Mark function arguments of type "Datum *" as "const Datum *" where possible

Several functions in the codebase accept "Datum *" parameters but do
not modify the pointed-to data.  These have been updated to take
"const Datum *" instead, improving type safety and making the
interfaces clearer about their intent.  This change helps the compiler
catch accidental modifications and better documents immutability of
arguments.

Most of "Datum *" parameters have a pairing "bool *isnull" parameter,
they are constified as well.

No functional behavior is changed by this patch.

Author: Chao Li <lic@highgo.com>
Discussion: https://www.postgresql.org/message-id/flat/CAEoWx2msfT0knvzUa72ZBwu9LR_RLY4on85w2a9YpE-o2By5HQ@mail.gmail.com

doc/src/sgml/spi.sgml

@@ -846,7 +846,7 @@ int SPI_execute_extended(const char *<parameter>command</parameter>,
 <synopsis>
 int SPI_execute_with_args(const char *<parameter>command</parameter>,
                           int <parameter>nargs</parameter>, Oid *<parameter>argtypes</parameter>,
-                          Datum *<parameter>values</parameter>, const char *<parameter>nulls</parameter>,
+                          const Datum *<parameter>values</parameter>, const char *<parameter>nulls</parameter>,
                           bool <parameter>read_only</parameter>, long <parameter>count</parameter>)
 </synopsis>
  </refsynopsisdiv>
@@ -1671,7 +1671,7 @@ bool SPI_is_cursor_plan(SPIPlanPtr <parameter>plan</parameter>)
 
  <refsynopsisdiv>
 <synopsis>
-int SPI_execute_plan(SPIPlanPtr <parameter>plan</parameter>, Datum * <parameter>values</parameter>, const char * <parameter>nulls</parameter>,
+int SPI_execute_plan(SPIPlanPtr <parameter>plan</parameter>, const Datum * <parameter>values</parameter>, const char * <parameter>nulls</parameter>,
                      bool <parameter>read_only</parameter>, long <parameter>count</parameter>)
 </synopsis>
  </refsynopsisdiv>
@@ -2317,7 +2317,7 @@ Portal SPI_cursor_open(const char * <parameter>name</parameter>, SPIPlanPtr <par
 Portal SPI_cursor_open_with_args(const char *<parameter>name</parameter>,
                                  const char *<parameter>command</parameter>,
                                  int <parameter>nargs</parameter>, Oid *<parameter>argtypes</parameter>,
-                                 Datum *<parameter>values</parameter>, const char *<parameter>nulls</parameter>,
+                                 const Datum *<parameter>values</parameter>, const char *<parameter>nulls</parameter>,
                                  bool <parameter>read_only</parameter>, int <parameter>cursorOptions</parameter>)
 </synopsis>
  </refsynopsisdiv>

src/backend/access/brin/brin_minmax_multi.c

@@ -276,7 +276,7 @@ static int	compare_values(const void *a, const void *b, void *arg);
  * function (which should be BTLessStrategyNumber).
  */
 static void
-AssertArrayOrder(FmgrInfo *cmp, Oid colloid, Datum *values, int nvalues)
+AssertArrayOrder(FmgrInfo *cmp, Oid colloid, const Datum *values, int nvalues)
 {
 	int			i;
 	Datum		lt;

src/backend/access/hash/hashutil.c

@@ -316,7 +316,7 @@ _hash_get_indextuple_hashkey(IndexTuple itup)
  */
 bool
 _hash_convert_tuple(Relation index,
-					Datum *user_values, bool *user_isnull,
+					const Datum *user_values, const bool *user_isnull,
 					Datum *index_values, bool *index_isnull)
 {
 	uint32		hashkey;

src/backend/access/heap/heaptoast.c

@@ -561,8 +561,8 @@ toast_flatten_tuple_to_datum(HeapTupleHeader tup,
  */
 HeapTuple
 toast_build_flattened_tuple(TupleDesc tupleDesc,
-							Datum *values,
-							bool *isnull)
+							const Datum *values,
+							const bool *isnull)
 {
 	HeapTuple	new_tuple;
 	int			numAttrs = tupleDesc->natts;

src/backend/access/nbtree/nbtpreprocesskeys.c

@@ -67,7 +67,7 @@ static int	_bt_num_array_keys(IndexScanDesc scan, Oid *skip_eq_ops_out,
 							   int *numSkipArrayKeys_out);
 static Datum _bt_find_extreme_element(IndexScanDesc scan, ScanKey skey,
 									  Oid elemtype, StrategyNumber strat,
-									  Datum *elems, int nelems);
+									  const Datum *elems, int nelems);
 static void _bt_setup_array_cmp(IndexScanDesc scan, ScanKey skey, Oid elemtype,
 								FmgrInfo *orderproc, FmgrInfo **sortprocp);
 static int	_bt_sort_array_elements(ScanKey skey, FmgrInfo *sortproc,
@@ -2569,7 +2569,7 @@ _bt_num_array_keys(IndexScanDesc scan, Oid *skip_eq_ops_out,
 static Datum
 _bt_find_extreme_element(IndexScanDesc scan, ScanKey skey, Oid elemtype,
 						 StrategyNumber strat,
-						 Datum *elems, int nelems)
+						 const Datum *elems, int nelems)
 {
 	Relation	rel = scan->indexRelation;
 	Oid			cmp_op;

src/backend/access/nbtree/nbtsort.c

@@ -258,7 +258,7 @@ static double _bt_spools_heapscan(Relation heap, Relation index,
 								  BTBuildState *buildstate, IndexInfo *indexInfo);
 static void _bt_spooldestroy(BTSpool *btspool);
 static void _bt_spool(BTSpool *btspool, const ItemPointerData *self,
-					  Datum *values, bool *isnull);
+					  const Datum *values, const bool *isnull);
 static void _bt_leafbuild(BTSpool *btspool, BTSpool *btspool2);
 static void _bt_build_callback(Relation index, ItemPointer tid, Datum *values,
 							   bool *isnull, bool tupleIsAlive, void *state);
@@ -525,7 +525,7 @@ _bt_spooldestroy(BTSpool *btspool)
  * spool an index entry into the sort file.
  */
 static void
-_bt_spool(BTSpool *btspool, const ItemPointerData *self, Datum *values, bool *isnull)
+_bt_spool(BTSpool *btspool, const ItemPointerData *self, const Datum *values, const bool *isnull)
 {
 	tuplesort_putindextuplevalues(btspool->sortstate, btspool->index,
 								  self, values, isnull);

src/backend/access/spgist/spgdoinsert.c

@@ -1908,7 +1908,7 @@ spgSplitNodeAction(Relation index, SpGistState *state,
  */
 bool
 spgdoinsert(Relation index, SpGistState *state,
-			const ItemPointerData *heapPtr, Datum *datums, bool *isnulls)
+			const ItemPointerData *heapPtr, const Datum *datums, const bool *isnulls)
 {
 	bool		result = true;
 	TupleDesc	leafDescriptor = state->leafTupDesc;

src/backend/access/spgist/spgtextproc.c

@@ -155,7 +155,7 @@ commonPrefix(const char *a, const char *b, int lena, int lenb)
  * On success, *i gets the match location; on failure, it gets where to insert
  */
 static bool
-searchChar(Datum *nodeLabels, int nNodes, int16 c, int *i)
+searchChar(const Datum *nodeLabels, int nNodes, int16 c, int *i)
 {
 	int			StopLow = 0,
 				StopHigh = nNodes;

src/backend/executor/execPartition.c

@@ -173,11 +173,11 @@ static void FormPartitionKeyDatum(PartitionDispatch pd,
 								  EState *estate,
 								  Datum *values,
 								  bool *isnull);
-static int	get_partition_for_tuple(PartitionDispatch pd, Datum *values,
-									bool *isnull);
+static int	get_partition_for_tuple(PartitionDispatch pd, const Datum *values,
+									const bool *isnull);
 static char *ExecBuildSlotPartitionKeyDescription(Relation rel,
-												  Datum *values,
-												  bool *isnull,
+												  const Datum *values,
+												  const bool *isnull,
 												  int maxfieldlen);
 static List *adjust_partition_colnos(List *colnos, ResultRelInfo *leaf_part_rri);
 static List *adjust_partition_colnos_using_map(List *colnos, AttrMap *attrMap);
@@ -1396,7 +1396,7 @@ FormPartitionKeyDatum(PartitionDispatch pd,
  * found or -1 if none found.
  */
 static int
-get_partition_for_tuple(PartitionDispatch pd, Datum *values, bool *isnull)
+get_partition_for_tuple(PartitionDispatch pd, const Datum *values, const bool *isnull)
 {
 	int			bound_offset = -1;
 	int			part_index = -1;
@@ -1617,8 +1617,8 @@ get_partition_for_tuple(PartitionDispatch pd, Datum *values, bool *isnull)
  */
 static char *
 ExecBuildSlotPartitionKeyDescription(Relation rel,
-									 Datum *values,
-									 bool *isnull,
+									 const Datum *values,
+									 const bool *isnull,
 									 int maxfieldlen)
 {
 	StringInfoData buf;

src/backend/executor/nodeIndexscan.c

@@ -65,7 +65,7 @@ static int	cmp_orderbyvals(const Datum *adist, const bool *anulls,
 static int	reorderqueue_cmp(const pairingheap_node *a,
 							 const pairingheap_node *b, void *arg);
 static void reorderqueue_push(IndexScanState *node, TupleTableSlot *slot,
-							  Datum *orderbyvals, bool *orderbynulls);
+							  const Datum *orderbyvals, const bool *orderbynulls);
 static HeapTuple reorderqueue_pop(IndexScanState *node);
 
 
@@ -458,7 +458,7 @@ reorderqueue_cmp(const pairingheap_node *a, const pairingheap_node *b,
  */
 static void
 reorderqueue_push(IndexScanState *node, TupleTableSlot *slot,
-				  Datum *orderbyvals, bool *orderbynulls)
+				  const Datum *orderbyvals, const bool *orderbynulls)
 {
 	IndexScanDesc scandesc = node->iss_ScanDesc;
 	EState	   *estate = node->ss.ps.state;

src/backend/executor/spi.c

@@ -68,7 +68,7 @@ static int	_SPI_execute_plan(SPIPlanPtr plan, const SPIExecuteOptions *options,
 							  bool fire_triggers);
 
 static ParamListInfo _SPI_convert_params(int nargs, Oid *argtypes,
-										 Datum *Values, const char *Nulls);
+										 const Datum *Values, const char *Nulls);
 
 static int	_SPI_pquery(QueryDesc *queryDesc, bool fire_triggers, uint64 tcount);
 
@@ -669,7 +669,7 @@ SPI_execute_extended(const char *src,
 
 /* Execute a previously prepared plan */
 int
-SPI_execute_plan(SPIPlanPtr plan, Datum *Values, const char *Nulls,
+SPI_execute_plan(SPIPlanPtr plan, const Datum *Values, const char *Nulls,
 				 bool read_only, long tcount)
 {
 	SPIExecuteOptions options;
@@ -771,7 +771,7 @@ SPI_execute_plan_with_paramlist(SPIPlanPtr plan, ParamListInfo params,
  */
 int
 SPI_execute_snapshot(SPIPlanPtr plan,
-					 Datum *Values, const char *Nulls,
+					 const Datum *Values, const char *Nulls,
 					 Snapshot snapshot, Snapshot crosscheck_snapshot,
 					 bool read_only, bool fire_triggers, long tcount)
 {
@@ -811,7 +811,7 @@ SPI_execute_snapshot(SPIPlanPtr plan,
 int
 SPI_execute_with_args(const char *src,
 					  int nargs, Oid *argtypes,
-					  Datum *Values, const char *Nulls,
+					  const Datum *Values, const char *Nulls,
 					  bool read_only, long tcount)
 {
 	int			res;
@@ -1443,7 +1443,7 @@ SPI_freetuptable(SPITupleTable *tuptable)
  */
 Portal
 SPI_cursor_open(const char *name, SPIPlanPtr plan,
-				Datum *Values, const char *Nulls,
+				const Datum *Values, const char *Nulls,
 				bool read_only)
 {
 	Portal		portal;
@@ -2847,7 +2847,7 @@ fail:
  */
 static ParamListInfo
 _SPI_convert_params(int nargs, Oid *argtypes,
-					Datum *Values, const char *Nulls)
+					const Datum *Values, const char *Nulls)
 {
 	ParamListInfo paramLI;
 

src/backend/partitioning/partbounds.c

@@ -3555,8 +3555,8 @@ partition_rbound_cmp(int partnatts, FmgrInfo *partsupfunc,
  */
 int32
 partition_rbound_datum_cmp(FmgrInfo *partsupfunc, Oid *partcollation,
-						   Datum *rb_datums, PartitionRangeDatumKind *rb_kind,
-						   Datum *tuple_datums, int n_tuple_datums)
+						   const Datum *rb_datums, PartitionRangeDatumKind *rb_kind,
+						   const Datum *tuple_datums, int n_tuple_datums)
 {
 	int			i;
 	int32		cmpval = -1;
@@ -3695,7 +3695,7 @@ partition_range_bsearch(int partnatts, FmgrInfo *partsupfunc,
 int
 partition_range_datum_bsearch(FmgrInfo *partsupfunc, Oid *partcollation,
 							  PartitionBoundInfo boundinfo,
-							  int nvalues, Datum *values, bool *is_equal)
+							  int nvalues, const Datum *values, bool *is_equal)
 {
 	int			lo,
 				hi,

src/backend/partitioning/partprune.c

@@ -179,13 +179,13 @@ static List *get_steps_using_prefix_recurse(GeneratePruningStepsContext *context
 											List *step_exprs,
 											List *step_cmpfns);
 static PruneStepResult *get_matching_hash_bounds(PartitionPruneContext *context,
-												 StrategyNumber opstrategy, Datum *values, int nvalues,
+												 StrategyNumber opstrategy, const Datum *values, int nvalues,
 												 FmgrInfo *partsupfunc, Bitmapset *nullkeys);
 static PruneStepResult *get_matching_list_bounds(PartitionPruneContext *context,
 												 StrategyNumber opstrategy, Datum value, int nvalues,
 												 FmgrInfo *partsupfunc, Bitmapset *nullkeys);
 static PruneStepResult *get_matching_range_bounds(PartitionPruneContext *context,
-												  StrategyNumber opstrategy, Datum *values, int nvalues,
+												  StrategyNumber opstrategy, const Datum *values, int nvalues,
 												  FmgrInfo *partsupfunc, Bitmapset *nullkeys);
 static Bitmapset *pull_exec_paramids(Expr *expr);
 static bool pull_exec_paramids_walker(Node *node, Bitmapset **context);
@@ -2690,7 +2690,7 @@ get_steps_using_prefix_recurse(GeneratePruningStepsContext *context,
  */
 static PruneStepResult *
 get_matching_hash_bounds(PartitionPruneContext *context,
-						 StrategyNumber opstrategy, Datum *values, int nvalues,
+						 StrategyNumber opstrategy, const Datum *values, int nvalues,
 						 FmgrInfo *partsupfunc, Bitmapset *nullkeys)
 {
 	PruneStepResult *result = (PruneStepResult *) palloc0(sizeof(PruneStepResult));
@@ -2978,7 +2978,7 @@ get_matching_list_bounds(PartitionPruneContext *context,
  */
 static PruneStepResult *
 get_matching_range_bounds(PartitionPruneContext *context,
-						  StrategyNumber opstrategy, Datum *values, int nvalues,
+						  StrategyNumber opstrategy, const Datum *values, int nvalues,
 						  FmgrInfo *partsupfunc, Bitmapset *nullkeys)
 {
 	PruneStepResult *result = (PruneStepResult *) palloc0(sizeof(PruneStepResult));

src/backend/statistics/attribute_stats.c

@@ -115,7 +115,7 @@ static void set_stats_slot(Datum *values, bool *nulls, bool *replaces,
 						   Datum stanumbers, bool stanumbers_isnull,
 						   Datum stavalues, bool stavalues_isnull);
 static void upsert_pg_statistic(Relation starel, HeapTuple oldtup,
-								Datum *values, bool *nulls, bool *replaces);
+								const Datum *values, const bool *nulls, const bool *replaces);
 static bool delete_pg_statistic(Oid reloid, AttrNumber attnum, bool stainherit);
 static void init_empty_stats_tuple(Oid reloid, int16 attnum, bool inherited,
 								   Datum *values, bool *nulls, bool *replaces);
@@ -819,7 +819,7 @@ set_stats_slot(Datum *values, bool *nulls, bool *replaces,
  */
 static void
 upsert_pg_statistic(Relation starel, HeapTuple oldtup,
-					Datum *values, bool *nulls, bool *replaces)
+					const Datum *values, const bool *nulls, const bool *replaces)
 {
 	HeapTuple	newtup;
 

src/backend/tsearch/ts_selfuncs.c

@@ -47,8 +47,8 @@ typedef struct
 
 static Selectivity tsquerysel(VariableStatData *vardata, Datum constval);
 static Selectivity mcelem_tsquery_selec(TSQuery query,
-										Datum *mcelem, int nmcelem,
-										float4 *numbers, int nnumbers);
+										const Datum *mcelem, int nmcelem,
+										const float4 *numbers, int nnumbers);
 static Selectivity tsquery_opr_selec(QueryItem *item, char *operand,
 									 TextFreq *lookup, int length, float4 minfreq);
 static int	compare_lexeme_textfreq(const void *e1, const void *e2);
@@ -204,8 +204,8 @@ tsquerysel(VariableStatData *vardata, Datum constval)
  * Extract data from the pg_statistic arrays into useful format.
  */
 static Selectivity
-mcelem_tsquery_selec(TSQuery query, Datum *mcelem, int nmcelem,
-					 float4 *numbers, int nnumbers)
+mcelem_tsquery_selec(TSQuery query, const Datum *mcelem, int nmcelem,
+					 const float4 *numbers, int nnumbers)
 {
 	float4		minfreq;
 	TextFreq   *lookup;

src/backend/utils/adt/array_selfuncs.c

@@ -39,25 +39,25 @@
 
 static Selectivity calc_arraycontsel(VariableStatData *vardata, Datum constval,
 									 Oid elemtype, Oid operator);
-static Selectivity mcelem_array_selec(ArrayType *array,
+static Selectivity mcelem_array_selec(const ArrayType *array,
 									  TypeCacheEntry *typentry,
-									  Datum *mcelem, int nmcelem,
-									  float4 *numbers, int nnumbers,
-									  float4 *hist, int nhist,
+									  const Datum *mcelem, int nmcelem,
+									  const float4 *numbers, int nnumbers,
+									  const float4 *hist, int nhist,
 									  Oid operator);
-static Selectivity mcelem_array_contain_overlap_selec(Datum *mcelem, int nmcelem,
-													  float4 *numbers, int nnumbers,
-													  Datum *array_data, int nitems,
+static Selectivity mcelem_array_contain_overlap_selec(const Datum *mcelem, int nmcelem,
+													  const float4 *numbers, int nnumbers,
+													  const Datum *array_data, int nitems,
 													  Oid operator, TypeCacheEntry *typentry);
-static Selectivity mcelem_array_contained_selec(Datum *mcelem, int nmcelem,
-												float4 *numbers, int nnumbers,
-												Datum *array_data, int nitems,
-												float4 *hist, int nhist,
+static Selectivity mcelem_array_contained_selec(const Datum *mcelem, int nmcelem,
+												const float4 *numbers, int nnumbers,
+												const Datum *array_data, int nitems,
+												const float4 *hist, int nhist,
 												Oid operator, TypeCacheEntry *typentry);
 static float *calc_hist(const float4 *hist, int nhist, int n);
 static float *calc_distr(const float *p, int n, int m, float rest);
 static int	floor_log2(uint32 n);
-static bool find_next_mcelem(Datum *mcelem, int nmcelem, Datum value,
+static bool find_next_mcelem(const Datum *mcelem, int nmcelem, Datum value,
 							 int *index, TypeCacheEntry *typentry);
 static int	element_compare(const void *key1, const void *key2, void *arg);
 static int	float_compare_desc(const void *key1, const void *key2);
@@ -425,10 +425,10 @@ calc_arraycontsel(VariableStatData *vardata, Datum constval,
  * mcelem_array_contained_selec depending on the operator.
  */
 static Selectivity
-mcelem_array_selec(ArrayType *array, TypeCacheEntry *typentry,
-				   Datum *mcelem, int nmcelem,
-				   float4 *numbers, int nnumbers,
-				   float4 *hist, int nhist,
+mcelem_array_selec(const ArrayType *array, TypeCacheEntry *typentry,
+				   const Datum *mcelem, int nmcelem,
+				   const float4 *numbers, int nnumbers,
+				   const float4 *hist, int nhist,
 				   Oid operator)
 {
 	Selectivity selec;
@@ -518,9 +518,9 @@ mcelem_array_selec(ArrayType *array, TypeCacheEntry *typentry,
  * fraction of nonempty arrays in the column.
  */
 static Selectivity
-mcelem_array_contain_overlap_selec(Datum *mcelem, int nmcelem,
-								   float4 *numbers, int nnumbers,
-								   Datum *array_data, int nitems,
+mcelem_array_contain_overlap_selec(const Datum *mcelem, int nmcelem,
+								   const float4 *numbers, int nnumbers,
+								   const Datum *array_data, int nitems,
 								   Oid operator, TypeCacheEntry *typentry)
 {
 	Selectivity selec,
@@ -699,10 +699,10 @@ mcelem_array_contain_overlap_selec(Datum *mcelem, int nmcelem,
  * ... * fn^on * (1 - fn)^(1 - on), o1, o2, ..., on) | o1 + o2 + .. on = m
  */
 static Selectivity
-mcelem_array_contained_selec(Datum *mcelem, int nmcelem,
-							 float4 *numbers, int nnumbers,
-							 Datum *array_data, int nitems,
-							 float4 *hist, int nhist,
+mcelem_array_contained_selec(const Datum *mcelem, int nmcelem,
+							 const float4 *numbers, int nnumbers,
+							 const Datum *array_data, int nitems,
+							 const float4 *hist, int nhist,
 							 Oid operator, TypeCacheEntry *typentry)
 {
 	int			mcelem_index,
@@ -1136,7 +1136,7 @@ floor_log2(uint32 n)
  * exact match.)
  */
 static bool
-find_next_mcelem(Datum *mcelem, int nmcelem, Datum value, int *index,
+find_next_mcelem(const Datum *mcelem, int nmcelem, Datum value, int *index,
 				 TypeCacheEntry *typentry)
 {
 	int			l = *index,

src/backend/utils/adt/arrayfuncs.c

@@ -960,8 +960,8 @@ ending_error:
  */
 void
 CopyArrayEls(ArrayType *array,
-			 Datum *values,
-			 bool *nulls,
+			 const Datum *values,
+			 const bool *nulls,
 			 int nitems,
 			 int typlen,
 			 bool typbyval,
@@ -3629,7 +3629,7 @@ construct_empty_expanded_array(Oid element_type,
  * to hard-wire values if the element type is hard-wired.
  */
 void
-deconstruct_array(ArrayType *array,
+deconstruct_array(const ArrayType *array,
 				  Oid elmtype,
 				  int elmlen, bool elmbyval, char elmalign,
 				  Datum **elemsp, bool **nullsp, int *nelemsp)
@@ -3695,7 +3695,7 @@ deconstruct_array(ArrayType *array,
  * useful when manipulating arrays from/for system catalogs.
  */
 void
-deconstruct_array_builtin(ArrayType *array,
+deconstruct_array_builtin(const ArrayType *array,
 						  Oid elmtype,
 						  Datum **elemsp, bool **nullsp, int *nelemsp)
 {
@@ -3765,7 +3765,7 @@ deconstruct_array_builtin(ArrayType *array,
  * if the array *might* contain a null.
  */
 bool
-array_contains_nulls(ArrayType *array)
+array_contains_nulls(const ArrayType *array)
 {
 	int			nelems;
 	bits8	   *bitmap;

src/backend/utils/adt/json.c

@@ -89,7 +89,7 @@ typedef struct JsonAggState
 static void composite_to_json(Datum composite, StringInfo result,
 							  bool use_line_feeds);
 static void array_dim_to_json(StringInfo result, int dim, int ndims, int *dims,
-							  Datum *vals, bool *nulls, int *valcount,
+							  const Datum *vals, const bool *nulls, int *valcount,
 							  JsonTypeCategory tcategory, Oid outfuncoid,
 							  bool use_line_feeds);
 static void array_to_json_internal(Datum array, StringInfo result,
@@ -429,8 +429,8 @@ JsonEncodeDateTime(char *buf, Datum value, Oid typid, const int *tzp)
  * ourselves recursively to process the next dimension.
  */
 static void
-array_dim_to_json(StringInfo result, int dim, int ndims, int *dims, Datum *vals,
-				  bool *nulls, int *valcount, JsonTypeCategory tcategory,
+array_dim_to_json(StringInfo result, int dim, int ndims, int *dims, const Datum *vals,
+				  const bool *nulls, int *valcount, JsonTypeCategory tcategory,
 				  Oid outfuncoid, bool use_line_feeds)
 {
 	int			i;

src/backend/utils/adt/jsonfuncs.c

@@ -477,16 +477,16 @@ static Datum populate_domain(DomainIOData *io, Oid typid, const char *colname,
 /* functions supporting jsonb_delete, jsonb_set and jsonb_concat */
 static JsonbValue *IteratorConcat(JsonbIterator **it1, JsonbIterator **it2,
 								  JsonbParseState **state);
-static JsonbValue *setPath(JsonbIterator **it, Datum *path_elems,
-						   bool *path_nulls, int path_len,
+static JsonbValue *setPath(JsonbIterator **it, const Datum *path_elems,
+						   const bool *path_nulls, int path_len,
 						   JsonbParseState **st, int level, JsonbValue *newval,
 						   int op_type);
-static void setPathObject(JsonbIterator **it, Datum *path_elems,
-						  bool *path_nulls, int path_len, JsonbParseState **st,
+static void setPathObject(JsonbIterator **it, const Datum *path_elems,
+						  const bool *path_nulls, int path_len, JsonbParseState **st,
 						  int level,
 						  JsonbValue *newval, uint32 npairs, int op_type);
-static void setPathArray(JsonbIterator **it, Datum *path_elems,
-						 bool *path_nulls, int path_len, JsonbParseState **st,
+static void setPathArray(JsonbIterator **it, const Datum *path_elems,
+						 const bool *path_nulls, int path_len, JsonbParseState **st,
 						 int level,
 						 JsonbValue *newval, uint32 nelems, int op_type);
 
@@ -1528,7 +1528,7 @@ get_jsonb_path_all(FunctionCallInfo fcinfo, bool as_text)
 }
 
 Datum
-jsonb_get_element(Jsonb *jb, Datum *path, int npath, bool *isnull, bool as_text)
+jsonb_get_element(Jsonb *jb, const Datum *path, int npath, bool *isnull, bool as_text)
 {
 	JsonbContainer *container = &jb->root;
 	JsonbValue *jbvp = NULL;
@@ -1676,7 +1676,7 @@ jsonb_get_element(Jsonb *jb, Datum *path, int npath, bool *isnull, bool as_text)
 }
 
 Datum
-jsonb_set_element(Jsonb *jb, Datum *path, int path_len,
+jsonb_set_element(Jsonb *jb, const Datum *path, int path_len,
 				  JsonbValue *newval)
 {
 	JsonbValue *res;
@@ -1718,8 +1718,8 @@ push_null_elements(JsonbParseState **ps, int num)
  * Caller is responsible to make sure such path does not exist yet.
  */
 static void
-push_path(JsonbParseState **st, int level, Datum *path_elems,
-		  bool *path_nulls, int path_len, JsonbValue *newval)
+push_path(JsonbParseState **st, int level, const Datum *path_elems,
+		  const bool *path_nulls, int path_len, JsonbValue *newval)
 {
 	/*
 	 * tpath contains expected type of an empty jsonb created at each level
@@ -5201,8 +5201,8 @@ IteratorConcat(JsonbIterator **it1, JsonbIterator **it2,
  * whatever bits in op_type are set, or nothing is done.
  */
 static JsonbValue *
-setPath(JsonbIterator **it, Datum *path_elems,
-		bool *path_nulls, int path_len,
+setPath(JsonbIterator **it, const Datum *path_elems,
+		const bool *path_nulls, int path_len,
 		JsonbParseState **st, int level, JsonbValue *newval, int op_type)
 {
 	JsonbValue	v;
@@ -5283,7 +5283,7 @@ setPath(JsonbIterator **it, Datum *path_elems,
  * Object walker for setPath
  */
 static void
-setPathObject(JsonbIterator **it, Datum *path_elems, bool *path_nulls,
+setPathObject(JsonbIterator **it, const Datum *path_elems, const bool *path_nulls,
 			  int path_len, JsonbParseState **st, int level,
 			  JsonbValue *newval, uint32 npairs, int op_type)
 {
@@ -5422,7 +5422,7 @@ setPathObject(JsonbIterator **it, Datum *path_elems, bool *path_nulls,
  * Array walker for setPath
  */
 static void
-setPathArray(JsonbIterator **it, Datum *path_elems, bool *path_nulls,
+setPathArray(JsonbIterator **it, const Datum *path_elems, const bool *path_nulls,
 			 int path_len, JsonbParseState **st, int level,
 			 JsonbValue *newval, uint32 nelems, int op_type)
 {

src/backend/utils/adt/multirangetypes_selfuncs.c

@@ -49,10 +49,10 @@ static float8 get_position(TypeCacheEntry *typcache, const RangeBound *value,
 static float8 get_len_position(double value, double hist1, double hist2);
 static float8 get_distance(TypeCacheEntry *typcache, const RangeBound *bound1,
 						   const RangeBound *bound2);
-static int	length_hist_bsearch(Datum *length_hist_values,
+static int	length_hist_bsearch(const Datum *length_hist_values,
 								int length_hist_nvalues, double value,
 								bool equal);
-static double calc_length_hist_frac(Datum *length_hist_values,
+static double calc_length_hist_frac(const Datum *length_hist_values,
 									int length_hist_nvalues, double length1,
 									double length2, bool equal);
 static double calc_hist_selectivity_contained(TypeCacheEntry *typcache,
@@ -60,14 +60,14 @@ static double calc_hist_selectivity_contained(TypeCacheEntry *typcache,
 											  RangeBound *upper,
 											  const RangeBound *hist_lower,
 											  int hist_nvalues,
-											  Datum *length_hist_values,
+											  const Datum *length_hist_values,
 											  int length_hist_nvalues);
 static double calc_hist_selectivity_contains(TypeCacheEntry *typcache,
 											 const RangeBound *lower,
 											 const RangeBound *upper,
 											 const RangeBound *hist_lower,
 											 int hist_nvalues,
-											 Datum *length_hist_values,
+											 const Datum *length_hist_values,
 											 int length_hist_nvalues);
 
 /*
@@ -765,7 +765,7 @@ rbound_bsearch(TypeCacheEntry *typcache, const RangeBound *value, const RangeBou
  * given length, returns -1.
  */
 static int
-length_hist_bsearch(Datum *length_hist_values, int length_hist_nvalues,
+length_hist_bsearch(const Datum *length_hist_values, int length_hist_nvalues,
 					double value, bool equal)
 {
 	int			lower = -1,
@@ -963,7 +963,7 @@ get_distance(TypeCacheEntry *typcache, const RangeBound *bound1, const RangeBoun
  * 'equal' is true).
  */
 static double
-calc_length_hist_frac(Datum *length_hist_values, int length_hist_nvalues,
+calc_length_hist_frac(const Datum *length_hist_values, int length_hist_nvalues,
 					  double length1, double length2, bool equal)
 {
 	double		frac;
@@ -1131,7 +1131,7 @@ static double
 calc_hist_selectivity_contained(TypeCacheEntry *typcache,
 								const RangeBound *lower, RangeBound *upper,
 								const RangeBound *hist_lower, int hist_nvalues,
-								Datum *length_hist_values, int length_hist_nvalues)
+								const Datum *length_hist_values, int length_hist_nvalues)
 {
 	int			i,
 				upper_index;
@@ -1252,7 +1252,7 @@ static double
 calc_hist_selectivity_contains(TypeCacheEntry *typcache,
 							   const RangeBound *lower, const RangeBound *upper,
 							   const RangeBound *hist_lower, int hist_nvalues,
-							   Datum *length_hist_values, int length_hist_nvalues)
+							   const Datum *length_hist_values, int length_hist_nvalues)
 {
 	int			i,
 				lower_index;

src/backend/utils/adt/network_selfuncs.c

@@ -48,17 +48,17 @@ static Selectivity networkjoinsel_inner(Oid operator,
 static Selectivity networkjoinsel_semi(Oid operator,
 									   VariableStatData *vardata1, VariableStatData *vardata2);
 static Selectivity mcv_population(float4 *mcv_numbers, int mcv_nvalues);
-static Selectivity inet_hist_value_sel(Datum *values, int nvalues,
+static Selectivity inet_hist_value_sel(const Datum *values, int nvalues,
 									   Datum constvalue, int opr_codenum);
 static Selectivity inet_mcv_join_sel(Datum *mcv1_values,
 									 float4 *mcv1_numbers, int mcv1_nvalues, Datum *mcv2_values,
 									 float4 *mcv2_numbers, int mcv2_nvalues, Oid operator);
-static Selectivity inet_mcv_hist_sel(Datum *mcv_values, float4 *mcv_numbers,
-									 int mcv_nvalues, Datum *hist_values, int hist_nvalues,
+static Selectivity inet_mcv_hist_sel(const Datum *mcv_values, float4 *mcv_numbers,
+									 int mcv_nvalues, const Datum *hist_values, int hist_nvalues,
 									 int opr_codenum);
-static Selectivity inet_hist_inclusion_join_sel(Datum *hist1_values,
+static Selectivity inet_hist_inclusion_join_sel(const Datum *hist1_values,
 												int hist1_nvalues,
-												Datum *hist2_values, int hist2_nvalues,
+												const Datum *hist2_values, int hist2_nvalues,
 												int opr_codenum);
 static Selectivity inet_semi_join_sel(Datum lhs_value,
 									  bool mcv_exists, Datum *mcv_values, int mcv_nvalues,
@@ -601,7 +601,7 @@ mcv_population(float4 *mcv_numbers, int mcv_nvalues)
  * better option than not considering these buckets at all.
  */
 static Selectivity
-inet_hist_value_sel(Datum *values, int nvalues, Datum constvalue,
+inet_hist_value_sel(const Datum *values, int nvalues, Datum constvalue,
 					int opr_codenum)
 {
 	Selectivity match = 0.0;
@@ -702,8 +702,8 @@ inet_mcv_join_sel(Datum *mcv1_values, float4 *mcv1_numbers, int mcv1_nvalues,
  * the histogram.
  */
 static Selectivity
-inet_mcv_hist_sel(Datum *mcv_values, float4 *mcv_numbers, int mcv_nvalues,
-				  Datum *hist_values, int hist_nvalues,
+inet_mcv_hist_sel(const Datum *mcv_values, float4 *mcv_numbers, int mcv_nvalues,
+				  const Datum *hist_values, int hist_nvalues,
 				  int opr_codenum)
 {
 	Selectivity selec = 0.0;
@@ -739,8 +739,8 @@ inet_mcv_hist_sel(Datum *mcv_values, float4 *mcv_numbers, int mcv_nvalues,
  * average?  That would at least avoid non-commutative estimation results.
  */
 static Selectivity
-inet_hist_inclusion_join_sel(Datum *hist1_values, int hist1_nvalues,
-							 Datum *hist2_values, int hist2_nvalues,
+inet_hist_inclusion_join_sel(const Datum *hist1_values, int hist1_nvalues,
+							 const Datum *hist2_values, int hist2_nvalues,
 							 int opr_codenum)
 {
 	double		match = 0.0;

src/backend/utils/adt/orderedsetaggs.c

@@ -660,8 +660,8 @@ pct_info_cmp(const void *pa, const void *pb)
  */
 static struct pct_info *
 setup_pct_info(int num_percentiles,
-			   Datum *percentiles_datum,
-			   bool *percentiles_null,
+			   const Datum *percentiles_datum,
+			   const bool *percentiles_null,
 			   int64 rowcount,
 			   bool continuous)
 {

src/backend/utils/adt/rangetypes_selfuncs.c

@@ -46,18 +46,18 @@ static float8 get_position(TypeCacheEntry *typcache, const RangeBound *value,
 static float8 get_len_position(double value, double hist1, double hist2);
 static float8 get_distance(TypeCacheEntry *typcache, const RangeBound *bound1,
 						   const RangeBound *bound2);
-static int	length_hist_bsearch(Datum *length_hist_values,
+static int	length_hist_bsearch(const Datum *length_hist_values,
 								int length_hist_nvalues, double value, bool equal);
-static double calc_length_hist_frac(Datum *length_hist_values,
+static double calc_length_hist_frac(const Datum *length_hist_values,
 									int length_hist_nvalues, double length1, double length2, bool equal);
 static double calc_hist_selectivity_contained(TypeCacheEntry *typcache,
 											  const RangeBound *lower, RangeBound *upper,
 											  const RangeBound *hist_lower, int hist_nvalues,
-											  Datum *length_hist_values, int length_hist_nvalues);
+											  const Datum *length_hist_values, int length_hist_nvalues);
 static double calc_hist_selectivity_contains(TypeCacheEntry *typcache,
 											 const RangeBound *lower, const RangeBound *upper,
 											 const RangeBound *hist_lower, int hist_nvalues,
-											 Datum *length_hist_values, int length_hist_nvalues);
+											 const Datum *length_hist_values, int length_hist_nvalues);
 
 /*
  * Returns a default selectivity estimate for given operator, when we don't
@@ -654,7 +654,7 @@ rbound_bsearch(TypeCacheEntry *typcache, const RangeBound *value, const RangeBou
  * given length, returns -1.
  */
 static int
-length_hist_bsearch(Datum *length_hist_values, int length_hist_nvalues,
+length_hist_bsearch(const Datum *length_hist_values, int length_hist_nvalues,
 					double value, bool equal)
 {
 	int			lower = -1,
@@ -852,7 +852,7 @@ get_distance(TypeCacheEntry *typcache, const RangeBound *bound1, const RangeBoun
  * 'equal' is true).
  */
 static double
-calc_length_hist_frac(Datum *length_hist_values, int length_hist_nvalues,
+calc_length_hist_frac(const Datum *length_hist_values, int length_hist_nvalues,
 					  double length1, double length2, bool equal)
 {
 	double		frac;
@@ -1018,7 +1018,7 @@ static double
 calc_hist_selectivity_contained(TypeCacheEntry *typcache,
 								const RangeBound *lower, RangeBound *upper,
 								const RangeBound *hist_lower, int hist_nvalues,
-								Datum *length_hist_values, int length_hist_nvalues)
+								const Datum *length_hist_values, int length_hist_nvalues)
 {
 	int			i,
 				upper_index;
@@ -1139,7 +1139,7 @@ static double
 calc_hist_selectivity_contains(TypeCacheEntry *typcache,
 							   const RangeBound *lower, const RangeBound *upper,
 							   const RangeBound *hist_lower, int hist_nvalues,
-							   Datum *length_hist_values, int length_hist_nvalues)
+							   const Datum *length_hist_values, int length_hist_nvalues)
 {
 	int			i,
 				lower_index;

src/backend/utils/adt/xml.c

@@ -891,8 +891,8 @@ xmltotext_with_options(xmltype *data, XmlOptionType xmloption_arg, bool indent)
 
 xmltype *
 xmlelement(XmlExpr *xexpr,
-		   Datum *named_argvalue, bool *named_argnull,
-		   Datum *argvalue, bool *argnull)
+		   const Datum *named_argvalue, const bool *named_argnull,
+		   const Datum *argvalue, const bool *argnull)
 {
 #ifdef USE_LIBXML
 	xmltype    *result;

src/backend/utils/cache/catcache.c

@@ -117,10 +117,10 @@ static CatCTup *CatalogCacheCreateEntry(CatCache *cache, HeapTuple ntp,
 
 static void ReleaseCatCacheWithOwner(HeapTuple tuple, ResourceOwner resowner);
 static void ReleaseCatCacheListWithOwner(CatCList *list, ResourceOwner resowner);
-static void CatCacheFreeKeys(TupleDesc tupdesc, int nkeys, int *attnos,
-							 Datum *keys);
-static void CatCacheCopyKeys(TupleDesc tupdesc, int nkeys, int *attnos,
-							 Datum *srckeys, Datum *dstkeys);
+static void CatCacheFreeKeys(TupleDesc tupdesc, int nkeys, const int *attnos,
+							 const Datum *keys);
+static void CatCacheCopyKeys(TupleDesc tupdesc, int nkeys, const int *attnos,
+							 const Datum *srckeys, Datum *dstkeys);
 
 
 /*
@@ -2279,7 +2279,7 @@ CatalogCacheCreateEntry(CatCache *cache, HeapTuple ntp, Datum *arguments,
  * Helper routine that frees keys stored in the keys array.
  */
 static void
-CatCacheFreeKeys(TupleDesc tupdesc, int nkeys, int *attnos, Datum *keys)
+CatCacheFreeKeys(TupleDesc tupdesc, int nkeys, const int *attnos, const Datum *keys)
 {
 	int			i;
 
@@ -2301,8 +2301,8 @@ CatCacheFreeKeys(TupleDesc tupdesc, int nkeys, int *attnos, Datum *keys)
  * context.
  */
 static void
-CatCacheCopyKeys(TupleDesc tupdesc, int nkeys, int *attnos,
-				 Datum *srckeys, Datum *dstkeys)
+CatCacheCopyKeys(TupleDesc tupdesc, int nkeys, const int *attnos,
+				 const Datum *srckeys, Datum *dstkeys)
 {
 	int			i;
 

src/include/access/hash.h

@@ -468,7 +468,7 @@ extern uint32 _hash_get_totalbuckets(uint32 splitpoint_phase);
 extern void _hash_checkpage(Relation rel, Buffer buf, int flags);
 extern uint32 _hash_get_indextuple_hashkey(IndexTuple itup);
 extern bool _hash_convert_tuple(Relation index,
-								Datum *user_values, bool *user_isnull,
+								const Datum *user_values, const bool *user_isnull,
 								Datum *index_values, bool *index_isnull);
 extern OffsetNumber _hash_binsearch(Page page, uint32 hash_value);
 extern OffsetNumber _hash_binsearch_last(Page page, uint32 hash_value);

src/include/access/heaptoast.h

@@ -133,8 +133,8 @@ extern Datum toast_flatten_tuple_to_datum(HeapTupleHeader tup,
  * ----------
  */
 extern HeapTuple toast_build_flattened_tuple(TupleDesc tupleDesc,
-											 Datum *values,
-											 bool *isnull);
+											 const Datum *values,
+											 const bool *isnull);
 
 /* ----------
  * heap_fetch_toast_slice

src/include/access/spgist_private.h

@@ -541,7 +541,7 @@ extern void spgPageIndexMultiDelete(SpGistState *state, Page page,
 									int firststate, int reststate,
 									BlockNumber blkno, OffsetNumber offnum);
 extern bool spgdoinsert(Relation index, SpGistState *state,
-						const ItemPointerData *heapPtr, Datum *datums, bool *isnulls);
+						const ItemPointerData *heapPtr, const Datum *datums, const bool *isnulls);
 
 /* spgproc.c */
 extern double *spg_key_orderbys_distances(Datum key, bool isLeaf,

src/include/executor/spi.h

@@ -111,7 +111,7 @@ extern int	SPI_finish(void);
 extern int	SPI_execute(const char *src, bool read_only, long tcount);
 extern int	SPI_execute_extended(const char *src,
 								 const SPIExecuteOptions *options);
-extern int	SPI_execute_plan(SPIPlanPtr plan, Datum *Values, const char *Nulls,
+extern int	SPI_execute_plan(SPIPlanPtr plan, const Datum *Values, const char *Nulls,
 							 bool read_only, long tcount);
 extern int	SPI_execute_plan_extended(SPIPlanPtr plan,
 									  const SPIExecuteOptions *options);
@@ -122,13 +122,13 @@ extern int	SPI_exec(const char *src, long tcount);
 extern int	SPI_execp(SPIPlanPtr plan, Datum *Values, const char *Nulls,
 					  long tcount);
 extern int	SPI_execute_snapshot(SPIPlanPtr plan,
-								 Datum *Values, const char *Nulls,
+								 const Datum *Values, const char *Nulls,
 								 Snapshot snapshot,
 								 Snapshot crosscheck_snapshot,
 								 bool read_only, bool fire_triggers, long tcount);
 extern int	SPI_execute_with_args(const char *src,
 								  int nargs, Oid *argtypes,
-								  Datum *Values, const char *Nulls,
+								  const Datum *Values, const char *Nulls,
 								  bool read_only, long tcount);
 extern SPIPlanPtr SPI_prepare(const char *src, int nargs, Oid *argtypes);
 extern SPIPlanPtr SPI_prepare_cursor(const char *src, int nargs, Oid *argtypes,
@@ -172,7 +172,7 @@ extern void SPI_freetuple(HeapTuple tuple);
 extern void SPI_freetuptable(SPITupleTable *tuptable);
 
 extern Portal SPI_cursor_open(const char *name, SPIPlanPtr plan,
-							  Datum *Values, const char *Nulls, bool read_only);
+							  const Datum *Values, const char *Nulls, bool read_only);
 extern Portal SPI_cursor_open_with_args(const char *name,
 										const char *src,
 										int nargs, Oid *argtypes,

src/include/partitioning/partbounds.h

@@ -130,8 +130,8 @@ extern void check_default_partition_contents(Relation parent,
 
 extern int32 partition_rbound_datum_cmp(FmgrInfo *partsupfunc,
 										Oid *partcollation,
-										Datum *rb_datums, PartitionRangeDatumKind *rb_kind,
-										Datum *tuple_datums, int n_tuple_datums);
+										const Datum *rb_datums, PartitionRangeDatumKind *rb_kind,
+										const Datum *tuple_datums, int n_tuple_datums);
 extern int	partition_list_bsearch(FmgrInfo *partsupfunc,
 								   Oid *partcollation,
 								   PartitionBoundInfo boundinfo,
@@ -139,7 +139,7 @@ extern int	partition_list_bsearch(FmgrInfo *partsupfunc,
 extern int	partition_range_datum_bsearch(FmgrInfo *partsupfunc,
 										  Oid *partcollation,
 										  PartitionBoundInfo boundinfo,
-										  int nvalues, Datum *values, bool *is_equal);
+										  int nvalues, const Datum *values, bool *is_equal);
 extern int	partition_hash_bsearch(PartitionBoundInfo boundinfo,
 								   int modulus, int remainder);
 

src/include/utils/array.h

@@ -352,8 +352,8 @@ extern PGDLLIMPORT bool Array_nulls;
  * prototypes for functions defined in arrayfuncs.c
  */
 extern void CopyArrayEls(ArrayType *array,
-						 Datum *values,
-						 bool *nulls,
+						 const Datum *values,
+						 const bool *nulls,
 						 int nitems,
 						 int typlen,
 						 bool typbyval,
@@ -405,14 +405,14 @@ extern ArrayType *construct_empty_array(Oid elmtype);
 extern ExpandedArrayHeader *construct_empty_expanded_array(Oid element_type,
 														   MemoryContext parentcontext,
 														   ArrayMetaState *metacache);
-extern void deconstruct_array(ArrayType *array,
+extern void deconstruct_array(const ArrayType *array,
 							  Oid elmtype,
 							  int elmlen, bool elmbyval, char elmalign,
 							  Datum **elemsp, bool **nullsp, int *nelemsp);
-extern void deconstruct_array_builtin(ArrayType *array,
+extern void deconstruct_array_builtin(const ArrayType *array,
 									  Oid elmtype,
 									  Datum **elemsp, bool **nullsp, int *nelemsp);
-extern bool array_contains_nulls(ArrayType *array);
+extern bool array_contains_nulls(const ArrayType *array);
 
 extern ArrayBuildState *initArrayResult(Oid element_type,
 										MemoryContext rcontext, bool subcontext);

src/include/utils/jsonb.h

@@ -426,9 +426,9 @@ extern char *JsonbUnquote(Jsonb *jb);
 extern bool JsonbExtractScalar(JsonbContainer *jbc, JsonbValue *res);
 extern const char *JsonbTypeName(JsonbValue *val);
 
-extern Datum jsonb_set_element(Jsonb *jb, Datum *path, int path_len,
+extern Datum jsonb_set_element(Jsonb *jb, const Datum *path, int path_len,
 							   JsonbValue *newval);
-extern Datum jsonb_get_element(Jsonb *jb, Datum *path, int npath,
+extern Datum jsonb_get_element(Jsonb *jb, const Datum *path, int npath,
 							   bool *isnull, bool as_text);
 extern bool to_jsonb_is_immutable(Oid typoid);
 extern Datum jsonb_build_object_worker(int nargs, const Datum *args, const bool *nulls,

src/include/utils/xml.h

@@ -71,8 +71,8 @@ extern void xml_ereport(PgXmlErrorContext *errcxt, int level, int sqlcode,
 
 extern xmltype *xmlconcat(List *args);
 extern xmltype *xmlelement(XmlExpr *xexpr,
-						   Datum *named_argvalue, bool *named_argnull,
-						   Datum *argvalue, bool *argnull);
+						   const Datum *named_argvalue, const bool *named_argnull,
+						   const Datum *argvalue, const bool *argnull);
 extern xmltype *xmlparse(text *data, XmlOptionType xmloption_arg, bool preserve_whitespace);
 extern xmltype *xmlpi(const char *target, text *arg, bool arg_is_null, bool *result_is_null);
 extern xmltype *xmlroot(xmltype *data, text *version, int standalone);

src/test/modules/spgist_name_ops/spgist_name_ops.c

@@ -94,7 +94,7 @@ commonPrefix(const char *a, const char *b, int lena, int lenb)
  * On success, *i gets the match location; on failure, it gets where to insert
  */
 static bool
-searchChar(Datum *nodeLabels, int nNodes, int16 c, int *i)
+searchChar(const Datum *nodeLabels, int nNodes, int16 c, int *i)
 {
 	int			StopLow = 0,
 				StopHigh = nNodes;