[Bug driver/99896] g++ drops -lc

[matz at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99896

Michael Matz <matz at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |matz at gcc dot gnu.org

--- Comment #7 from Michael Matz <matz at gcc dot gnu.org> ---
(In reply to Jonathan Wakely from comment #1)
> (In reply to Tom de Vries from comment #0)
> > With g++, we have instead:
> > ...
> > collect2 ... main.o foo.o -lpcre2-posix ...
> > ...
> 
> It isn't dropped, it's moved to the end:
> 
> main.o foo.o -lpcre2-posix -lstdc++ -lm -lc -lgcc_s -lgcc -lc -lgcc_s -lgcc
> 
> If you need it before foo.o then -Wl,-lc seems like the right workaround for
> me.

Workaround is the correct term here.  The correct thing would be for g++ to not
reorder -l arguments.  The similarity to -I is superficial: duplicated -l
arguments have meaning (with static archives for instance) and their position
in relation to object and source files matters.  g++ can validly tack on
additional -l arguments to the end, and arguably also replace a lone -lc
argument that was originally at the end of the command line or implicit (e.g.
to inject its unwinder), but it shouldn't otherwise reorder such arguments.

I will of course agree that the issue that the added -lc "solves" is actually
a bug in the testcase (and gdb).  But that should be immaterial here.  At the
very least gcc and g++ should behave the same in this respect.