type-map: Work around LLVM 22 “out of bounds index” error #247

1. 
   ryanofsky commented at 10:20 pm on March 1, 2026: collaborator

   This workaround is needed to fix “parameter pack may not be accessed at an out of bounds index” compile errors in https://github.com/bitcoin/bitcoin/pull/29409 due in sanitizer jobs due to https://github.com/bitcoin/bitcoin/pull/34660 which updates sanitizers to use LLVM 22 instead of LLVM 21:

   https://github.com/bitcoin/bitcoin/actions/runs/22501264518/job/65188721708?pr=29409 https://github.com/bitcoin/bitcoin/actions/runs/22501264518/job/65188721733?pr=29409

   0/cxx_build/include/c++/v1/__fwd/tuple.h:40:52: error: a parameter pack may not be accessed at an out of bounds index
   1   40 |   using type _LIBCPP_NODEBUG = __type_pack_element<_Ip, _Tp...>;
   2      |                                                    ^
   3/cxx_build/include/c++/v1/__utility/try_key_extraction.h:82:67: note: in instantiation of template class 'std::tuple_element<0, std::tuple<>>' requested here
   4   82 |                             is_same<__remove_const_ref_t<typename tuple_element<0, _Tuple1>::type>, _KeyT>::value,
   5      |                                                                   ^
   

   The upstream LLVM bug is https://github.com/llvm/llvm-project/issues/167709 and fix is https://github.com/llvm/llvm-project/pull/183614

2. type-map: Work around LLVM 22 "out of bounds index" error

   This workaround is needed to fix "parameter pack may not be accessed at an out
   of bounds index" compile errors in
   https://github.com/bitcoin/bitcoin/pull/29409 due in sanitizer jobs due to
   https://github.com/bitcoin/bitcoin/pull/34660 which updates sanitizers to use
   LLVM 22 instead of LLVM 21:
   
   https://github.com/bitcoin/bitcoin/actions/runs/22501264518/job/65188721708?pr=29409
   https://github.com/bitcoin/bitcoin/actions/runs/22501264518/job/65188721733?pr=29409
   
   ```c++
   /cxx_build/include/c++/v1/__fwd/tuple.h:40:52: error: a parameter pack may not be accessed at an out of bounds index
      40 |   using type _LIBCPP_NODEBUG = __type_pack_element<_Ip, _Tp...>;
         |                                                    ^
   /cxx_build/include/c++/v1/__utility/try_key_extraction.h:82:67: note: in instantiation of template class 'std::tuple_element<0, std::tuple<>>' requested here
      82 |                             is_same<__remove_const_ref_t<typename tuple_element<0, _Tuple1>::type>, _KeyT>::value,
         |                                                                   ^
   ```
   
   The upstream LLVM bug is https://github.com/llvm/llvm-project/issues/167709 and
   fix is https://github.com/llvm/llvm-project/pull/183614

   f61af48721
3. 
   DrahtBot commented at 10:21 pm on March 1, 2026: none

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4. hebasto approved
5. 
   hebasto commented at 11:46 am on March 2, 2026: member

   ACK f61af487217a3e3bd9c0aaddc7b66e35eb97c6e1, I have reviewed the code and it looks OK.

Contributors
ryanofsky DrahtBot hebasto