Thread: Linking PostgreSQL as a C++ program
Hi all
--
In my ongoing efforts to make Tom look at me in horror, I've compiled PostgreSQL with C++ objects linked into the core server. Currently this is just my notes on how, in case anyone else needs to later.
To do it you really only have to change src/backend/Makefile to use g++ as a linker:
postgres: $(OBJS)
- $(CC) $(CFLAGS) $(LDFLAGS) $(LDFLAGS_EX) $(export_dynamic) $(call expand_subsys,$^) $(LIBS) -o $@
+ $(CXX) $(CFLAGS) $(LDFLAGS) $(LDFLAGS_EX) $(export_dynamic) $(call expand_subsys,$^) $(LIBS) -o $@
so it links to libstdc++.
To use the postgres headers within C++ code you must also:
extern "C" {
#include "postgres.h"
}
since we only do that automagically for the frontend headers.
Currently it's also necessary to add a "_THROW" annotation to src/include/port.h's definition of inet_net_ntop to stop it conflicting with <inet/arpa.h>'s definition.
The Makefiles already support building and linking C++ objects, so a normal Makefile can specify c++ sources in "OBJS", e.g. "blah.o" will get compiled from "blah.cpp".
If what I'm prototyping works out I'll do my best to move it into an extension, because I can just imagine how likely a patch that adds c++11 code to the core server would be to get accepted ;)
On Mon, Jan 29, 2018 at 05:46:54PM +1300, Craig Ringer wrote:
> extern "C" {
> #include "postgres.h"
> }
Don't you need __cplusplus as well? More or less that:
#ifdef __cplusplus
extern "C" {
#endif
#include "postgres.h"
#ifdef __cplusplus
}
#endif
--
Michael
Attachment
On 29 January 2018 at 18:02, Michael Paquier <michael.paquier@gmail.com> wrote:
On Mon, Jan 29, 2018 at 05:46:54PM +1300, Craig Ringer wrote:
> extern "C" {
> #include "postgres.h"
> }
Don't you need __cplusplus as well? More or less that:
#ifdef __cplusplus
extern "C" {
#endif
#include "postgres.h"
#ifdef __cplusplus
}
#endif
For headers used by both C and C++ code, yes.
For C++ sources, no.