Bug 828856 – app-admin/authbind-2.1.2 fails to compile with clang/lld

• Product: Gentoo Linux
• Status: CONFIRMED ---

[Description Agostino Sarubbo 2021-12-10 18:46:24 UTC]

https://blogs.gentoo.org/ago/2020/07/04/gentoo-tinderbox/

Issue: app-admin/authbind-2.1.2 fails to compile with clang/lld.
Discovered on: amd64 (internal ref: tinderbox)

NOTE:
This machine uses clang as a compiler and lld as a linker.

[Comment 1 Agostino Sarubbo 2021-12-10 18:46:26 UTC]

Created attachment 758311 [details]
build.log

build log and emerge --info

[Comment 2 Agostino Sarubbo 2021-12-10 18:46:27 UTC]

Error(s) that match a know pattern:

ld.lld: error: unable to find library -ldl

[Comment 3 Sam James 2022-06-14 13:23:22 UTC]

I think this is caused by setting LD which we consider to be unsupported. You should just set -fuse-ld instead.

[Comment 4 Agostino Sarubbo 2022-06-14 13:32:32 UTC]

(In reply to Sam James from comment #3)
> I think this is caused by setting LD which we consider to be unsupported.
> You should just set -fuse-ld instead.

This is what was done, unless I misunderstood what are you saying:

x86_64-pc-linux-gnu-clang -Wl,-O1 -Wl,--as-needed -Wl,--defsym=__gentoo_check_ldflags__=0 -fuse-ld=lld  authbind.o   -o authbind

[Comment 5 Sam James 2022-06-14 13:40:15 UTC]

(In reply to Agostino Sarubbo from comment #4)
> (In reply to Sam James from comment #3)
> > I think this is caused by setting LD which we consider to be unsupported.
> > You should just set -fuse-ld instead.
> 
> This is what was done, unless I misunderstood what are you saying:
> 
> x86_64-pc-linux-gnu-clang -Wl,-O1 -Wl,--as-needed
> -Wl,--defsym=__gentoo_check_ldflags__=0 -fuse-ld=lld  authbind.o   -o
> authbind

So, it works for me if I *just* do *FLAGS="... -fuse-ld=lld", but if I set LD=ld.lld, it fails like in this bug.

Setting LD (and calling LD directly in the build system) is considered obsolete and most things don't support it. It's because calling LD is inflexible and doesn't allow passing options correctly.

So, I would not bother setting LD=... in the tinderbox. Only -fuse-ld=foo.

[Comment 6 Agostino Sarubbo 2022-06-14 13:53:09 UTC]

(In reply to Sam James from comment #5)
> (In reply to Agostino Sarubbo from comment #4)
> > (In reply to Sam James from comment #3)
> > > I think this is caused by setting LD which we consider to be unsupported.
> > > You should just set -fuse-ld instead.
> > 
> > This is what was done, unless I misunderstood what are you saying:
> > 
> > x86_64-pc-linux-gnu-clang -Wl,-O1 -Wl,--as-needed
> > -Wl,--defsym=__gentoo_check_ldflags__=0 -fuse-ld=lld  authbind.o   -o
> > authbind
> 
> So, it works for me if I *just* do *FLAGS="... -fuse-ld=lld", but if I set
> LD=ld.lld, it fails like in this bug.

Right, but I guess this is a case where it uses $LD instead of $CC/CXX for link

[Comment 7 Sam James 2022-06-14 14:02:07 UTC]

(In reply to Agostino Sarubbo from comment #6)
> (In reply to Sam James from comment #5)
> > (In reply to Agostino Sarubbo from comment #4)
> > > (In reply to Sam James from comment #3)
> > > > I think this is caused by setting LD which we consider to be unsupported.
> > > > You should just set -fuse-ld instead.
> > > 
> > > This is what was done, unless I misunderstood what are you saying:
> > > 
> > > x86_64-pc-linux-gnu-clang -Wl,-O1 -Wl,--as-needed
> > > -Wl,--defsym=__gentoo_check_ldflags__=0 -fuse-ld=lld  authbind.o   -o
> > > authbind
> > 
> > So, it works for me if I *just* do *FLAGS="... -fuse-ld=lld", but if I set
> > LD=ld.lld, it fails like in this bug.
> 
> Right, but I guess this is a case where it uses $LD instead of $CC/CXX for
> link

Ah! I was about to write "I think it uses LD if it's set, but if it's not, it'll do the right thing" (this has happened lots before), but you're right!

But there's some bad news too:
ld.lld: error: duplicate symbol: _init
>>> defined at /usr/lib/gcc/x86_64-pc-linux-gnu/12.1.1/../../../../lib64/crti.o:(.init+0x0)
>>> defined at libauthbind.c:116 (/var/tmp/portage/app-admin/authbind-2.1.2/work/authbind/libauthbind.c:116)
>>>            libauthbind.o:(.text+0x340)
collect2: error: ld returned 1 exit status

It's doing something quite naughty :(

[Comment 8 Sam James 2022-06-14 14:30:02 UTC]

Created attachment 785003 [details, diff]
0001-app-admin-authbind-don-t-call-LD-directly.patch

I'm not sure if the attached patch is right or not. The behaviour differs when invoked as ld vs via the gcc driver. I tried to see the relevant options but didn't figure it out.

I'm not sure how to test the authbind library either. Hm.