Work around cross-version-upgrade issues created by commit 9e38c2bb5.

Summarily changing the STYPE of regression-test aggregates that
depend on array_append or array_cat is an issue for the buildfarm's
cross-version-upgrade tests, because those aggregates (as defined
in the back branches) now won't load into HEAD.  Although this seems
like only a minimal risk for genuine user-defined aggregates, we
need to do something for the buildfarm.  Hence, adjust the aggregate
definitions, in both HEAD and the back branches.

Discussion: https://postgr.es/m/1401824.1604537031@sss.pgh.pa.us
Discussion: https://postgr.es/m/E1kaQ2c-0005lx-Eg@gemulon.postgresql.org

src/test/regress/expected/polymorphism.out

@@ -729,24 +729,24 @@ select q2, sql_if(q2 > 0, q2, q2 + 1) from int8_tbl;
 (5 rows)
 
 -- another sort of polymorphic aggregate
-CREATE AGGREGATE array_cat_accum (anycompatiblearray)
+CREATE AGGREGATE array_larger_accum (anyarray)
 (
-    sfunc = array_cat,
+    sfunc = array_larger,
-    stype = anycompatiblearray,
+    stype = anyarray,
     initcond = '{}'
 );
-SELECT array_cat_accum(i)
+SELECT array_larger_accum(i)
 FROM (VALUES (ARRAY[1,2]), (ARRAY[3,4])) as t(i);
- array_cat_accum 
+ array_larger_accum 
------------------
+--------------------
- {1,2,3,4}
+ {3,4}
 (1 row)
 
-SELECT array_cat_accum(i)
+SELECT array_larger_accum(i)
 FROM (VALUES (ARRAY[row(1,2),row(3,4)]), (ARRAY[row(5,6),row(7,8)])) as t(i);
-          array_cat_accum          
+ array_larger_accum 
------------------------------------
+--------------------
- {"(1,2)","(3,4)","(5,6)","(7,8)"}
+ {"(5,6)","(7,8)"}
 (1 row)
 
 -- another kind of polymorphic aggregate
@@ -786,16 +786,18 @@ create aggregate build_group(int8, integer) (
   STYPE = int8[]
 );
 -- check proper resolution of data types for polymorphic transfn/finalfn
-create function first_el(anycompatiblearray) returns anycompatible as
+create function first_el_transfn(anyarray, anyelement) returns anyarray as
+'select $1 || $2' language sql immutable;
+create function first_el(anyarray) returns anyelement as
 'select $1[1]' language sql strict immutable;
 create aggregate first_el_agg_f8(float8) (
   SFUNC = array_append,
   STYPE = float8[],
   FINALFUNC = first_el
 );
-create aggregate first_el_agg_any(anycompatible) (
+create aggregate first_el_agg_any(anyelement) (
-  SFUNC = array_append,
+  SFUNC = first_el_transfn,
-  STYPE = anycompatiblearray,
+  STYPE = anyarray,
   FINALFUNC = first_el
 );
 select first_el_agg_f8(x::float8) from generate_series(1,10) x;

src/test/regress/sql/polymorphism.sql

@@ -498,17 +498,17 @@ select q2, sql_if(q2 > 0, q2, q2 + 1) from int8_tbl;
 
 -- another sort of polymorphic aggregate
 
-CREATE AGGREGATE array_cat_accum (anycompatiblearray)
+CREATE AGGREGATE array_larger_accum (anyarray)
 (
-    sfunc = array_cat,
+    sfunc = array_larger,
-    stype = anycompatiblearray,
+    stype = anyarray,
     initcond = '{}'
 );
 
-SELECT array_cat_accum(i)
+SELECT array_larger_accum(i)
 FROM (VALUES (ARRAY[1,2]), (ARRAY[3,4])) as t(i);
 
-SELECT array_cat_accum(i)
+SELECT array_larger_accum(i)
 FROM (VALUES (ARRAY[row(1,2),row(3,4)]), (ARRAY[row(5,6),row(7,8)])) as t(i);
 
 -- another kind of polymorphic aggregate
@@ -549,7 +549,10 @@ create aggregate build_group(int8, integer) (
 
 -- check proper resolution of data types for polymorphic transfn/finalfn
 
-create function first_el(anycompatiblearray) returns anycompatible as
+create function first_el_transfn(anyarray, anyelement) returns anyarray as
+'select $1 || $2' language sql immutable;
+
+create function first_el(anyarray) returns anyelement as
 'select $1[1]' language sql strict immutable;
 
 create aggregate first_el_agg_f8(float8) (
@@ -558,9 +561,9 @@ create aggregate first_el_agg_f8(float8) (
   FINALFUNC = first_el
 );
 
-create aggregate first_el_agg_any(anycompatible) (
+create aggregate first_el_agg_any(anyelement) (
-  SFUNC = array_append,
+  SFUNC = first_el_transfn,
-  STYPE = anycompatiblearray,
+  STYPE = anyarray,
   FINALFUNC = first_el
 );