[PATCH] D55741: Implementation Feature Test Macros for P0722R3

[Stephan Bergmann via Phabricator via cfe-commits]

sberg added a comment.

One problem I found with the macro `__cpp_impl_destroying_delete` not being conditional on language version is the following: Recent GCC trunk (since https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=76b94d4ba654e9af1882865933343d11f5c3b18b "Implement P0722R3, destroying operator delete.") contains

  #if __cpp_impl_destroying_delete
  #define __cpp_lib_destroying_delete 201806L
  namespace std
  {
    struct destroying_delete_t
    {
      explicit destroying_delete_t() = default;
    };
    inline constexpr destroying_delete_t destroying_delete{};
  }
  #endif // destroying delete

at "top-level" (i.e., not in a C++20-only `#if` or similar) in `libstdc++-v3/libsupc++/new`.  That means that when using Clang against that GCC toolchain, `#include <new>` in C++03 mode will cause `error: unknown type name 'constexpr'`.


Repository:
  rC Clang

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  https://reviews.llvm.org/D55741/new/

https://reviews.llvm.org/D55741