Fix incorrect Datum conversion in timestamptz_trunc_internal()

The code used a PG_RETURN_TIMESTAMPTZ() where the return type is
TimestampTz and not a Datum.

On 64-bit systems, there is no effect since this just ends up casting
64-bit integers back and forth.  On 32-bit systems, timestamptz is
pass-by-reference.  PG_RETURN_TIMESTAMPTZ() allocates new memory and
returns the address, meaning that the caller could interpret this as a
timestamp value.

The effect is using "date_trunc(..., 'infinity'::timestamptz) will
return random values (instead of the correct return value 'infinity').

Bug introduced in commit d85ce012f99f.

Author: Peter Eisentraut <peter@eisentraut.org>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/2d320b6f-b4af-4fbc-9eec-5d0fa15d187b@eisentraut.org
Discussion: https://postgr.es/m/4bf60a84-2862-4a53-acd5-8eddf134a60e@eisentraut.org
Backpatch-through: 18

diff --git a/src/backend/utils/adt/timestamp.c b/src/backend/utils/adt/timestamp.c
index 25cff56c3d07ec85c8b2c9137a8bc315d1f23dbf..e640b48205b404855023368168f4a92b787ce59e 100644 (file)
--- a/src/backend/utils/adt/timestamp.c
+++ b/src/backend/utils/adt/timestamp.c
@@ -4954,7 +4954,7 @@ timestamptz_trunc_internal(text *units, TimestampTz timestamp, pg_tz *tzp)
                                case DTK_SECOND:
                                case DTK_MILLISEC:
                                case DTK_MICROSEC:
-                                       PG_RETURN_TIMESTAMPTZ(timestamp);
+                                       return timestamp;
                                        break;
 
                                default: