[all-commits] [llvm/llvm-project] 540294: [Clang] Reject increment of bool value in unevalua...

[yronglin via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 540294845babbb2be909ea456323d7bc8a1763df
      https://github.com/llvm/llvm-project/commit/540294845babbb2be909ea456323d7bc8a1763df
  Author: yronglin <yronglin777 at gmail.com>
  Date:   2023-06-06 (Tue, 06 Jun 2023)

  Changed paths:
    M clang/docs/ReleaseNotes.rst
    M clang/include/clang/Basic/DiagnosticSemaKinds.td
    A clang/test/SemaCXX/bool-increment-SFINAE.cpp

  Log Message:
  -----------
  [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