[clang] [llvm] [DebugInfo] Use DW_op_bit_piece for structured bindings of bitfields (PR #85665)

[John Brawn via cfe-commits]

john-brawn-arm wrote:

After doing some more testing it turns out that DW_OP_bit_piece actually doesn't work when we have a signed bitfield, as both gdb and lldb treat the upper bits as zero. I think instead we have to do a sequence of operations to extract the relevant bits from the value. I've created #93990 for adding a DW_OP for doing this, with patches for using it in clang and making optimisations handle it on the way.

https://github.com/llvm/llvm-project/pull/85665