Remove "invalid concatenation of jsonb objects" error case.

The jsonb || jsonb operator arbitrarily rejected certain combinations
of scalar and non-scalar inputs, while being willing to concatenate
other combinations.  This was of course quite undocumented.  Rather
than trying to document it, let's just remove the restriction,
creating a uniform rule that unless we are handling an object-to-object
concatenation, non-array inputs are converted to one-element arrays,
resulting in an array-to-array concatenation.  (This does not change
the behavior for any case that didn't throw an error before.)

Per complaint from Joel Jacobson.  Back-patch to all supported branches.

Discussion: https://postgr.es/m/163099.1608312033@sss.pgh.pa.us

1 files changed, 5 insertions, 0 deletions

diff --git a/src/test/regress/sql/jsonb.sql b/src/test/regress/sql/jsonb.sql
index 4c195b5527a..f1539682abd 100644
--- a/src/test/regress/sql/jsonb.sql
+++ b/src/test/regress/sql/jsonb.sql
@@ -772,6 +772,11 @@ select '{"a":"b"}'::jsonb || '[]'::jsonb;
 select '"a"'::jsonb || '{"a":1}';
 select '{"a":1}' || '"a"'::jsonb;
 
+select '[3]'::jsonb || '{}'::jsonb;
+select '3'::jsonb || '[]'::jsonb;
+select '3'::jsonb || '4'::jsonb;
+select '3'::jsonb || '{}'::jsonb;
+
 select '["a", "b"]'::jsonb || '{"c":1}';
 select '{"c": 1}'::jsonb || '["a", "b"]';