Unknown variable errors with plpgsql composite types

[pauldzy]

Hi Lele, great project,

When parsing a plpgsql function with a composite type, the parse fails with an unknown variable error.

Example:

  CREATE TYPE public.dz_sumthing
  AS(sumattribute INTEGER);
  
  CREATE FUNCTION public.dz_sumfunc(
      IN  p_in  INTEGER
     ,OUT p_out public.dz_sumthing
  )
  AS $BODY$ 
  DECLARE
  BEGIN
     p_out.sumattribute := p_in;
  END;
  $BODY$
  LANGUAGE plpgsql;
  
  SELECT * FROM public.dz_sumfunc(123);

In this case I'd like to parse the function code:

from pglast import parse_plpgsql

str_sql = """
    CREATE FUNCTION public.dz_sumfunc(
        IN  p_in  INTEGER
       ,OUT p_out public.dz_sumthing
    )
    AS $BODY$ 
    DECLARE
    BEGIN
       p_out.sumattribute := p_in;
    END;
    $BODY$
    LANGUAGE plpgsql;
""";

root = parse_plpgsql(str_sql);

This returns

ParseError: "p_out.sumattribute" is not a known variable

I assume the code does not currently support cross-referencing the attributes of the type when variables are checked? Is there a way to avoid the check and just accept that p_out.sumattribute is valid?

Thanks!
Paul

[lelit]

Hi, I cannot check since I'm away for a brief vacation, but this could be related to #154, that is, a problem in the underlying libpg_query, possibly solved by a not-yet-merged PR.

[lelit]

Hi! Re-reading your report I see that it is clearly unrelated to #154, and indeed the following C program

#include <pg_query.h>
#include <stdio.h>
#include <stdlib.h>

int main() {
  PgQueryPlpgsqlParseResult result;

  result = pg_query_parse_plpgsql(" \
    CREATE FUNCTION public.dz_sumfunc(\
        IN  p_in  INTEGER\
       ,OUT p_out public.dz_sumthing\
    )\
    AS $BODY$\
    DECLARE\
    BEGIN\
       p_out.sumattribute := p_in;\
    END;\
    $BODY$\
    LANGUAGE plpgsql;");

  if (result.error) {
    printf("error: %s at %d\n", result.error->message, result.error->cursorpos);
  } else {
    printf("%s\n", result.plpgsql_funcs);
  }

  pg_query_free_plpgsql_parse_result(result);

  // Optional, this ensures all memory is freed upon program exit (useful when running Valgrind)
  pg_query_exit();

  return 0;
}

fails even with svenklemm's branch.

So I'm afraid there's little I can do on the pglast side. Maybe you could post the question on the libpg_query issues?

[pauldzy]

Thanks for your help, I passed the problem over to libpg_query as pganalyze/libpg_query#260
Looking at the history of such issues its might be useful to tag these errors more clearly as coming from libpg_query.
Cheers!

[lelit]

This is fixed in just released v6.8.