Fix broken ruleutils support for function TRANSFORM clauses.

I chanced to notice that this dumped core due to a faulty Assert.
To add insult to injury, the output has been misformatted since v11.
Obviously we need some regression testing here.

Discussion: https://postgr.es/m/d1cc628c-3953-4209-957b-29427acc38c8@www.fastmail.com

contrib/hstore_plpython/expected/hstore_plpython.out

@@ -47,19 +47,29 @@ SELECT test1arr(array['aa=>bb, cc=>NULL'::hstore, 'dd=>ee']);
 (1 row)
 
 -- test python -> hstore
-CREATE FUNCTION test2() RETURNS hstore
+CREATE FUNCTION test2(a int, b text) RETURNS hstore
 LANGUAGE plpythonu
 TRANSFORM FOR TYPE hstore
 AS $$
-val = {'a': 1, 'b': 'boo', 'c': None}
+val = {'a': a, 'b': b, 'c': None}
 return val
 $$;
-SELECT test2();
+SELECT test2(1, 'boo');
               test2              
 ---------------------------------
  "a"=>"1", "b"=>"boo", "c"=>NULL
 (1 row)
 
+--- test ruleutils
+\sf test2
+CREATE OR REPLACE FUNCTION public.test2(a integer, b text)
+ RETURNS hstore
+ TRANSFORM FOR TYPE hstore
+ LANGUAGE plpythonu
+AS $function$
+val = {'a': a, 'b': b, 'c': None}
+return val
+$function$
 -- test python -> hstore[]
 CREATE FUNCTION test2arr() RETURNS hstore[]
 LANGUAGE plpythonu

contrib/hstore_plpython/sql/hstore_plpython.sql

@@ -40,15 +40,18 @@ SELECT test1arr(array['aa=>bb, cc=>NULL'::hstore, 'dd=>ee']);
 
 
 -- test python -> hstore
-CREATE FUNCTION test2() RETURNS hstore
+CREATE FUNCTION test2(a int, b text) RETURNS hstore
 LANGUAGE plpythonu
 TRANSFORM FOR TYPE hstore
 AS $$
-val = {'a': 1, 'b': 'boo', 'c': None}
+val = {'a': a, 'b': b, 'c': None}
 return val
 $$;
 
-SELECT test2();
+SELECT test2(1, 'boo');
+
+--- test ruleutils
+\sf test2
 
 
 -- test python -> hstore[]

src/backend/utils/adt/ruleutils.c

@@ -3103,13 +3103,14 @@ print_function_trftypes(StringInfo buf, HeapTuple proctup)
 	{
 		int			i;
 
-		appendStringInfoString(buf, "\n TRANSFORM ");
+		appendStringInfoString(buf, " TRANSFORM ");
 		for (i = 0; i < ntypes; i++)
 		{
 			if (i != 0)
 				appendStringInfoString(buf, ", ");
 			appendStringInfo(buf, "FOR TYPE %s", format_type_be(trftypes[i]));
 		}
+		appendStringInfoChar(buf, '\n');
 	}
 }
 

src/backend/utils/fmgr/funcapi.c

@@ -972,7 +972,9 @@ get_func_arg_info(HeapTuple procTup,
 /*
  * get_func_trftypes
  *
- * Returns the number of transformed types used by function.
+ * Returns the number of transformed types used by the function.
+ * If there are any, a palloc'd array of the type OIDs is returned
+ * into *p_trftypes.
  */
 int
 get_func_trftypes(HeapTuple procTup,
@@ -1001,7 +1003,6 @@ get_func_trftypes(HeapTuple procTup,
 			ARR_HASNULL(arr) ||
 			ARR_ELEMTYPE(arr) != OIDOID)
 			elog(ERROR, "protrftypes is not a 1-D Oid array");
-		Assert(nelems >= ((Form_pg_proc) GETSTRUCT(procTup))->pronargs);
 		*p_trftypes = (Oid *) palloc(nelems * sizeof(Oid));
 		memcpy(*p_trftypes, ARR_DATA_PTR(arr),
 			   nelems * sizeof(Oid));