openvpn-auth-ldap, -export-dynamic and ld.lld -e (was: Re: amd64-clang bulk build report (llvm 15))

On Sun, Jan 08 2023, Jeremie Courreges-Anglas <jca@wxcvbn.org> wrote:

[...]

>> https://wxcvbn.org/~jca/build-failures/amd64-clang/2023-01-03/net/openvpn-auth-ldap.txt
> [patch]
> Incorrect LDFLAGS
> ===> making all in src
> gmake[1]: Entering directory '/usr/ports/pobj/openvpn-auth-ldap-2.0.4/build-amd64/src'
> ../tools/lemon -T/usr/ports/pobj/openvpn-auth-ldap-2.0.4/openvpn-auth-ldap-auth-ldap-2.0.4/tools/lempar.c -m -q /usr/ports/pobj/openvpn-auth-ldap-2.0.4/openvpn-auth-ldap-auth-ldap-2.0.4/src/TRConfigParser.lemon -OTRConfigParser.m
> gmake[1]: *** [../Mk/compile.mk:12: TRConfigParser.m] Segmentation fault (core dumped)

This one is funny. There is a behavior difference between lld 13:

shannon /tmp$ cc -export-dynamic main.c

ld: warning: cannot find entry symbol xport-dynamic; defaulting to 0x1660
shannon /tmp$ ./a.out
hello, world!

and lld 15:

pbuild-amd64 /tmp$ cc -export-dynamic main.c
ld: warning: cannot find entry symbol xport-dynamic; not setting start address
pbuild-amd64 /tmp$ ./a.out
Segmentation fault (core dumped)

Why "cannot find entry symbol xport-dynamic"? Because ld.lld(1)
interprets this as -e xport-dynamic, and -e (--entry) sets the entry
point.

Now in the example above, 0x1660 is the start of the .text section. It
somehow works with a trivial hello world example, openvpn-auth-ldap
seems to rely on it and it's quite possible that other ports rely on
this behavior.

I have committed the fix for openvpn-auth-ldap.

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