GCC-12: Compiler error with C++20 mode on char* + string.

[danakj]

Describe the issue

Compile error in gtest-all.cc with GCC-12 and C++20 mode.

Steps to reproduce the problem

There were no errors compiling with GCC-11, but with GCC-12 I get this error:

FAILED: third_party/googletest/googletest/CMakeFiles/gtest.dir/src/gtest-all.cc.o 
/usr/bin/g++-12  -I/home/runner/work/subspace/subspace/third_party/googletest/googletest/include -I/home/runner/work/subspace/subspace/third_party/googletest/googletest -O3 -DNDEBUG -Wall -Wshadow -Werror -Wno-error=dangling-else -DGTEST_HAS_PTHREAD=1 -fexceptions -Wextra -Wno-unused-parameter -Wno-missing-field-initializers -std=c++20 -MD -MT third_party/googletest/googletest/CMakeFiles/gtest.dir/src/gtest-all.cc.o -MF third_party/googletest/googletest/CMakeFiles/gtest.dir/src/gtest-all.cc.o.d -o third_party/googletest/googletest/CMakeFiles/gtest.dir/src/gtest-all.cc.o -c /home/runner/work/subspace/subspace/third_party/googletest/googletest/src/gtest-all.cc
In file included from /usr/include/c++/12/ios:40,
                 from /usr/include/c++/12/ostream:38,
                 from /usr/include/c++/12/bits/unique_ptr.h:41,
                 from /usr/include/c++/12/memory:76,
                 from /home/runner/work/subspace/subspace/third_party/googletest/googletest/include/gtest/gtest.h:57,
                 from /home/runner/work/subspace/subspace/third_party/googletest/googletest/src/gtest-all.cc:38:
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>::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:2171:19,
    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:1928:22,
    inlined from ‘constexpr std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const _CharT*, __cxx11::basic_string<_CharT, _Traits, _Allocator>&&) [with _CharT = char; _Traits = char_traits<char>; _Alloc = allocator<char>]’ at /usr/include/c++/12/bits/basic_string.h:3541:36,
    inlined from ‘static std::string testing::internal::StreamingListener::UrlEncode(const char*)’ at /home/runner/work/subspace/subspace/third_party/googletest/googletest/src/gtest.cc:4882:27:
/usr/include/c++/12/bits/char_traits.h:431:56: error: ‘void* __builtin_memcpy(void*, const void*, long unsigned int)’ accessing 9223[37](https://github.com/chromium/subspace/actions/runs/3814961661/jobs/6489651472#step:7:38)2036854775810 or more bytes at offsets [2, 9223372036854775807] and 1 may overlap up to 9223372036854775813 bytes at offset -3 [-Werror=restrict]
  [43](https://github.com/chromium/subspace/actions/runs/3814961661/jobs/6489651472#step:7:44)1 |         return static_cast<char_type*>(__builtin_memcpy(__s1, __s2, __n));
      |                                        ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~
cc1plus: all warnings being treated as errors

Clearly 9223372036854775813 is a lot of bytes.

https://github.com/chromium/subspace/actions/runs/3814961661/jobs/6489651472 demonstrates the error.

chromium/subspace@ecded91 fixes the error.

-        result.append("%" + String::FormatByte(static_cast<unsigned char>(ch)));
+        result.push_back('%');
+        result.append(String::FormatByte(static_cast<unsigned char>(ch)));

What version of GoogleTest are you using?

googletest 1.11

What operating system and version are you using?

Ubuntu 22.04.1 LTS

What compiler and version are you using?

gcc 12.1.0
Compiling with -std=c++20

What build system are you using?

cmake on github actions

Additional context

No response

[derekmauro]

A small reproduction is here: https://godbolt.org/z/Pe5aE59xG

I'm not sure how GCC managed to ship this in 12.1 and then didn't fix it for 12.2. It looks fixed in trunk though.

I'll add a workaround similar to your patch. Thanks.