[libcxx-commits] [PATCH] D80452: [libc++] Complete overhaul of constexpr support in std::array

[Leonard Chan via Phabricator via libcxx-commits]

leonardchan added a comment.

Hi! I think this patch might be the cause of the bug at https://bugs.llvm.org/show_bug.cgi?id=46137.

Essentially, we get an error when attempting to create `std::array<S, 0>` if S has a non-trivial destructor (full example at the bug link):

  test.cc:20:20: error: call to implicitly-deleted default constructor of 'std::array<S, 0>'
    std::array<S, 0> x;  // bad
                     ^
  /usr/local/google/home/leonardchan/llvm-monorepo/llvm-build-1-master-fuchsia-toolchain/install/bin/../include/c++/v1/array:252:7: note: default constructor of 'array<S, 0>' is implicitly deleted because field '__w' has a deleted destructor
      } __w;
        ^
  /usr/local/google/home/leonardchan/llvm-monorepo/llvm-build-1-master-fuchsia-toolchain/install/bin/../include/c++/v1/array:248:9: note: explicitly defaulted function was implicitly deleted here
          ~__wrapper() = default;
          ^
  /usr/local/google/home/leonardchan/llvm-monorepo/llvm-build-1-master-fuchsia-toolchain/install/bin/../include/c++/v1/array:251:13: note: destructor of '__wrapper' is implicitly deleted because variant field '__t' has a non-trivial destructor
          _Tp __t;
              ^
  test.cc:20:20: error: attempt to use a deleted function
    std::array<S, 0> x;  // bad
                     ^

I believe std::arrays of size 0 should be legal regardless of constraints on the element type.


Repository:
  rG LLVM Github Monorepo

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https://reviews.llvm.org/D80452