Add some const decorations (htup.h)

Discussion: https://www.postgresql.org/message-id/flat/5b558da8-99fb-0a99-83dd-f72f05388517@enterprisedb.com

src/backend/access/heap/heapam.c

@@ -7437,10 +7437,10 @@ MultiXactIdGetUpdateXid(TransactionId xmax, uint16 t_infomask)
  * checking the hint bits.
  */
 TransactionId
-HeapTupleGetUpdateXid(HeapTupleHeader tuple)
+HeapTupleGetUpdateXid(const HeapTupleHeaderData *tup)
 {
-	return MultiXactIdGetUpdateXid(HeapTupleHeaderGetRawXmax(tuple),
+	return MultiXactIdGetUpdateXid(HeapTupleHeaderGetRawXmax(tup),
-								   tuple->t_infomask);
+								   tup->t_infomask);
 }
 
 /*

src/backend/utils/time/combocid.c

@@ -101,7 +101,7 @@ static CommandId GetRealCmax(CommandId combocid);
  */
 
 CommandId
-HeapTupleHeaderGetCmin(HeapTupleHeader tup)
+HeapTupleHeaderGetCmin(const HeapTupleHeaderData *tup)
 {
 	CommandId	cid = HeapTupleHeaderGetRawCommandId(tup);
 
@@ -115,7 +115,7 @@ HeapTupleHeaderGetCmin(HeapTupleHeader tup)
 }
 
 CommandId
-HeapTupleHeaderGetCmax(HeapTupleHeader tup)
+HeapTupleHeaderGetCmax(const HeapTupleHeaderData *tup)
 {
 	CommandId	cid = HeapTupleHeaderGetRawCommandId(tup);
 
@@ -150,7 +150,7 @@ HeapTupleHeaderGetCmax(HeapTupleHeader tup)
  * changes the tuple in shared buffers.
  */
 void
-HeapTupleHeaderAdjustCmax(HeapTupleHeader tup,
+HeapTupleHeaderAdjustCmax(const HeapTupleHeaderData *tup,
 						  CommandId *cmax,
 						  bool *iscombo)
 {

src/include/access/htup.h

@@ -78,12 +78,12 @@ typedef HeapTupleData *HeapTuple;
 #define HeapTupleIsValid(tuple) PointerIsValid(tuple)
 
 /* HeapTupleHeader functions implemented in utils/time/combocid.c */
-extern CommandId HeapTupleHeaderGetCmin(HeapTupleHeader tup);
+extern CommandId HeapTupleHeaderGetCmin(const HeapTupleHeaderData *tup);
-extern CommandId HeapTupleHeaderGetCmax(HeapTupleHeader tup);
+extern CommandId HeapTupleHeaderGetCmax(const HeapTupleHeaderData *tup);
-extern void HeapTupleHeaderAdjustCmax(HeapTupleHeader tup,
+extern void HeapTupleHeaderAdjustCmax(const HeapTupleHeaderData *tup,
 									  CommandId *cmax, bool *iscombo);
 
 /* Prototype for HeapTupleHeader accessors in heapam.c */
-extern TransactionId HeapTupleGetUpdateXid(HeapTupleHeader tuple);
+extern TransactionId HeapTupleGetUpdateXid(const HeapTupleHeaderData *tup);
 
 #endif							/* HTUP_H */