Re: Compiling C Extension Functions against PostgreSQL 12

TalGloz <glozmantal@gmail.com> writes:
> I dont understand why the output for Postgres  12 
> g++ -Wall -Wpointer-arith -Wendif-labels -Wmissing-format-attribute
> -Wformat-security -fno-strict-aliasing -fwrapv -O2 -o seal_diff_cpp.o -c
> seal_diff_cpp.cpp
> seal_diff_cpp.cpp:2:10: fatal error: postgres.h: No such file or directory
>     2 | #include "postgres.h"
>       |          ^~~~~~~~~~~~

> looks different form the ones of Postgres 10

Looking at your Makefile, it seems to be expecting that CXXFLAGS will
be honored in the build, and it isn't being.

As far as I can see from pgxs.mk, you're supposed to spell that
PG_CXXFLAGS.  Probably, it accidentally worked to do it the other
way in v10, but no longer does, likely as a result of the fact that
there's now some minimal amount of C++ code in core PG.

I'm a little dubious about whether overriding CXX is a good idea now, too.
(Likely the core setting is the same, but if it were pointing at a
different compiler that could cause trouble.)

            regards, tom lane