Horton

Re: pl/perl extension fails on Windows

Andrew Dunstan <andrew.dunstan@2ndquadrant.com>

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From: Andrew Dunstan <andrew.dunstan@2ndquadrant.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Ashutosh Sharma <ashu.coek88@gmail.com>, Dave Page <dpage@pgadmin.org>, Sandeep Thakkar <sandeep.thakkar@enterprisedb.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2017-07-13T16:14:19Z
Lists: pgsql-hackers 

On 07/13/2017 10:36 AM, Tom Lane wrote:
> Andrew Dunstan <andrew.dunstan@2ndquadrant.com> writes:
>> On 07/13/2017 08:08 AM, Ashutosh Sharma wrote:
>>> -    dVAR; dXSBOOTARGSAPIVERCHK;
>>> +    dVAR; dXSBOOTARGSNOVERCHK;
>> Good job hunting this down!
>> One suggestion I saw in a little googling was that we add this to the XS
>> file after the inclusion of XSUB.h:
>>     #undef dXSBOOTARGSAPIVERCHK
>>     #define dXSBOOTARGSAPIVERCHK dXSBOOTARGSNOVERCHK
> I don't see anything even vaguely like that in the Util.c file generated
> by Perl 5.10.1, which is what I've got on my RHEL machine.




This is all fairly modern, so it's hardly surprising that it doesn't
happen with the ancient perl 5.10.

here's a snippet from the generated Util.c on crake (Fedora 25, perl 5.24):

    XS_EXTERNAL(boot_PostgreSQL__InServer__Util); /* prototype to pass
    -Wmissing-prototypes */
    XS_EXTERNAL(boot_PostgreSQL__InServer__Util)
    {
    #if PERL_VERSION_LE(5, 21, 5)
        dVAR; dXSARGS;
    #else
        dVAR; dXSBOOTARGSAPIVERCHK;
    #endif



>
> What I do notice is this in Util.xs:
>
> VERSIONCHECK: DISABLE
>
> which leads immediately to two questions:
>
> 1. Why is your version of xsubpp apparently ignoring this directive
> and generating a version check anyway?
>
> 2. Why do we have this directive in the first place?  It does not seem
> to me like a terribly great idea to ignore low-level version mismatches.
>
> In the same vein, I'm suspicious of proposals to "fix" this problem
> by removing the version check, which seems to be where Ashutosh
> is headed.  In the long run that seems certain to cause huge headaches.



That is a different version check. It's the equivalent of xsubpp's
--noversioncheck flag. The versions it would check are the object file
and the corresponding pm file.

In fact the usage I suggested seems to be blessed in XSUB.h in this comment:

    /* dXSBOOTARGSNOVERCHK has no API in xsubpp to choose it so do
    #undef dXSBOOTARGSXSAPIVERCHK
    #define dXSBOOTARGSXSAPIVERCHK dXSBOOTARGSNOVERCHK */





It would be nice to get to the bottom of why we're getting a version
mismatch on Windows, since we're clearly not getting one on Linux. But
since we've got on happily all these years without the API version check
we might well survive a few more going on as we are.

cheers

andrew

-- 
Andrew Dunstan                https://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

Commits

  1. MSVC: Test whether 32-bit Perl needs -D_USE_32BIT_TIME_T.

  2. Further tweaks to compiler flags for PL/Perl on Windows.

  3. Absorb -D_USE_32BIT_TIME_T switch from Perl, if relevant.

  4. PL/Perl portability fix: absorb relevant -D switches from Perl.

  5. PL/Perl portability fix: avoid including XSUB.h in plperl.c.