postgresql/contrib/postgres_fdw
Tom Lane dddfc4cb2e Prevent accidental linking of system-supplied copies of libpq.so etc.
We were being careless in some places about the order of -L switches in
link command lines, such that -L switches referring to external directories
could come before those referring to directories within the build tree.
This made it possible to accidentally link a system-supplied library, for
example /usr/lib/libpq.so, in place of the one built in the build tree.
Hilarity ensued, the more so the older the system-supplied library is.

To fix, break LDFLAGS into two parts, a sub-variable LDFLAGS_INTERNAL
and the main LDFLAGS variable, both of which are "recursively expanded"
so that they can be incrementally adjusted by different makefiles.
Establish a policy that -L switches for directories in the build tree
must always be added to LDFLAGS_INTERNAL, while -L switches for external
directories must always be added to LDFLAGS.  This is sufficient to
ensure a safe search order.  For simplicity, we typically also put -l
switches for the respective libraries into those same variables.
(Traditional make usage would have us put -l switches into LIBS, but
cleaning that up is a project for another day, as there's no clear
need for it.)

This turns out to also require separating SHLIB_LINK into two variables,
SHLIB_LINK and SHLIB_LINK_INTERNAL, with a similar rule about which
switches go into which variable.  And likewise for PG_LIBS.

Although this change might appear to affect external users of pgxs.mk,
I think it doesn't; they shouldn't have any need to touch the _INTERNAL
variables.

In passing, tweak src/common/Makefile so that the value of CPPFLAGS
recorded in pg_config lacks "-DFRONTEND" and the recorded value of
LDFLAGS lacks "-L../../../src/common".  Both of those things are
mistakes, apparently introduced during prior code rearrangements,
as old versions of pg_config don't print them.  In general we don't
want anything that's specific to the src/common subdirectory to
appear in those outputs.

This is certainly a bug fix, but in view of the lack of field
complaints, I'm unsure whether it's worth the risk of back-patching.
In any case it seems wise to see what the buildfarm makes of it first.

Discussion: https://postgr.es/m/25214.1522604295@sss.pgh.pa.us
2018-04-03 16:26:05 -04:00
..
expected postgres_fdw: Push down partition-wise aggregation. 2018-04-02 10:51:50 -04:00
sql postgres_fdw: Push down partition-wise aggregation. 2018-04-02 10:51:50 -04:00
.gitignore Add postgres_fdw contrib module. 2013-02-21 05:27:16 -05:00
connection.c Improve style guideline compliance of assorted error-report messages. 2018-03-22 17:33:10 -04:00
deparse.c Fix format_type() to restore its old behavior. 2018-03-01 11:37:46 -05:00
Makefile Prevent accidental linking of system-supplied copies of libpq.so etc. 2018-04-03 16:26:05 -04:00
option.c Improve style guideline compliance of assorted error-report messages. 2018-03-22 17:33:10 -04:00
postgres_fdw--1.0.sql Add postgres_fdw contrib module. 2013-02-21 05:27:16 -05:00
postgres_fdw.c postgres_fdw: Push down partition-wise aggregation. 2018-04-02 10:51:50 -04:00
postgres_fdw.control Add postgres_fdw contrib module. 2013-02-21 05:27:16 -05:00
postgres_fdw.h postgres_fdw: Push down UPDATE/DELETE joins to remote servers. 2018-02-07 15:34:30 -05:00
shippable.c Update copyright for 2018 2018-01-02 23:30:12 -05:00