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

9 files changed, 33 insertions, 83 deletions

diff --git a/src/backend/utils/adt/acl.c b/src/backend/utils/adt/acl.c
index b7fd3bcf057..6fa58dd8eb0 100644
--- a/src/backend/utils/adt/acl.c
+++ b/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);
 
diff --git a/src/backend/utils/adt/arrayfuncs.c b/src/backend/utils/adt/arrayfuncs.c
index b0c37ede87d..fb167f226a0 100644
--- a/src/backend/utils/adt/arrayfuncs.c
+++ b/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));
diff --git a/src/backend/utils/adt/datetime.c b/src/backend/utils/adt/datetime.c
index 4c12c4d6630..43fff50d490 100644
--- a/src/backend/utils/adt/datetime.c
+++ b/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 : "");
 
diff --git a/src/backend/utils/adt/lockfuncs.c b/src/backend/utils/adt/lockfuncs.c
index dedee7af5cb..f9b324efec7 100644
--- a/src/backend/utils/adt/lockfuncs.c
+++ b/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);
diff --git a/src/backend/utils/adt/partitionfuncs.c b/src/backend/utils/adt/partitionfuncs.c
index 0243bc061f6..109dc8023e1 100644
--- a/src/backend/utils/adt/partitionfuncs.c
+++ b/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);
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 893690dad52..d9e2a793829 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/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 */
diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c
index fa1f589fad8..6f99b5b2437 100644
--- a/src/backend/utils/adt/selfuncs.c
+++ b/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);
 
 	/*
diff --git a/src/backend/utils/adt/timestamp.c b/src/backend/utils/adt/timestamp.c
index f70f829d830..49cdb290ac2 100644
--- a/src/backend/utils/adt/timestamp.c
+++ b/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)
diff --git a/src/backend/utils/mmgr/portalmem.c b/src/backend/utils/mmgr/portalmem.c
index d549f66d4af..3a161bdb88d 100644
--- a/src/backend/utils/mmgr/portalmem.c
+++ b/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);