Re: GUC variables invisible to contrib/ modules

> -----Original Message-----
> From: pgsql-hackers-win32-owner(at)postgresql(dot)org
> [mailto:pgsql-hackers-win32-owner(at)postgresql(dot)org] On Behalf
> Of Andreas Pflug
> Sent: 11 August 2004 17:15
> To: Mark Cave-Ayland
> Cc: pgsql-hackers-win32(at)postgresql(dot)org
> Subject: Re: [pgsql-hackers-win32] GUC variables invisible to
> contrib/ modules
>
>
> Mark Cave-Ayland wrote:
> > Under Linux, PostGIS compiles and links fine without any trouble.
> > However, when compiling under Win32 we get the following message:
> >
> > Info: resolving _default_statistics_target by linking to
> > __imp__default_statistics_target (auto-import)
> > fu000024.o(.idata$3+0xc): undefined reference to
> `libpostgres_a_iname'
> > nmth000023.o(.idata$4+0x0): undefined reference to
> > `_nm__default_statistics_target'
> > c:\mingw\bin\dllwrap.exe: c:\mingw\bin\gcc exited with status 1
> >
> >
> > The current "fix" to enable this to work correctly is to change the
> > relevant line in /src/include/commands/vacuum.h from "extern int
> > default_statistics_target;" to "extern DLLIMPORT int
> > default_statistics_target;". However, I'm not convinced this is the
> > correct fix given that other contrib modules may require access to
> > other GUC variables.
>
>
> It would be fine if all non-static variables would be defined
> extern DLLIMPORT, but since non-backend modules don't
> regularly access
> those variables most won't have that keyword. Additionally,
> this is yet
> another M$ issue, non-existent anywhere else.
>
> A work around is to redefine the prototype when you use it,
> i.e. after
> all pgsql includes you define
> extern DLLIMPORT int default_statistics_target;
> in your sources. Apparently, the compiler will respect the latest
> definition and resolve the reference cleanly.
>
> Regards,
> Andreas

Hi Andreas,

Thanks for the suggestion - it worked exactly as you suspected, and the
compile completed without any further problems. Since no-one else has
commented on the correct method to access GUC variables (particularly
custom variables), I'll go for this approach at the moment.

Many thanks,

Mark.

---

Mark Cave-Ayland
Webbased Ltd.
Tamar Science Park
Derriford
Plymouth
PL6 8BX
England

Tel: +44 (0)1752 764445
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