https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97844
Bug ID: 97844
Summary: Unsigned Integer Overflow when comparing strings
(|s1|<|s2|)
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: jerryc443 at gmail dot com
Target Milestone: ---
Sample code:
```cpp
bool b = std::string() < "1";
```
Run this with UBSAN enabled, I got the following output: (`clang 11 using
libstdc++, -std=c++20`)
```
/usr/bin/../lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/bits/basic_string.h:403:51:
runtime error: unsigned integer overflow: 0 - 1 cannot be represented in type
'unsigned long'
#0 0x428a8e in std::__cxx11::basic_string<char, std::char_traits<char>,
std::allocator<char> >::_S_compare(unsigned long, unsigned long)
/usr/bin/../lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/bits/basic_string.h:403:51
#1 0x42870c in std::__cxx11::basic_string<char, std::char_traits<char>,
std::allocator<char> >::compare(char const*) const
/usr/bin/../lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/bits/basic_string.tcc:1429:8
#2 0x4273b7 in
decltype(__detail::__char_traits_cmp_cat<std::char_traits<char> >(0))
std::operator<=><char, std::char_traits<char>, std::allocator<char>
>(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>
> const&, char const*)
/usr/bin/../lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/bits/basic_string.h:6216:61
#3 0x4271f5 in main ***
#4 0x7f13e917dcc9 in __libc_start_main csu/../csu/libc-start.c:308:16
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior
/usr/bin/../lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/bits/basic_string.h:403:51
in
```
See: https://github.com/google/sanitizers/issues/1346
