| Issue |
107844
|
| Summary |
Clang C++ optimiser generates incorrect code
|
| Labels |
clang
|
| Assignees |
|
| Reporter |
filiplukasik
|
`
#include <optional>
#include <iostream>
inline std::optional<int> fail() {
std::terminate();
}
std::optional<int> test(int index) {
if (0 == index) {
return std::optional<int>{};
} else {
return fail();
}
}
int main(int argc, const char * argv[]) {
// This should evaluate to an empty optional
auto color = test(0);
if (color.has_value()) {
// With -Os set, we hit this branch on armv8
std::cout << color.value() << std::endl;
} else {
// Without optimisations we hit this branch
std::cout << "Color Empty" << std::endl;
}
return 0;
}
`
The code above results in "bad_optional_access" exception being thrown when compiled for armv8 in clang 18.1.0 and -Os (it also seems to crash in clang 17 and 16 according to compiler explorer + corresponding Apple clang forks - tested with Xcode 15.3 and Xcode 16 betas)
https://godbolt.org/z/r1qbfb4nE
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