Add coccinele checking for AttrNumberGetAttrOffset

Postgres has `AttrNumberGetAttrOffset()` macro to proper access Datum
array members, so added a new coccinele static analysis to check for
missing macro usage.

Example:
`datum[attrno - 1]` should be `datum[AttrNumberGetAttrOffset(attrno)]`

Reference:
* https://github.com/postgres/postgres/blob/master/src/include/access/attnum.h)

coccinelle/attrnumbergetattroffset.cocci

@@ -0,0 +1,30 @@
+//
+// find missing `AttrNumberGetAttrOffset` usage
+//
+// Postgres has `AttrNumberGetAttrOffset()` macro to proper access Datum array members
+// (see https://github.com/postgres/postgres/blob/master/src/include/access/attnum.h).
+//
+// For example:
+//    `datum[attrno - 1]` should be `datum[AttrNumberGetAttrOffset(attrno)]`
+//
+
+@@
+typedef Datum;
+expression attrno;
+Datum [] datum;
+@@
+
+- datum[attrno - 1]
++ /* use AttrNumberGetAttrOffset() for acessing Datum array members */
++ datum[AttrNumberGetAttrOffset(attrno)]
+
+@@
+typedef bool;
+expression attrno;
+bool [] isnull;
+@@
+
+- isnull[attrno - 1]
++ /* use AttrNumberGetAttrOffset() for acessing bool array members */
++ isnull[AttrNumberGetAttrOffset(attrno)]
+

src/dimension.c

@@ -192,8 +192,8 @@ dimension_fill_in_from_tuple(Dimension *d, TupleInfo *ti, Oid main_table_relid)
 		   DatumGetName(values[AttrNumberGetAttrOffset(Anum_dimension_column_name)]),
 		   NAMEDATALEN);
 
-	if (!isnull[Anum_dimension_partitioning_func_schema - 1] &&
-		!isnull[Anum_dimension_partitioning_func - 1])
+	if (!isnull[AttrNumberGetAttrOffset(Anum_dimension_partitioning_func_schema)] &&
+		!isnull[AttrNumberGetAttrOffset(Anum_dimension_partitioning_func)])
 	{
 		MemoryContext old;
 
@@ -218,8 +218,8 @@ dimension_fill_in_from_tuple(Dimension *d, TupleInfo *ti, Oid main_table_relid)
 		MemoryContextSwitchTo(old);
 	}
 
-	if (!isnull[Anum_dimension_integer_now_func_schema - 1] &&
-		!isnull[Anum_dimension_integer_now_func - 1])
+	if (!isnull[AttrNumberGetAttrOffset(Anum_dimension_integer_now_func_schema)] &&
+		!isnull[AttrNumberGetAttrOffset(Anum_dimension_integer_now_func)])
 	{
 		namestrcpy(&d->fd.integer_now_func_schema,
 				   DatumGetCString(
@@ -230,12 +230,13 @@ dimension_fill_in_from_tuple(Dimension *d, TupleInfo *ti, Oid main_table_relid)
 	}
 
 	if (IS_CLOSED_DIMENSION(d))
-		d->fd.num_slices = DatumGetInt16(values[Anum_dimension_num_slices - 1]);
+		d->fd.num_slices =
+			DatumGetInt16(values[AttrNumberGetAttrOffset(Anum_dimension_num_slices)]);
 	else
 	{
 		d->fd.interval_length =
 			DatumGetInt64(values[AttrNumberGetAttrOffset(Anum_dimension_interval_length)]);
-		if (!isnull[Anum_dimension_compress_interval_length - 1])
+		if (!isnull[AttrNumberGetAttrOffset(Anum_dimension_compress_interval_length)])
 			d->fd.compress_interval_length = DatumGetInt64(
 				values[AttrNumberGetAttrOffset(Anum_dimension_compress_interval_length)]);
 	}

src/ts_catalog/continuous_agg.c

@@ -426,27 +426,29 @@ continuous_agg_fill_bucket_function(int32 mat_hypertable_id, ContinuousAggsBucke
 		 */
 		heap_deform_tuple(tuple, ts_scan_iterator_tupledesc(&iterator), values, isnull);
 
-		Assert(!isnull[Anum_continuous_aggs_bucket_function_experimental - 1]);
-		bf->experimental =
-			DatumGetBool(values[Anum_continuous_aggs_bucket_function_experimental - 1]);
+		Assert(!isnull[AttrNumberGetAttrOffset(Anum_continuous_aggs_bucket_function_experimental)]);
+		bf->experimental = DatumGetBool(
+			values[AttrNumberGetAttrOffset(Anum_continuous_aggs_bucket_function_experimental)]);
 
-		Assert(!isnull[Anum_continuous_aggs_bucket_function_name - 1]);
-		bf->name = TextDatumGetCString(values[Anum_continuous_aggs_bucket_function_name - 1]);
+		Assert(!isnull[AttrNumberGetAttrOffset(Anum_continuous_aggs_bucket_function_name)]);
+		bf->name = TextDatumGetCString(
+			values[AttrNumberGetAttrOffset(Anum_continuous_aggs_bucket_function_name)]);
 
 		/*
 		 * So far bucket_width is stored as TEXT for flexibility, but it's type
 		 * most likely is going to change to Interval when the variable-sized
 		 * buckets feature will stabilize.
 		 */
-		Assert(!isnull[Anum_continuous_aggs_bucket_function_bucket_width - 1]);
-		bucket_width_str =
-			TextDatumGetCString(values[Anum_continuous_aggs_bucket_function_bucket_width - 1]);
+		Assert(!isnull[AttrNumberGetAttrOffset(Anum_continuous_aggs_bucket_function_bucket_width)]);
+		bucket_width_str = TextDatumGetCString(
+			values[AttrNumberGetAttrOffset(Anum_continuous_aggs_bucket_function_bucket_width)]);
 		Assert(strlen(bucket_width_str) > 0);
 		bf->bucket_width = DatumGetIntervalP(
 			DirectFunctionCall3(interval_in, CStringGetDatum(bucket_width_str), InvalidOid, -1));
 
-		Assert(!isnull[Anum_continuous_aggs_bucket_function_origin - 1]);
-		origin_str = TextDatumGetCString(values[Anum_continuous_aggs_bucket_function_origin - 1]);
+		Assert(!isnull[AttrNumberGetAttrOffset(Anum_continuous_aggs_bucket_function_origin)]);
+		origin_str = TextDatumGetCString(
+			values[AttrNumberGetAttrOffset(Anum_continuous_aggs_bucket_function_origin)]);
 		if (strlen(origin_str) == 0)
 			TIMESTAMP_NOBEGIN(bf->origin);
 		else
@@ -455,9 +457,9 @@ continuous_agg_fill_bucket_function(int32 mat_hypertable_id, ContinuousAggsBucke
 															   ObjectIdGetDatum(InvalidOid),
 															   Int32GetDatum(-1)));
 
-		Assert(!isnull[Anum_continuous_aggs_bucket_function_timezone - 1]);
-		bf->timezone =
-			TextDatumGetCString(values[Anum_continuous_aggs_bucket_function_timezone - 1]);
+		Assert(!isnull[AttrNumberGetAttrOffset(Anum_continuous_aggs_bucket_function_timezone)]);
+		bf->timezone = TextDatumGetCString(
+			values[AttrNumberGetAttrOffset(Anum_continuous_aggs_bucket_function_timezone)]);
 
 		count++;
 

src/utils.c

@@ -1543,8 +1543,8 @@ ts_copy_relation_acl(const Oid source_relid, const Oid target_relid, const Oid o
 		bool new_repl[Natts_pg_class] = { false };
 		Acl *acl = DatumGetAclP(acl_datum);
 
-		new_repl[Anum_pg_class_relacl - 1] = true;
-		new_val[Anum_pg_class_relacl - 1] = PointerGetDatum(acl);
+		new_repl[AttrNumberGetAttrOffset(Anum_pg_class_relacl)] = true;
+		new_val[AttrNumberGetAttrOffset(Anum_pg_class_relacl)] = PointerGetDatum(acl);
 
 		/* Find the tuple for the target in `pg_class` */
 		target_tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(target_relid));