Replace many MemSet calls with struct initialization

This replaces all MemSet() calls with struct initialization where that
is easily and obviously possible.  (For example, some cases have to
worry about padding bits, so I left those.)

(The same could be done with appropriate memset() calls, but this
patch is part of an effort to phase out MemSet(), so it doesn't touch
memset() calls.)

Reviewed-by: Ranier Vilela <ranier.vf@gmail.com>
Reviewed-by: Alvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://www.postgresql.org/message-id/9847b13c-b785-f4e2-75c3-12ec77a3b05c@enterprisedb.com

src/backend/utils/adt/acl.c

@@ -1785,7 +1785,7 @@ aclexplode(PG_FUNCTION_ARGS)
 		{
 			Datum		result;
 			Datum		values[4];
-			bool		nulls[4];
+			bool		nulls[4] = {0};
 			HeapTuple	tuple;
 
 			values[0] = ObjectIdGetDatum(aidata->ai_grantor);
@@ -1793,8 +1793,6 @@ aclexplode(PG_FUNCTION_ARGS)
 			values[2] = CStringGetTextDatum(convert_aclright_to_string(priv_bit));
 			values[3] = BoolGetDatum((ACLITEM_GET_GOPTIONS(*aidata) & priv_bit) != 0);
 
-			MemSet(nulls, 0, sizeof(nulls));
-
 			tuple = heap_form_tuple(funcctx->tuple_desc, values, nulls);
 			result = HeapTupleGetDatum(tuple);
 

src/backend/utils/adt/arrayfuncs.c

@@ -742,11 +742,10 @@ ReadArrayStr(char *arrayStr,
 	bool		eoArray = false;
 	bool		hasnull;
 	int32		totbytes;
-	int			indx[MAXDIM],
+	int			indx[MAXDIM] = {0},
 				prod[MAXDIM];
 
 	mda_get_prod(ndim, dim, prod);
-	MemSet(indx, 0, sizeof(indx));
 
 	/* Initialize is-null markers to true */
 	memset(nulls, true, nitems * sizeof(bool));

src/backend/utils/adt/datetime.c

@@ -4924,7 +4924,7 @@ pg_timezone_abbrevs(PG_FUNCTION_ARGS)
 	Datum		result;
 	HeapTuple	tuple;
 	Datum		values[3];
-	bool		nulls[3];
+	bool		nulls[3] = {0};
 	const datetkn *tp;
 	char		buffer[TOKMAXLEN + 1];
 	int			gmtoffset;
@@ -5011,8 +5011,6 @@ pg_timezone_abbrevs(PG_FUNCTION_ARGS)
 			break;
 	}
 
-	MemSet(nulls, 0, sizeof(nulls));
-
 	/*
 	 * Convert name to text, using upcasing conversion that is the inverse of
 	 * what ParseDateTime() uses.
@@ -5051,7 +5049,7 @@ pg_timezone_names(PG_FUNCTION_ARGS)
 	pg_tzenum  *tzenum;
 	pg_tz	   *tz;
 	Datum		values[4];
-	bool		nulls[4];
+	bool		nulls[4] = {0};
 	int			tzoff;
 	struct pg_tm tm;
 	fsec_t		fsec;
@@ -5088,8 +5086,6 @@ pg_timezone_names(PG_FUNCTION_ARGS)
 		if (tzn && strlen(tzn) > 31)
 			continue;
 
-		MemSet(nulls, 0, sizeof(nulls));
-
 		values[0] = CStringGetTextDatum(pg_get_timezone_name(tz));
 		values[1] = CStringGetTextDatum(tzn ? tzn : "");
 

src/backend/utils/adt/lockfuncs.c

@@ -172,8 +172,8 @@ pg_lock_status(PG_FUNCTION_ARGS)
 		LOCKMODE	mode = 0;
 		const char *locktypename;
 		char		tnbuf[32];
-		Datum		values[NUM_LOCK_STATUS_COLUMNS];
-		bool		nulls[NUM_LOCK_STATUS_COLUMNS];
+		Datum		values[NUM_LOCK_STATUS_COLUMNS] = {0};
+		bool		nulls[NUM_LOCK_STATUS_COLUMNS] = {0};
 		HeapTuple	tuple;
 		Datum		result;
 		LockInstanceData *instance;
@@ -230,8 +230,6 @@ pg_lock_status(PG_FUNCTION_ARGS)
 		/*
 		 * Form tuple with appropriate data.
 		 */
-		MemSet(values, 0, sizeof(values));
-		MemSet(nulls, false, sizeof(nulls));
 
 		if (instance->locktag.locktag_type <= LOCKTAG_LAST_TYPE)
 			locktypename = LockTagTypeNames[instance->locktag.locktag_type];
@@ -359,8 +357,8 @@ pg_lock_status(PG_FUNCTION_ARGS)
 
 		PREDICATELOCKTARGETTAG *predTag = &(predLockData->locktags[mystatus->predLockIdx]);
 		SERIALIZABLEXACT *xact = &(predLockData->xacts[mystatus->predLockIdx]);
-		Datum		values[NUM_LOCK_STATUS_COLUMNS];
-		bool		nulls[NUM_LOCK_STATUS_COLUMNS];
+		Datum		values[NUM_LOCK_STATUS_COLUMNS] = {0};
+		bool		nulls[NUM_LOCK_STATUS_COLUMNS] = {0};
 		HeapTuple	tuple;
 		Datum		result;
 
@@ -369,8 +367,6 @@ pg_lock_status(PG_FUNCTION_ARGS)
 		/*
 		 * Form tuple with appropriate data.
 		 */
-		MemSet(values, 0, sizeof(values));
-		MemSet(nulls, false, sizeof(nulls));
 
 		/* lock type */
 		lockType = GET_PREDICATELOCKTARGETTAG_TYPE(*predTag);

src/backend/utils/adt/partitionfuncs.c

@@ -113,8 +113,8 @@ pg_partition_tree(PG_FUNCTION_ARGS)
 	if (funcctx->call_cntr < list_length(partitions))
 	{
 		Datum		result;
-		Datum		values[PG_PARTITION_TREE_COLS];
-		bool		nulls[PG_PARTITION_TREE_COLS];
+		Datum		values[PG_PARTITION_TREE_COLS] = {0};
+		bool		nulls[PG_PARTITION_TREE_COLS] = {0};
 		HeapTuple	tuple;
 		Oid			parentid = InvalidOid;
 		Oid			relid = list_nth_oid(partitions, funcctx->call_cntr);
@@ -126,8 +126,6 @@ pg_partition_tree(PG_FUNCTION_ARGS)
 		/*
 		 * Form tuple with appropriate data.
 		 */
-		MemSet(nulls, 0, sizeof(nulls));
-		MemSet(values, 0, sizeof(values));
 
 		/* relid */
 		values[0] = ObjectIdGetDatum(relid);

src/backend/utils/adt/pgstatfuncs.c

@@ -488,13 +488,10 @@ pg_stat_get_progress_info(PG_FUNCTION_ARGS)
 	{
 		LocalPgBackendStatus *local_beentry;
 		PgBackendStatus *beentry;
-		Datum		values[PG_STAT_GET_PROGRESS_COLS];
-		bool		nulls[PG_STAT_GET_PROGRESS_COLS];
+		Datum		values[PG_STAT_GET_PROGRESS_COLS] = {0};
+		bool		nulls[PG_STAT_GET_PROGRESS_COLS] = {0};
 		int			i;
 
-		MemSet(values, 0, sizeof(values));
-		MemSet(nulls, 0, sizeof(nulls));
-
 		local_beentry = pgstat_fetch_stat_local_beentry(curr_backend);
 
 		if (!local_beentry)
@@ -551,17 +548,14 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 	for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
 	{
 		/* for each row */
-		Datum		values[PG_STAT_GET_ACTIVITY_COLS];
-		bool		nulls[PG_STAT_GET_ACTIVITY_COLS];
+		Datum		values[PG_STAT_GET_ACTIVITY_COLS] = {0};
+		bool		nulls[PG_STAT_GET_ACTIVITY_COLS] = {0};
 		LocalPgBackendStatus *local_beentry;
 		PgBackendStatus *beentry;
 		PGPROC	   *proc;
 		const char *wait_event_type = NULL;
 		const char *wait_event = NULL;
 
-		MemSet(values, 0, sizeof(values));
-		MemSet(nulls, 0, sizeof(nulls));
-
 		/* Get the next one in the list */
 		local_beentry = pgstat_fetch_stat_local_beentry(curr_backend);
 		if (!local_beentry)
@@ -1747,15 +1741,11 @@ pg_stat_get_wal(PG_FUNCTION_ARGS)
 {
 #define PG_STAT_GET_WAL_COLS	9
 	TupleDesc	tupdesc;
-	Datum		values[PG_STAT_GET_WAL_COLS];
-	bool		nulls[PG_STAT_GET_WAL_COLS];
+	Datum		values[PG_STAT_GET_WAL_COLS] = {0};
+	bool		nulls[PG_STAT_GET_WAL_COLS] = {0};
 	char		buf[256];
 	PgStat_WalStats *wal_stats;
 
-	/* Initialise values and NULL flags arrays */
-	MemSet(values, 0, sizeof(values));
-	MemSet(nulls, 0, sizeof(nulls));
-
 	/* Initialise attributes information in the tuple descriptor */
 	tupdesc = CreateTemplateTupleDesc(PG_STAT_GET_WAL_COLS);
 	TupleDescInitEntry(tupdesc, (AttrNumber) 1, "wal_records",
@@ -1826,8 +1816,8 @@ pg_stat_get_slru(PG_FUNCTION_ARGS)
 	for (i = 0;; i++)
 	{
 		/* for each row */
-		Datum		values[PG_STAT_GET_SLRU_COLS];
-		bool		nulls[PG_STAT_GET_SLRU_COLS];
+		Datum		values[PG_STAT_GET_SLRU_COLS] = {0};
+		bool		nulls[PG_STAT_GET_SLRU_COLS] = {0};
 		PgStat_SLRUStats stat;
 		const char *name;
 
@@ -1837,8 +1827,6 @@ pg_stat_get_slru(PG_FUNCTION_ARGS)
 			break;
 
 		stat = stats[i];
-		MemSet(values, 0, sizeof(values));
-		MemSet(nulls, 0, sizeof(nulls));
 
 		values[0] = PointerGetDatum(cstring_to_text(name));
 		values[1] = Int64GetDatum(stat.blocks_zeroed);
@@ -2201,14 +2189,10 @@ Datum
 pg_stat_get_archiver(PG_FUNCTION_ARGS)
 {
 	TupleDesc	tupdesc;
-	Datum		values[7];
-	bool		nulls[7];
+	Datum		values[7] = {0};
+	bool		nulls[7] = {0};
 	PgStat_ArchiverStats *archiver_stats;
 
-	/* Initialise values and NULL flags arrays */
-	MemSet(values, 0, sizeof(values));
-	MemSet(nulls, 0, sizeof(nulls));
-
 	/* Initialise attributes information in the tuple descriptor */
 	tupdesc = CreateTemplateTupleDesc(7);
 	TupleDescInitEntry(tupdesc, (AttrNumber) 1, "archived_count",
@@ -2274,15 +2258,11 @@ pg_stat_get_replication_slot(PG_FUNCTION_ARGS)
 	text	   *slotname_text = PG_GETARG_TEXT_P(0);
 	NameData	slotname;
 	TupleDesc	tupdesc;
-	Datum		values[PG_STAT_GET_REPLICATION_SLOT_COLS];
-	bool		nulls[PG_STAT_GET_REPLICATION_SLOT_COLS];
+	Datum		values[PG_STAT_GET_REPLICATION_SLOT_COLS] = {0};
+	bool		nulls[PG_STAT_GET_REPLICATION_SLOT_COLS] = {0};
 	PgStat_StatReplSlotEntry *slotent;
 	PgStat_StatReplSlotEntry allzero;
 
-	/* Initialise values and NULL flags arrays */
-	MemSet(values, 0, sizeof(values));
-	MemSet(nulls, 0, sizeof(nulls));
-
 	/* Initialise attributes information in the tuple descriptor */
 	tupdesc = CreateTemplateTupleDesc(PG_STAT_GET_REPLICATION_SLOT_COLS);
 	TupleDescInitEntry(tupdesc, (AttrNumber) 1, "slot_name",
@@ -2348,8 +2328,8 @@ pg_stat_get_subscription_stats(PG_FUNCTION_ARGS)
 #define PG_STAT_GET_SUBSCRIPTION_STATS_COLS	4
 	Oid			subid = PG_GETARG_OID(0);
 	TupleDesc	tupdesc;
-	Datum		values[PG_STAT_GET_SUBSCRIPTION_STATS_COLS];
-	bool		nulls[PG_STAT_GET_SUBSCRIPTION_STATS_COLS];
+	Datum		values[PG_STAT_GET_SUBSCRIPTION_STATS_COLS] = {0};
+	bool		nulls[PG_STAT_GET_SUBSCRIPTION_STATS_COLS] = {0};
 	PgStat_StatSubEntry *subentry;
 	PgStat_StatSubEntry allzero;
 
@@ -2368,10 +2348,6 @@ pg_stat_get_subscription_stats(PG_FUNCTION_ARGS)
 					   TIMESTAMPTZOID, -1, 0);
 	BlessTupleDesc(tupdesc);
 
-	/* Initialise values and NULL flags arrays */
-	MemSet(values, 0, sizeof(values));
-	MemSet(nulls, 0, sizeof(nulls));
-
 	if (!subentry)
 	{
 		/* If the subscription is not found, initialise its stats */

src/backend/utils/adt/selfuncs.c

@@ -6642,10 +6642,10 @@ btcostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
 			   double *indexPages)
 {
 	IndexOptInfo *index = path->indexinfo;
-	GenericCosts costs;
+	GenericCosts costs = {0};
 	Oid			relid;
 	AttrNumber	colnum;
-	VariableStatData vardata;
+	VariableStatData vardata = {0};
 	double		numIndexTuples;
 	Cost		descentCost;
 	List	   *indexBoundQuals;
@@ -6797,7 +6797,6 @@ btcostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
 	/*
 	 * Now do generic index cost estimation.
 	 */
-	MemSet(&costs, 0, sizeof(costs));
 	costs.numIndexTuples = numIndexTuples;
 
 	genericcostestimate(root, path, loop_count, &costs);
@@ -6842,8 +6841,6 @@ btcostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
 	 * ordering, but don't negate it entirely.  Before 8.0 we divided the
 	 * correlation by the number of columns, but that seems too strong.)
 	 */
-	MemSet(&vardata, 0, sizeof(vardata));
-
 	if (index->indexkeys[0] != 0)
 	{
 		/* Simple variable --- look to stats for the underlying table */
@@ -6947,9 +6944,7 @@ hashcostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
 				 Selectivity *indexSelectivity, double *indexCorrelation,
 				 double *indexPages)
 {
-	GenericCosts costs;
-
-	MemSet(&costs, 0, sizeof(costs));
+	GenericCosts costs = {0};
 
 	genericcostestimate(root, path, loop_count, &costs);
 
@@ -6992,11 +6987,9 @@ gistcostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
 				 double *indexPages)
 {
 	IndexOptInfo *index = path->indexinfo;
-	GenericCosts costs;
+	GenericCosts costs = {0};
 	Cost		descentCost;
 
-	MemSet(&costs, 0, sizeof(costs));
-
 	genericcostestimate(root, path, loop_count, &costs);
 
 	/*
@@ -7049,11 +7042,9 @@ spgcostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
 				double *indexPages)
 {
 	IndexOptInfo *index = path->indexinfo;
-	GenericCosts costs;
+	GenericCosts costs = {0};
 	Cost		descentCost;
 
-	MemSet(&costs, 0, sizeof(costs));
-
 	genericcostestimate(root, path, loop_count, &costs);
 
 	/*

src/backend/utils/adt/timestamp.c

@@ -2403,7 +2403,7 @@ interval_cmp_value(const Interval *interval)
 }
 
 static int
-interval_cmp_internal(Interval *interval1, Interval *interval2)
+interval_cmp_internal(const Interval *interval1, const Interval *interval2)
 {
 	INT128		span1 = interval_cmp_value(interval1);
 	INT128		span2 = interval_cmp_value(interval2);
@@ -5777,7 +5777,7 @@ generate_series_timestamp(PG_FUNCTION_ARGS)
 		Timestamp	finish = PG_GETARG_TIMESTAMP(1);
 		Interval   *step = PG_GETARG_INTERVAL_P(2);
 		MemoryContext oldcontext;
-		Interval	interval_zero;
+		const Interval interval_zero = {0};
 
 		/* create a function context for cross-call persistence */
 		funcctx = SRF_FIRSTCALL_INIT();
@@ -5800,7 +5800,6 @@ generate_series_timestamp(PG_FUNCTION_ARGS)
 		fctx->step = *step;
 
 		/* Determine sign of the interval */
-		MemSet(&interval_zero, 0, sizeof(Interval));
 		fctx->step_sign = interval_cmp_internal(&fctx->step, &interval_zero);
 
 		if (fctx->step_sign == 0)
@@ -5857,7 +5856,7 @@ generate_series_timestamptz(PG_FUNCTION_ARGS)
 		TimestampTz finish = PG_GETARG_TIMESTAMPTZ(1);
 		Interval   *step = PG_GETARG_INTERVAL_P(2);
 		MemoryContext oldcontext;
-		Interval	interval_zero;
+		const Interval interval_zero = {0};
 
 		/* create a function context for cross-call persistence */
 		funcctx = SRF_FIRSTCALL_INIT();
@@ -5880,7 +5879,6 @@ generate_series_timestamptz(PG_FUNCTION_ARGS)
 		fctx->step = *step;
 
 		/* Determine sign of the interval */
-		MemSet(&interval_zero, 0, sizeof(Interval));
 		fctx->step_sign = interval_cmp_internal(&fctx->step, &interval_zero);
 
 		if (fctx->step_sign == 0)

src/backend/utils/mmgr/portalmem.c

@@ -1146,14 +1146,12 @@ pg_cursor(PG_FUNCTION_ARGS)
 	{
 		Portal		portal = hentry->portal;
 		Datum		values[6];
-		bool		nulls[6];
+		bool		nulls[6] = {0};
 
 		/* report only "visible" entries */
 		if (!portal->visible)
 			continue;
 
-		MemSet(nulls, 0, sizeof(nulls));
-
 		values[0] = CStringGetTextDatum(portal->name);
 		values[1] = CStringGetTextDatum(portal->sourceText);
 		values[2] = BoolGetDatum(portal->cursorOptions & CURSOR_OPT_HOLD);