sure this is dead code in WebKit. We don’t use Int128 with an ostream. So we shouldn’t waste any time on this.

[TingPing]

I found the bug reported here: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105329

Reported 2022 but still unfixed. I'll add the link to the commit message.

I don't believe there is anything wrong with our code at all. But I don't know if GCC is doing the right thing so it could be unsafe there.

[TingPing]

Oh it was already merged, well it's documented here :)

[webkit-commit-queue]

Committed 277203@main (bd1249c): https://commits.webkit.org/277203@main

Reviewed commits have been landed. Closing PR #26961 and removing active labels.