On recent Red Hat platforms (at least RHEL 8 and Fedora 30, maybe older),
configure's probe for libperl failed if the user forces CFLAGS to be -O0.
This is because some code in perl's inline.h fails to be optimized away
at -O0, and said code doesn't work if compiled without -fPIC.
To fix, add CFLAGS_SL to the compile flags used during the libperl probe.
This is a better simulation of the way that plperl is built, anyway,
so it might forestall other issues in future.
Per gripe from Kyotaro Horiguchi. Back-patch to all supported branches,
since people might want to build older branches on these platforms.
Discussion: https://postgr.es/m/
20191010.144533.
263180400.horikyota.ntt@gmail.com
# On most platforms, if perl.h is there then libperl.so will be too, but at
# this writing Debian packages them separately. There is no known reason to
# waste cycles on separate probes for the Tcl or Python libraries, though.
+ # On some Red Hat platforms, the link attempt can fail if we don't use
+ # CFLAGS_SL while building the test program.
+ ac_save_CFLAGS=$CFLAGS
+ CFLAGS="$CFLAGS $CFLAGS_SL"
pgac_save_LIBS=$LIBS
LIBS="$perl_embed_ldflags"
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for libperl" >&5
rm -f core conftest.err conftest.$ac_objext \
conftest$ac_exeext conftest.$ac_ext
LIBS=$pgac_save_LIBS
+ CFLAGS=$ac_save_CFLAGS
CPPFLAGS=$ac_save_CPPFLAGS
fi
# On most platforms, if perl.h is there then libperl.so will be too, but at
# this writing Debian packages them separately. There is no known reason to
# waste cycles on separate probes for the Tcl or Python libraries, though.
+ # On some Red Hat platforms, the link attempt can fail if we don't use
+ # CFLAGS_SL while building the test program.
+ ac_save_CFLAGS=$CFLAGS
+ CFLAGS="$CFLAGS $CFLAGS_SL"
pgac_save_LIBS=$LIBS
LIBS="$perl_embed_ldflags"
AC_MSG_CHECKING([for libperl])
[AC_MSG_RESULT(no)
AC_MSG_ERROR([libperl library is required for Perl])])
LIBS=$pgac_save_LIBS
+ CFLAGS=$ac_save_CFLAGS
CPPFLAGS=$ac_save_CPPFLAGS
fi