Re: [HACKERS] New compile warnings - Mailing list pgsql-patches

Tom Lane wrote:

>Bruce Momjian <pgman@candle.pha.pa.us> writes:
>
>
>>I am seeing the following compile warnings in CVS. I am using for perl:
>>    Summary of my perl5 (5.0 patchlevel 5 subversion 3) configuration:
>>
>>
>
>I believe these two:
>
>
>
>>plperl.c:948: warning: `ret_hv' might be used uninitialized in this function
>>plperl.c:949: warning: `ret_av' might be used uninitialized in this function
>>
>>
>
>indicate an actual bug --- at least, it's far from clear that the code
>can't try to use an uninitialized value.  I trust that the authors of
>plperl will step up and fix it; I'm not sufficiently clear on what cases
>they are trying to support to want to touch it.
>
>

I don't currently have the resources to clean this up properly. The
attached patch tries to make clear in a comment what the code is doing,
and also initializes these variables to NULL. If someone wants to take a
stab at cleaning this up they are welcome to - I don't expect to be able
to for quite a while.

>The others indicate sloppiness in the C code generated by perl's XS
>functionality.  There's nothing we can do about them.  FWIW, less
>obsolete versions of Perl generate fewer warnings --- the only one of
>these that I see on 5.8.0 and up is
>
>
>
>>SPI.c:158: warning: unused variable `items'
>>
>>
>
>
>
>

The patch also addresses this issue.

cheers

andrew
Index: SPI.xs
===================================================================
RCS file: /home/cvsmirror/pgsql/src/pl/plperl/SPI.xs,v
retrieving revision 1.10
diff -c -r1.10 SPI.xs
*** SPI.xs    20 Nov 2004 19:07:40 -0000    1.10
--- SPI.xs    21 Nov 2004 15:02:15 -0000
***************
*** 94,96 ****
--- 94,100 ----
          RETVAL = newRV_noinc((SV*) ret_hash);
      OUTPUT:
          RETVAL
+
+
+ BOOT:
+     items = 0;  /* avoid 'unused variable' warning */
Index: plperl.c
===================================================================
RCS file: /home/cvsmirror/pgsql/src/pl/plperl/plperl.c,v
retrieving revision 1.59
diff -c -r1.59 plperl.c
*** plperl.c    20 Nov 2004 19:07:40 -0000    1.59
--- plperl.c    21 Nov 2004 20:40:50 -0000
***************
*** 963,971 ****

      if (prodesc->fn_retistuple && fcinfo->resultinfo)    /* set of tuples */
      {
          /* SRF support */
!         HV           *ret_hv;
!         AV           *ret_av;
          FuncCallContext *funcctx;
          int            call_cntr;
          int            max_calls;
--- 963,988 ----

      if (prodesc->fn_retistuple && fcinfo->resultinfo)    /* set of tuples */
      {
+
+         /*
+          *  This branch will be taken when the function call
+          *  appears on a context that can return a set of tuples
+          *  even if it only actually returns a single tuple
+          *  (e.g. select a from foo() where foor returns a singletone
+          *  of some composite type with member a). In this case, the
+          *  return value will be a hashref. If a rowset is returned
+          *  it will be an arrayref whose members will be hashrefs.
+          *
+          *  Care is taken in the code only to refer to the appropriate
+          *  one of ret_hv and ret_av, only one of which is therefore
+          *  valid for any given call.
+          *
+          *  XXX This code is in dire need of cleanup.
+          */
+
          /* SRF support */
!         HV           *ret_hv = NULL;
!         AV           *ret_av = NULL;
          FuncCallContext *funcctx;
          int            call_cntr;
          int            max_calls;