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From: "vries at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug driver/99896] g++ drops -lc
Date: Sat, 03 Apr 2021 16:57:55 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D99896

--- Comment #2 from Tom de Vries <vries 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 ...
> > ...
>=20
> It isn't dropped, it's moved to the end:
>=20
> main.o foo.o -lpcre2-posix -lstdc++ -lm -lc -lgcc_s -lgcc -lc -lgcc_s -lg=
cc
>=20

I don't understand. AFAICT, it's dropped.  It's not moved to the end, becau=
se
-lc is already at the end without specifying -lc.=20

> If you need it before foo.o then -Wl,-lc seems like the right workaround =
for
> me.
>=20

Um, for my understanding, does that mean you agree this is a bug in g++?

> Why is it needed there anyway though?

main.o is intended to use regcomp from glibc.  Foo.o is intended to use
pcre2_regcomp from pcre2-posix (which is also accessible using plain regcom=
p).=20
When -lc is droppend, regcomp from pcre2-posix is used by main instead, whi=
ch
is incompatible with using re_search from glibc.=