In the location of "o" ("0: 5"), the "5" means "there are 5 bits left
relative to the size of the underlying type.
I find this very difficult to follow. On irc, Sergio said that this
choice came because it is what pahole does. However, I think it's not
very useful, and maybe is just an artifact of the way that
DW_AT_bit_offset was defined in DWARF 3.
This patch changes ptype/o to print the offset of a bitfield in a more
natural way, that is, using the bit number according to the platform's
bit numbering.
This is better, IMO, because now the "offset" of a bitfield is
consistent with the offset of an ordinary member, referring to its
offset from the start of the structure.
gdb/ChangeLog
2019-05-08 Tom Tromey <tromey@adacore.com>
* typeprint.c (print_offset_data::update): Print the bit offset,
not the number of bits remaining.
gdb/doc/ChangeLog
2019-05-08 Tom Tromey <tromey@adacore.com>
* gdb.texinfo (Symbols): Document change to ptype/o.
gdb/testsuite/ChangeLog
2019-05-08 Tom Tromey <tromey@adacore.com>