https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113826
Bug ID: 113826
Summary: string_view::find sometimes not working in constexpr
contexts under -fsanitize=undefined
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: ivan.lazaric.gcc at gmail dot com
Target Milestone: ---
https://godbolt.org/z/qKvecx48W
```
#include <string_view>
template <unsigned N> struct fixed_string {
char buf[N + 1]{};
consteval fixed_string(char const *s) {
for (unsigned i = 0; i != N; ++i)
buf[i] = s[i];
buf[N] = 0;
}
consteval operator std::string_view() const {return {buf, N};}
};
template <unsigned N> fixed_string(char const (&)[N]) -> fixed_string<N - 1>;
template <fixed_string Str> struct storage {
inline static constexpr std::string_view sv{Str};
inline static constexpr bool hasA = sv.find('A') != std::string_view::npos;
};
int main(){
using NS = storage<"ABC">;
return NS::hasA;
}
```
Locally I am using g++ version 14.0.1
When building with flags `-std=c++20` it builds normally
When building with flags `-std=c++20 -fsanitize=undefined` it explodes
When building with clang with flags `-std=c++20 -fsanitize=undefined` it works
normally
Error message:
```
In file included from
/home/ilazaric/installs/gcc-latest/include/c++/14.0.1/string_view:898,
from ex.cpp:1:
/home/ilazaric/installs/gcc-latest/include/c++/14.0.1/bits/string_view.tcc: In
instantiation of ‘constexpr const bool storage<fixed_string<3>{"ABC"}>::hasA’:
ex.cpp:21:16: required from here
21 | return NS::hasA;
| ^~~~
ex.cpp:16:46: in ‘constexpr’ expansion of
‘storage<fixed_string<3>{"ABC"}>::sv.std::basic_string_view<char>::find(65, 0)’
/home/ilazaric/installs/gcc-latest/include/c++/14.0.1/bits/string_view.tcc:88:15:
error: ‘(((const char*)(& fixed_string<3>{"ABC"}.fixed_string<3>::buf)) != 0)’
is not a constant expression
88 | if (__p)
| ^~~
```
Might be related to https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104426
