[Clang] Reject increment of bool value in unevaluated contexts after C++17
Clang now incorrectly allowed increment of bool in unevaluated contexts, we set `diagnostic::ext_increment_bool` to be SFINAEFailure to fix this issue.
```
template<class T> auto f(T t) -> decltype(++t);
auto f(...) -> void;
void g() {
f(true); // Clang wrongly makes this a hard error
}
```
```
template <class T>
concept can_increment = requires(T t) { ++t; };
template <class T> void f() {
static_assert(requires(T t) { ++t; }); // Incorrectly allowed
}
int main() {
f<bool>();
static_assert(!can_increment<bool>); // Incorrectly fails
bool b = false;
++b; // Correctly rejected
}
```
Fix issue: https://github.com/llvm/llvm-project/issues/47517
Reviewed By: erichkeane
Differential Revision: https://reviews.llvm.org/D152259
parent
2c0e1524
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