Created attachment 20066 [details]
Crash log

Here's a minimal example that I came up with

// clang++ -std=c++17 -Wbinding-in-condition -o main main.cpp

#include <tuple>

struct X {
  template<int I>
  int get() { return 0; }

  operator bool() { return true; }
};

namespace std {
  template<>
  struct tuple_size<X> { static constexpr std::size_t value = 1; };
  template<>
  struct tuple_element<0, X> { using type = int; };
}

int main() {
  if (auto[a] = X())
    return a;
}

The above crashes with the attached log.