Re: The difference in behavior between ld and gold when processing "start group/end group" option

[Cary Coutant <ccoutant at google dot com>]

Gold flattens the nested groups, by design:

// Called by the bison parser to start a group.  If we are already in
// a group, that means that this script was invoked within a
// --start-group --end-group sequence on the command line, or that
// this script was found in a GROUP of another script.  In that case,
// we simply continue the existing group, rather than starting a new
// one.  It is possible to construct a case in which this will do
// something other than what would happen if we did a recursive group,
// but it's hard to imagine why the different behaviour would be
// useful for a real program.  Avoiding recursive groups is simpler
// and more efficient.

If you try to nest a --start-group option within another, you'll get
an error, but if you use a script with a GROUP inside a --start-group,
we simply flatten it.

How much sympathy I have for builds that break because of this: none, sorry.

-cary


On Tue, Mar 3, 2015 at 3:16 PM, Alan Modra <amodra@gmail.com> wrote:
> On Tue, Mar 03, 2015 at 06:19:45PM +0100, Nikola Ikonic wrote:
>> Which of these linkers behave correctly?
>
> I would say, GNU ld.  The innermost group ought to be repeatedly
> searched until no new objects are extracted from libraries, before
> looking at any other input files.  GROUP ( libtest2.a libdummy.a )
> ought to cause head_dummy.o to be extracted from libdummy.a then
> test2.o from libtest2.a, before the linker considers libtest.a.
>
> --
> Alan Modra
> Australia Development Lab, IBM