Re: GUC variables invisible to contrib/ modules

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

---------------------------------------------------------------------------

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
> Fax: +44 (0)1752 764446
> 
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Index: src/include/commands/vacuum.h
===================================================================
RCS file: /cvsroot/pgsql-server/src/include/commands/vacuum.h,v
retrieving revision 1.54
diff -c -c -r1.54 vacuum.h
*** src/include/commands/vacuum.h	3 Jun 2004 02:08:05 -0000	1.54
--- src/include/commands/vacuum.h	17 Aug 2004 02:50:26 -0000
***************
*** 121,127 ****
  } VacRUsage;
  
  /* Default statistics target (GUC parameter) */
! extern int	default_statistics_target;
  
  
  /* in commands/vacuum.c */
--- 121,127 ----
  } VacRUsage;
  
  /* Default statistics target (GUC parameter) */
! extern DLLIMPORT int	default_statistics_target;	/* DLLIMPORT for PostGIS */
  
  
  /* in commands/vacuum.c */