Fix recursive RECORD-returning plpython functions.

If we recursed to a new call of the same function, with a different
coldeflist (AS clause), it would fail because the inner call would
overwrite the outer call's idea of what to return.  This is vaguely
like 1d2fe56e4 and c5bec5426, but it's not due to any API decisions:
it's just that we computed the actual output rowtype at the start of
the call, and saved it in the per-procedure data structure.  We can
fix it at basically zero cost by doing the computation at the end
of each call instead of the start.

It's not clear that there's any real-world use-case for such a
function, but given that it doesn't cost anything to fix,
it'd be silly not to.

Per report from Andreas Karlsson.  Back-patch to all supported
branches.

Discussion: https://postgr.es/m/1651a46d-3c15-4028-a8c1-d74937b54e19@proxel.se

1 files changed, 17 insertions, 16 deletions

diff --git a/src/pl/plpython/plpy_exec.c b/src/pl/plpython/plpy_exec.c
index 9553c72e5ee..a7f7f6c553d 100644
--- a/src/pl/plpython/plpy_exec.c
+++ b/src/pl/plpython/plpy_exec.c
@@ -231,7 +231,23 @@ PLy_exec_function(FunctionCallInfo fcinfo, PLyProcedure *proc)
 		}
 		else
 		{
-			/* Normal conversion of result */
+			/*
+			 * Normal conversion of result.  However, if the result is of type
+			 * RECORD, we have to set up for that each time through, since it
+			 * might be different from last time.
+			 */
+			if (proc->result.typoid == RECORDOID)
+			{
+				TupleDesc	desc;
+
+				if (get_call_result_type(fcinfo, NULL, &desc) != TYPEFUNC_COMPOSITE)
+					ereport(ERROR,
+							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+							 errmsg("function returning record called in context "
+									"that cannot accept type record")));
+				PLy_output_setup_record(&proc->result, desc, proc);
+			}
+
 			rv = PLy_output_convert(&proc->result, plrv,
 									&fcinfo->isnull);
 		}
@@ -458,21 +474,6 @@ PLy_function_build_args(FunctionCallInfo fcinfo, PLyProcedure *proc)
 				PLy_elog(ERROR, "PyDict_SetItemString() failed, while setting up arguments");
 			arg = NULL;
 		}
-
-		/* Set up output conversion for functions returning RECORD */
-		if (proc->result.typoid == RECORDOID)
-		{
-			TupleDesc	desc;
-
-			if (get_call_result_type(fcinfo, NULL, &desc) != TYPEFUNC_COMPOSITE)
-				ereport(ERROR,
-						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-						 errmsg("function returning record called in context "
-								"that cannot accept type record")));
-
-			/* cache the output conversion functions */
-			PLy_output_setup_record(&proc->result, desc, proc);
-		}
 	}
 	PG_CATCH();
 	{