Re: GUC variables invisible to contrib/ modules

Yep, DLLIMPORT is the right fix. Patch attached and applied.

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Mark Cave-Ayland wrote:
> Hi everyone,
>
> I've been experimenting with compiling PostGIS (a contrib module) under
> Win32 and I've noticed a difference in accessing GUC variables between
> Linux and Win32 using PostgreSQL 8.0 beta 1. In part of the PostGIS
> statistics routines we have a check like this:
>
>
> #include "commands/vacuum.h"
> ...
>
> /* If the attstattarget column is negative, use the default
> value */
> /* NB: it is okay to scribble on stats->attr since it's a copy
> */
> if (attr->attstattarget < 0)
> attr->attstattarget = default_statistics_target;
>
>
> 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.
>
> I've looked at guc.c and found GetConfigOption() which I think may be a
> better option since I don't think accessing the variable directly will
> work when using custom variables. Would this be the "correct" way to
> access GUC variable values from within other modules that would work
> correctly under both Win32 and UNIX-type OSs?
>
>
> Cheers,
>
> Mark.
>
> ---
>
> Mark Cave-Ayland
> Webbased Ltd.
> Tamar Science Park
> Derriford
> Plymouth
> PL6 8BX
> England
>
> Tel: +44 (0)1752 764445
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>
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