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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
PostgreSQL Database Management System ===================================== This directory contains the source code distribution of the PostgreSQL database management system. PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings. PostgreSQL has many language interfaces, many of which are listed here: https://www.postgresql.org/download See the file INSTALL for instructions on how to build and install PostgreSQL. That file also lists supported operating systems and hardware platforms and contains information regarding any other software packages that are required to build or run the PostgreSQL system. Copyright and license information can be found in the file COPYRIGHT. A comprehensive documentation set is included in this distribution; it can be read as described in the installation instructions. The latest version of this software may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.