Remove Item type

This type is just char * underneath, it provides no real value, no
type safety, and just makes the code one level more mysterious.  It is
more idiomatic to refer to blobs of memory by a combination of void *
and size_t, so change it to that.

Also, since this type hides the pointerness, we can't apply qualifiers
to what is pointed to, which requires some unconstify nonsense.  This
change allows fixing that.

Extension code that uses the Item type can change its code to use
void * to be backward compatible.

Reviewed-by: Nathan Bossart <nathandbossart@gmail.com>
Reviewed-by: Peter Geoghegan <pg@bowt.ie>
Discussion: https://www.postgresql.org/message-id/flat/c75cccf5-5709-407b-a36a-2ae6570be766@eisentraut.org

1 files changed, 17 insertions, 31 deletions

diff --git a/src/backend/access/nbtree/nbtxlog.c b/src/backend/access/nbtree/nbtxlog.c
index 69ea668bb0d..d4a26de06a3 100644
--- a/src/backend/access/nbtree/nbtxlog.c
+++ b/src/backend/access/nbtree/nbtxlog.c
@@ -38,7 +38,7 @@ _bt_restore_page(Page page, char *from, int len)
 	IndexTupleData itupdata;
 	Size		itemsz;
 	char	   *end = from + len;
-	Item		items[MaxIndexTuplesPerPage];
+	void	   *items[MaxIndexTuplesPerPage];
 	uint16		itemsizes[MaxIndexTuplesPerPage];
 	int			i;
 	int			nitems;
@@ -53,16 +53,15 @@ _bt_restore_page(Page page, char *from, int len)
 	{
 		/*
 		 * As we step through the items, 'from' won't always be properly
-		 * aligned, so we need to use memcpy().  Further, we use Item (which
-		 * is just a char*) here for our items array for the same reason;
-		 * wouldn't want the compiler or anyone thinking that an item is
-		 * aligned when it isn't.
+		 * aligned, so we need to use memcpy().  Further, we use void * here
+		 * for our items array for the same reason; wouldn't want the compiler
+		 * or anyone thinking that an item is aligned when it isn't.
 		 */
 		memcpy(&itupdata, from, sizeof(IndexTupleData));
 		itemsz = IndexTupleSize(&itupdata);
 		itemsz = MAXALIGN(itemsz);
 
-		items[i] = (Item) from;
+		items[i] = from;
 		itemsizes[i] = itemsz;
 		i++;
 
@@ -72,8 +71,7 @@ _bt_restore_page(Page page, char *from, int len)
 
 	for (i = nitems - 1; i >= 0; i--)
 	{
-		if (PageAddItem(page, items[i], itemsizes[i], nitems - i,
-						false, false) == InvalidOffsetNumber)
+		if (PageAddItem(page, items[i], itemsizes[i], nitems - i, false, false) == InvalidOffsetNumber)
 			elog(PANIC, "_bt_restore_page: cannot add item to page");
 	}
 }
@@ -186,8 +184,7 @@ btree_xlog_insert(bool isleaf, bool ismeta, bool posting,
 		if (!posting)
 		{
 			/* Simple retail insertion */
-			if (PageAddItem(page, (Item) datapos, datalen, xlrec->offnum,
-							false, false) == InvalidOffsetNumber)
+			if (PageAddItem(page, datapos, datalen, xlrec->offnum, false, false) == InvalidOffsetNumber)
 				elog(PANIC, "failed to add new item");
 		}
 		else
@@ -225,8 +222,7 @@ btree_xlog_insert(bool isleaf, bool ismeta, bool posting,
 
 			/* Insert "final" new item (not orignewitem from WAL stream) */
 			Assert(IndexTupleSize(newitem) == datalen);
-			if (PageAddItem(page, (Item) newitem, datalen, xlrec->offnum,
-							false, false) == InvalidOffsetNumber)
+			if (PageAddItem(page, newitem, datalen, xlrec->offnum, false, false) == InvalidOffsetNumber)
 				elog(PANIC, "failed to add posting split new item");
 		}
 
@@ -368,8 +364,7 @@ btree_xlog_split(bool newitemonleft, XLogReaderState *record)
 
 		/* Add high key tuple from WAL record to temp page */
 		leftoff = P_HIKEY;
-		if (PageAddItem(leftpage, (Item) left_hikey, left_hikeysz, P_HIKEY,
-						false, false) == InvalidOffsetNumber)
+		if (PageAddItem(leftpage, left_hikey, left_hikeysz, P_HIKEY, false, false) == InvalidOffsetNumber)
 			elog(ERROR, "failed to add high key to left page after split");
 		leftoff = OffsetNumberNext(leftoff);
 
@@ -384,9 +379,7 @@ btree_xlog_split(bool newitemonleft, XLogReaderState *record)
 			{
 				Assert(newitemonleft ||
 					   xlrec->firstrightoff == xlrec->newitemoff);
-				if (PageAddItem(leftpage, (Item) nposting,
-								MAXALIGN(IndexTupleSize(nposting)), leftoff,
-								false, false) == InvalidOffsetNumber)
+				if (PageAddItem(leftpage, nposting, MAXALIGN(IndexTupleSize(nposting)), leftoff, false, false) == InvalidOffsetNumber)
 					elog(ERROR, "failed to add new posting list item to left page after split");
 				leftoff = OffsetNumberNext(leftoff);
 				continue;		/* don't insert oposting */
@@ -395,8 +388,7 @@ btree_xlog_split(bool newitemonleft, XLogReaderState *record)
 			/* add the new item if it was inserted on left page */
 			else if (newitemonleft && off == xlrec->newitemoff)
 			{
-				if (PageAddItem(leftpage, (Item) newitem, newitemsz, leftoff,
-								false, false) == InvalidOffsetNumber)
+				if (PageAddItem(leftpage, newitem, newitemsz, leftoff, false, false) == InvalidOffsetNumber)
 					elog(ERROR, "failed to add new item to left page after split");
 				leftoff = OffsetNumberNext(leftoff);
 			}
@@ -404,8 +396,7 @@ btree_xlog_split(bool newitemonleft, XLogReaderState *record)
 			itemid = PageGetItemId(origpage, off);
 			itemsz = ItemIdGetLength(itemid);
 			item = (IndexTuple) PageGetItem(origpage, itemid);
-			if (PageAddItem(leftpage, (Item) item, itemsz, leftoff,
-							false, false) == InvalidOffsetNumber)
+			if (PageAddItem(leftpage, item, itemsz, leftoff, false, false) == InvalidOffsetNumber)
 				elog(ERROR, "failed to add old item to left page after split");
 			leftoff = OffsetNumberNext(leftoff);
 		}
@@ -413,8 +404,7 @@ btree_xlog_split(bool newitemonleft, XLogReaderState *record)
 		/* cope with possibility that newitem goes at the end */
 		if (newitemonleft && off == xlrec->newitemoff)
 		{
-			if (PageAddItem(leftpage, (Item) newitem, newitemsz, leftoff,
-							false, false) == InvalidOffsetNumber)
+			if (PageAddItem(leftpage, newitem, newitemsz, leftoff, false, false) == InvalidOffsetNumber)
 				elog(ERROR, "failed to add new item to left page after split");
 			leftoff = OffsetNumberNext(leftoff);
 		}
@@ -503,8 +493,7 @@ btree_xlog_dedup(XLogReaderState *record)
 			Size		itemsz = ItemIdGetLength(itemid);
 			IndexTuple	item = (IndexTuple) PageGetItem(page, itemid);
 
-			if (PageAddItem(newpage, (Item) item, itemsz, P_HIKEY,
-							false, false) == InvalidOffsetNumber)
+			if (PageAddItem(newpage, item, itemsz, P_HIKEY, false, false) == InvalidOffsetNumber)
 				elog(ERROR, "deduplication failed to add highkey");
 		}
 
@@ -580,8 +569,7 @@ btree_xlog_updates(Page page, OffsetNumber *updatedoffsets,
 
 		/* Overwrite updated version of tuple */
 		itemsz = MAXALIGN(IndexTupleSize(vacposting->itup));
-		if (!PageIndexTupleOverwrite(page, updatedoffsets[i],
-									 (Item) vacposting->itup, itemsz))
+		if (!PageIndexTupleOverwrite(page, updatedoffsets[i], vacposting->itup, itemsz))
 			elog(PANIC, "failed to update partially dead item");
 
 		pfree(vacposting->itup);
@@ -788,8 +776,7 @@ btree_xlog_mark_page_halfdead(uint8 info, XLogReaderState *record)
 	trunctuple.t_info = sizeof(IndexTupleData);
 	BTreeTupleSetTopParent(&trunctuple, xlrec->topparent);
 
-	if (PageAddItem(page, (Item) &trunctuple, sizeof(IndexTupleData), P_HIKEY,
-					false, false) == InvalidOffsetNumber)
+	if (PageAddItem(page, &trunctuple, sizeof(IndexTupleData), P_HIKEY, false, false) == InvalidOffsetNumber)
 		elog(ERROR, "could not add dummy high key to half-dead page");
 
 	PageSetLSN(page, lsn);
@@ -923,8 +910,7 @@ btree_xlog_unlink_page(uint8 info, XLogReaderState *record)
 		trunctuple.t_info = sizeof(IndexTupleData);
 		BTreeTupleSetTopParent(&trunctuple, xlrec->leaftopparent);
 
-		if (PageAddItem(page, (Item) &trunctuple, sizeof(IndexTupleData), P_HIKEY,
-						false, false) == InvalidOffsetNumber)
+		if (PageAddItem(page, &trunctuple, sizeof(IndexTupleData), P_HIKEY, false, false) == InvalidOffsetNumber)
 			elog(ERROR, "could not add dummy high key to half-dead page");
 
 		PageSetLSN(page, lsn);