Clang++ crashes when instantiating a particular template class with a static constexpr data member.

[cassioneri]

This code makes clang++ to crash:

template <typename>
struct S {
  static constexpr char c{};
  static constexpr decltype(&c) p = nullptr;
};

auto f() {
  return S<int>::p;
}

GCC and MSVC have no issue to compile the code.

https://godbolt.org/z/edr4h4v99

If instead of being deduced, the type of S::p or the return type of f is explicitly given (const char*), then compilation succeeds.

[llvmbot]

@llvm/issue-subscribers-clang-codegen

Author: Cassio Neri (cassioneri)

This code makes clang++ to crash: ``` template <typename> struct S { static constexpr char c{}; static constexpr decltype(&c) p = nullptr; };

auto f() {
return S<int>::p;
}

GCC and MSVC have no issue to compile the code.

https://godbolt.org/z/edr4h4v99

If instead of being deduced, the type of `S::p` or the return type of `f` is explicitly given (`const char*`), then compilation succeeds.
</details>

[MagentaTreehouse]

Maybe related:
#75847
#124326