A newer version of GCC will now emit member locations using just
DW_AT_data_bit_offset, like:
<3><14fe>: Abbrev Number: 1 (DW_TAG_member)
<14ff> DW_AT_name : (indirect string, offset: 0x215e): nb_bytes
<1503> DW_AT_decl_file : 1
<1503> DW_AT_decl_line : 10
<1504> DW_AT_decl_column : 7
<1505> DW_AT_type : <0x150b>
<1509> DW_AT_bit_size : 31
<150a> DW_AT_data_bit_offset: 64
whereas earlier versions would emit something like:
<3><164f>: Abbrev Number: 7 (DW_TAG_member)
<1650> DW_AT_name : (indirect string, offset: 0x218d): nb_bytes
<1654> DW_AT_decl_file : 1
<1655> DW_AT_decl_line : 10
<1656> DW_AT_decl_column : 7
<1657> DW_AT_type : <0x165f>
<165b> DW_AT_byte_size : 4
<165c> DW_AT_bit_size : 31
<165d> DW_AT_bit_offset : 1
<165e> DW_AT_data_member_location: 8
That is, DW_AT_data_member_location is not emitted any more. This is
a change due to the switch to DWARF 5 by default.
This change pointed out an existing bug in gdb, namely that the
attr_to_dynamic_prop depends on the presence of
DW_AT_data_member_location. This patch moves the handling of
DW_AT_data_bit_offset into handle_data_member_location, and updates
attr_to_dynamic_prop to handle this new case.
A new test case is included. This test fails with GCC 11, but passes
with an earlier version of GCC.
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