Expanding the use of FLEXIBLE_ARRAY_MEMBER for declarations like foo[1]

From 509e9e28e523624881b2584ce05c78fc422cff44 Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@otacoo.com>
Date: Mon, 16 Feb 2015 02:44:10 +0900
Subject: [PATCH 1/4] First cut with FLEXIBLE_ARRAY_MEMBER

This is targetted to prevent false positive errors that static code
analyzers may do by assuming that some structures have an unvarying
size.
---
 contrib/cube/cubedata.h                     |  7 +++----
 contrib/intarray/_int.h                     |  4 ++--
 contrib/ltree/ltree.h                       | 14 +++++++-------
 contrib/pg_trgm/trgm.h                      |  2 +-
 src/backend/catalog/namespace.c             |  4 ++--
 src/backend/commands/prepare.c              |  4 ++--
 src/backend/executor/functions.c            |  3 +--
 src/backend/executor/spi.c                  |  3 +--
 src/backend/nodes/params.c                  |  3 +--
 src/backend/tcop/postgres.c                 |  3 +--
 src/bin/pg_dump/dumputils.c                 |  3 +--
 src/bin/pg_dump/dumputils.h                 |  2 +-
 src/include/access/gin_private.h            |  2 +-
 src/include/access/gist_private.h           |  5 +++--
 src/include/access/heapam_xlog.h            |  2 +-
 src/include/access/spgist_private.h         | 10 +++++-----
 src/include/access/xact.h                   |  8 ++++----
 src/include/c.h                             |  4 ++--
 src/include/catalog/namespace.h             |  4 ++--
 src/include/commands/dbcommands.h           |  4 ++--
 src/include/commands/tablespace.h           |  2 +-
 src/include/executor/hashjoin.h             |  2 +-
 src/include/nodes/bitmapset.h               |  4 ++--
 src/include/nodes/params.h                  |  2 +-
 src/include/nodes/tidbitmap.h               |  2 +-
 src/include/postgres.h                      |  9 +++++----
 src/include/postmaster/syslogger.h          |  2 +-
 src/include/replication/walsender_private.h |  2 +-
 src/include/storage/bufpage.h               |  3 ++-
 src/include/storage/fsm_internals.h         |  2 +-
 src/include/storage/standby.h               |  4 ++--
 src/include/tsearch/dicts/regis.h           |  2 +-
 src/include/tsearch/dicts/spell.h           |  6 +++---
 src/include/tsearch/ts_type.h               |  6 +++---
 src/include/utils/catcache.h                |  4 ++--
 src/include/utils/datetime.h                |  5 +++--
 src/include/utils/geo_decls.h               |  5 +++--
 src/include/utils/jsonb.h                   |  2 +-
 src/include/utils/relmapper.h               |  2 +-
 src/include/utils/varbit.h                  |  3 ++-
 40 files changed, 80 insertions(+), 80 deletions(-)

diff --git a/contrib/cube/cubedata.h b/contrib/cube/cubedata.h
index 5d44e11..3535847 100644
--- a/contrib/cube/cubedata.h
+++ b/contrib/cube/cubedata.h
@@ -23,11 +23,10 @@ typedef struct NDBOX
 	unsigned int header;
 
 	/*
-	 * Variable length array. The lower left coordinates for each dimension
-	 * come first, followed by upper right coordinates unless the point flag
-	 * is set.
+	 * The lower left coordinates for each dimension come first, followed
+	 * by upper right coordinates unless the point flag is set.
 	 */
-	double		x[1];
+	double		x[FLEXIBLE_ARRAY_MEMBER];
 } NDBOX;
 
 #define POINT_BIT			0x80000000
diff --git a/contrib/intarray/_int.h b/contrib/intarray/_int.h
index 7f93206..d524f0f 100644
--- a/contrib/intarray/_int.h
+++ b/contrib/intarray/_int.h
@@ -73,7 +73,7 @@ typedef struct
 {
 	int32		vl_len_;		/* varlena header (do not touch directly!) */
 	int32		flag;
-	char		data[1];
+	char		data[FLEXIBLE_ARRAY_MEMBER];
 } GISTTYPE;
 
 #define ALLISTRUE		0x04
@@ -133,7 +133,7 @@ typedef struct QUERYTYPE
 {
 	int32		vl_len_;		/* varlena header (do not touch directly!) */
 	int32		size;			/* number of ITEMs */
-	ITEM		items[1];		/* variable length array */
+	ITEM		items[FLEXIBLE_ARRAY_MEMBER];
 } QUERYTYPE;
 
 #define HDRSIZEQT	offsetof(QUERYTYPE, items)
diff --git a/contrib/ltree/ltree.h b/contrib/ltree/ltree.h
index 1b1305b..c604357 100644
--- a/contrib/ltree/ltree.h
+++ b/contrib/ltree/ltree.h
@@ -10,7 +10,7 @@
 typedef struct
 {
 	uint16		len;
-	char		name[1];
+	char		name[FLEXIBLE_ARRAY_MEMBER];
 } ltree_level;
 
 #define LEVEL_HDRSIZE	(offsetof(ltree_level,name))
@@ -20,7 +20,7 @@ typedef struct
 {
 	int32		vl_len_;		/* varlena header (do not touch directly!) */
 	uint16		numlevel;
-	char		data[1];
+	char		data[FLEXIBLE_ARRAY_MEMBER];
 } ltree;
 
 #define LTREE_HDRSIZE	MAXALIGN( offsetof(ltree, data) )
@@ -34,7 +34,7 @@ typedef struct
 	int32		val;
 	uint16		len;
 	uint8		flag;
-	char		name[1];
+	char		name[FLEXIBLE_ARRAY_MEMBER];
 } lquery_variant;
 
 #define LVAR_HDRSIZE   MAXALIGN(offsetof(lquery_variant, name))
@@ -51,7 +51,7 @@ typedef struct
 	uint16		numvar;
 	uint16		low;
 	uint16		high;
-	char		variants[1];
+	char		variants[FLEXIBLE_ARRAY_MEMBER];
 } lquery_level;
 
 #define LQL_HDRSIZE MAXALIGN( offsetof(lquery_level,variants) )
@@ -72,7 +72,7 @@ typedef struct
 	uint16		numlevel;
 	uint16		firstgood;
 	uint16		flag;
-	char		data[1];
+	char		data[FLEXIBLE_ARRAY_MEMBER];
 } lquery;
 
 #define LQUERY_HDRSIZE	 MAXALIGN( offsetof(lquery, data) )
@@ -107,7 +107,7 @@ typedef struct
 {
 	int32		vl_len_;		/* varlena header (do not touch directly!) */
 	int32		size;
-	char		data[1];
+	char		data[FLEXIBLE_ARRAY_MEMBER];
 } ltxtquery;
 
 #define HDRSIZEQT		MAXALIGN(VARHDRSZ + sizeof(int32))
@@ -208,7 +208,7 @@ typedef struct
 {
 	int32		vl_len_;		/* varlena header (do not touch directly!) */
 	uint32		flag;
-	char		data[1];
+	char		data[FLEXIBLE_ARRAY_MEMBER];
 } ltree_gist;
 
 #define LTG_ONENODE 0x01
diff --git a/contrib/pg_trgm/trgm.h b/contrib/pg_trgm/trgm.h
index ed649b8..f030558 100644
--- a/contrib/pg_trgm/trgm.h
+++ b/contrib/pg_trgm/trgm.h
@@ -63,7 +63,7 @@ typedef struct
 {
 	int32		vl_len_;		/* varlena header (do not touch directly!) */
 	uint8		flag;
-	char		data[1];
+	char		data[FLEXIBLE_ARRAY_MEMBER];
 } TRGM;
 
 #define TRGMHDRSIZE		  (VARHDRSZ + sizeof(uint8))
diff --git a/src/backend/catalog/namespace.c b/src/backend/catalog/namespace.c
index bfb4fdc..1ee0755 100644
--- a/src/backend/catalog/namespace.c
+++ b/src/backend/catalog/namespace.c
@@ -1075,8 +1075,8 @@ FuncnameGetCandidates(List *names, int nargs, List *argnames,
 		 */
 		effective_nargs = Max(pronargs, nargs);
 		newResult = (FuncCandidateList)
-			palloc(sizeof(struct _FuncCandidateList) - sizeof(Oid)
-				   + effective_nargs * sizeof(Oid));
+			palloc(sizeof(struct _FuncCandidateList) +
+				   effective_nargs * sizeof(Oid));
 		newResult->pathpos = pathpos;
 		newResult->oid = HeapTupleGetOid(proctup);
 		newResult->nargs = effective_nargs;
diff --git a/src/backend/commands/prepare.c b/src/backend/commands/prepare.c
index 71b08f0..d36e1be 100644
--- a/src/backend/commands/prepare.c
+++ b/src/backend/commands/prepare.c
@@ -383,10 +383,10 @@ EvaluateParams(PreparedStatement *pstmt, List *params,
 	/* Prepare the expressions for execution */
 	exprstates = (List *) ExecPrepareExpr((Expr *) params, estate);
 
-	/* sizeof(ParamListInfoData) includes the first array element */
 	paramLI = (ParamListInfo)
 		palloc(sizeof(ParamListInfoData) +
-			   (num_params - 1) * sizeof(ParamExternData));
+			   num_params * sizeof(ParamExternData));
+
 	/* we have static list of params, so no hooks needed */
 	paramLI->paramFetch = NULL;
 	paramLI->paramFetchArg = NULL;
diff --git a/src/backend/executor/functions.c b/src/backend/executor/functions.c
index 84be37c..a1ab662 100644
--- a/src/backend/executor/functions.c
+++ b/src/backend/executor/functions.c
@@ -896,9 +896,8 @@ postquel_sub_params(SQLFunctionCachePtr fcache,
 
 		if (fcache->paramLI == NULL)
 		{
-			/* sizeof(ParamListInfoData) includes the first array element */
 			paramLI = (ParamListInfo) palloc(sizeof(ParamListInfoData) +
-									  (nargs - 1) * sizeof(ParamExternData));
+											 nargs * sizeof(ParamExternData));
 			/* we have static list of params, so no hooks needed */
 			paramLI->paramFetch = NULL;
 			paramLI->paramFetchArg = NULL;
diff --git a/src/backend/executor/spi.c b/src/backend/executor/spi.c
index 4b86e91..12406b3 100644
--- a/src/backend/executor/spi.c
+++ b/src/backend/executor/spi.c
@@ -2290,9 +2290,8 @@ _SPI_convert_params(int nargs, Oid *argtypes,
 	{
 		int			i;
 
-		/* sizeof(ParamListInfoData) includes the first array element */
 		paramLI = (ParamListInfo) palloc(sizeof(ParamListInfoData) +
-									  (nargs - 1) * sizeof(ParamExternData));
+									  nargs * sizeof(ParamExternData));
 		/* we have static list of params, so no hooks needed */
 		paramLI->paramFetch = NULL;
 		paramLI->paramFetchArg = NULL;
diff --git a/src/backend/nodes/params.c b/src/backend/nodes/params.c
index 2f2f5ed..3107de8 100644
--- a/src/backend/nodes/params.c
+++ b/src/backend/nodes/params.c
@@ -40,9 +40,8 @@ copyParamList(ParamListInfo from)
 	if (from == NULL || from->numParams <= 0)
 		return NULL;
 
-	/* sizeof(ParamListInfoData) includes the first array element */
 	size = sizeof(ParamListInfoData) +
-		(from->numParams - 1) * sizeof(ParamExternData);
+		from->numParams * sizeof(ParamExternData);
 
 	retval = (ParamListInfo) palloc(size);
 	retval->paramFetch = NULL;
diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index 28af40c..22fbc83 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -1619,9 +1619,8 @@ exec_bind_message(StringInfo input_message)
 	{
 		int			paramno;
 
-		/* sizeof(ParamListInfoData) includes the first array element */
 		params = (ParamListInfo) palloc(sizeof(ParamListInfoData) +
-								  (numParams - 1) * sizeof(ParamExternData));
+										numParams * sizeof(ParamExternData));
 		/* we have static list of params, so no hooks needed */
 		params->paramFetch = NULL;
 		params->paramFetchArg = NULL;
diff --git a/src/bin/pg_dump/dumputils.c b/src/bin/pg_dump/dumputils.c
index 095c507..892d3fa 100644
--- a/src/bin/pg_dump/dumputils.c
+++ b/src/bin/pg_dump/dumputils.c
@@ -1217,8 +1217,7 @@ simple_string_list_append(SimpleStringList *list, const char *val)
 	SimpleStringListCell *cell;
 
 	/* this calculation correctly accounts for the null trailing byte */
-	cell = (SimpleStringListCell *)
-		pg_malloc(sizeof(SimpleStringListCell) + strlen(val));
+	cell = (SimpleStringListCell *) pg_malloc(sizeof(SimpleStringListCell));
 
 	cell->next = NULL;
 	strcpy(cell->val, val);
diff --git a/src/bin/pg_dump/dumputils.h b/src/bin/pg_dump/dumputils.h
index a39c1b6..94476a9 100644
--- a/src/bin/pg_dump/dumputils.h
+++ b/src/bin/pg_dump/dumputils.h
@@ -38,7 +38,7 @@ typedef struct SimpleOidList
 typedef struct SimpleStringListCell
 {
 	struct SimpleStringListCell *next;
-	char		val[1];			/* VARIABLE LENGTH FIELD */
+	char		val[FLEXIBLE_ARRAY_MEMBER];
 } SimpleStringListCell;
 
 typedef struct SimpleStringList
diff --git a/src/include/access/gin_private.h b/src/include/access/gin_private.h
index bda7c28..d3abbc0 100644
--- a/src/include/access/gin_private.h
+++ b/src/include/access/gin_private.h
@@ -389,7 +389,7 @@ typedef struct
 {
 	ItemPointerData first;		/* first item in this posting list (unpacked) */
 	uint16		nbytes;			/* number of bytes that follow */
-	unsigned char bytes[1];		/* varbyte encoded items (variable length) */
+	unsigned char bytes[FLEXIBLE_ARRAY_MEMBER];	/* varbyte encoded items */
 } GinPostingList;
 
 #define SizeOfGinPostingList(plist) (offsetof(GinPostingList, bytes) + SHORTALIGN((plist)->nbytes) )
diff --git a/src/include/access/gist_private.h b/src/include/access/gist_private.h
index 382826e..36f5257 100644
--- a/src/include/access/gist_private.h
+++ b/src/include/access/gist_private.h
@@ -47,7 +47,7 @@ typedef struct
 {
 	BlockNumber prev;
 	uint32		freespace;
-	char		tupledata[1];
+	char		tupledata[FLEXIBLE_ARRAY_MEMBER];
 } GISTNodeBufferPage;
 
 #define BUFFER_PAGE_DATA_OFFSET MAXALIGN(offsetof(GISTNodeBufferPage, tupledata))
@@ -131,7 +131,8 @@ typedef struct GISTSearchItem
 		/* we must store parentlsn to detect whether a split occurred */
 		GISTSearchHeapItem heap;	/* heap info, if heap tuple */
 	}			data;
-	double		distances[1];	/* array with numberOfOrderBys entries */
+	double distances[FLEXIBLE_ARRAY_MEMBER]; /* array with numberOfOrderBys
+											  * entries */
 } GISTSearchItem;
 
 #define GISTSearchItemIsHeap(item)	((item).blkno == InvalidBlockNumber)
diff --git a/src/include/access/heapam_xlog.h b/src/include/access/heapam_xlog.h
index a2ed2a0..f0f89de 100644
--- a/src/include/access/heapam_xlog.h
+++ b/src/include/access/heapam_xlog.h
@@ -132,7 +132,7 @@ typedef struct xl_heap_multi_insert
 {
 	uint8		flags;
 	uint16		ntuples;
-	OffsetNumber offsets[1];
+	OffsetNumber offsets[FLEXIBLE_ARRAY_MEMBER];
 } xl_heap_multi_insert;
 
 #define SizeOfHeapMultiInsert	offsetof(xl_heap_multi_insert, offsets)
diff --git a/src/include/access/spgist_private.h b/src/include/access/spgist_private.h
index f11d8ef..0492ef6 100644
--- a/src/include/access/spgist_private.h
+++ b/src/include/access/spgist_private.h
@@ -426,7 +426,7 @@ typedef struct spgxlogMoveLeafs
 	 * the dead tuple from the source
 	 *----------
 	 */
-	OffsetNumber offsets[1];
+	OffsetNumber offsets[FLEXIBLE_ARRAY_MEMBER];
 } spgxlogMoveLeafs;
 
 #define SizeOfSpgxlogMoveLeafs	offsetof(spgxlogMoveLeafs, offsets)
@@ -534,7 +534,7 @@ typedef struct spgxlogPickSplit
 	 *		list of leaf tuples, length nInsert (unaligned!)
 	 *----------
 	 */
-	OffsetNumber offsets[1];
+	OffsetNumber offsets[FLEXIBLE_ARRAY_MEMBER];
 } spgxlogPickSplit;
 
 #define SizeOfSpgxlogPickSplit offsetof(spgxlogPickSplit, offsets)
@@ -558,7 +558,7 @@ typedef struct spgxlogVacuumLeaf
 	 *		tuple numbers to insert in nextOffset links
 	 *----------
 	 */
-	OffsetNumber offsets[1];
+	OffsetNumber offsets[FLEXIBLE_ARRAY_MEMBER];
 } spgxlogVacuumLeaf;
 
 #define SizeOfSpgxlogVacuumLeaf offsetof(spgxlogVacuumLeaf, offsets)
@@ -571,7 +571,7 @@ typedef struct spgxlogVacuumRoot
 	spgxlogState stateSrc;
 
 	/* offsets of tuples to delete follow */
-	OffsetNumber offsets[1];
+	OffsetNumber offsets[FLEXIBLE_ARRAY_MEMBER];
 } spgxlogVacuumRoot;
 
 #define SizeOfSpgxlogVacuumRoot offsetof(spgxlogVacuumRoot, offsets)
@@ -583,7 +583,7 @@ typedef struct spgxlogVacuumRedirect
 	TransactionId newestRedirectXid;	/* newest XID of removed redirects */
 
 	/* offsets of redirect tuples to make placeholders follow */
-	OffsetNumber offsets[1];
+	OffsetNumber offsets[FLEXIBLE_ARRAY_MEMBER];
 } spgxlogVacuumRedirect;
 
 #define SizeOfSpgxlogVacuumRedirect offsetof(spgxlogVacuumRedirect, offsets)
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 8205504..9b95f10 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -118,7 +118,7 @@ typedef struct xl_xact_assignment
 {
 	TransactionId xtop;			/* assigned XID's top-level XID */
 	int			nsubxacts;		/* number of subtransaction XIDs */
-	TransactionId xsub[1];		/* assigned subxids */
+	TransactionId xsub[FLEXIBLE_ARRAY_MEMBER];		/* assigned subxids */
 } xl_xact_assignment;
 
 #define MinSizeOfXactAssignment offsetof(xl_xact_assignment, xsub)
@@ -128,7 +128,7 @@ typedef struct xl_xact_commit_compact
 	TimestampTz xact_time;		/* time of commit */
 	int			nsubxacts;		/* number of subtransaction XIDs */
 	/* ARRAY OF COMMITTED SUBTRANSACTION XIDs FOLLOWS */
-	TransactionId subxacts[1];	/* VARIABLE LENGTH ARRAY */
+	TransactionId subxacts[FLEXIBLE_ARRAY_MEMBER];
 } xl_xact_commit_compact;
 
 #define MinSizeOfXactCommitCompact offsetof(xl_xact_commit_compact, subxacts)
@@ -143,7 +143,7 @@ typedef struct xl_xact_commit
 	Oid			dbId;			/* MyDatabaseId */
 	Oid			tsId;			/* MyDatabaseTableSpace */
 	/* Array of RelFileNode(s) to drop at commit */
-	RelFileNode xnodes[1];		/* VARIABLE LENGTH ARRAY */
+	RelFileNode xnodes[FLEXIBLE_ARRAY_MEMBER];
 	/* ARRAY OF COMMITTED SUBTRANSACTION XIDs FOLLOWS */
 	/* ARRAY OF SHARED INVALIDATION MESSAGES FOLLOWS */
 } xl_xact_commit;
@@ -171,7 +171,7 @@ typedef struct xl_xact_abort
 	int			nrels;			/* number of RelFileNodes */
 	int			nsubxacts;		/* number of subtransaction XIDs */
 	/* Array of RelFileNode(s) to drop at abort */
-	RelFileNode xnodes[1];		/* VARIABLE LENGTH ARRAY */
+	RelFileNode xnodes[FLEXIBLE_ARRAY_MEMBER];
 	/* ARRAY OF ABORTED SUBTRANSACTION XIDs FOLLOWS */
 } xl_xact_abort;
 
diff --git a/src/include/c.h b/src/include/c.h
index b187520..bbd0d53 100644
--- a/src/include/c.h
+++ b/src/include/c.h
@@ -424,7 +424,7 @@ typedef struct
 	Oid			elemtype;
 	int			dim1;
 	int			lbound1;
-	int16		values[1];		/* VARIABLE LENGTH ARRAY */
+	int16		values[FLEXIBLE_ARRAY_MEMBER];
 } int2vector;					/* VARIABLE LENGTH STRUCT */
 
 typedef struct
@@ -435,7 +435,7 @@ typedef struct
 	Oid			elemtype;
 	int			dim1;
 	int			lbound1;
-	Oid			values[1];		/* VARIABLE LENGTH ARRAY */
+	Oid			values[FLEXIBLE_ARRAY_MEMBER];
 } oidvector;					/* VARIABLE LENGTH STRUCT */
 
 /*
diff --git a/src/include/catalog/namespace.h b/src/include/catalog/namespace.h
index d2e5198..cf5f7d0 100644
--- a/src/include/catalog/namespace.h
+++ b/src/include/catalog/namespace.h
@@ -34,8 +34,8 @@ typedef struct _FuncCandidateList
 	int			nvargs;			/* number of args to become variadic array */
 	int			ndargs;			/* number of defaulted args */
 	int		   *argnumbers;		/* args' positional indexes, if named call */
-	Oid			args[1];		/* arg types --- VARIABLE LENGTH ARRAY */
-}	*FuncCandidateList;	/* VARIABLE LENGTH STRUCT */
+	Oid			args[FLEXIBLE_ARRAY_MEMBER];	/* arg types */
+}	*FuncCandidateList;
 
 /*
  *	Structure for xxxOverrideSearchPath functions
diff --git a/src/include/commands/dbcommands.h b/src/include/commands/dbcommands.h
index cb7cc0e..be1cac2 100644
--- a/src/include/commands/dbcommands.h
+++ b/src/include/commands/dbcommands.h
@@ -26,7 +26,7 @@ typedef struct xl_dbase_create_rec_old
 {
 	/* Records copying of a single subdirectory incl. contents */
 	Oid			db_id;
-	char		src_path[1];	/* VARIABLE LENGTH STRING */
+	char		src_path[FLEXIBLE_ARRAY_MEMBER];
 	/* dst_path follows src_path */
 }	xl_dbase_create_rec_old;
 
@@ -34,7 +34,7 @@ typedef struct xl_dbase_drop_rec_old
 {
 	/* Records dropping of a single subdirectory incl. contents */
 	Oid			db_id;
-	char		dir_path[1];	/* VARIABLE LENGTH STRING */
+	char		dir_path[FLEXIBLE_ARRAY_MEMBER];
 }	xl_dbase_drop_rec_old;
 
 typedef struct xl_dbase_create_rec
diff --git a/src/include/commands/tablespace.h b/src/include/commands/tablespace.h
index e8b9bc4..9e40e31 100644
--- a/src/include/commands/tablespace.h
+++ b/src/include/commands/tablespace.h
@@ -25,7 +25,7 @@
 typedef struct xl_tblspc_create_rec
 {
 	Oid			ts_id;
-	char		ts_path[1];		/* VARIABLE LENGTH STRING */
+	char		ts_path[FLEXIBLE_ARRAY_MEMBER];
 } xl_tblspc_create_rec;
 
 typedef struct xl_tblspc_drop_rec
diff --git a/src/include/executor/hashjoin.h b/src/include/executor/hashjoin.h
index e79df71..71099b1 100644
--- a/src/include/executor/hashjoin.h
+++ b/src/include/executor/hashjoin.h
@@ -114,7 +114,7 @@ typedef struct HashMemoryChunkData
 
 	struct HashMemoryChunkData *next; /* pointer to the next chunk (linked list) */
 
-	char		data[1];	/* buffer allocated at the end */
+	char		data[FLEXIBLE_ARRAY_MEMBER];	/* buffer allocated at the end */
 } HashMemoryChunkData;
 
 typedef struct HashMemoryChunkData *HashMemoryChunk;
diff --git a/src/include/nodes/bitmapset.h b/src/include/nodes/bitmapset.h
index 5f45f4d..3a556ee 100644
--- a/src/include/nodes/bitmapset.h
+++ b/src/include/nodes/bitmapset.h
@@ -32,8 +32,8 @@ typedef int32 signedbitmapword; /* must be the matching signed type */
 typedef struct Bitmapset
 {
 	int			nwords;			/* number of words in array */
-	bitmapword	words[1];		/* really [nwords] */
-} Bitmapset;					/* VARIABLE LENGTH STRUCT */
+	bitmapword	words[FLEXIBLE_ARRAY_MEMBER];	/* really [nwords] */
+} Bitmapset;
 
 
 /* result of bms_subset_compare */
diff --git a/src/include/nodes/params.h b/src/include/nodes/params.h
index 5b096c5..a0f7dd0 100644
--- a/src/include/nodes/params.h
+++ b/src/include/nodes/params.h
@@ -71,7 +71,7 @@ typedef struct ParamListInfoData
 	ParserSetupHook parserSetup;	/* parser setup hook */
 	void	   *parserSetupArg;
 	int			numParams;		/* number of ParamExternDatas following */
-	ParamExternData params[1];	/* VARIABLE LENGTH ARRAY */
+	ParamExternData params[FLEXIBLE_ARRAY_MEMBER];
 }	ParamListInfoData;
 
 
diff --git a/src/include/nodes/tidbitmap.h b/src/include/nodes/tidbitmap.h
index fb62c9e..bfbc0fb 100644
--- a/src/include/nodes/tidbitmap.h
+++ b/src/include/nodes/tidbitmap.h
@@ -41,7 +41,7 @@ typedef struct
 	int			ntuples;		/* -1 indicates lossy result */
 	bool		recheck;		/* should the tuples be rechecked? */
 	/* Note: recheck is always true if ntuples < 0 */
-	OffsetNumber offsets[1];	/* VARIABLE LENGTH ARRAY */
+	OffsetNumber offsets[FLEXIBLE_ARRAY_MEMBER];
 } TBMIterateResult;				/* VARIABLE LENGTH STRUCT */
 
 /* function prototypes in nodes/tidbitmap.c */
diff --git a/src/include/postgres.h b/src/include/postgres.h
index 082c75b..482e676 100644
--- a/src/include/postgres.h
+++ b/src/include/postgres.h
@@ -117,20 +117,20 @@ typedef union
 	struct						/* Normal varlena (4-byte length) */
 	{
 		uint32		va_header;
-		char		va_data[1];
+		char		va_data[FLEXIBLE_ARRAY_MEMBER];
 	}			va_4byte;
 	struct						/* Compressed-in-line format */
 	{
 		uint32		va_header;
 		uint32		va_rawsize; /* Original data size (excludes header) */
-		char		va_data[1]; /* Compressed data */
+		char		va_data[FLEXIBLE_ARRAY_MEMBER]; /* Compressed data */
 	}			va_compressed;
 } varattrib_4b;
 
 typedef struct
 {
 	uint8		va_header;
-	char		va_data[1];		/* Data begins here */
+	char		va_data[FLEXIBLE_ARRAY_MEMBER];	/* Data begins here */
 } varattrib_1b;
 
 /* TOAST pointers are a subset of varattrib_1b with an identifying tag byte */
@@ -138,7 +138,8 @@ typedef struct
 {
 	uint8		va_header;		/* Always 0x80 or 0x01 */
 	uint8		va_tag;			/* Type of datum */
-	char		va_data[1];		/* Data (of the type indicated by va_tag) */
+	char		va_data[FLEXIBLE_ARRAY_MEMBER];	/* Data (of the type
+												 * indicated by va_tag) */
 } varattrib_1b_e;
 
 /*
diff --git a/src/include/postmaster/syslogger.h b/src/include/postmaster/syslogger.h
index 602b13c..89a535c 100644
--- a/src/include/postmaster/syslogger.h
+++ b/src/include/postmaster/syslogger.h
@@ -48,7 +48,7 @@ typedef struct
 	int32		pid;			/* writer's pid */
 	char		is_last;		/* last chunk of message? 't' or 'f' ('T' or
 								 * 'F' for CSV case) */
-	char		data[1];		/* data payload starts here */
+	char		data[FLEXIBLE_ARRAY_MEMBER];	/* data payload starts here */
 } PipeProtoHeader;
 
 typedef union
diff --git a/src/include/replication/walsender_private.h b/src/include/replication/walsender_private.h
index 8867750..02faad8 100644
--- a/src/include/replication/walsender_private.h
+++ b/src/include/replication/walsender_private.h
@@ -88,7 +88,7 @@ typedef struct
 	 */
 	bool		sync_standbys_defined;
 
-	WalSnd		walsnds[1];		/* VARIABLE LENGTH ARRAY */
+	WalSnd		walsnds[FLEXIBLE_ARRAY_MEMBER];
 } WalSndCtlData;
 
 extern WalSndCtlData *WalSndCtl;
diff --git a/src/include/storage/bufpage.h b/src/include/storage/bufpage.h
index f693032..b7dbd6f 100644
--- a/src/include/storage/bufpage.h
+++ b/src/include/storage/bufpage.h
@@ -156,7 +156,8 @@ typedef struct PageHeaderData
 	LocationIndex pd_special;	/* offset to start of special space */
 	uint16		pd_pagesize_version;
 	TransactionId pd_prune_xid; /* oldest prunable XID, or zero if none */
-	ItemIdData	pd_linp[1];		/* beginning of line pointer array */
+	ItemIdData	pd_linp[FLEXIBLE_ARRAY_MEMBER];	/* beginning of line pointer
+												 * array */
 } PageHeaderData;
 
 typedef PageHeaderData *PageHeader;
diff --git a/src/include/storage/fsm_internals.h b/src/include/storage/fsm_internals.h
index 1decd90..26340b4 100644
--- a/src/include/storage/fsm_internals.h
+++ b/src/include/storage/fsm_internals.h
@@ -39,7 +39,7 @@ typedef struct
 	 * NonLeafNodesPerPage elements are upper nodes, and the following
 	 * LeafNodesPerPage elements are leaf nodes. Unused nodes are zero.
 	 */
-	uint8		fp_nodes[1];
+	uint8		fp_nodes[FLEXIBLE_ARRAY_MEMBER];
 } FSMPageData;
 
 typedef FSMPageData *FSMPage;
diff --git a/src/include/storage/standby.h b/src/include/storage/standby.h
index c32c963..7626c4c 100644
--- a/src/include/storage/standby.h
+++ b/src/include/storage/standby.h
@@ -60,7 +60,7 @@ extern void StandbyReleaseOldLocks(int nxids, TransactionId *xids);
 typedef struct xl_standby_locks
 {
 	int			nlocks;			/* number of entries in locks array */
-	xl_standby_lock locks[1];	/* VARIABLE LENGTH ARRAY */
+	xl_standby_lock locks[FLEXIBLE_ARRAY_MEMBER];
 } xl_standby_locks;
 
 /*
@@ -75,7 +75,7 @@ typedef struct xl_running_xacts
 	TransactionId oldestRunningXid;		/* *not* oldestXmin */
 	TransactionId latestCompletedXid;	/* so we can set xmax */
 
-	TransactionId xids[1];		/* VARIABLE LENGTH ARRAY */
+	TransactionId xids[FLEXIBLE_ARRAY_MEMBER];
 } xl_running_xacts;
 
 #define MinSizeOfXactRunningXacts offsetof(xl_running_xacts, xids)
diff --git a/src/include/tsearch/dicts/regis.h b/src/include/tsearch/dicts/regis.h
index 081a502..ddf5b60 100644
--- a/src/include/tsearch/dicts/regis.h
+++ b/src/include/tsearch/dicts/regis.h
@@ -21,7 +21,7 @@ typedef struct RegisNode
 				len:16,
 				unused:14;
 	struct RegisNode *next;
-	unsigned char data[1];
+	unsigned char data[FLEXIBLE_ARRAY_MEMBER];
 } RegisNode;
 
 #define  RNHDRSZ	(offsetof(RegisNode,data))
diff --git a/src/include/tsearch/dicts/spell.h b/src/include/tsearch/dicts/spell.h
index a75552b..e512532 100644
--- a/src/include/tsearch/dicts/spell.h
+++ b/src/include/tsearch/dicts/spell.h
@@ -49,7 +49,7 @@ typedef struct
 typedef struct SPNode
 {
 	uint32		length;
-	SPNodeData	data[1];
+	SPNodeData	data[FLEXIBLE_ARRAY_MEMBER];
 } SPNode;
 
 #define SPNHDRSZ	(offsetof(SPNode,data))
@@ -70,7 +70,7 @@ typedef struct spell_struct
 			int			len;
 		}			d;
 	}			p;
-	char		word[1];		/* variable length, null-terminated */
+	char		word[FLEXIBLE_ARRAY_MEMBER];
 } SPELL;
 
 #define SPELLHDRSZ	(offsetof(SPELL, word))
@@ -120,7 +120,7 @@ typedef struct AffixNode
 {
 	uint32		isvoid:1,
 				length:31;
-	AffixNodeData data[1];
+	AffixNodeData data[FLEXIBLE_ARRAY_MEMBER];
 } AffixNode;
 
 #define ANHRDSZ		   (offsetof(AffixNode, data))
diff --git a/src/include/tsearch/ts_type.h b/src/include/tsearch/ts_type.h
index 1cdfa82..ce919a2 100644
--- a/src/include/tsearch/ts_type.h
+++ b/src/include/tsearch/ts_type.h
@@ -63,7 +63,7 @@ typedef uint16 WordEntryPos;
 typedef struct
 {
 	uint16		npos;
-	WordEntryPos pos[1];		/* variable length */
+	WordEntryPos pos[FLEXIBLE_ARRAY_MEMBER];
 } WordEntryPosVector;
 
 
@@ -82,7 +82,7 @@ typedef struct
 {
 	int32		vl_len_;		/* varlena header (do not touch directly!) */
 	int32		size;
-	WordEntry	entries[1];		/* variable length */
+	WordEntry	entries[FLEXIBLE_ARRAY_MEMBER];
 	/* lexemes follow the entries[] array */
 } TSVectorData;
 
@@ -233,7 +233,7 @@ typedef struct
 {
 	int32		vl_len_;		/* varlena header (do not touch directly!) */
 	int32		size;			/* number of QueryItems */
-	char		data[1];		/* data starts here */
+	char		data[FLEXIBLE_ARRAY_MEMBER];	/* data starts here */
 } TSQueryData;
 
 typedef TSQueryData *TSQuery;
diff --git a/src/include/utils/catcache.h b/src/include/utils/catcache.h
index 8084785..da261e8 100644
--- a/src/include/utils/catcache.h
+++ b/src/include/utils/catcache.h
@@ -147,8 +147,8 @@ typedef struct catclist
 	uint32		hash_value;		/* hash value for lookup keys */
 	HeapTupleData tuple;		/* header for tuple holding keys */
 	int			n_members;		/* number of member tuples */
-	CatCTup    *members[1];		/* members --- VARIABLE LENGTH ARRAY */
-} CatCList;						/* VARIABLE LENGTH STRUCT */
+	CatCTup    *members[FLEXIBLE_ARRAY_MEMBER];	/* members */
+} CatCList;
 
 
 typedef struct catcacheheader
diff --git a/src/include/utils/datetime.h b/src/include/utils/datetime.h
index 8912ba5..d36f297 100644
--- a/src/include/utils/datetime.h
+++ b/src/include/utils/datetime.h
@@ -219,7 +219,7 @@ typedef struct TimeZoneAbbrevTable
 {
 	Size		tblsize;		/* size in bytes of TimeZoneAbbrevTable */
 	int			numabbrevs;		/* number of entries in abbrevs[] array */
-	datetkn		abbrevs[1];		/* VARIABLE LENGTH ARRAY */
+	datetkn		abbrevs[FLEXIBLE_ARRAY_MEMBER];
 	/* DynamicZoneAbbrev(s) may follow the abbrevs[] array */
 } TimeZoneAbbrevTable;
 
@@ -227,7 +227,8 @@ typedef struct TimeZoneAbbrevTable
 typedef struct DynamicZoneAbbrev
 {
 	pg_tz	   *tz;				/* NULL if not yet looked up */
-	char		zone[1];		/* zone name (var length, NUL-terminated) */
+	char		zone[FLEXIBLE_ARRAY_MEMBER];	/* zone name (var length,
+												 * NUL-terminated) */
 } DynamicZoneAbbrev;
 
 
diff --git a/src/include/utils/geo_decls.h b/src/include/utils/geo_decls.h
index 0b6d3c3..a0f779b 100644
--- a/src/include/utils/geo_decls.h
+++ b/src/include/utils/geo_decls.h
@@ -80,7 +80,8 @@ typedef struct
 	int32		npts;
 	int32		closed;			/* is this a closed polygon? */
 	int32		dummy;			/* padding to make it double align */
-	Point		p[1];			/* variable length array of POINTs */
+	Point		p[FLEXIBLE_ARRAY_MEMBER];	/* variable length array
+											 * of POINTs */
 } PATH;
 
 
@@ -115,7 +116,7 @@ typedef struct
 	int32		vl_len_;		/* varlena header (do not touch directly!) */
 	int32		npts;
 	BOX			boundbox;
-	Point		p[1];			/* variable length array of POINTs */
+	Point		p[FLEXIBLE_ARRAY_MEMBER];
 } POLYGON;
 
 /*---------------------------------------------------------------------
diff --git a/src/include/utils/jsonb.h b/src/include/utils/jsonb.h
index 887eb9b..9d1770e 100644
--- a/src/include/utils/jsonb.h
+++ b/src/include/utils/jsonb.h
@@ -194,7 +194,7 @@ typedef struct JsonbContainer
 {
 	uint32		header;			/* number of elements or key/value pairs, and
 								 * flags */
-	JEntry		children[1];	/* variable length */
+	JEntry		children[FLEXIBLE_ARRAY_MEMBER];
 
 	/* the data for each child node follows. */
 } JsonbContainer;
diff --git a/src/include/utils/relmapper.h b/src/include/utils/relmapper.h
index 420310d..73b4905 100644
--- a/src/include/utils/relmapper.h
+++ b/src/include/utils/relmapper.h
@@ -29,7 +29,7 @@ typedef struct xl_relmap_update
 	Oid			dbid;			/* database ID, or 0 for shared map */
 	Oid			tsid;			/* database's tablespace, or pg_global */
 	int32		nbytes;			/* size of relmap data */
-	char		data[1];		/* VARIABLE LENGTH ARRAY */
+	char		data[FLEXIBLE_ARRAY_MEMBER];
 } xl_relmap_update;
 
 #define MinSizeOfRelmapUpdate offsetof(xl_relmap_update, data)
diff --git a/src/include/utils/varbit.h b/src/include/utils/varbit.h
index 8afc3b1..bd5bf52 100644
--- a/src/include/utils/varbit.h
+++ b/src/include/utils/varbit.h
@@ -26,7 +26,8 @@ typedef struct
 {
 	int32		vl_len_;		/* varlena header (do not touch directly!) */
 	int32		bit_len;		/* number of valid bits */
-	bits8		bit_dat[1];		/* bit string, most sig. byte first */
+	bits8		bit_dat[FLEXIBLE_ARRAY_MEMBER];	/* bit string, most sig.
+												 * byte first */
 } VarBit;
 
 /*
-- 
2.3.0

From 0a0b6b58224c8f1b361dbf202a2d8ab0e300a2e3 Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@otacoo.com>
Date: Thu, 19 Feb 2015 13:40:59 +0900
Subject: [PATCH 2/4] Add forgotten CATALOG_VARLEN pg_authid

The laste two fields of this catalog table, rolvaliduntil and rolpassword
can be null, but were not marked as such.
---
 src/include/catalog/pg_authid.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/include/catalog/pg_authid.h b/src/include/catalog/pg_authid.h
index e01e6aa..5b34288 100644
--- a/src/include/catalog/pg_authid.h
+++ b/src/include/catalog/pg_authid.h
@@ -55,9 +55,10 @@ CATALOG(pg_authid,1260) BKI_SHARED_RELATION BKI_ROWTYPE_OID(2842) BKI_SCHEMA_MAC
 	bool		rolbypassrls;	/* allowed to bypass row level security? */
 	int32		rolconnlimit;	/* max connections allowed (-1=no limit) */
 
-	/* remaining fields may be null; use heap_getattr to read them! */
+#ifdef CATALOG_VARLEN
 	text		rolpassword;	/* password, if any */
 	timestamptz rolvaliduntil;	/* password expiration time, if any */
+#endif
 } FormData_pg_authid;
 
 #undef timestamptz
-- 
2.3.0

From a62c4cc8ede6600f8ae636dfe9f56c6fd119c638 Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@otacoo.com>
Date: Thu, 19 Feb 2015 14:02:14 +0900
Subject: [PATCH 3/4] Switch varlena to use FLEXIBLE_ARRAY_MEMBER

As compilers normally complain about a flexible-array element not at the
end of a structure (clang does, while gcc sometimes does not), this has
needed some modifications in structures using bytea as such. This commit
ensures as well that those structures have enough room to work as intended
as well.
---
 src/backend/access/heap/tuptoaster.c       | 4 ++--
 src/backend/storage/large_object/inv_api.c | 8 ++++----
 src/include/c.h                            | 2 +-
 3 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/src/backend/access/heap/tuptoaster.c b/src/backend/access/heap/tuptoaster.c
index f8c1401..547f21f 100644
--- a/src/backend/access/heap/tuptoaster.c
+++ b/src/backend/access/heap/tuptoaster.c
@@ -1365,10 +1365,10 @@ toast_save_datum(Relation rel, Datum value,
 	CommandId	mycid = GetCurrentCommandId(true);
 	struct varlena *result;
 	struct varatt_external toast_pointer;
-	struct
+	union
 	{
 		struct varlena hdr;
-		char		data[TOAST_MAX_CHUNK_SIZE]; /* make struct big enough */
+		char		data[TOAST_MAX_CHUNK_SIZE + VARHDRSZ]; /* make struct big enough */
 		int32		align_it;	/* ensure struct is aligned well enough */
 	}			chunk_data;
 	int32		chunk_size;
diff --git a/src/backend/storage/large_object/inv_api.c b/src/backend/storage/large_object/inv_api.c
index a19c401..2e877bc 100644
--- a/src/backend/storage/large_object/inv_api.c
+++ b/src/backend/storage/large_object/inv_api.c
@@ -562,10 +562,10 @@ inv_write(LargeObjectDesc *obj_desc, const char *buf, int nbytes)
 	bool		neednextpage;
 	bytea	   *datafield;
 	bool		pfreeit;
-	struct
+	union
 	{
 		bytea		hdr;
-		char		data[LOBLKSIZE];	/* make struct big enough */
+		char		data[LOBLKSIZE + VARHDRSZ];	/* make struct big enough */
 		int32		align_it;	/* ensure struct is aligned well enough */
 	}			workbuf;
 	char	   *workb = VARDATA(&workbuf.hdr);
@@ -748,10 +748,10 @@ inv_truncate(LargeObjectDesc *obj_desc, int64 len)
 	SysScanDesc sd;
 	HeapTuple	oldtuple;
 	Form_pg_largeobject olddata;
-	struct
+	union
 	{
 		bytea		hdr;
-		char		data[LOBLKSIZE];	/* make struct big enough */
+		char		data[LOBLKSIZE + VARHDRSZ];	/* make struct big enough */
 		int32		align_it;	/* ensure struct is aligned well enough */
 	}			workbuf;
 	char	   *workb = VARDATA(&workbuf.hdr);
diff --git a/src/include/c.h b/src/include/c.h
index bbd0d53..36ec468 100644
--- a/src/include/c.h
+++ b/src/include/c.h
@@ -391,7 +391,7 @@ typedef struct
 struct varlena
 {
 	char		vl_len_[4];		/* Do not touch this field directly! */
-	char		vl_dat[1];
+	char		vl_dat[FLEXIBLE_ARRAY_MEMBER];
 };
 
 #define VARHDRSZ		((int32) sizeof(int32))
-- 
2.3.0

From cd2016bdd021785daf42ba83919c3175db6337ed Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@otacoo.com>
Date: Thu, 19 Feb 2015 14:29:57 +0900
Subject: [PATCH 4/4] Replace some struct declarations with union in heapam.c

To ensure that there is enough room for operations, add a size equivalent
to the tuple header data.
---
 src/backend/access/heap/heapam.c  | 12 ++++++------
 src/include/access/htup_details.h |  2 ++
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 46060bc1..c4b825d 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -7351,10 +7351,10 @@ heap_xlog_insert(XLogReaderState *record)
 	xl_heap_insert *xlrec = (xl_heap_insert *) XLogRecGetData(record);
 	Buffer		buffer;
 	Page		page;
-	struct
+	union
 	{
 		HeapTupleHeaderData hdr;
-		char		data[MaxHeapTupleSize];
+		char		data[SizeOfHeapTupleHeaderData + MaxHeapTupleSize];
 	}			tbuf;
 	HeapTupleHeader htup;
 	xl_heap_header xlhdr;
@@ -7469,10 +7469,10 @@ heap_xlog_multi_insert(XLogReaderState *record)
 	BlockNumber blkno;
 	Buffer		buffer;
 	Page		page;
-	struct
+	union
 	{
 		HeapTupleHeaderData hdr;
-		char		data[MaxHeapTupleSize];
+		char		data[SizeOfHeapTupleHeaderData + MaxHeapTupleSize];
 	}			tbuf;
 	HeapTupleHeader htup;
 	uint32		newlen;
@@ -7618,10 +7618,10 @@ heap_xlog_update(XLogReaderState *record, bool hot_update)
 	uint16		prefixlen = 0,
 				suffixlen = 0;
 	char	   *newp;
-	struct
+	union
 	{
 		HeapTupleHeaderData hdr;
-		char		data[MaxHeapTupleSize];
+		char		data[SizeOfHeapTupleHeaderData + MaxHeapTupleSize];
 	}			tbuf;
 	xl_heap_header xlhdr;
 	uint32		newlen;
diff --git a/src/include/access/htup_details.h b/src/include/access/htup_details.h
index d2ad910..2da4f42 100644
--- a/src/include/access/htup_details.h
+++ b/src/include/access/htup_details.h
@@ -155,6 +155,8 @@ struct HeapTupleHeaderData
 	/* MORE DATA FOLLOWS AT END OF STRUCT */
 };
 
+#define SizeOfHeapTupleHeaderData	MAXALIGN(sizeof(HeapTupleHeaderData))
+
 /* typedef appears in tupbasics.h */
 
 /*
-- 
2.3.0

From ca92019afc1db4da147ebb5c436164a787f7fa62 Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@otacoo.com>
Date: Mon, 16 Feb 2015 02:44:10 +0900
Subject: [PATCH 1/4] First cut with FLEXIBLE_ARRAY_MEMBER

This is targetted to prevent false positive errors that static code
analyzers may do by assuming that some structures have an unvarying
size.
---
 contrib/cube/cubedata.h                     |  7 +++----
 contrib/intarray/_int.h                     |  4 ++--
 contrib/ltree/ltree.h                       | 14 +++++++-------
 contrib/pg_trgm/trgm.h                      |  2 +-
 src/backend/catalog/namespace.c             |  4 ++--
 src/backend/commands/prepare.c              |  6 +++---
 src/backend/executor/functions.c            |  6 +++---
 src/backend/executor/spi.c                  |  5 ++---
 src/backend/nodes/params.c                  |  5 ++---
 src/backend/tcop/postgres.c                 |  5 ++---
 src/bin/pg_dump/dumputils.c                 |  3 +--
 src/bin/pg_dump/dumputils.h                 |  2 +-
 src/include/access/gin_private.h            |  2 +-
 src/include/access/gist_private.h           |  5 +++--
 src/include/access/heapam_xlog.h            |  2 +-
 src/include/access/spgist_private.h         | 10 +++++-----
 src/include/access/xact.h                   |  8 ++++----
 src/include/c.h                             |  4 ++--
 src/include/catalog/namespace.h             |  4 ++--
 src/include/commands/dbcommands.h           |  4 ++--
 src/include/commands/tablespace.h           |  2 +-
 src/include/executor/hashjoin.h             |  2 +-
 src/include/nodes/bitmapset.h               |  4 ++--
 src/include/nodes/params.h                  |  2 +-
 src/include/nodes/tidbitmap.h               |  2 +-
 src/include/postgres.h                      |  9 +++++----
 src/include/postmaster/syslogger.h          |  2 +-
 src/include/replication/walsender_private.h |  2 +-
 src/include/storage/bufpage.h               |  3 ++-
 src/include/storage/fsm_internals.h         |  2 +-
 src/include/storage/standby.h               |  4 ++--
 src/include/tsearch/dicts/regis.h           |  2 +-
 src/include/tsearch/dicts/spell.h           |  6 +++---
 src/include/tsearch/ts_type.h               |  6 +++---
 src/include/utils/catcache.h                |  4 ++--
 src/include/utils/datetime.h                |  5 +++--
 src/include/utils/geo_decls.h               |  5 +++--
 src/include/utils/jsonb.h                   |  2 +-
 src/include/utils/relmapper.h               |  2 +-
 src/include/utils/varbit.h                  |  3 ++-
 40 files changed, 86 insertions(+), 85 deletions(-)

diff --git a/contrib/cube/cubedata.h b/contrib/cube/cubedata.h
index 5d44e11..3535847 100644
--- a/contrib/cube/cubedata.h
+++ b/contrib/cube/cubedata.h
@@ -23,11 +23,10 @@ typedef struct NDBOX
 	unsigned int header;
 
 	/*
-	 * Variable length array. The lower left coordinates for each dimension
-	 * come first, followed by upper right coordinates unless the point flag
-	 * is set.
+	 * The lower left coordinates for each dimension come first, followed
+	 * by upper right coordinates unless the point flag is set.
 	 */
-	double		x[1];
+	double		x[FLEXIBLE_ARRAY_MEMBER];
 } NDBOX;
 
 #define POINT_BIT			0x80000000
diff --git a/contrib/intarray/_int.h b/contrib/intarray/_int.h
index 7f93206..d524f0f 100644
--- a/contrib/intarray/_int.h
+++ b/contrib/intarray/_int.h
@@ -73,7 +73,7 @@ typedef struct
 {
 	int32		vl_len_;		/* varlena header (do not touch directly!) */
 	int32		flag;
-	char		data[1];
+	char		data[FLEXIBLE_ARRAY_MEMBER];
 } GISTTYPE;
 
 #define ALLISTRUE		0x04
@@ -133,7 +133,7 @@ typedef struct QUERYTYPE
 {
 	int32		vl_len_;		/* varlena header (do not touch directly!) */
 	int32		size;			/* number of ITEMs */
-	ITEM		items[1];		/* variable length array */
+	ITEM		items[FLEXIBLE_ARRAY_MEMBER];
 } QUERYTYPE;
 
 #define HDRSIZEQT	offsetof(QUERYTYPE, items)
diff --git a/contrib/ltree/ltree.h b/contrib/ltree/ltree.h
index 1b1305b..c604357 100644
--- a/contrib/ltree/ltree.h
+++ b/contrib/ltree/ltree.h
@@ -10,7 +10,7 @@
 typedef struct
 {
 	uint16		len;
-	char		name[1];
+	char		name[FLEXIBLE_ARRAY_MEMBER];
 } ltree_level;
 
 #define LEVEL_HDRSIZE	(offsetof(ltree_level,name))
@@ -20,7 +20,7 @@ typedef struct
 {
 	int32		vl_len_;		/* varlena header (do not touch directly!) */
 	uint16		numlevel;
-	char		data[1];
+	char		data[FLEXIBLE_ARRAY_MEMBER];
 } ltree;
 
 #define LTREE_HDRSIZE	MAXALIGN( offsetof(ltree, data) )
@@ -34,7 +34,7 @@ typedef struct
 	int32		val;
 	uint16		len;
 	uint8		flag;
-	char		name[1];
+	char		name[FLEXIBLE_ARRAY_MEMBER];
 } lquery_variant;
 
 #define LVAR_HDRSIZE   MAXALIGN(offsetof(lquery_variant, name))
@@ -51,7 +51,7 @@ typedef struct
 	uint16		numvar;
 	uint16		low;
 	uint16		high;
-	char		variants[1];
+	char		variants[FLEXIBLE_ARRAY_MEMBER];
 } lquery_level;
 
 #define LQL_HDRSIZE MAXALIGN( offsetof(lquery_level,variants) )
@@ -72,7 +72,7 @@ typedef struct
 	uint16		numlevel;
 	uint16		firstgood;
 	uint16		flag;
-	char		data[1];
+	char		data[FLEXIBLE_ARRAY_MEMBER];
 } lquery;
 
 #define LQUERY_HDRSIZE	 MAXALIGN( offsetof(lquery, data) )
@@ -107,7 +107,7 @@ typedef struct
 {
 	int32		vl_len_;		/* varlena header (do not touch directly!) */
 	int32		size;
-	char		data[1];
+	char		data[FLEXIBLE_ARRAY_MEMBER];
 } ltxtquery;
 
 #define HDRSIZEQT		MAXALIGN(VARHDRSZ + sizeof(int32))
@@ -208,7 +208,7 @@ typedef struct
 {
 	int32		vl_len_;		/* varlena header (do not touch directly!) */
 	uint32		flag;
-	char		data[1];
+	char		data[FLEXIBLE_ARRAY_MEMBER];
 } ltree_gist;
 
 #define LTG_ONENODE 0x01
diff --git a/contrib/pg_trgm/trgm.h b/contrib/pg_trgm/trgm.h
index ed649b8..f030558 100644
--- a/contrib/pg_trgm/trgm.h
+++ b/contrib/pg_trgm/trgm.h
@@ -63,7 +63,7 @@ typedef struct
 {
 	int32		vl_len_;		/* varlena header (do not touch directly!) */
 	uint8		flag;
-	char		data[1];
+	char		data[FLEXIBLE_ARRAY_MEMBER];
 } TRGM;
 
 #define TRGMHDRSIZE		  (VARHDRSZ + sizeof(uint8))
diff --git a/src/backend/catalog/namespace.c b/src/backend/catalog/namespace.c
index bfb4fdc..d47b523 100644
--- a/src/backend/catalog/namespace.c
+++ b/src/backend/catalog/namespace.c
@@ -1075,8 +1075,8 @@ FuncnameGetCandidates(List *names, int nargs, List *argnames,
 		 */
 		effective_nargs = Max(pronargs, nargs);
 		newResult = (FuncCandidateList)
-			palloc(sizeof(struct _FuncCandidateList) - sizeof(Oid)
-				   + effective_nargs * sizeof(Oid));
+			palloc(offsetof(struct _FuncCandidateList, args) +
+				   effective_nargs * sizeof(Oid));
 		newResult->pathpos = pathpos;
 		newResult->oid = HeapTupleGetOid(proctup);
 		newResult->nargs = effective_nargs;
diff --git a/src/backend/commands/prepare.c b/src/backend/commands/prepare.c
index 71b08f0..36e21c1 100644
--- a/src/backend/commands/prepare.c
+++ b/src/backend/commands/prepare.c
@@ -383,10 +383,10 @@ EvaluateParams(PreparedStatement *pstmt, List *params,
 	/* Prepare the expressions for execution */
 	exprstates = (List *) ExecPrepareExpr((Expr *) params, estate);
 
-	/* sizeof(ParamListInfoData) includes the first array element */
 	paramLI = (ParamListInfo)
-		palloc(sizeof(ParamListInfoData) +
-			   (num_params - 1) * sizeof(ParamExternData));
+		palloc(offsetof(ParamListInfoData, params) +
+			   num_params * sizeof(ParamExternData));
+
 	/* we have static list of params, so no hooks needed */
 	paramLI->paramFetch = NULL;
 	paramLI->paramFetchArg = NULL;
diff --git a/src/backend/executor/functions.c b/src/backend/executor/functions.c
index 84be37c..6c3eff7 100644
--- a/src/backend/executor/functions.c
+++ b/src/backend/executor/functions.c
@@ -896,9 +896,9 @@ postquel_sub_params(SQLFunctionCachePtr fcache,
 
 		if (fcache->paramLI == NULL)
 		{
-			/* sizeof(ParamListInfoData) includes the first array element */
-			paramLI = (ParamListInfo) palloc(sizeof(ParamListInfoData) +
-									  (nargs - 1) * sizeof(ParamExternData));
+			paramLI = (ParamListInfo)
+				palloc(offsetof(ParamListInfoData, params) +
+					   nargs * sizeof(ParamExternData));
 			/* we have static list of params, so no hooks needed */
 			paramLI->paramFetch = NULL;
 			paramLI->paramFetchArg = NULL;
diff --git a/src/backend/executor/spi.c b/src/backend/executor/spi.c
index 4b86e91..d101fcd 100644
--- a/src/backend/executor/spi.c
+++ b/src/backend/executor/spi.c
@@ -2290,9 +2290,8 @@ _SPI_convert_params(int nargs, Oid *argtypes,
 	{
 		int			i;
 
-		/* sizeof(ParamListInfoData) includes the first array element */
-		paramLI = (ParamListInfo) palloc(sizeof(ParamListInfoData) +
-									  (nargs - 1) * sizeof(ParamExternData));
+		paramLI = (ParamListInfo) palloc(offsetof(ParamListInfoData, params) +
+									  nargs * sizeof(ParamExternData));
 		/* we have static list of params, so no hooks needed */
 		paramLI->paramFetch = NULL;
 		paramLI->paramFetchArg = NULL;
diff --git a/src/backend/nodes/params.c b/src/backend/nodes/params.c
index 2f2f5ed..fb803f8 100644
--- a/src/backend/nodes/params.c
+++ b/src/backend/nodes/params.c
@@ -40,9 +40,8 @@ copyParamList(ParamListInfo from)
 	if (from == NULL || from->numParams <= 0)
 		return NULL;
 
-	/* sizeof(ParamListInfoData) includes the first array element */
-	size = sizeof(ParamListInfoData) +
-		(from->numParams - 1) * sizeof(ParamExternData);
+	size = offsetof(ParamListInfoData, params) +
+		from->numParams * sizeof(ParamExternData);
 
 	retval = (ParamListInfo) palloc(size);
 	retval->paramFetch = NULL;
diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index 28af40c..33720e8 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -1619,9 +1619,8 @@ exec_bind_message(StringInfo input_message)
 	{
 		int			paramno;
 
-		/* sizeof(ParamListInfoData) includes the first array element */
-		params = (ParamListInfo) palloc(sizeof(ParamListInfoData) +
-								  (numParams - 1) * sizeof(ParamExternData));
+		params = (ParamListInfo) palloc(offsetof(ParamListInfoData, params) +
+										numParams * sizeof(ParamExternData));
 		/* we have static list of params, so no hooks needed */
 		params->paramFetch = NULL;
 		params->paramFetchArg = NULL;
diff --git a/src/bin/pg_dump/dumputils.c b/src/bin/pg_dump/dumputils.c
index 095c507..892d3fa 100644
--- a/src/bin/pg_dump/dumputils.c
+++ b/src/bin/pg_dump/dumputils.c
@@ -1217,8 +1217,7 @@ simple_string_list_append(SimpleStringList *list, const char *val)
 	SimpleStringListCell *cell;
 
 	/* this calculation correctly accounts for the null trailing byte */
-	cell = (SimpleStringListCell *)
-		pg_malloc(sizeof(SimpleStringListCell) + strlen(val));
+	cell = (SimpleStringListCell *) pg_malloc(sizeof(SimpleStringListCell));
 
 	cell->next = NULL;
 	strcpy(cell->val, val);
diff --git a/src/bin/pg_dump/dumputils.h b/src/bin/pg_dump/dumputils.h
index a39c1b6..94476a9 100644
--- a/src/bin/pg_dump/dumputils.h
+++ b/src/bin/pg_dump/dumputils.h
@@ -38,7 +38,7 @@ typedef struct SimpleOidList
 typedef struct SimpleStringListCell
 {
 	struct SimpleStringListCell *next;
-	char		val[1];			/* VARIABLE LENGTH FIELD */
+	char		val[FLEXIBLE_ARRAY_MEMBER];
 } SimpleStringListCell;
 
 typedef struct SimpleStringList
diff --git a/src/include/access/gin_private.h b/src/include/access/gin_private.h
index bda7c28..d3abbc0 100644
--- a/src/include/access/gin_private.h
+++ b/src/include/access/gin_private.h
@@ -389,7 +389,7 @@ typedef struct
 {
 	ItemPointerData first;		/* first item in this posting list (unpacked) */
 	uint16		nbytes;			/* number of bytes that follow */
-	unsigned char bytes[1];		/* varbyte encoded items (variable length) */
+	unsigned char bytes[FLEXIBLE_ARRAY_MEMBER];	/* varbyte encoded items */
 } GinPostingList;
 
 #define SizeOfGinPostingList(plist) (offsetof(GinPostingList, bytes) + SHORTALIGN((plist)->nbytes) )
diff --git a/src/include/access/gist_private.h b/src/include/access/gist_private.h
index 382826e..36f5257 100644
--- a/src/include/access/gist_private.h
+++ b/src/include/access/gist_private.h
@@ -47,7 +47,7 @@ typedef struct
 {
 	BlockNumber prev;
 	uint32		freespace;
-	char		tupledata[1];
+	char		tupledata[FLEXIBLE_ARRAY_MEMBER];
 } GISTNodeBufferPage;
 
 #define BUFFER_PAGE_DATA_OFFSET MAXALIGN(offsetof(GISTNodeBufferPage, tupledata))
@@ -131,7 +131,8 @@ typedef struct GISTSearchItem
 		/* we must store parentlsn to detect whether a split occurred */
 		GISTSearchHeapItem heap;	/* heap info, if heap tuple */
 	}			data;
-	double		distances[1];	/* array with numberOfOrderBys entries */
+	double distances[FLEXIBLE_ARRAY_MEMBER]; /* array with numberOfOrderBys
+											  * entries */
 } GISTSearchItem;
 
 #define GISTSearchItemIsHeap(item)	((item).blkno == InvalidBlockNumber)
diff --git a/src/include/access/heapam_xlog.h b/src/include/access/heapam_xlog.h
index a2ed2a0..f0f89de 100644
--- a/src/include/access/heapam_xlog.h
+++ b/src/include/access/heapam_xlog.h
@@ -132,7 +132,7 @@ typedef struct xl_heap_multi_insert
 {
 	uint8		flags;
 	uint16		ntuples;
-	OffsetNumber offsets[1];
+	OffsetNumber offsets[FLEXIBLE_ARRAY_MEMBER];
 } xl_heap_multi_insert;
 
 #define SizeOfHeapMultiInsert	offsetof(xl_heap_multi_insert, offsets)
diff --git a/src/include/access/spgist_private.h b/src/include/access/spgist_private.h
index f11d8ef..0492ef6 100644
--- a/src/include/access/spgist_private.h
+++ b/src/include/access/spgist_private.h
@@ -426,7 +426,7 @@ typedef struct spgxlogMoveLeafs
 	 * the dead tuple from the source
 	 *----------
 	 */
-	OffsetNumber offsets[1];
+	OffsetNumber offsets[FLEXIBLE_ARRAY_MEMBER];
 } spgxlogMoveLeafs;
 
 #define SizeOfSpgxlogMoveLeafs	offsetof(spgxlogMoveLeafs, offsets)
@@ -534,7 +534,7 @@ typedef struct spgxlogPickSplit
 	 *		list of leaf tuples, length nInsert (unaligned!)
 	 *----------
 	 */
-	OffsetNumber offsets[1];
+	OffsetNumber offsets[FLEXIBLE_ARRAY_MEMBER];
 } spgxlogPickSplit;
 
 #define SizeOfSpgxlogPickSplit offsetof(spgxlogPickSplit, offsets)
@@ -558,7 +558,7 @@ typedef struct spgxlogVacuumLeaf
 	 *		tuple numbers to insert in nextOffset links
 	 *----------
 	 */
-	OffsetNumber offsets[1];
+	OffsetNumber offsets[FLEXIBLE_ARRAY_MEMBER];
 } spgxlogVacuumLeaf;
 
 #define SizeOfSpgxlogVacuumLeaf offsetof(spgxlogVacuumLeaf, offsets)
@@ -571,7 +571,7 @@ typedef struct spgxlogVacuumRoot
 	spgxlogState stateSrc;
 
 	/* offsets of tuples to delete follow */
-	OffsetNumber offsets[1];
+	OffsetNumber offsets[FLEXIBLE_ARRAY_MEMBER];
 } spgxlogVacuumRoot;
 
 #define SizeOfSpgxlogVacuumRoot offsetof(spgxlogVacuumRoot, offsets)
@@ -583,7 +583,7 @@ typedef struct spgxlogVacuumRedirect
 	TransactionId newestRedirectXid;	/* newest XID of removed redirects */
 
 	/* offsets of redirect tuples to make placeholders follow */
-	OffsetNumber offsets[1];
+	OffsetNumber offsets[FLEXIBLE_ARRAY_MEMBER];
 } spgxlogVacuumRedirect;
 
 #define SizeOfSpgxlogVacuumRedirect offsetof(spgxlogVacuumRedirect, offsets)
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 8205504..9b95f10 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -118,7 +118,7 @@ typedef struct xl_xact_assignment
 {
 	TransactionId xtop;			/* assigned XID's top-level XID */
 	int			nsubxacts;		/* number of subtransaction XIDs */
-	TransactionId xsub[1];		/* assigned subxids */
+	TransactionId xsub[FLEXIBLE_ARRAY_MEMBER];		/* assigned subxids */
 } xl_xact_assignment;
 
 #define MinSizeOfXactAssignment offsetof(xl_xact_assignment, xsub)
@@ -128,7 +128,7 @@ typedef struct xl_xact_commit_compact
 	TimestampTz xact_time;		/* time of commit */
 	int			nsubxacts;		/* number of subtransaction XIDs */
 	/* ARRAY OF COMMITTED SUBTRANSACTION XIDs FOLLOWS */
-	TransactionId subxacts[1];	/* VARIABLE LENGTH ARRAY */
+	TransactionId subxacts[FLEXIBLE_ARRAY_MEMBER];
 } xl_xact_commit_compact;
 
 #define MinSizeOfXactCommitCompact offsetof(xl_xact_commit_compact, subxacts)
@@ -143,7 +143,7 @@ typedef struct xl_xact_commit
 	Oid			dbId;			/* MyDatabaseId */
 	Oid			tsId;			/* MyDatabaseTableSpace */
 	/* Array of RelFileNode(s) to drop at commit */
-	RelFileNode xnodes[1];		/* VARIABLE LENGTH ARRAY */
+	RelFileNode xnodes[FLEXIBLE_ARRAY_MEMBER];
 	/* ARRAY OF COMMITTED SUBTRANSACTION XIDs FOLLOWS */
 	/* ARRAY OF SHARED INVALIDATION MESSAGES FOLLOWS */
 } xl_xact_commit;
@@ -171,7 +171,7 @@ typedef struct xl_xact_abort
 	int			nrels;			/* number of RelFileNodes */
 	int			nsubxacts;		/* number of subtransaction XIDs */
 	/* Array of RelFileNode(s) to drop at abort */
-	RelFileNode xnodes[1];		/* VARIABLE LENGTH ARRAY */
+	RelFileNode xnodes[FLEXIBLE_ARRAY_MEMBER];
 	/* ARRAY OF ABORTED SUBTRANSACTION XIDs FOLLOWS */
 } xl_xact_abort;
 
diff --git a/src/include/c.h b/src/include/c.h
index b187520..bbd0d53 100644
--- a/src/include/c.h
+++ b/src/include/c.h
@@ -424,7 +424,7 @@ typedef struct
 	Oid			elemtype;
 	int			dim1;
 	int			lbound1;
-	int16		values[1];		/* VARIABLE LENGTH ARRAY */
+	int16		values[FLEXIBLE_ARRAY_MEMBER];
 } int2vector;					/* VARIABLE LENGTH STRUCT */
 
 typedef struct
@@ -435,7 +435,7 @@ typedef struct
 	Oid			elemtype;
 	int			dim1;
 	int			lbound1;
-	Oid			values[1];		/* VARIABLE LENGTH ARRAY */
+	Oid			values[FLEXIBLE_ARRAY_MEMBER];
 } oidvector;					/* VARIABLE LENGTH STRUCT */
 
 /*
diff --git a/src/include/catalog/namespace.h b/src/include/catalog/namespace.h
index d2e5198..cf5f7d0 100644
--- a/src/include/catalog/namespace.h
+++ b/src/include/catalog/namespace.h
@@ -34,8 +34,8 @@ typedef struct _FuncCandidateList
 	int			nvargs;			/* number of args to become variadic array */
 	int			ndargs;			/* number of defaulted args */
 	int		   *argnumbers;		/* args' positional indexes, if named call */
-	Oid			args[1];		/* arg types --- VARIABLE LENGTH ARRAY */
-}	*FuncCandidateList;	/* VARIABLE LENGTH STRUCT */
+	Oid			args[FLEXIBLE_ARRAY_MEMBER];	/* arg types */
+}	*FuncCandidateList;
 
 /*
  *	Structure for xxxOverrideSearchPath functions
diff --git a/src/include/commands/dbcommands.h b/src/include/commands/dbcommands.h
index cb7cc0e..be1cac2 100644
--- a/src/include/commands/dbcommands.h
+++ b/src/include/commands/dbcommands.h
@@ -26,7 +26,7 @@ typedef struct xl_dbase_create_rec_old
 {
 	/* Records copying of a single subdirectory incl. contents */
 	Oid			db_id;
-	char		src_path[1];	/* VARIABLE LENGTH STRING */
+	char		src_path[FLEXIBLE_ARRAY_MEMBER];
 	/* dst_path follows src_path */
 }	xl_dbase_create_rec_old;
 
@@ -34,7 +34,7 @@ typedef struct xl_dbase_drop_rec_old
 {
 	/* Records dropping of a single subdirectory incl. contents */
 	Oid			db_id;
-	char		dir_path[1];	/* VARIABLE LENGTH STRING */
+	char		dir_path[FLEXIBLE_ARRAY_MEMBER];
 }	xl_dbase_drop_rec_old;
 
 typedef struct xl_dbase_create_rec
diff --git a/src/include/commands/tablespace.h b/src/include/commands/tablespace.h
index e8b9bc4..9e40e31 100644
--- a/src/include/commands/tablespace.h
+++ b/src/include/commands/tablespace.h
@@ -25,7 +25,7 @@
 typedef struct xl_tblspc_create_rec
 {
 	Oid			ts_id;
-	char		ts_path[1];		/* VARIABLE LENGTH STRING */
+	char		ts_path[FLEXIBLE_ARRAY_MEMBER];
 } xl_tblspc_create_rec;
 
 typedef struct xl_tblspc_drop_rec
diff --git a/src/include/executor/hashjoin.h b/src/include/executor/hashjoin.h
index e79df71..71099b1 100644
--- a/src/include/executor/hashjoin.h
+++ b/src/include/executor/hashjoin.h
@@ -114,7 +114,7 @@ typedef struct HashMemoryChunkData
 
 	struct HashMemoryChunkData *next; /* pointer to the next chunk (linked list) */
 
-	char		data[1];	/* buffer allocated at the end */
+	char		data[FLEXIBLE_ARRAY_MEMBER];	/* buffer allocated at the end */
 } HashMemoryChunkData;
 
 typedef struct HashMemoryChunkData *HashMemoryChunk;
diff --git a/src/include/nodes/bitmapset.h b/src/include/nodes/bitmapset.h
index 5f45f4d..3a556ee 100644
--- a/src/include/nodes/bitmapset.h
+++ b/src/include/nodes/bitmapset.h
@@ -32,8 +32,8 @@ typedef int32 signedbitmapword; /* must be the matching signed type */
 typedef struct Bitmapset
 {
 	int			nwords;			/* number of words in array */
-	bitmapword	words[1];		/* really [nwords] */
-} Bitmapset;					/* VARIABLE LENGTH STRUCT */
+	bitmapword	words[FLEXIBLE_ARRAY_MEMBER];	/* really [nwords] */
+} Bitmapset;
 
 
 /* result of bms_subset_compare */
diff --git a/src/include/nodes/params.h b/src/include/nodes/params.h
index 5b096c5..a0f7dd0 100644
--- a/src/include/nodes/params.h
+++ b/src/include/nodes/params.h
@@ -71,7 +71,7 @@ typedef struct ParamListInfoData
 	ParserSetupHook parserSetup;	/* parser setup hook */
 	void	   *parserSetupArg;
 	int			numParams;		/* number of ParamExternDatas following */
-	ParamExternData params[1];	/* VARIABLE LENGTH ARRAY */
+	ParamExternData params[FLEXIBLE_ARRAY_MEMBER];
 }	ParamListInfoData;
 
 
diff --git a/src/include/nodes/tidbitmap.h b/src/include/nodes/tidbitmap.h
index fb62c9e..bfbc0fb 100644
--- a/src/include/nodes/tidbitmap.h
+++ b/src/include/nodes/tidbitmap.h
@@ -41,7 +41,7 @@ typedef struct
 	int			ntuples;		/* -1 indicates lossy result */
 	bool		recheck;		/* should the tuples be rechecked? */
 	/* Note: recheck is always true if ntuples < 0 */
-	OffsetNumber offsets[1];	/* VARIABLE LENGTH ARRAY */
+	OffsetNumber offsets[FLEXIBLE_ARRAY_MEMBER];
 } TBMIterateResult;				/* VARIABLE LENGTH STRUCT */
 
 /* function prototypes in nodes/tidbitmap.c */
diff --git a/src/include/postgres.h b/src/include/postgres.h
index 082c75b..482e676 100644
--- a/src/include/postgres.h
+++ b/src/include/postgres.h
@@ -117,20 +117,20 @@ typedef union
 	struct						/* Normal varlena (4-byte length) */
 	{
 		uint32		va_header;
-		char		va_data[1];
+		char		va_data[FLEXIBLE_ARRAY_MEMBER];
 	}			va_4byte;
 	struct						/* Compressed-in-line format */
 	{
 		uint32		va_header;
 		uint32		va_rawsize; /* Original data size (excludes header) */
-		char		va_data[1]; /* Compressed data */
+		char		va_data[FLEXIBLE_ARRAY_MEMBER]; /* Compressed data */
 	}			va_compressed;
 } varattrib_4b;
 
 typedef struct
 {
 	uint8		va_header;
-	char		va_data[1];		/* Data begins here */
+	char		va_data[FLEXIBLE_ARRAY_MEMBER];	/* Data begins here */
 } varattrib_1b;
 
 /* TOAST pointers are a subset of varattrib_1b with an identifying tag byte */
@@ -138,7 +138,8 @@ typedef struct
 {
 	uint8		va_header;		/* Always 0x80 or 0x01 */
 	uint8		va_tag;			/* Type of datum */
-	char		va_data[1];		/* Data (of the type indicated by va_tag) */
+	char		va_data[FLEXIBLE_ARRAY_MEMBER];	/* Data (of the type
+												 * indicated by va_tag) */
 } varattrib_1b_e;
 
 /*
diff --git a/src/include/postmaster/syslogger.h b/src/include/postmaster/syslogger.h
index 602b13c..89a535c 100644
--- a/src/include/postmaster/syslogger.h
+++ b/src/include/postmaster/syslogger.h
@@ -48,7 +48,7 @@ typedef struct
 	int32		pid;			/* writer's pid */
 	char		is_last;		/* last chunk of message? 't' or 'f' ('T' or
 								 * 'F' for CSV case) */
-	char		data[1];		/* data payload starts here */
+	char		data[FLEXIBLE_ARRAY_MEMBER];	/* data payload starts here */
 } PipeProtoHeader;
 
 typedef union
diff --git a/src/include/replication/walsender_private.h b/src/include/replication/walsender_private.h
index 8867750..02faad8 100644
--- a/src/include/replication/walsender_private.h
+++ b/src/include/replication/walsender_private.h
@@ -88,7 +88,7 @@ typedef struct
 	 */
 	bool		sync_standbys_defined;
 
-	WalSnd		walsnds[1];		/* VARIABLE LENGTH ARRAY */
+	WalSnd		walsnds[FLEXIBLE_ARRAY_MEMBER];
 } WalSndCtlData;
 
 extern WalSndCtlData *WalSndCtl;
diff --git a/src/include/storage/bufpage.h b/src/include/storage/bufpage.h
index f693032..b7dbd6f 100644
--- a/src/include/storage/bufpage.h
+++ b/src/include/storage/bufpage.h
@@ -156,7 +156,8 @@ typedef struct PageHeaderData
 	LocationIndex pd_special;	/* offset to start of special space */
 	uint16		pd_pagesize_version;
 	TransactionId pd_prune_xid; /* oldest prunable XID, or zero if none */
-	ItemIdData	pd_linp[1];		/* beginning of line pointer array */
+	ItemIdData	pd_linp[FLEXIBLE_ARRAY_MEMBER];	/* beginning of line pointer
+												 * array */
 } PageHeaderData;
 
 typedef PageHeaderData *PageHeader;
diff --git a/src/include/storage/fsm_internals.h b/src/include/storage/fsm_internals.h
index 1decd90..26340b4 100644
--- a/src/include/storage/fsm_internals.h
+++ b/src/include/storage/fsm_internals.h
@@ -39,7 +39,7 @@ typedef struct
 	 * NonLeafNodesPerPage elements are upper nodes, and the following
 	 * LeafNodesPerPage elements are leaf nodes. Unused nodes are zero.
 	 */
-	uint8		fp_nodes[1];
+	uint8		fp_nodes[FLEXIBLE_ARRAY_MEMBER];
 } FSMPageData;
 
 typedef FSMPageData *FSMPage;
diff --git a/src/include/storage/standby.h b/src/include/storage/standby.h
index c32c963..7626c4c 100644
--- a/src/include/storage/standby.h
+++ b/src/include/storage/standby.h
@@ -60,7 +60,7 @@ extern void StandbyReleaseOldLocks(int nxids, TransactionId *xids);
 typedef struct xl_standby_locks
 {
 	int			nlocks;			/* number of entries in locks array */
-	xl_standby_lock locks[1];	/* VARIABLE LENGTH ARRAY */
+	xl_standby_lock locks[FLEXIBLE_ARRAY_MEMBER];
 } xl_standby_locks;
 
 /*
@@ -75,7 +75,7 @@ typedef struct xl_running_xacts
 	TransactionId oldestRunningXid;		/* *not* oldestXmin */
 	TransactionId latestCompletedXid;	/* so we can set xmax */
 
-	TransactionId xids[1];		/* VARIABLE LENGTH ARRAY */
+	TransactionId xids[FLEXIBLE_ARRAY_MEMBER];
 } xl_running_xacts;
 
 #define MinSizeOfXactRunningXacts offsetof(xl_running_xacts, xids)
diff --git a/src/include/tsearch/dicts/regis.h b/src/include/tsearch/dicts/regis.h
index 081a502..ddf5b60 100644
--- a/src/include/tsearch/dicts/regis.h
+++ b/src/include/tsearch/dicts/regis.h
@@ -21,7 +21,7 @@ typedef struct RegisNode
 				len:16,
 				unused:14;
 	struct RegisNode *next;
-	unsigned char data[1];
+	unsigned char data[FLEXIBLE_ARRAY_MEMBER];
 } RegisNode;
 
 #define  RNHDRSZ	(offsetof(RegisNode,data))
diff --git a/src/include/tsearch/dicts/spell.h b/src/include/tsearch/dicts/spell.h
index a75552b..e512532 100644
--- a/src/include/tsearch/dicts/spell.h
+++ b/src/include/tsearch/dicts/spell.h
@@ -49,7 +49,7 @@ typedef struct
 typedef struct SPNode
 {
 	uint32		length;
-	SPNodeData	data[1];
+	SPNodeData	data[FLEXIBLE_ARRAY_MEMBER];
 } SPNode;
 
 #define SPNHDRSZ	(offsetof(SPNode,data))
@@ -70,7 +70,7 @@ typedef struct spell_struct
 			int			len;
 		}			d;
 	}			p;
-	char		word[1];		/* variable length, null-terminated */
+	char		word[FLEXIBLE_ARRAY_MEMBER];
 } SPELL;
 
 #define SPELLHDRSZ	(offsetof(SPELL, word))
@@ -120,7 +120,7 @@ typedef struct AffixNode
 {
 	uint32		isvoid:1,
 				length:31;
-	AffixNodeData data[1];
+	AffixNodeData data[FLEXIBLE_ARRAY_MEMBER];
 } AffixNode;
 
 #define ANHRDSZ		   (offsetof(AffixNode, data))
diff --git a/src/include/tsearch/ts_type.h b/src/include/tsearch/ts_type.h
index 1cdfa82..ce919a2 100644
--- a/src/include/tsearch/ts_type.h
+++ b/src/include/tsearch/ts_type.h
@@ -63,7 +63,7 @@ typedef uint16 WordEntryPos;
 typedef struct
 {
 	uint16		npos;
-	WordEntryPos pos[1];		/* variable length */
+	WordEntryPos pos[FLEXIBLE_ARRAY_MEMBER];
 } WordEntryPosVector;
 
 
@@ -82,7 +82,7 @@ typedef struct
 {
 	int32		vl_len_;		/* varlena header (do not touch directly!) */
 	int32		size;
-	WordEntry	entries[1];		/* variable length */
+	WordEntry	entries[FLEXIBLE_ARRAY_MEMBER];
 	/* lexemes follow the entries[] array */
 } TSVectorData;
 
@@ -233,7 +233,7 @@ typedef struct
 {
 	int32		vl_len_;		/* varlena header (do not touch directly!) */
 	int32		size;			/* number of QueryItems */
-	char		data[1];		/* data starts here */
+	char		data[FLEXIBLE_ARRAY_MEMBER];	/* data starts here */
 } TSQueryData;
 
 typedef TSQueryData *TSQuery;
diff --git a/src/include/utils/catcache.h b/src/include/utils/catcache.h
index 8084785..da261e8 100644
--- a/src/include/utils/catcache.h
+++ b/src/include/utils/catcache.h
@@ -147,8 +147,8 @@ typedef struct catclist
 	uint32		hash_value;		/* hash value for lookup keys */
 	HeapTupleData tuple;		/* header for tuple holding keys */
 	int			n_members;		/* number of member tuples */
-	CatCTup    *members[1];		/* members --- VARIABLE LENGTH ARRAY */
-} CatCList;						/* VARIABLE LENGTH STRUCT */
+	CatCTup    *members[FLEXIBLE_ARRAY_MEMBER];	/* members */
+} CatCList;
 
 
 typedef struct catcacheheader
diff --git a/src/include/utils/datetime.h b/src/include/utils/datetime.h
index 8912ba5..d36f297 100644
--- a/src/include/utils/datetime.h
+++ b/src/include/utils/datetime.h
@@ -219,7 +219,7 @@ typedef struct TimeZoneAbbrevTable
 {
 	Size		tblsize;		/* size in bytes of TimeZoneAbbrevTable */
 	int			numabbrevs;		/* number of entries in abbrevs[] array */
-	datetkn		abbrevs[1];		/* VARIABLE LENGTH ARRAY */
+	datetkn		abbrevs[FLEXIBLE_ARRAY_MEMBER];
 	/* DynamicZoneAbbrev(s) may follow the abbrevs[] array */
 } TimeZoneAbbrevTable;
 
@@ -227,7 +227,8 @@ typedef struct TimeZoneAbbrevTable
 typedef struct DynamicZoneAbbrev
 {
 	pg_tz	   *tz;				/* NULL if not yet looked up */
-	char		zone[1];		/* zone name (var length, NUL-terminated) */
+	char		zone[FLEXIBLE_ARRAY_MEMBER];	/* zone name (var length,
+												 * NUL-terminated) */
 } DynamicZoneAbbrev;
 
 
diff --git a/src/include/utils/geo_decls.h b/src/include/utils/geo_decls.h
index 0b6d3c3..a0f779b 100644
--- a/src/include/utils/geo_decls.h
+++ b/src/include/utils/geo_decls.h
@@ -80,7 +80,8 @@ typedef struct
 	int32		npts;
 	int32		closed;			/* is this a closed polygon? */
 	int32		dummy;			/* padding to make it double align */
-	Point		p[1];			/* variable length array of POINTs */
+	Point		p[FLEXIBLE_ARRAY_MEMBER];	/* variable length array
+											 * of POINTs */
 } PATH;
 
 
@@ -115,7 +116,7 @@ typedef struct
 	int32		vl_len_;		/* varlena header (do not touch directly!) */
 	int32		npts;
 	BOX			boundbox;
-	Point		p[1];			/* variable length array of POINTs */
+	Point		p[FLEXIBLE_ARRAY_MEMBER];
 } POLYGON;
 
 /*---------------------------------------------------------------------
diff --git a/src/include/utils/jsonb.h b/src/include/utils/jsonb.h
index 887eb9b..9d1770e 100644
--- a/src/include/utils/jsonb.h
+++ b/src/include/utils/jsonb.h
@@ -194,7 +194,7 @@ typedef struct JsonbContainer
 {
 	uint32		header;			/* number of elements or key/value pairs, and
 								 * flags */
-	JEntry		children[1];	/* variable length */
+	JEntry		children[FLEXIBLE_ARRAY_MEMBER];
 
 	/* the data for each child node follows. */
 } JsonbContainer;
diff --git a/src/include/utils/relmapper.h b/src/include/utils/relmapper.h
index 420310d..73b4905 100644
--- a/src/include/utils/relmapper.h
+++ b/src/include/utils/relmapper.h
@@ -29,7 +29,7 @@ typedef struct xl_relmap_update
 	Oid			dbid;			/* database ID, or 0 for shared map */
 	Oid			tsid;			/* database's tablespace, or pg_global */
 	int32		nbytes;			/* size of relmap data */
-	char		data[1];		/* VARIABLE LENGTH ARRAY */
+	char		data[FLEXIBLE_ARRAY_MEMBER];
 } xl_relmap_update;
 
 #define MinSizeOfRelmapUpdate offsetof(xl_relmap_update, data)
diff --git a/src/include/utils/varbit.h b/src/include/utils/varbit.h
index 8afc3b1..bd5bf52 100644
--- a/src/include/utils/varbit.h
+++ b/src/include/utils/varbit.h
@@ -26,7 +26,8 @@ typedef struct
 {
 	int32		vl_len_;		/* varlena header (do not touch directly!) */
 	int32		bit_len;		/* number of valid bits */
-	bits8		bit_dat[1];		/* bit string, most sig. byte first */
+	bits8		bit_dat[FLEXIBLE_ARRAY_MEMBER];	/* bit string, most sig.
+												 * byte first */
 } VarBit;
 
 /*
-- 
2.3.0

From a30ec54acc9bcc997a3a5f5d5c731cbc3b0b21e2 Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@otacoo.com>
Date: Thu, 19 Feb 2015 13:40:59 +0900
Subject: [PATCH 2/4] Add forgotten CATALOG_VARLEN pg_authid

The laste two fields of this catalog table, rolvaliduntil and rolpassword
can be null, but were not marked as such.
---
 src/include/catalog/pg_authid.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/include/catalog/pg_authid.h b/src/include/catalog/pg_authid.h
index e01e6aa..5b34288 100644
--- a/src/include/catalog/pg_authid.h
+++ b/src/include/catalog/pg_authid.h
@@ -55,9 +55,10 @@ CATALOG(pg_authid,1260) BKI_SHARED_RELATION BKI_ROWTYPE_OID(2842) BKI_SCHEMA_MAC
 	bool		rolbypassrls;	/* allowed to bypass row level security? */
 	int32		rolconnlimit;	/* max connections allowed (-1=no limit) */
 
-	/* remaining fields may be null; use heap_getattr to read them! */
+#ifdef CATALOG_VARLEN
 	text		rolpassword;	/* password, if any */
 	timestamptz rolvaliduntil;	/* password expiration time, if any */
+#endif
 } FormData_pg_authid;
 
 #undef timestamptz
-- 
2.3.0

From d59e066f252fbe9697bc9ef5b9ded0442e853797 Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@otacoo.com>
Date: Thu, 19 Feb 2015 14:02:14 +0900
Subject: [PATCH 3/4] Switch varlena to use FLEXIBLE_ARRAY_MEMBER

As compilers normally complain about a flexible-array element not at the
end of a structure (clang does, while gcc sometimes does not), this has
needed some modifications in structures using bytea as such. This commit
ensures as well that those structures have enough room to work as intended
as well.
---
 src/backend/access/heap/tuptoaster.c       | 4 ++--
 src/backend/storage/large_object/inv_api.c | 8 ++++----
 src/include/c.h                            | 2 +-
 3 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/src/backend/access/heap/tuptoaster.c b/src/backend/access/heap/tuptoaster.c
index f8c1401..547f21f 100644
--- a/src/backend/access/heap/tuptoaster.c
+++ b/src/backend/access/heap/tuptoaster.c
@@ -1365,10 +1365,10 @@ toast_save_datum(Relation rel, Datum value,
 	CommandId	mycid = GetCurrentCommandId(true);
 	struct varlena *result;
 	struct varatt_external toast_pointer;
-	struct
+	union
 	{
 		struct varlena hdr;
-		char		data[TOAST_MAX_CHUNK_SIZE]; /* make struct big enough */
+		char		data[TOAST_MAX_CHUNK_SIZE + VARHDRSZ]; /* make struct big enough */
 		int32		align_it;	/* ensure struct is aligned well enough */
 	}			chunk_data;
 	int32		chunk_size;
diff --git a/src/backend/storage/large_object/inv_api.c b/src/backend/storage/large_object/inv_api.c
index a19c401..2e877bc 100644
--- a/src/backend/storage/large_object/inv_api.c
+++ b/src/backend/storage/large_object/inv_api.c
@@ -562,10 +562,10 @@ inv_write(LargeObjectDesc *obj_desc, const char *buf, int nbytes)
 	bool		neednextpage;
 	bytea	   *datafield;
 	bool		pfreeit;
-	struct
+	union
 	{
 		bytea		hdr;
-		char		data[LOBLKSIZE];	/* make struct big enough */
+		char		data[LOBLKSIZE + VARHDRSZ];	/* make struct big enough */
 		int32		align_it;	/* ensure struct is aligned well enough */
 	}			workbuf;
 	char	   *workb = VARDATA(&workbuf.hdr);
@@ -748,10 +748,10 @@ inv_truncate(LargeObjectDesc *obj_desc, int64 len)
 	SysScanDesc sd;
 	HeapTuple	oldtuple;
 	Form_pg_largeobject olddata;
-	struct
+	union
 	{
 		bytea		hdr;
-		char		data[LOBLKSIZE];	/* make struct big enough */
+		char		data[LOBLKSIZE + VARHDRSZ];	/* make struct big enough */
 		int32		align_it;	/* ensure struct is aligned well enough */
 	}			workbuf;
 	char	   *workb = VARDATA(&workbuf.hdr);
diff --git a/src/include/c.h b/src/include/c.h
index bbd0d53..36ec468 100644
--- a/src/include/c.h
+++ b/src/include/c.h
@@ -391,7 +391,7 @@ typedef struct
 struct varlena
 {
 	char		vl_len_[4];		/* Do not touch this field directly! */
-	char		vl_dat[1];
+	char		vl_dat[FLEXIBLE_ARRAY_MEMBER];
 };
 
 #define VARHDRSZ		((int32) sizeof(int32))
-- 
2.3.0

From f41eea583f806cd8bbb4f604ee81b49c81f69cbe Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@otacoo.com>
Date: Thu, 19 Feb 2015 14:29:57 +0900
Subject: [PATCH 4/4] Replace some struct declarations with union in heapam.c

To ensure that there is enough room for operations, add a size equivalent
to the tuple header data.
---
 src/backend/access/heap/heapam.c  | 12 ++++++------
 src/include/access/htup_details.h |  2 ++
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 46060bc1..c4b825d 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -7351,10 +7351,10 @@ heap_xlog_insert(XLogReaderState *record)
 	xl_heap_insert *xlrec = (xl_heap_insert *) XLogRecGetData(record);
 	Buffer		buffer;
 	Page		page;
-	struct
+	union
 	{
 		HeapTupleHeaderData hdr;
-		char		data[MaxHeapTupleSize];
+		char		data[SizeOfHeapTupleHeaderData + MaxHeapTupleSize];
 	}			tbuf;
 	HeapTupleHeader htup;
 	xl_heap_header xlhdr;
@@ -7469,10 +7469,10 @@ heap_xlog_multi_insert(XLogReaderState *record)
 	BlockNumber blkno;
 	Buffer		buffer;
 	Page		page;
-	struct
+	union
 	{
 		HeapTupleHeaderData hdr;
-		char		data[MaxHeapTupleSize];
+		char		data[SizeOfHeapTupleHeaderData + MaxHeapTupleSize];
 	}			tbuf;
 	HeapTupleHeader htup;
 	uint32		newlen;
@@ -7618,10 +7618,10 @@ heap_xlog_update(XLogReaderState *record, bool hot_update)
 	uint16		prefixlen = 0,
 				suffixlen = 0;
 	char	   *newp;
-	struct
+	union
 	{
 		HeapTupleHeaderData hdr;
-		char		data[MaxHeapTupleSize];
+		char		data[SizeOfHeapTupleHeaderData + MaxHeapTupleSize];
 	}			tbuf;
 	xl_heap_header xlhdr;
 	uint32		newlen;
diff --git a/src/include/access/htup_details.h b/src/include/access/htup_details.h
index d2ad910..2da4f42 100644
--- a/src/include/access/htup_details.h
+++ b/src/include/access/htup_details.h
@@ -155,6 +155,8 @@ struct HeapTupleHeaderData
 	/* MORE DATA FOLLOWS AT END OF STRUCT */
 };
 
+#define SizeOfHeapTupleHeaderData	MAXALIGN(sizeof(HeapTupleHeaderData))
+
 /* typedef appears in tupbasics.h */
 
 /*
-- 
2.3.0

diff --git a/src/bin/pg_dump/dumputils.c b/src/bin/pg_dump/dumputils.c
index 892d3fa..3459adc 100644
--- a/src/bin/pg_dump/dumputils.c
+++ b/src/bin/pg_dump/dumputils.c
@@ -1217,7 +1217,7 @@ simple_string_list_append(SimpleStringList *list, const char *val)
 	SimpleStringListCell *cell;
 
 	/* this calculation correctly accounts for the null trailing byte */
-	cell = (SimpleStringListCell *) pg_malloc(sizeof(SimpleStringListCell));
+	cell = (SimpleStringListCell *) pg_malloc(offsetof(SimpleStringListCell, val));
 
 	cell->next = NULL;
 	strcpy(cell->val, val);

From 0e5ed0864a5b840e447ffdc2186b8d50c4b632b4 Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@otacoo.com>
Date: Thu, 19 Feb 2015 14:02:14 +0900
Subject: [PATCH 1/3] Switch varlena to use FLEXIBLE_ARRAY_MEMBER

As compilers normally complain about a flexible-array element not at the
end of a structure (clang does, while gcc sometimes does not), this has
needed some modifications in structures using bytea as such. This commit
ensures as well that those structures have enough room to work as intended
as well.
---
 src/backend/access/heap/tuptoaster.c       | 4 ++--
 src/backend/storage/large_object/inv_api.c | 8 ++++----
 src/include/c.h                            | 2 +-
 3 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/src/backend/access/heap/tuptoaster.c b/src/backend/access/heap/tuptoaster.c
index f8c1401..547f21f 100644
--- a/src/backend/access/heap/tuptoaster.c
+++ b/src/backend/access/heap/tuptoaster.c
@@ -1365,10 +1365,10 @@ toast_save_datum(Relation rel, Datum value,
 	CommandId	mycid = GetCurrentCommandId(true);
 	struct varlena *result;
 	struct varatt_external toast_pointer;
-	struct
+	union
 	{
 		struct varlena hdr;
-		char		data[TOAST_MAX_CHUNK_SIZE]; /* make struct big enough */
+		char		data[TOAST_MAX_CHUNK_SIZE + VARHDRSZ]; /* make struct big enough */
 		int32		align_it;	/* ensure struct is aligned well enough */
 	}			chunk_data;
 	int32		chunk_size;
diff --git a/src/backend/storage/large_object/inv_api.c b/src/backend/storage/large_object/inv_api.c
index a19c401..2e877bc 100644
--- a/src/backend/storage/large_object/inv_api.c
+++ b/src/backend/storage/large_object/inv_api.c
@@ -562,10 +562,10 @@ inv_write(LargeObjectDesc *obj_desc, const char *buf, int nbytes)
 	bool		neednextpage;
 	bytea	   *datafield;
 	bool		pfreeit;
-	struct
+	union
 	{
 		bytea		hdr;
-		char		data[LOBLKSIZE];	/* make struct big enough */
+		char		data[LOBLKSIZE + VARHDRSZ];	/* make struct big enough */
 		int32		align_it;	/* ensure struct is aligned well enough */
 	}			workbuf;
 	char	   *workb = VARDATA(&workbuf.hdr);
@@ -748,10 +748,10 @@ inv_truncate(LargeObjectDesc *obj_desc, int64 len)
 	SysScanDesc sd;
 	HeapTuple	oldtuple;
 	Form_pg_largeobject olddata;
-	struct
+	union
 	{
 		bytea		hdr;
-		char		data[LOBLKSIZE];	/* make struct big enough */
+		char		data[LOBLKSIZE + VARHDRSZ];	/* make struct big enough */
 		int32		align_it;	/* ensure struct is aligned well enough */
 	}			workbuf;
 	char	   *workb = VARDATA(&workbuf.hdr);
diff --git a/src/include/c.h b/src/include/c.h
index 2de86f9..663d8f8 100644
--- a/src/include/c.h
+++ b/src/include/c.h
@@ -391,7 +391,7 @@ typedef struct
 struct varlena
 {
 	char		vl_len_[4];		/* Do not touch this field directly! */
-	char		vl_dat[1];
+	char		vl_dat[FLEXIBLE_ARRAY_MEMBER];
 };
 
 #define VARHDRSZ		((int32) sizeof(int32))
-- 
2.3.0

From 3efab471b04755812aec5a45850f8a6bdcd49b79 Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@otacoo.com>
Date: Fri, 20 Feb 2015 16:42:28 +0900
Subject: [PATCH 2/3] Switch HeapTupleHeaderData and MinimalTupleData to use
 flexible arrays

This is some more hacking related to FLEXIBLE_ARRAY_MEMBER.
---
 contrib/file_fdw/file_fdw.c                     |  2 +-
 contrib/postgres_fdw/postgres_fdw.c             |  3 ++-
 src/backend/access/heap/heapam.c                | 12 ++++++------
 src/backend/executor/nodeHash.c                 |  2 +-
 src/backend/optimizer/path/costsize.c           |  7 ++++---
 src/backend/optimizer/plan/planner.c            |  6 ++++--
 src/backend/optimizer/plan/subselect.c          |  9 +++++----
 src/backend/optimizer/prep/prepunion.c          |  3 ++-
 src/backend/optimizer/util/plancat.c            |  2 +-
 src/backend/replication/logical/decode.c        | 24 +++++++++++------------
 src/backend/replication/logical/reorderbuffer.c | 26 +++++++++++--------------
 src/include/access/htup_details.h               |  4 ++--
 src/include/replication/reorderbuffer.h         |  7 +++++--
 13 files changed, 56 insertions(+), 51 deletions(-)

diff --git a/contrib/file_fdw/file_fdw.c b/contrib/file_fdw/file_fdw.c
index d569760..4cc168f 100644
--- a/contrib/file_fdw/file_fdw.c
+++ b/contrib/file_fdw/file_fdw.c
@@ -932,7 +932,7 @@ estimate_size(PlannerInfo *root, RelOptInfo *baserel,
 		int			tuple_width;
 
 		tuple_width = MAXALIGN(baserel->width) +
-			MAXALIGN(sizeof(HeapTupleHeaderData));
+			MAXALIGN(offsetof(HeapTupleHeaderData, t_bits));
 		ntuples = clamp_row_est((double) stat_buf.st_size /
 								(double) tuple_width);
 	}
diff --git a/contrib/postgres_fdw/postgres_fdw.c b/contrib/postgres_fdw/postgres_fdw.c
index d76e739..f94d54a 100644
--- a/contrib/postgres_fdw/postgres_fdw.c
+++ b/contrib/postgres_fdw/postgres_fdw.c
@@ -519,7 +519,8 @@ postgresGetForeignRelSize(PlannerInfo *root,
 		{
 			baserel->pages = 10;
 			baserel->tuples =
-				(10 * BLCKSZ) / (baserel->width + sizeof(HeapTupleHeaderData));
+				(10 * BLCKSZ) /
+				(baserel->width + offsetof(HeapTupleHeaderData, t_bits));
 		}
 
 		/* Estimate baserel size as best we can with local statistics. */
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 46060bc1..15fff73 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -7351,7 +7351,7 @@ heap_xlog_insert(XLogReaderState *record)
 	xl_heap_insert *xlrec = (xl_heap_insert *) XLogRecGetData(record);
 	Buffer		buffer;
 	Page		page;
-	struct
+	union
 	{
 		HeapTupleHeaderData hdr;
 		char		data[MaxHeapTupleSize];
@@ -7415,7 +7415,7 @@ heap_xlog_insert(XLogReaderState *record)
 		data += SizeOfHeapHeader;
 
 		htup = &tbuf.hdr;
-		MemSet((char *) htup, 0, sizeof(HeapTupleHeaderData));
+		MemSet((char *) htup, 0, offsetof(HeapTupleHeaderData, t_bits));
 		/* PG73FORMAT: get bitmap [+ padding] [+ oid] + data */
 		memcpy((char *) htup + offsetof(HeapTupleHeaderData, t_bits),
 			   data,
@@ -7469,7 +7469,7 @@ heap_xlog_multi_insert(XLogReaderState *record)
 	BlockNumber blkno;
 	Buffer		buffer;
 	Page		page;
-	struct
+	union
 	{
 		HeapTupleHeaderData hdr;
 		char		data[MaxHeapTupleSize];
@@ -7548,7 +7548,7 @@ heap_xlog_multi_insert(XLogReaderState *record)
 			newlen = xlhdr->datalen;
 			Assert(newlen <= MaxHeapTupleSize);
 			htup = &tbuf.hdr;
-			MemSet((char *) htup, 0, sizeof(HeapTupleHeaderData));
+			MemSet((char *) htup, 0, offsetof(HeapTupleHeaderData, t_bits));
 			/* PG73FORMAT: get bitmap [+ padding] [+ oid] + data */
 			memcpy((char *) htup + offsetof(HeapTupleHeaderData, t_bits),
 				   (char *) tupdata,
@@ -7618,7 +7618,7 @@ heap_xlog_update(XLogReaderState *record, bool hot_update)
 	uint16		prefixlen = 0,
 				suffixlen = 0;
 	char	   *newp;
-	struct
+	union
 	{
 		HeapTupleHeaderData hdr;
 		char		data[MaxHeapTupleSize];
@@ -7780,7 +7780,7 @@ heap_xlog_update(XLogReaderState *record, bool hot_update)
 		Assert(tuplen <= MaxHeapTupleSize);
 
 		htup = &tbuf.hdr;
-		MemSet((char *) htup, 0, sizeof(HeapTupleHeaderData));
+		MemSet((char *) htup, 0, offsetof(HeapTupleHeaderData, t_bits));
 
 		/*
 		 * Reconstruct the new tuple using the prefix and/or suffix from the
diff --git a/src/backend/executor/nodeHash.c b/src/backend/executor/nodeHash.c
index abd70b3..4b922b9 100644
--- a/src/backend/executor/nodeHash.c
+++ b/src/backend/executor/nodeHash.c
@@ -439,7 +439,7 @@ ExecChooseHashTableSize(double ntuples, int tupwidth, bool useskew,
 	 * don't count palloc overhead either.
 	 */
 	tupsize = HJTUPLE_OVERHEAD +
-		MAXALIGN(sizeof(MinimalTupleData)) +
+		MAXALIGN(offsetof(MinimalTupleData, t_bits)) +
 		MAXALIGN(tupwidth);
 	inner_rel_bytes = ntuples * tupsize;
 
diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c
index 020558b..dea45c0 100644
--- a/src/backend/optimizer/path/costsize.c
+++ b/src/backend/optimizer/path/costsize.c
@@ -4036,11 +4036,11 @@ set_rel_width(PlannerInfo *root, RelOptInfo *rel)
 
 	/*
 	 * If we have a whole-row reference, estimate its width as the sum of
-	 * per-column widths plus sizeof(HeapTupleHeaderData).
+	 * per-column widths plus offsetof(HeapTupleHeaderData, t_bits).
 	 */
 	if (have_wholerow_var)
 	{
-		int32		wholerow_width = sizeof(HeapTupleHeaderData);
+		int32		wholerow_width = offsetof(HeapTupleHeaderData, t_bits);
 
 		if (reloid != InvalidOid)
 		{
@@ -4078,7 +4078,8 @@ set_rel_width(PlannerInfo *root, RelOptInfo *rel)
 static double
 relation_byte_size(double tuples, int width)
 {
-	return tuples * (MAXALIGN(width) + MAXALIGN(sizeof(HeapTupleHeaderData)));
+	return tuples * (MAXALIGN(width) +
+					 MAXALIGN(offsetof(HeapTupleHeaderData, t_bits)));
 }
 
 /*
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 5c4884f..1e6680c 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -2755,7 +2755,8 @@ choose_hashed_grouping(PlannerInfo *root,
 	 */
 
 	/* Estimate per-hash-entry space at tuple width... */
-	hashentrysize = MAXALIGN(path_width) + MAXALIGN(sizeof(MinimalTupleData));
+	hashentrysize = MAXALIGN(path_width) +
+		MAXALIGN(offsetof(MinimalTupleData, t_bits));
 	/* plus space for pass-by-ref transition values... */
 	hashentrysize += agg_costs->transitionSpace;
 	/* plus the per-hash-entry overhead */
@@ -2923,7 +2924,8 @@ choose_hashed_distinct(PlannerInfo *root,
 	 */
 
 	/* Estimate per-hash-entry space at tuple width... */
-	hashentrysize = MAXALIGN(path_width) + MAXALIGN(sizeof(MinimalTupleData));
+	hashentrysize = MAXALIGN(path_width) +
+		MAXALIGN(offsetof(MinimalTupleData, t_bits));
 	/* plus the per-hash-entry overhead */
 	hashentrysize += hash_agg_entry_size(0);
 
diff --git a/src/backend/optimizer/plan/subselect.c b/src/backend/optimizer/plan/subselect.c
index 78fb6b1..918a5cf 100644
--- a/src/backend/optimizer/plan/subselect.c
+++ b/src/backend/optimizer/plan/subselect.c
@@ -974,12 +974,13 @@ subplan_is_hashable(Plan *plan)
 
 	/*
 	 * The estimated size of the subquery result must fit in work_mem. (Note:
-	 * we use sizeof(HeapTupleHeaderData) here even though the tuples will
-	 * actually be stored as MinimalTuples; this provides some fudge factor
-	 * for hashtable overhead.)
+	 * we use offsetof(HeapTupleHeaderData, t_bits) here even though the tuples
+	 * will actually be stored as MinimalTuples; this provides some fudge
+	 * factor for hashtable overhead.)
 	 */
 	subquery_size = plan->plan_rows *
-		(MAXALIGN(plan->plan_width) + MAXALIGN(sizeof(HeapTupleHeaderData)));
+		(MAXALIGN(plan->plan_width) +
+		 MAXALIGN(offsetof(HeapTupleHeaderData, t_bits)));
 	if (subquery_size > work_mem * 1024L)
 		return false;
 
diff --git a/src/backend/optimizer/prep/prepunion.c b/src/backend/optimizer/prep/prepunion.c
index 05f601e..b290a08 100644
--- a/src/backend/optimizer/prep/prepunion.c
+++ b/src/backend/optimizer/prep/prepunion.c
@@ -832,7 +832,8 @@ choose_hashed_setop(PlannerInfo *root, List *groupClauses,
 	 * Don't do it if it doesn't look like the hashtable will fit into
 	 * work_mem.
 	 */
-	hashentrysize = MAXALIGN(input_plan->plan_width) + MAXALIGN(sizeof(MinimalTupleData));
+	hashentrysize = MAXALIGN(input_plan->plan_width) +
+		MAXALIGN(offsetof(MinimalTupleData, t_bits));
 
 	if (hashentrysize * dNumGroups > work_mem * 1024L)
 		return false;
diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index fb7db6d..4a0a377 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -508,7 +508,7 @@ estimate_rel_size(Relation rel, int32 *attr_widths,
 				int32		tuple_width;
 
 				tuple_width = get_rel_data_width(rel, attr_widths);
-				tuple_width += sizeof(HeapTupleHeaderData);
+				tuple_width += offsetof(HeapTupleHeaderData, t_bits);
 				tuple_width += sizeof(ItemIdData);
 				/* note: integer division is intentional here */
 				density = (BLCKSZ - SizeOfPageHeaderData) / tuple_width;
diff --git a/src/backend/replication/logical/decode.c b/src/backend/replication/logical/decode.c
index 77c02ba..574f63b 100644
--- a/src/backend/replication/logical/decode.c
+++ b/src/backend/replication/logical/decode.c
@@ -765,21 +765,21 @@ DecodeMultiInsert(LogicalDecodingContext *ctx, XLogRecordBuffer *buf)
 			 * transactions.
 			 */
 			tuple->tuple.t_tableOid = InvalidOid;
-			tuple->tuple.t_data = &tuple->header;
+			tuple->tuple.t_data = &tuple->t_data.header;
 			tuple->tuple.t_len = datalen
 				+ offsetof(HeapTupleHeaderData, t_bits);
 
-			memset(&tuple->header, 0, sizeof(HeapTupleHeaderData));
+			memset(&tuple->t_data.header, 0, offsetof(HeapTupleHeaderData, t_bits));
 
-			memcpy((char *) &tuple->header
+			memcpy((char *) &tuple->t_data.header
 				   + offsetof(HeapTupleHeaderData, t_bits),
 				   (char *) data,
 				   datalen);
 			data += datalen;
 
-			tuple->header.t_infomask = xlhdr->t_infomask;
-			tuple->header.t_infomask2 = xlhdr->t_infomask2;
-			tuple->header.t_hoff = xlhdr->t_hoff;
+			tuple->t_data.header.t_infomask = xlhdr->t_infomask;
+			tuple->t_data.header.t_infomask2 = xlhdr->t_infomask2;
+			tuple->t_data.header.t_hoff = xlhdr->t_hoff;
 		}
 
 		/*
@@ -822,20 +822,20 @@ DecodeXLogTuple(char *data, Size len, ReorderBufferTupleBuf *tuple)
 
 	/* we can only figure this out after reassembling the transactions */
 	tuple->tuple.t_tableOid = InvalidOid;
-	tuple->tuple.t_data = &tuple->header;
+	tuple->tuple.t_data = &tuple->t_data.header;
 
 	/* data is not stored aligned, copy to aligned storage */
 	memcpy((char *) &xlhdr,
 		   data,
 		   SizeOfHeapHeader);
 
-	memset(&tuple->header, 0, sizeof(HeapTupleHeaderData));
+	memset(&tuple->t_data.header, 0, offsetof(HeapTupleHeaderData, t_bits));
 
-	memcpy((char *) &tuple->header + offsetof(HeapTupleHeaderData, t_bits),
+	memcpy((char *) &tuple->t_data.header + offsetof(HeapTupleHeaderData, t_bits),
 		   data + SizeOfHeapHeader,
 		   datalen);
 
-	tuple->header.t_infomask = xlhdr.t_infomask;
-	tuple->header.t_infomask2 = xlhdr.t_infomask2;
-	tuple->header.t_hoff = xlhdr.t_hoff;
+	tuple->t_data.header.t_infomask = xlhdr.t_infomask;
+	tuple->t_data.header.t_infomask2 = xlhdr.t_infomask2;
+	tuple->t_data.header.t_hoff = xlhdr.t_hoff;
 }
diff --git a/src/backend/replication/logical/reorderbuffer.c b/src/backend/replication/logical/reorderbuffer.c
index bcd5896..3226405 100644
--- a/src/backend/replication/logical/reorderbuffer.c
+++ b/src/backend/replication/logical/reorderbuffer.c
@@ -2014,14 +2014,12 @@ ReorderBufferSerializeChange(ReorderBuffer *rb, ReorderBufferTXN *txn,
 				newtup = change->data.tp.newtuple;
 
 				if (oldtup)
-					oldlen = offsetof(ReorderBufferTupleBuf, data)
-						+oldtup->tuple.t_len
-						- offsetof(HeapTupleHeaderData, t_bits);
+					oldlen = offsetof(ReorderBufferTupleBuf, t_data) +
+						oldtup->tuple.t_len;
 
 				if (newtup)
-					newlen = offsetof(ReorderBufferTupleBuf, data)
-						+newtup->tuple.t_len
-						- offsetof(HeapTupleHeaderData, t_bits);
+					newlen = offsetof(ReorderBufferTupleBuf, t_data) +
+						newtup->tuple.t_len;
 
 				sz += oldlen;
 				sz += newlen;
@@ -2262,27 +2260,25 @@ ReorderBufferRestoreChange(ReorderBuffer *rb, ReorderBufferTXN *txn,
 		case REORDER_BUFFER_CHANGE_DELETE:
 			if (change->data.tp.newtuple)
 			{
-				Size		len = offsetof(ReorderBufferTupleBuf, data)
-				+((ReorderBufferTupleBuf *) data)->tuple.t_len
-				- offsetof(HeapTupleHeaderData, t_bits);
+				Size		len = offsetof(ReorderBufferTupleBuf, t_data) +
+					((ReorderBufferTupleBuf *) data)->tuple.t_len;
 
 				change->data.tp.newtuple = ReorderBufferGetTupleBuf(rb);
 				memcpy(change->data.tp.newtuple, data, len);
 				change->data.tp.newtuple->tuple.t_data =
-					&change->data.tp.newtuple->header;
+					&change->data.tp.newtuple->t_data.header;
 				data += len;
 			}
 
 			if (change->data.tp.oldtuple)
 			{
-				Size		len = offsetof(ReorderBufferTupleBuf, data)
-				+((ReorderBufferTupleBuf *) data)->tuple.t_len
-				- offsetof(HeapTupleHeaderData, t_bits);
+				Size		len = offsetof(ReorderBufferTupleBuf, t_data) +
+					((ReorderBufferTupleBuf *) data)->tuple.t_len;
 
 				change->data.tp.oldtuple = ReorderBufferGetTupleBuf(rb);
 				memcpy(change->data.tp.oldtuple, data, len);
 				change->data.tp.oldtuple->tuple.t_data =
-					&change->data.tp.oldtuple->header;
+					&change->data.tp.oldtuple->t_data.header;
 				data += len;
 			}
 			break;
@@ -2660,7 +2656,7 @@ ReorderBufferToastReplace(ReorderBuffer *rb, ReorderBufferTXN *txn,
 	 */
 	tmphtup = heap_form_tuple(desc, attrs, isnull);
 	Assert(newtup->tuple.t_len <= MaxHeapTupleSize);
-	Assert(&newtup->header == newtup->tuple.t_data);
+	Assert(&newtup->t_data.header == newtup->tuple.t_data);
 
 	memcpy(newtup->tuple.t_data, tmphtup->t_data, tmphtup->t_len);
 	newtup->tuple.t_len = tmphtup->t_len;
diff --git a/src/include/access/htup_details.h b/src/include/access/htup_details.h
index d2ad910..475377c 100644
--- a/src/include/access/htup_details.h
+++ b/src/include/access/htup_details.h
@@ -150,7 +150,7 @@ struct HeapTupleHeaderData
 
 	/* ^ - 23 bytes - ^ */
 
-	bits8		t_bits[1];		/* bitmap of NULLs -- VARIABLE LENGTH */
+	bits8		t_bits[FLEXIBLE_ARRAY_MEMBER];	/* bitmap of NULLs */
 
 	/* MORE DATA FOLLOWS AT END OF STRUCT */
 };
@@ -579,7 +579,7 @@ struct MinimalTupleData
 
 	/* ^ - 23 bytes - ^ */
 
-	bits8		t_bits[1];		/* bitmap of NULLs -- VARIABLE LENGTH */
+	bits8		t_bits[FLEXIBLE_ARRAY_MEMBER];	/* bitmap of NULLs */
 
 	/* MORE DATA FOLLOWS AT END OF STRUCT */
 };
diff --git a/src/include/replication/reorderbuffer.h b/src/include/replication/reorderbuffer.h
index 5a1d9a0..dcfe2b3 100644
--- a/src/include/replication/reorderbuffer.h
+++ b/src/include/replication/reorderbuffer.h
@@ -28,8 +28,11 @@ typedef struct ReorderBufferTupleBuf
 
 	/* tuple, stored sequentially */
 	HeapTupleData tuple;
-	HeapTupleHeaderData header;
-	char		data[MaxHeapTupleSize];
+	union
+	{
+		HeapTupleHeaderData header;
+		char		data[MaxHeapTupleSize];
+	}	t_data;
 } ReorderBufferTupleBuf;
 
 /*
-- 
2.3.0

From 2ca26a01e49ad79649f2db19b7cb2ef0983842fa Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@otacoo.com>
Date: Fri, 20 Feb 2015 16:53:27 +0900
Subject: [PATCH 3/3] Switch RecordIOData to use FLEXIBLE_ARRAY_MEMBER

This impacts hstore, json functions and rowtypes.
---
 contrib/hstore/hstore_io.c        | 18 +++++++++---------
 src/backend/utils/adt/jsonfuncs.c | 18 +++++++++---------
 src/backend/utils/adt/rowtypes.c  | 34 +++++++++++++++++-----------------
 3 files changed, 35 insertions(+), 35 deletions(-)

diff --git a/contrib/hstore/hstore_io.c b/contrib/hstore/hstore_io.c
index 079f662..7d89867 100644
--- a/contrib/hstore/hstore_io.c
+++ b/contrib/hstore/hstore_io.c
@@ -747,7 +747,7 @@ typedef struct RecordIOData
 	Oid			record_type;
 	int32		record_typmod;
 	int			ncolumns;
-	ColumnIOData columns[1];	/* VARIABLE LENGTH ARRAY */
+	ColumnIOData columns[FLEXIBLE_ARRAY_MEMBER];
 } RecordIOData;
 
 PG_FUNCTION_INFO_V1(hstore_from_record);
@@ -805,8 +805,8 @@ hstore_from_record(PG_FUNCTION_ARGS)
 	{
 		fcinfo->flinfo->fn_extra =
 			MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
-							   sizeof(RecordIOData) - sizeof(ColumnIOData)
-							   + ncolumns * sizeof(ColumnIOData));
+							   offsetof(RecordIOData, columns) +
+							   ncolumns * sizeof(ColumnIOData));
 		my_extra = (RecordIOData *) fcinfo->flinfo->fn_extra;
 		my_extra->record_type = InvalidOid;
 		my_extra->record_typmod = 0;
@@ -816,8 +816,8 @@ hstore_from_record(PG_FUNCTION_ARGS)
 		my_extra->record_typmod != tupTypmod)
 	{
 		MemSet(my_extra, 0,
-			   sizeof(RecordIOData) - sizeof(ColumnIOData)
-			   + ncolumns * sizeof(ColumnIOData));
+			   offsetof(RecordIOData, columns) +
+			   ncolumns * sizeof(ColumnIOData));
 		my_extra->record_type = tupType;
 		my_extra->record_typmod = tupTypmod;
 		my_extra->ncolumns = ncolumns;
@@ -990,8 +990,8 @@ hstore_populate_record(PG_FUNCTION_ARGS)
 	{
 		fcinfo->flinfo->fn_extra =
 			MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
-							   sizeof(RecordIOData) - sizeof(ColumnIOData)
-							   + ncolumns * sizeof(ColumnIOData));
+							   offsetof(RecordIOData, columns) +
+							   ncolumns * sizeof(ColumnIOData));
 		my_extra = (RecordIOData *) fcinfo->flinfo->fn_extra;
 		my_extra->record_type = InvalidOid;
 		my_extra->record_typmod = 0;
@@ -1001,8 +1001,8 @@ hstore_populate_record(PG_FUNCTION_ARGS)
 		my_extra->record_typmod != tupTypmod)
 	{
 		MemSet(my_extra, 0,
-			   sizeof(RecordIOData) - sizeof(ColumnIOData)
-			   + ncolumns * sizeof(ColumnIOData));
+			   offsetof(RecordIOData, columns) +
+			   ncolumns * sizeof(ColumnIOData));
 		my_extra->record_type = tupType;
 		my_extra->record_typmod = tupTypmod;
 		my_extra->ncolumns = ncolumns;
diff --git a/src/backend/utils/adt/jsonfuncs.c b/src/backend/utils/adt/jsonfuncs.c
index 3688163..a8cdeaa 100644
--- a/src/backend/utils/adt/jsonfuncs.c
+++ b/src/backend/utils/adt/jsonfuncs.c
@@ -216,7 +216,7 @@ typedef struct RecordIOData
 	Oid			record_type;
 	int32		record_typmod;
 	int			ncolumns;
-	ColumnIOData columns[1];	/* VARIABLE LENGTH ARRAY */
+	ColumnIOData columns[FLEXIBLE_ARRAY_MEMBER];
 } RecordIOData;
 
 /* state for populate_recordset */
@@ -2148,8 +2148,8 @@ populate_record_worker(FunctionCallInfo fcinfo, const char *funcname,
 	{
 		fcinfo->flinfo->fn_extra =
 			MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
-							   sizeof(RecordIOData) - sizeof(ColumnIOData)
-							   + ncolumns * sizeof(ColumnIOData));
+							   offsetof(RecordIOData, columns) +
+							   ncolumns * sizeof(ColumnIOData));
 		my_extra = (RecordIOData *) fcinfo->flinfo->fn_extra;
 		my_extra->record_type = InvalidOid;
 		my_extra->record_typmod = 0;
@@ -2161,8 +2161,8 @@ populate_record_worker(FunctionCallInfo fcinfo, const char *funcname,
 							my_extra->record_typmod != tupTypmod))
 	{
 		MemSet(my_extra, 0,
-			   sizeof(RecordIOData) - sizeof(ColumnIOData)
-			   + ncolumns * sizeof(ColumnIOData));
+			   offsetof(RecordIOData, columns) +
+			   ncolumns * sizeof(ColumnIOData));
 		my_extra->record_type = tupType;
 		my_extra->record_typmod = tupTypmod;
 		my_extra->ncolumns = ncolumns;
@@ -2653,8 +2653,8 @@ populate_recordset_worker(FunctionCallInfo fcinfo, const char *funcname,
 	{
 		fcinfo->flinfo->fn_extra =
 			MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
-							   sizeof(RecordIOData) - sizeof(ColumnIOData)
-							   + ncolumns * sizeof(ColumnIOData));
+							   offsetof(RecordIOData, columns) +
+							   ncolumns * sizeof(ColumnIOData));
 		my_extra = (RecordIOData *) fcinfo->flinfo->fn_extra;
 		my_extra->record_type = InvalidOid;
 		my_extra->record_typmod = 0;
@@ -2664,8 +2664,8 @@ populate_recordset_worker(FunctionCallInfo fcinfo, const char *funcname,
 		my_extra->record_typmod != tupTypmod)
 	{
 		MemSet(my_extra, 0,
-			   sizeof(RecordIOData) - sizeof(ColumnIOData)
-			   + ncolumns * sizeof(ColumnIOData));
+			   offsetof(RecordIOData, columns) +
+			   ncolumns * sizeof(ColumnIOData));
 		my_extra->record_type = tupType;
 		my_extra->record_typmod = tupTypmod;
 		my_extra->ncolumns = ncolumns;
diff --git a/src/backend/utils/adt/rowtypes.c b/src/backend/utils/adt/rowtypes.c
index 3dc9a84..16d2b7f 100644
--- a/src/backend/utils/adt/rowtypes.c
+++ b/src/backend/utils/adt/rowtypes.c
@@ -43,7 +43,7 @@ typedef struct RecordIOData
 	Oid			record_type;
 	int32		record_typmod;
 	int			ncolumns;
-	ColumnIOData columns[1];	/* VARIABLE LENGTH ARRAY */
+	ColumnIOData columns[FLEXIBLE_ARRAY_MEMBER];
 } RecordIOData;
 
 /*
@@ -120,8 +120,8 @@ record_in(PG_FUNCTION_ARGS)
 	{
 		fcinfo->flinfo->fn_extra =
 			MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
-							   sizeof(RecordIOData) - sizeof(ColumnIOData)
-							   + ncolumns * sizeof(ColumnIOData));
+							   offsetof(RecordIOData, columns) +
+							   ncolumns * sizeof(ColumnIOData));
 		my_extra = (RecordIOData *) fcinfo->flinfo->fn_extra;
 		my_extra->record_type = InvalidOid;
 		my_extra->record_typmod = 0;
@@ -131,8 +131,8 @@ record_in(PG_FUNCTION_ARGS)
 		my_extra->record_typmod != tupTypmod)
 	{
 		MemSet(my_extra, 0,
-			   sizeof(RecordIOData) - sizeof(ColumnIOData)
-			   + ncolumns * sizeof(ColumnIOData));
+			   offsetof(RecordIOData, columns) +
+			   ncolumns * sizeof(ColumnIOData));
 		my_extra->record_type = tupType;
 		my_extra->record_typmod = tupTypmod;
 		my_extra->ncolumns = ncolumns;
@@ -334,8 +334,8 @@ record_out(PG_FUNCTION_ARGS)
 	{
 		fcinfo->flinfo->fn_extra =
 			MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
-							   sizeof(RecordIOData) - sizeof(ColumnIOData)
-							   + ncolumns * sizeof(ColumnIOData));
+							   offsetof(RecordIOData, columns) +
+							   ncolumns * sizeof(ColumnIOData));
 		my_extra = (RecordIOData *) fcinfo->flinfo->fn_extra;
 		my_extra->record_type = InvalidOid;
 		my_extra->record_typmod = 0;
@@ -345,8 +345,8 @@ record_out(PG_FUNCTION_ARGS)
 		my_extra->record_typmod != tupTypmod)
 	{
 		MemSet(my_extra, 0,
-			   sizeof(RecordIOData) - sizeof(ColumnIOData)
-			   + ncolumns * sizeof(ColumnIOData));
+			   offsetof(RecordIOData, columns) +
+			   ncolumns * sizeof(ColumnIOData));
 		my_extra->record_type = tupType;
 		my_extra->record_typmod = tupTypmod;
 		my_extra->ncolumns = ncolumns;
@@ -489,8 +489,8 @@ record_recv(PG_FUNCTION_ARGS)
 	{
 		fcinfo->flinfo->fn_extra =
 			MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
-							   sizeof(RecordIOData) - sizeof(ColumnIOData)
-							   + ncolumns * sizeof(ColumnIOData));
+							   offsetof(RecordIOData, columns) +
+							   ncolumns * sizeof(ColumnIOData));
 		my_extra = (RecordIOData *) fcinfo->flinfo->fn_extra;
 		my_extra->record_type = InvalidOid;
 		my_extra->record_typmod = 0;
@@ -500,8 +500,8 @@ record_recv(PG_FUNCTION_ARGS)
 		my_extra->record_typmod != tupTypmod)
 	{
 		MemSet(my_extra, 0,
-			   sizeof(RecordIOData) - sizeof(ColumnIOData)
-			   + ncolumns * sizeof(ColumnIOData));
+			   offsetof(RecordIOData, columns) +
+			   ncolumns * sizeof(ColumnIOData));
 		my_extra->record_type = tupType;
 		my_extra->record_typmod = tupTypmod;
 		my_extra->ncolumns = ncolumns;
@@ -677,8 +677,8 @@ record_send(PG_FUNCTION_ARGS)
 	{
 		fcinfo->flinfo->fn_extra =
 			MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
-							   sizeof(RecordIOData) - sizeof(ColumnIOData)
-							   + ncolumns * sizeof(ColumnIOData));
+							   offsetof(RecordIOData, columns) +
+							   ncolumns * sizeof(ColumnIOData));
 		my_extra = (RecordIOData *) fcinfo->flinfo->fn_extra;
 		my_extra->record_type = InvalidOid;
 		my_extra->record_typmod = 0;
@@ -688,8 +688,8 @@ record_send(PG_FUNCTION_ARGS)
 		my_extra->record_typmod != tupTypmod)
 	{
 		MemSet(my_extra, 0,
-			   sizeof(RecordIOData) - sizeof(ColumnIOData)
-			   + ncolumns * sizeof(ColumnIOData));
+			   offsetof(RecordIOData, columns) +
+			   ncolumns * sizeof(ColumnIOData));
 		my_extra->record_type = tupType;
 		my_extra->record_typmod = tupTypmod;
 		my_extra->ncolumns = ncolumns;
-- 
2.3.0

From 072c0b80f00a5ca460391279a955f5e95f22d439 Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@otacoo.com>
Date: Thu, 19 Feb 2015 14:02:14 +0900
Subject: [PATCH 1/4] Switch varlena to use FLEXIBLE_ARRAY_MEMBER

As compilers normally complain about a flexible-array element not at the
end of a structure (clang does, while gcc sometimes does not), this has
needed some modifications in structures using bytea as such. This commit
ensures as well that those structures have enough room to work as intended
as well.
---
 src/backend/access/heap/tuptoaster.c       | 4 ++--
 src/backend/storage/large_object/inv_api.c | 8 ++++----
 src/include/c.h                            | 2 +-
 3 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/src/backend/access/heap/tuptoaster.c b/src/backend/access/heap/tuptoaster.c
index f8c1401..547f21f 100644
--- a/src/backend/access/heap/tuptoaster.c
+++ b/src/backend/access/heap/tuptoaster.c
@@ -1365,10 +1365,10 @@ toast_save_datum(Relation rel, Datum value,
 	CommandId	mycid = GetCurrentCommandId(true);
 	struct varlena *result;
 	struct varatt_external toast_pointer;
-	struct
+	union
 	{
 		struct varlena hdr;
-		char		data[TOAST_MAX_CHUNK_SIZE]; /* make struct big enough */
+		char		data[TOAST_MAX_CHUNK_SIZE + VARHDRSZ]; /* make struct big enough */
 		int32		align_it;	/* ensure struct is aligned well enough */
 	}			chunk_data;
 	int32		chunk_size;
diff --git a/src/backend/storage/large_object/inv_api.c b/src/backend/storage/large_object/inv_api.c
index a19c401..2e877bc 100644
--- a/src/backend/storage/large_object/inv_api.c
+++ b/src/backend/storage/large_object/inv_api.c
@@ -562,10 +562,10 @@ inv_write(LargeObjectDesc *obj_desc, const char *buf, int nbytes)
 	bool		neednextpage;
 	bytea	   *datafield;
 	bool		pfreeit;
-	struct
+	union
 	{
 		bytea		hdr;
-		char		data[LOBLKSIZE];	/* make struct big enough */
+		char		data[LOBLKSIZE + VARHDRSZ];	/* make struct big enough */
 		int32		align_it;	/* ensure struct is aligned well enough */
 	}			workbuf;
 	char	   *workb = VARDATA(&workbuf.hdr);
@@ -748,10 +748,10 @@ inv_truncate(LargeObjectDesc *obj_desc, int64 len)
 	SysScanDesc sd;
 	HeapTuple	oldtuple;
 	Form_pg_largeobject olddata;
-	struct
+	union
 	{
 		bytea		hdr;
-		char		data[LOBLKSIZE];	/* make struct big enough */
+		char		data[LOBLKSIZE + VARHDRSZ];	/* make struct big enough */
 		int32		align_it;	/* ensure struct is aligned well enough */
 	}			workbuf;
 	char	   *workb = VARDATA(&workbuf.hdr);
diff --git a/src/include/c.h b/src/include/c.h
index 2de86f9..663d8f8 100644
--- a/src/include/c.h
+++ b/src/include/c.h
@@ -391,7 +391,7 @@ typedef struct
 struct varlena
 {
 	char		vl_len_[4];		/* Do not touch this field directly! */
-	char		vl_dat[1];
+	char		vl_dat[FLEXIBLE_ARRAY_MEMBER];
 };
 
 #define VARHDRSZ		((int32) sizeof(int32))
-- 
2.3.0

From 58aa911e66a5509fd9e4d6ff3b36c76745b3db7f Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@otacoo.com>
Date: Fri, 20 Feb 2015 16:42:28 +0900
Subject: [PATCH 2/4] Switch HeapTupleHeaderData and MinimalTupleData to use
 flexible arrays

This is some more hacking related to FLEXIBLE_ARRAY_MEMBER.
---
 contrib/file_fdw/file_fdw.c                     |  2 +-
 contrib/postgres_fdw/postgres_fdw.c             |  3 ++-
 src/backend/access/heap/heapam.c                | 12 ++++++------
 src/backend/executor/nodeHash.c                 |  2 +-
 src/backend/optimizer/path/costsize.c           |  7 ++++---
 src/backend/optimizer/plan/planner.c            |  6 ++++--
 src/backend/optimizer/plan/subselect.c          |  9 +++++----
 src/backend/optimizer/prep/prepunion.c          |  3 ++-
 src/backend/optimizer/util/plancat.c            |  2 +-
 src/backend/replication/logical/decode.c        | 24 +++++++++++------------
 src/backend/replication/logical/reorderbuffer.c | 26 +++++++++++--------------
 src/include/access/htup_details.h               |  4 ++--
 src/include/replication/reorderbuffer.h         |  7 +++++--
 13 files changed, 56 insertions(+), 51 deletions(-)

diff --git a/contrib/file_fdw/file_fdw.c b/contrib/file_fdw/file_fdw.c
index d569760..4cc168f 100644
--- a/contrib/file_fdw/file_fdw.c
+++ b/contrib/file_fdw/file_fdw.c
@@ -932,7 +932,7 @@ estimate_size(PlannerInfo *root, RelOptInfo *baserel,
 		int			tuple_width;
 
 		tuple_width = MAXALIGN(baserel->width) +
-			MAXALIGN(sizeof(HeapTupleHeaderData));
+			MAXALIGN(offsetof(HeapTupleHeaderData, t_bits));
 		ntuples = clamp_row_est((double) stat_buf.st_size /
 								(double) tuple_width);
 	}
diff --git a/contrib/postgres_fdw/postgres_fdw.c b/contrib/postgres_fdw/postgres_fdw.c
index d76e739..f94d54a 100644
--- a/contrib/postgres_fdw/postgres_fdw.c
+++ b/contrib/postgres_fdw/postgres_fdw.c
@@ -519,7 +519,8 @@ postgresGetForeignRelSize(PlannerInfo *root,
 		{
 			baserel->pages = 10;
 			baserel->tuples =
-				(10 * BLCKSZ) / (baserel->width + sizeof(HeapTupleHeaderData));
+				(10 * BLCKSZ) /
+				(baserel->width + offsetof(HeapTupleHeaderData, t_bits));
 		}
 
 		/* Estimate baserel size as best we can with local statistics. */
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 46060bc1..15fff73 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -7351,7 +7351,7 @@ heap_xlog_insert(XLogReaderState *record)
 	xl_heap_insert *xlrec = (xl_heap_insert *) XLogRecGetData(record);
 	Buffer		buffer;
 	Page		page;
-	struct
+	union
 	{
 		HeapTupleHeaderData hdr;
 		char		data[MaxHeapTupleSize];
@@ -7415,7 +7415,7 @@ heap_xlog_insert(XLogReaderState *record)
 		data += SizeOfHeapHeader;
 
 		htup = &tbuf.hdr;
-		MemSet((char *) htup, 0, sizeof(HeapTupleHeaderData));
+		MemSet((char *) htup, 0, offsetof(HeapTupleHeaderData, t_bits));
 		/* PG73FORMAT: get bitmap [+ padding] [+ oid] + data */
 		memcpy((char *) htup + offsetof(HeapTupleHeaderData, t_bits),
 			   data,
@@ -7469,7 +7469,7 @@ heap_xlog_multi_insert(XLogReaderState *record)
 	BlockNumber blkno;
 	Buffer		buffer;
 	Page		page;
-	struct
+	union
 	{
 		HeapTupleHeaderData hdr;
 		char		data[MaxHeapTupleSize];
@@ -7548,7 +7548,7 @@ heap_xlog_multi_insert(XLogReaderState *record)
 			newlen = xlhdr->datalen;
 			Assert(newlen <= MaxHeapTupleSize);
 			htup = &tbuf.hdr;
-			MemSet((char *) htup, 0, sizeof(HeapTupleHeaderData));
+			MemSet((char *) htup, 0, offsetof(HeapTupleHeaderData, t_bits));
 			/* PG73FORMAT: get bitmap [+ padding] [+ oid] + data */
 			memcpy((char *) htup + offsetof(HeapTupleHeaderData, t_bits),
 				   (char *) tupdata,
@@ -7618,7 +7618,7 @@ heap_xlog_update(XLogReaderState *record, bool hot_update)
 	uint16		prefixlen = 0,
 				suffixlen = 0;
 	char	   *newp;
-	struct
+	union
 	{
 		HeapTupleHeaderData hdr;
 		char		data[MaxHeapTupleSize];
@@ -7780,7 +7780,7 @@ heap_xlog_update(XLogReaderState *record, bool hot_update)
 		Assert(tuplen <= MaxHeapTupleSize);
 
 		htup = &tbuf.hdr;
-		MemSet((char *) htup, 0, sizeof(HeapTupleHeaderData));
+		MemSet((char *) htup, 0, offsetof(HeapTupleHeaderData, t_bits));
 
 		/*
 		 * Reconstruct the new tuple using the prefix and/or suffix from the
diff --git a/src/backend/executor/nodeHash.c b/src/backend/executor/nodeHash.c
index abd70b3..4b922b9 100644
--- a/src/backend/executor/nodeHash.c
+++ b/src/backend/executor/nodeHash.c
@@ -439,7 +439,7 @@ ExecChooseHashTableSize(double ntuples, int tupwidth, bool useskew,
 	 * don't count palloc overhead either.
 	 */
 	tupsize = HJTUPLE_OVERHEAD +
-		MAXALIGN(sizeof(MinimalTupleData)) +
+		MAXALIGN(offsetof(MinimalTupleData, t_bits)) +
 		MAXALIGN(tupwidth);
 	inner_rel_bytes = ntuples * tupsize;
 
diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c
index 020558b..dea45c0 100644
--- a/src/backend/optimizer/path/costsize.c
+++ b/src/backend/optimizer/path/costsize.c
@@ -4036,11 +4036,11 @@ set_rel_width(PlannerInfo *root, RelOptInfo *rel)
 
 	/*
 	 * If we have a whole-row reference, estimate its width as the sum of
-	 * per-column widths plus sizeof(HeapTupleHeaderData).
+	 * per-column widths plus offsetof(HeapTupleHeaderData, t_bits).
 	 */
 	if (have_wholerow_var)
 	{
-		int32		wholerow_width = sizeof(HeapTupleHeaderData);
+		int32		wholerow_width = offsetof(HeapTupleHeaderData, t_bits);
 
 		if (reloid != InvalidOid)
 		{
@@ -4078,7 +4078,8 @@ set_rel_width(PlannerInfo *root, RelOptInfo *rel)
 static double
 relation_byte_size(double tuples, int width)
 {
-	return tuples * (MAXALIGN(width) + MAXALIGN(sizeof(HeapTupleHeaderData)));
+	return tuples * (MAXALIGN(width) +
+					 MAXALIGN(offsetof(HeapTupleHeaderData, t_bits)));
 }
 
 /*
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 5c4884f..1e6680c 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -2755,7 +2755,8 @@ choose_hashed_grouping(PlannerInfo *root,
 	 */
 
 	/* Estimate per-hash-entry space at tuple width... */
-	hashentrysize = MAXALIGN(path_width) + MAXALIGN(sizeof(MinimalTupleData));
+	hashentrysize = MAXALIGN(path_width) +
+		MAXALIGN(offsetof(MinimalTupleData, t_bits));
 	/* plus space for pass-by-ref transition values... */
 	hashentrysize += agg_costs->transitionSpace;
 	/* plus the per-hash-entry overhead */
@@ -2923,7 +2924,8 @@ choose_hashed_distinct(PlannerInfo *root,
 	 */
 
 	/* Estimate per-hash-entry space at tuple width... */
-	hashentrysize = MAXALIGN(path_width) + MAXALIGN(sizeof(MinimalTupleData));
+	hashentrysize = MAXALIGN(path_width) +
+		MAXALIGN(offsetof(MinimalTupleData, t_bits));
 	/* plus the per-hash-entry overhead */
 	hashentrysize += hash_agg_entry_size(0);
 
diff --git a/src/backend/optimizer/plan/subselect.c b/src/backend/optimizer/plan/subselect.c
index 78fb6b1..918a5cf 100644
--- a/src/backend/optimizer/plan/subselect.c
+++ b/src/backend/optimizer/plan/subselect.c
@@ -974,12 +974,13 @@ subplan_is_hashable(Plan *plan)
 
 	/*
 	 * The estimated size of the subquery result must fit in work_mem. (Note:
-	 * we use sizeof(HeapTupleHeaderData) here even though the tuples will
-	 * actually be stored as MinimalTuples; this provides some fudge factor
-	 * for hashtable overhead.)
+	 * we use offsetof(HeapTupleHeaderData, t_bits) here even though the tuples
+	 * will actually be stored as MinimalTuples; this provides some fudge
+	 * factor for hashtable overhead.)
 	 */
 	subquery_size = plan->plan_rows *
-		(MAXALIGN(plan->plan_width) + MAXALIGN(sizeof(HeapTupleHeaderData)));
+		(MAXALIGN(plan->plan_width) +
+		 MAXALIGN(offsetof(HeapTupleHeaderData, t_bits)));
 	if (subquery_size > work_mem * 1024L)
 		return false;
 
diff --git a/src/backend/optimizer/prep/prepunion.c b/src/backend/optimizer/prep/prepunion.c
index 05f601e..b290a08 100644
--- a/src/backend/optimizer/prep/prepunion.c
+++ b/src/backend/optimizer/prep/prepunion.c
@@ -832,7 +832,8 @@ choose_hashed_setop(PlannerInfo *root, List *groupClauses,
 	 * Don't do it if it doesn't look like the hashtable will fit into
 	 * work_mem.
 	 */
-	hashentrysize = MAXALIGN(input_plan->plan_width) + MAXALIGN(sizeof(MinimalTupleData));
+	hashentrysize = MAXALIGN(input_plan->plan_width) +
+		MAXALIGN(offsetof(MinimalTupleData, t_bits));
 
 	if (hashentrysize * dNumGroups > work_mem * 1024L)
 		return false;
diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index fb7db6d..4a0a377 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -508,7 +508,7 @@ estimate_rel_size(Relation rel, int32 *attr_widths,
 				int32		tuple_width;
 
 				tuple_width = get_rel_data_width(rel, attr_widths);
-				tuple_width += sizeof(HeapTupleHeaderData);
+				tuple_width += offsetof(HeapTupleHeaderData, t_bits);
 				tuple_width += sizeof(ItemIdData);
 				/* note: integer division is intentional here */
 				density = (BLCKSZ - SizeOfPageHeaderData) / tuple_width;
diff --git a/src/backend/replication/logical/decode.c b/src/backend/replication/logical/decode.c
index 77c02ba..574f63b 100644
--- a/src/backend/replication/logical/decode.c
+++ b/src/backend/replication/logical/decode.c
@@ -765,21 +765,21 @@ DecodeMultiInsert(LogicalDecodingContext *ctx, XLogRecordBuffer *buf)
 			 * transactions.
 			 */
 			tuple->tuple.t_tableOid = InvalidOid;
-			tuple->tuple.t_data = &tuple->header;
+			tuple->tuple.t_data = &tuple->t_data.header;
 			tuple->tuple.t_len = datalen
 				+ offsetof(HeapTupleHeaderData, t_bits);
 
-			memset(&tuple->header, 0, sizeof(HeapTupleHeaderData));
+			memset(&tuple->t_data.header, 0, offsetof(HeapTupleHeaderData, t_bits));
 
-			memcpy((char *) &tuple->header
+			memcpy((char *) &tuple->t_data.header
 				   + offsetof(HeapTupleHeaderData, t_bits),
 				   (char *) data,
 				   datalen);
 			data += datalen;
 
-			tuple->header.t_infomask = xlhdr->t_infomask;
-			tuple->header.t_infomask2 = xlhdr->t_infomask2;
-			tuple->header.t_hoff = xlhdr->t_hoff;
+			tuple->t_data.header.t_infomask = xlhdr->t_infomask;
+			tuple->t_data.header.t_infomask2 = xlhdr->t_infomask2;
+			tuple->t_data.header.t_hoff = xlhdr->t_hoff;
 		}
 
 		/*
@@ -822,20 +822,20 @@ DecodeXLogTuple(char *data, Size len, ReorderBufferTupleBuf *tuple)
 
 	/* we can only figure this out after reassembling the transactions */
 	tuple->tuple.t_tableOid = InvalidOid;
-	tuple->tuple.t_data = &tuple->header;
+	tuple->tuple.t_data = &tuple->t_data.header;
 
 	/* data is not stored aligned, copy to aligned storage */
 	memcpy((char *) &xlhdr,
 		   data,
 		   SizeOfHeapHeader);
 
-	memset(&tuple->header, 0, sizeof(HeapTupleHeaderData));
+	memset(&tuple->t_data.header, 0, offsetof(HeapTupleHeaderData, t_bits));
 
-	memcpy((char *) &tuple->header + offsetof(HeapTupleHeaderData, t_bits),
+	memcpy((char *) &tuple->t_data.header + offsetof(HeapTupleHeaderData, t_bits),
 		   data + SizeOfHeapHeader,
 		   datalen);
 
-	tuple->header.t_infomask = xlhdr.t_infomask;
-	tuple->header.t_infomask2 = xlhdr.t_infomask2;
-	tuple->header.t_hoff = xlhdr.t_hoff;
+	tuple->t_data.header.t_infomask = xlhdr.t_infomask;
+	tuple->t_data.header.t_infomask2 = xlhdr.t_infomask2;
+	tuple->t_data.header.t_hoff = xlhdr.t_hoff;
 }
diff --git a/src/backend/replication/logical/reorderbuffer.c b/src/backend/replication/logical/reorderbuffer.c
index bcd5896..3226405 100644
--- a/src/backend/replication/logical/reorderbuffer.c
+++ b/src/backend/replication/logical/reorderbuffer.c
@@ -2014,14 +2014,12 @@ ReorderBufferSerializeChange(ReorderBuffer *rb, ReorderBufferTXN *txn,
 				newtup = change->data.tp.newtuple;
 
 				if (oldtup)
-					oldlen = offsetof(ReorderBufferTupleBuf, data)
-						+oldtup->tuple.t_len
-						- offsetof(HeapTupleHeaderData, t_bits);
+					oldlen = offsetof(ReorderBufferTupleBuf, t_data) +
+						oldtup->tuple.t_len;
 
 				if (newtup)
-					newlen = offsetof(ReorderBufferTupleBuf, data)
-						+newtup->tuple.t_len
-						- offsetof(HeapTupleHeaderData, t_bits);
+					newlen = offsetof(ReorderBufferTupleBuf, t_data) +
+						newtup->tuple.t_len;
 
 				sz += oldlen;
 				sz += newlen;
@@ -2262,27 +2260,25 @@ ReorderBufferRestoreChange(ReorderBuffer *rb, ReorderBufferTXN *txn,
 		case REORDER_BUFFER_CHANGE_DELETE:
 			if (change->data.tp.newtuple)
 			{
-				Size		len = offsetof(ReorderBufferTupleBuf, data)
-				+((ReorderBufferTupleBuf *) data)->tuple.t_len
-				- offsetof(HeapTupleHeaderData, t_bits);
+				Size		len = offsetof(ReorderBufferTupleBuf, t_data) +
+					((ReorderBufferTupleBuf *) data)->tuple.t_len;
 
 				change->data.tp.newtuple = ReorderBufferGetTupleBuf(rb);
 				memcpy(change->data.tp.newtuple, data, len);
 				change->data.tp.newtuple->tuple.t_data =
-					&change->data.tp.newtuple->header;
+					&change->data.tp.newtuple->t_data.header;
 				data += len;
 			}
 
 			if (change->data.tp.oldtuple)
 			{
-				Size		len = offsetof(ReorderBufferTupleBuf, data)
-				+((ReorderBufferTupleBuf *) data)->tuple.t_len
-				- offsetof(HeapTupleHeaderData, t_bits);
+				Size		len = offsetof(ReorderBufferTupleBuf, t_data) +
+					((ReorderBufferTupleBuf *) data)->tuple.t_len;
 
 				change->data.tp.oldtuple = ReorderBufferGetTupleBuf(rb);
 				memcpy(change->data.tp.oldtuple, data, len);
 				change->data.tp.oldtuple->tuple.t_data =
-					&change->data.tp.oldtuple->header;
+					&change->data.tp.oldtuple->t_data.header;
 				data += len;
 			}
 			break;
@@ -2660,7 +2656,7 @@ ReorderBufferToastReplace(ReorderBuffer *rb, ReorderBufferTXN *txn,
 	 */
 	tmphtup = heap_form_tuple(desc, attrs, isnull);
 	Assert(newtup->tuple.t_len <= MaxHeapTupleSize);
-	Assert(&newtup->header == newtup->tuple.t_data);
+	Assert(&newtup->t_data.header == newtup->tuple.t_data);
 
 	memcpy(newtup->tuple.t_data, tmphtup->t_data, tmphtup->t_len);
 	newtup->tuple.t_len = tmphtup->t_len;
diff --git a/src/include/access/htup_details.h b/src/include/access/htup_details.h
index d2ad910..475377c 100644
--- a/src/include/access/htup_details.h
+++ b/src/include/access/htup_details.h
@@ -150,7 +150,7 @@ struct HeapTupleHeaderData
 
 	/* ^ - 23 bytes - ^ */
 
-	bits8		t_bits[1];		/* bitmap of NULLs -- VARIABLE LENGTH */
+	bits8		t_bits[FLEXIBLE_ARRAY_MEMBER];	/* bitmap of NULLs */
 
 	/* MORE DATA FOLLOWS AT END OF STRUCT */
 };
@@ -579,7 +579,7 @@ struct MinimalTupleData
 
 	/* ^ - 23 bytes - ^ */
 
-	bits8		t_bits[1];		/* bitmap of NULLs -- VARIABLE LENGTH */
+	bits8		t_bits[FLEXIBLE_ARRAY_MEMBER];	/* bitmap of NULLs */
 
 	/* MORE DATA FOLLOWS AT END OF STRUCT */
 };
diff --git a/src/include/replication/reorderbuffer.h b/src/include/replication/reorderbuffer.h
index 5a1d9a0..dcfe2b3 100644
--- a/src/include/replication/reorderbuffer.h
+++ b/src/include/replication/reorderbuffer.h
@@ -28,8 +28,11 @@ typedef struct ReorderBufferTupleBuf
 
 	/* tuple, stored sequentially */
 	HeapTupleData tuple;
-	HeapTupleHeaderData header;
-	char		data[MaxHeapTupleSize];
+	union
+	{
+		HeapTupleHeaderData header;
+		char		data[MaxHeapTupleSize];
+	}	t_data;
 } ReorderBufferTupleBuf;
 
 /*
-- 
2.3.0

From 03ace39d9d9effb97e8b7fcdcfac456892a6333e Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@otacoo.com>
Date: Fri, 20 Feb 2015 16:53:27 +0900
Subject: [PATCH 3/4] Switch RecordIOData to use FLEXIBLE_ARRAY_MEMBER

This impacts hstore, json functions and rowtypes.
---
 contrib/hstore/hstore_io.c        | 18 +++++++++---------
 src/backend/utils/adt/jsonfuncs.c | 18 +++++++++---------
 2 files changed, 18 insertions(+), 18 deletions(-)

diff --git a/contrib/hstore/hstore_io.c b/contrib/hstore/hstore_io.c
index 079f662..7d89867 100644
--- a/contrib/hstore/hstore_io.c
+++ b/contrib/hstore/hstore_io.c
@@ -747,7 +747,7 @@ typedef struct RecordIOData
 	Oid			record_type;
 	int32		record_typmod;
 	int			ncolumns;
-	ColumnIOData columns[1];	/* VARIABLE LENGTH ARRAY */
+	ColumnIOData columns[FLEXIBLE_ARRAY_MEMBER];
 } RecordIOData;
 
 PG_FUNCTION_INFO_V1(hstore_from_record);
@@ -805,8 +805,8 @@ hstore_from_record(PG_FUNCTION_ARGS)
 	{
 		fcinfo->flinfo->fn_extra =
 			MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
-							   sizeof(RecordIOData) - sizeof(ColumnIOData)
-							   + ncolumns * sizeof(ColumnIOData));
+							   offsetof(RecordIOData, columns) +
+							   ncolumns * sizeof(ColumnIOData));
 		my_extra = (RecordIOData *) fcinfo->flinfo->fn_extra;
 		my_extra->record_type = InvalidOid;
 		my_extra->record_typmod = 0;
@@ -816,8 +816,8 @@ hstore_from_record(PG_FUNCTION_ARGS)
 		my_extra->record_typmod != tupTypmod)
 	{
 		MemSet(my_extra, 0,
-			   sizeof(RecordIOData) - sizeof(ColumnIOData)
-			   + ncolumns * sizeof(ColumnIOData));
+			   offsetof(RecordIOData, columns) +
+			   ncolumns * sizeof(ColumnIOData));
 		my_extra->record_type = tupType;
 		my_extra->record_typmod = tupTypmod;
 		my_extra->ncolumns = ncolumns;
@@ -990,8 +990,8 @@ hstore_populate_record(PG_FUNCTION_ARGS)
 	{
 		fcinfo->flinfo->fn_extra =
 			MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
-							   sizeof(RecordIOData) - sizeof(ColumnIOData)
-							   + ncolumns * sizeof(ColumnIOData));
+							   offsetof(RecordIOData, columns) +
+							   ncolumns * sizeof(ColumnIOData));
 		my_extra = (RecordIOData *) fcinfo->flinfo->fn_extra;
 		my_extra->record_type = InvalidOid;
 		my_extra->record_typmod = 0;
@@ -1001,8 +1001,8 @@ hstore_populate_record(PG_FUNCTION_ARGS)
 		my_extra->record_typmod != tupTypmod)
 	{
 		MemSet(my_extra, 0,
-			   sizeof(RecordIOData) - sizeof(ColumnIOData)
-			   + ncolumns * sizeof(ColumnIOData));
+			   offsetof(RecordIOData, columns) +
+			   ncolumns * sizeof(ColumnIOData));
 		my_extra->record_type = tupType;
 		my_extra->record_typmod = tupTypmod;
 		my_extra->ncolumns = ncolumns;
diff --git a/src/backend/utils/adt/jsonfuncs.c b/src/backend/utils/adt/jsonfuncs.c
index 3688163..a8cdeaa 100644
--- a/src/backend/utils/adt/jsonfuncs.c
+++ b/src/backend/utils/adt/jsonfuncs.c
@@ -216,7 +216,7 @@ typedef struct RecordIOData
 	Oid			record_type;
 	int32		record_typmod;
 	int			ncolumns;
-	ColumnIOData columns[1];	/* VARIABLE LENGTH ARRAY */
+	ColumnIOData columns[FLEXIBLE_ARRAY_MEMBER];
 } RecordIOData;
 
 /* state for populate_recordset */
@@ -2148,8 +2148,8 @@ populate_record_worker(FunctionCallInfo fcinfo, const char *funcname,
 	{
 		fcinfo->flinfo->fn_extra =
 			MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
-							   sizeof(RecordIOData) - sizeof(ColumnIOData)
-							   + ncolumns * sizeof(ColumnIOData));
+							   offsetof(RecordIOData, columns) +
+							   ncolumns * sizeof(ColumnIOData));
 		my_extra = (RecordIOData *) fcinfo->flinfo->fn_extra;
 		my_extra->record_type = InvalidOid;
 		my_extra->record_typmod = 0;
@@ -2161,8 +2161,8 @@ populate_record_worker(FunctionCallInfo fcinfo, const char *funcname,
 							my_extra->record_typmod != tupTypmod))
 	{
 		MemSet(my_extra, 0,
-			   sizeof(RecordIOData) - sizeof(ColumnIOData)
-			   + ncolumns * sizeof(ColumnIOData));
+			   offsetof(RecordIOData, columns) +
+			   ncolumns * sizeof(ColumnIOData));
 		my_extra->record_type = tupType;
 		my_extra->record_typmod = tupTypmod;
 		my_extra->ncolumns = ncolumns;
@@ -2653,8 +2653,8 @@ populate_recordset_worker(FunctionCallInfo fcinfo, const char *funcname,
 	{
 		fcinfo->flinfo->fn_extra =
 			MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
-							   sizeof(RecordIOData) - sizeof(ColumnIOData)
-							   + ncolumns * sizeof(ColumnIOData));
+							   offsetof(RecordIOData, columns) +
+							   ncolumns * sizeof(ColumnIOData));
 		my_extra = (RecordIOData *) fcinfo->flinfo->fn_extra;
 		my_extra->record_type = InvalidOid;
 		my_extra->record_typmod = 0;
@@ -2664,8 +2664,8 @@ populate_recordset_worker(FunctionCallInfo fcinfo, const char *funcname,
 		my_extra->record_typmod != tupTypmod)
 	{
 		MemSet(my_extra, 0,
-			   sizeof(RecordIOData) - sizeof(ColumnIOData)
-			   + ncolumns * sizeof(ColumnIOData));
+			   offsetof(RecordIOData, columns) +
+			   ncolumns * sizeof(ColumnIOData));
 		my_extra->record_type = tupType;
 		my_extra->record_typmod = tupTypmod;
 		my_extra->ncolumns = ncolumns;
-- 
2.3.0

From 0cda8f44d1e0f9b03c23bba8f206e6eb15e3e662 Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@otacoo.com>
Date: Fri, 20 Feb 2015 19:35:53 +0900
Subject: [PATCH 4/4] Switch remaining structures to FLEXIBLE_ARRAY_MEMBER in
 backend code

---
 src/backend/access/nbtree/nbtutils.c   |  4 ++--
 src/backend/access/transam/multixact.c |  4 ++--
 src/backend/access/transam/twophase.c  |  9 +++------
 src/backend/commands/tablespace.c      |  2 +-
 src/backend/commands/trigger.c         | 10 +++++-----
 src/backend/executor/nodeAgg.c         | 14 +++++++-------
 src/backend/postmaster/checkpointer.c  |  2 +-
 src/backend/storage/ipc/pmsignal.c     |  2 +-
 src/backend/storage/ipc/procarray.c    |  5 ++---
 src/backend/utils/cache/inval.c        | 12 ++++++------
 src/backend/utils/cache/typcache.c     |  2 +-
 11 files changed, 31 insertions(+), 35 deletions(-)

diff --git a/src/backend/access/nbtree/nbtutils.c b/src/backend/access/nbtree/nbtutils.c
index 43e048c..379dac9 100644
--- a/src/backend/access/nbtree/nbtutils.c
+++ b/src/backend/access/nbtree/nbtutils.c
@@ -1836,7 +1836,7 @@ typedef struct BTVacInfo
 	BTCycleId	cycle_ctr;		/* cycle ID most recently assigned */
 	int			num_vacuums;	/* number of currently active VACUUMs */
 	int			max_vacuums;	/* allocated length of vacuums[] array */
-	BTOneVacInfo vacuums[1];	/* VARIABLE LENGTH ARRAY */
+	BTOneVacInfo vacuums[FLEXIBLE_ARRAY_MEMBER];
 } BTVacInfo;
 
 static BTVacInfo *btvacinfo;
@@ -1984,7 +1984,7 @@ BTreeShmemSize(void)
 {
 	Size		size;
 
-	size = offsetof(BTVacInfo, vacuums[0]);
+	size = offsetof(BTVacInfo, vacuums);
 	size = add_size(size, mul_size(MaxBackends, sizeof(BTOneVacInfo)));
 	return size;
 }
diff --git a/src/backend/access/transam/multixact.c b/src/backend/access/transam/multixact.c
index b2cf770..e3db6f8 100644
--- a/src/backend/access/transam/multixact.c
+++ b/src/backend/access/transam/multixact.c
@@ -258,7 +258,7 @@ typedef struct MultiXactStateData
 	 * stored in pg_control and used as truncation point for pg_multixact.  At
 	 * checkpoint or restartpoint, unneeded segments are removed.
 	 */
-	MultiXactId perBackendXactIds[1];	/* VARIABLE LENGTH ARRAY */
+	MultiXactId perBackendXactIds[FLEXIBLE_ARRAY_MEMBER];
 } MultiXactStateData;
 
 /*
@@ -1745,7 +1745,7 @@ MultiXactShmemSize(void)
 	Size		size;
 
 #define SHARED_MULTIXACT_STATE_SIZE \
-	add_size(sizeof(MultiXactStateData), \
+	add_size(offsetof(MultiXactStateData, perBackendXactIds),	\
 			 mul_size(sizeof(MultiXactId) * 2, MaxOldestSlot))
 
 	size = SHARED_MULTIXACT_STATE_SIZE;
diff --git a/src/backend/access/transam/twophase.c b/src/backend/access/transam/twophase.c
index 6c7029e..6edc227 100644
--- a/src/backend/access/transam/twophase.c
+++ b/src/backend/access/transam/twophase.c
@@ -134,12 +134,9 @@ typedef struct TwoPhaseStateData
 	/* Number of valid prepXacts entries. */
 	int			numPrepXacts;
 
-	/*
-	 * There are max_prepared_xacts items in this array, but C wants a
-	 * fixed-size array.
-	 */
-	GlobalTransaction prepXacts[1];		/* VARIABLE LENGTH ARRAY */
-} TwoPhaseStateData;			/* VARIABLE LENGTH STRUCT */
+	/* There are max_prepared_xacts items in this array */
+	GlobalTransaction prepXacts[FLEXIBLE_ARRAY_MEMBER];
+} TwoPhaseStateData;
 
 static TwoPhaseStateData *TwoPhaseState;
 
diff --git a/src/backend/commands/tablespace.c b/src/backend/commands/tablespace.c
index e098b9f..03cc8fe 100644
--- a/src/backend/commands/tablespace.c
+++ b/src/backend/commands/tablespace.c
@@ -1088,7 +1088,7 @@ GetDefaultTablespace(char relpersistence)
 typedef struct
 {
 	int			numSpcs;
-	Oid			tblSpcs[1];		/* VARIABLE LENGTH ARRAY */
+	Oid			tblSpcs[FLEXIBLE_ARRAY_MEMBER];
 } temp_tablespaces_extra;
 
 /* check_hook: validate new temp_tablespaces */
diff --git a/src/backend/commands/trigger.c b/src/backend/commands/trigger.c
index 5c1c1be..4223398 100644
--- a/src/backend/commands/trigger.c
+++ b/src/backend/commands/trigger.c
@@ -3005,7 +3005,7 @@ typedef struct SetConstraintStateData
 	bool		all_isdeferred;
 	int			numstates;		/* number of trigstates[] entries in use */
 	int			numalloc;		/* allocated size of trigstates[] */
-	SetConstraintTriggerData trigstates[1];		/* VARIABLE LENGTH ARRAY */
+	SetConstraintTriggerData trigstates[FLEXIBLE_ARRAY_MEMBER];
 } SetConstraintStateData;
 
 typedef SetConstraintStateData *SetConstraintState;
@@ -4398,8 +4398,8 @@ SetConstraintStateCreate(int numalloc)
 	 */
 	state = (SetConstraintState)
 		MemoryContextAllocZero(TopTransactionContext,
-							   sizeof(SetConstraintStateData) +
-						   (numalloc - 1) *sizeof(SetConstraintTriggerData));
+							   offsetof(SetConstraintStateData, trigstates) +
+						   numalloc *sizeof(SetConstraintTriggerData));
 
 	state->numalloc = numalloc;
 
@@ -4440,8 +4440,8 @@ SetConstraintStateAddItem(SetConstraintState state,
 		newalloc = Max(newalloc, 8);	/* in case original has size 0 */
 		state = (SetConstraintState)
 			repalloc(state,
-					 sizeof(SetConstraintStateData) +
-					 (newalloc - 1) *sizeof(SetConstraintTriggerData));
+					 offsetof(SetConstraintStateData, trigstates) +
+					 newalloc * sizeof(SetConstraintTriggerData));
 		state->numalloc = newalloc;
 		Assert(state->numstates < state->numalloc);
 	}
diff --git a/src/backend/executor/nodeAgg.c b/src/backend/executor/nodeAgg.c
index 8079d97..9ff0eff 100644
--- a/src/backend/executor/nodeAgg.c
+++ b/src/backend/executor/nodeAgg.c
@@ -297,9 +297,9 @@ typedef struct AggHashEntryData *AggHashEntry;
 typedef struct AggHashEntryData
 {
 	TupleHashEntryData shared;	/* common header for hash table entries */
-	/* per-aggregate transition status array - must be last! */
-	AggStatePerGroupData pergroup[1];	/* VARIABLE LENGTH ARRAY */
-}	AggHashEntryData;	/* VARIABLE LENGTH STRUCT */
+	/* per-aggregate transition status array */
+	AggStatePerGroupData pergroup[FLEXIBLE_ARRAY_MEMBER];
+}	AggHashEntryData;
 
 
 static void initialize_aggregates(AggState *aggstate,
@@ -941,8 +941,8 @@ build_hash_table(AggState *aggstate)
 	Assert(node->aggstrategy == AGG_HASHED);
 	Assert(node->numGroups > 0);
 
-	entrysize = sizeof(AggHashEntryData) +
-		(aggstate->numaggs - 1) * sizeof(AggStatePerGroupData);
+	entrysize = offsetof(AggHashEntryData, pergroup) +
+		aggstate->numaggs * sizeof(AggStatePerGroupData);
 
 	aggstate->hashtable = BuildTupleHashTable(node->numCols,
 											  node->grpColIdx,
@@ -1013,8 +1013,8 @@ hash_agg_entry_size(int numAggs)
 	Size		entrysize;
 
 	/* This must match build_hash_table */
-	entrysize = sizeof(AggHashEntryData) +
-		(numAggs - 1) * sizeof(AggStatePerGroupData);
+	entrysize = offsetof(AggHashEntryData, pergroup) +
+		numAggs * sizeof(AggStatePerGroupData);
 	entrysize = MAXALIGN(entrysize);
 	/* Account for hashtable overhead (assuming fill factor = 1) */
 	entrysize += 3 * sizeof(void *);
diff --git a/src/backend/postmaster/checkpointer.c b/src/backend/postmaster/checkpointer.c
index 237be12..cfad08d 100644
--- a/src/backend/postmaster/checkpointer.c
+++ b/src/backend/postmaster/checkpointer.c
@@ -130,7 +130,7 @@ typedef struct
 
 	int			num_requests;	/* current # of requests */
 	int			max_requests;	/* allocated array size */
-	CheckpointerRequest requests[1];	/* VARIABLE LENGTH ARRAY */
+	CheckpointerRequest requests[FLEXIBLE_ARRAY_MEMBER];
 } CheckpointerShmemStruct;
 
 static CheckpointerShmemStruct *CheckpointerShmem;
diff --git a/src/backend/storage/ipc/pmsignal.c b/src/backend/storage/ipc/pmsignal.c
index 0c89eb7..ea3fe20 100644
--- a/src/backend/storage/ipc/pmsignal.c
+++ b/src/backend/storage/ipc/pmsignal.c
@@ -66,7 +66,7 @@ struct PMSignalData
 	/* per-child-process flags */
 	int			num_child_flags;	/* # of entries in PMChildFlags[] */
 	int			next_child_flag;	/* next slot to try to assign */
-	sig_atomic_t PMChildFlags[1];		/* VARIABLE LENGTH ARRAY */
+	sig_atomic_t PMChildFlags[FLEXIBLE_ARRAY_MEMBER];
 };
 
 NON_EXEC_STATIC volatile PMSignalData *PMSignalState = NULL;
diff --git a/src/backend/storage/ipc/procarray.c b/src/backend/storage/ipc/procarray.c
index a1ebc72..39846d6 100644
--- a/src/backend/storage/ipc/procarray.c
+++ b/src/backend/storage/ipc/procarray.c
@@ -91,10 +91,9 @@ typedef struct ProcArrayStruct
 	TransactionId replication_slot_catalog_xmin;
 
 	/*
-	 * We declare pgprocnos[] as 1 entry because C wants a fixed-size array,
-	 * but actually it is maxProcs entries long.
+	 * Number of procs with maxProcs entries.
 	 */
-	int			pgprocnos[1];	/* VARIABLE LENGTH ARRAY */
+	int			pgprocnos[FLEXIBLE_ARRAY_MEMBER];
 } ProcArrayStruct;
 
 static ProcArrayStruct *procArray;
diff --git a/src/backend/utils/cache/inval.c b/src/backend/utils/cache/inval.c
index 0f2192c..8826a5d 100644
--- a/src/backend/utils/cache/inval.c
+++ b/src/backend/utils/cache/inval.c
@@ -122,8 +122,8 @@ typedef struct InvalidationChunk
 	struct InvalidationChunk *next;		/* list link */
 	int			nitems;			/* # items currently stored in chunk */
 	int			maxitems;		/* size of allocated array in this chunk */
-	SharedInvalidationMessage msgs[1];	/* VARIABLE LENGTH ARRAY */
-} InvalidationChunk;			/* VARIABLE LENGTH STRUCTURE */
+	SharedInvalidationMessage msgs[FLEXIBLE_ARRAY_MEMBER];
+} InvalidationChunk;
 
 typedef struct InvalidationListHeader
 {
@@ -225,8 +225,8 @@ AddInvalidationMessage(InvalidationChunk **listHdr,
 #define FIRSTCHUNKSIZE 32
 		chunk = (InvalidationChunk *)
 			MemoryContextAlloc(CurTransactionContext,
-							   sizeof(InvalidationChunk) +
-					(FIRSTCHUNKSIZE - 1) *sizeof(SharedInvalidationMessage));
+							   offsetof(InvalidationChunk, msgs) +
+					FIRSTCHUNKSIZE * sizeof(SharedInvalidationMessage));
 		chunk->nitems = 0;
 		chunk->maxitems = FIRSTCHUNKSIZE;
 		chunk->next = *listHdr;
@@ -239,8 +239,8 @@ AddInvalidationMessage(InvalidationChunk **listHdr,
 
 		chunk = (InvalidationChunk *)
 			MemoryContextAlloc(CurTransactionContext,
-							   sizeof(InvalidationChunk) +
-						 (chunksize - 1) *sizeof(SharedInvalidationMessage));
+							   offsetof(InvalidationChunk, msgs) +
+						 chunksize * sizeof(SharedInvalidationMessage));
 		chunk->nitems = 0;
 		chunk->maxitems = chunksize;
 		chunk->next = *listHdr;
diff --git a/src/backend/utils/cache/typcache.c b/src/backend/utils/cache/typcache.c
index 82b6668..0492718 100644
--- a/src/backend/utils/cache/typcache.c
+++ b/src/backend/utils/cache/typcache.c
@@ -93,7 +93,7 @@ typedef struct TypeCacheEnumData
 	Oid			bitmap_base;	/* OID corresponding to bit 0 of bitmapset */
 	Bitmapset  *sorted_values;	/* Set of OIDs known to be in order */
 	int			num_values;		/* total number of values in enum */
-	EnumItem	enum_values[1]; /* VARIABLE LENGTH ARRAY */
+	EnumItem	enum_values[FLEXIBLE_ARRAY_MEMBER];
 } TypeCacheEnumData;
 
 /*
-- 
2.3.0

From 3951d103d5bff49f300c89e34d2fa7bd893b9fd4 Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@otacoo.com>
Date: Fri, 20 Feb 2015 16:42:28 +0900
Subject: [PATCH] Switch HeapTupleHeaderData and MinimalTupleData to use
 flexible arrays

This is some more hacking related to FLEXIBLE_ARRAY_MEMBER.
---
 contrib/file_fdw/file_fdw.c                     |  2 +-
 contrib/postgres_fdw/postgres_fdw.c             |  2 +-
 src/backend/access/common/heaptuple.c           |  2 +-
 src/backend/access/heap/heapam.c                | 56 ++++++++++++-------------
 src/backend/access/heap/tuptoaster.c            | 10 ++---
 src/backend/catalog/toasting.c                  |  2 +-
 src/backend/executor/nodeHash.c                 |  2 +-
 src/backend/optimizer/path/costsize.c           |  7 ++--
 src/backend/optimizer/plan/planner.c            |  6 ++-
 src/backend/optimizer/plan/subselect.c          |  9 ++--
 src/backend/optimizer/prep/prepunion.c          |  3 +-
 src/backend/optimizer/util/plancat.c            |  2 +-
 src/backend/replication/logical/decode.c        | 30 ++++++-------
 src/backend/replication/logical/reorderbuffer.c | 26 +++++-------
 src/backend/utils/adt/trigfuncs.c               |  6 +--
 src/include/access/htup_details.h               | 10 +++--
 src/include/access/tuptoaster.h                 |  2 +-
 src/include/replication/reorderbuffer.h         |  7 +++-
 18 files changed, 95 insertions(+), 89 deletions(-)

diff --git a/contrib/file_fdw/file_fdw.c b/contrib/file_fdw/file_fdw.c
index d569760..4368897 100644
--- a/contrib/file_fdw/file_fdw.c
+++ b/contrib/file_fdw/file_fdw.c
@@ -932,7 +932,7 @@ estimate_size(PlannerInfo *root, RelOptInfo *baserel,
 		int			tuple_width;
 
 		tuple_width = MAXALIGN(baserel->width) +
-			MAXALIGN(sizeof(HeapTupleHeaderData));
+			MAXALIGN(SizeofHeapTupleHeader);
 		ntuples = clamp_row_est((double) stat_buf.st_size /
 								(double) tuple_width);
 	}
diff --git a/contrib/postgres_fdw/postgres_fdw.c b/contrib/postgres_fdw/postgres_fdw.c
index d76e739..8bb1c80 100644
--- a/contrib/postgres_fdw/postgres_fdw.c
+++ b/contrib/postgres_fdw/postgres_fdw.c
@@ -519,7 +519,7 @@ postgresGetForeignRelSize(PlannerInfo *root,
 		{
 			baserel->pages = 10;
 			baserel->tuples =
-				(10 * BLCKSZ) / (baserel->width + sizeof(HeapTupleHeaderData));
+				(10 * BLCKSZ) / (baserel->width + SizeofHeapTupleHeader);
 		}
 
 		/* Estimate baserel size as best we can with local statistics. */
diff --git a/src/backend/access/common/heaptuple.c b/src/backend/access/common/heaptuple.c
index 867035d..66db9c6 100644
--- a/src/backend/access/common/heaptuple.c
+++ b/src/backend/access/common/heaptuple.c
@@ -694,7 +694,7 @@ heap_form_tuple(TupleDesc tupleDescriptor,
 	/*
 	 * Determine total space needed
 	 */
-	len = offsetof(HeapTupleHeaderData, t_bits);
+	len = SizeofHeapTupleHeader;
 
 	if (hasnull)
 		len += BITMAPLEN(numberOfAttributes);
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 46060bc1..00f3b94 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -2186,8 +2186,8 @@ heap_insert(Relation relation, HeapTuple tup, CommandId cid,
 		XLogRegisterBufData(0, (char *) &xlhdr, SizeOfHeapHeader);
 		/* PG73FORMAT: write bitmap [+ padding] [+ oid] + data */
 		XLogRegisterBufData(0,
-			(char *) heaptup->t_data + offsetof(HeapTupleHeaderData, t_bits),
-					 heaptup->t_len - offsetof(HeapTupleHeaderData, t_bits));
+			(char *) heaptup->t_data + SizeofHeapTupleHeader,
+					 heaptup->t_len - SizeofHeapTupleHeader);
 
 		recptr = XLogInsert(RM_HEAP_ID, info);
 
@@ -2460,9 +2460,9 @@ heap_multi_insert(Relation relation, HeapTuple *tuples, int ntuples,
 				tuphdr->t_hoff = heaptup->t_data->t_hoff;
 
 				/* write bitmap [+ padding] [+ oid] + data */
-				datalen = heaptup->t_len - offsetof(HeapTupleHeaderData, t_bits);
+				datalen = heaptup->t_len - SizeofHeapTupleHeader;
 				memcpy(scratchptr,
-					   (char *) heaptup->t_data + offsetof(HeapTupleHeaderData, t_bits),
+					   (char *) heaptup->t_data + SizeofHeapTupleHeader,
 					   datalen);
 				tuphdr->datalen = datalen;
 				scratchptr += datalen;
@@ -2904,9 +2904,9 @@ l1:
 
 			XLogRegisterData((char *) &xlhdr, SizeOfHeapHeader);
 			XLogRegisterData((char *) old_key_tuple->t_data
-							 + offsetof(HeapTupleHeaderData, t_bits),
+							 + SizeofHeapTupleHeader,
 							 old_key_tuple->t_len
-							 - offsetof(HeapTupleHeaderData, t_bits));
+							 - SizeofHeapTupleHeader);
 		}
 
 		recptr = XLogInsert(RM_HEAP_ID, XLOG_HEAP_DELETE);
@@ -6732,7 +6732,7 @@ log_heap_update(Relation reln, Buffer oldbuf,
 	xlhdr.t_infomask2 = newtup->t_data->t_infomask2;
 	xlhdr.t_infomask = newtup->t_data->t_infomask;
 	xlhdr.t_hoff = newtup->t_data->t_hoff;
-	Assert(offsetof(HeapTupleHeaderData, t_bits) + prefixlen + suffixlen <= newtup->t_len);
+	Assert(SizeofHeapTupleHeader + prefixlen + suffixlen <= newtup->t_len);
 
 	/*
 	 * PG73FORMAT: write bitmap [+ padding] [+ oid] + data
@@ -6743,8 +6743,8 @@ log_heap_update(Relation reln, Buffer oldbuf,
 	if (prefixlen == 0)
 	{
 		XLogRegisterBufData(0,
-		   ((char *) newtup->t_data) + offsetof(HeapTupleHeaderData, t_bits),
-		   newtup->t_len - offsetof(HeapTupleHeaderData, t_bits) -suffixlen);
+		   ((char *) newtup->t_data) + SizeofHeapTupleHeader,
+		   newtup->t_len - SizeofHeapTupleHeader -suffixlen);
 	}
 	else
 	{
@@ -6753,11 +6753,11 @@ log_heap_update(Relation reln, Buffer oldbuf,
 		 * two separate rdata entries.
 		 */
 		/* bitmap [+ padding] [+ oid] */
-		if (newtup->t_data->t_hoff - offsetof(HeapTupleHeaderData, t_bits) >0)
+		if (newtup->t_data->t_hoff - SizeofHeapTupleHeader >0)
 		{
 			XLogRegisterBufData(0,
-			((char *) newtup->t_data) + offsetof(HeapTupleHeaderData, t_bits),
-			 newtup->t_data->t_hoff - offsetof(HeapTupleHeaderData, t_bits));
+			((char *) newtup->t_data) + SizeofHeapTupleHeader,
+			 newtup->t_data->t_hoff - SizeofHeapTupleHeader);
 		}
 
 		/* data after common prefix */
@@ -6777,8 +6777,8 @@ log_heap_update(Relation reln, Buffer oldbuf,
 		XLogRegisterData((char *) &xlhdr_idx, SizeOfHeapHeader);
 
 		/* PG73FORMAT: write bitmap [+ padding] [+ oid] + data */
-		XLogRegisterData((char *) old_key_tuple->t_data + offsetof(HeapTupleHeaderData, t_bits),
-			   old_key_tuple->t_len - offsetof(HeapTupleHeaderData, t_bits));
+		XLogRegisterData((char *) old_key_tuple->t_data + SizeofHeapTupleHeader,
+			   old_key_tuple->t_len - SizeofHeapTupleHeader);
 	}
 
 	recptr = XLogInsert(RM_HEAP_ID, info);
@@ -7351,7 +7351,7 @@ heap_xlog_insert(XLogReaderState *record)
 	xl_heap_insert *xlrec = (xl_heap_insert *) XLogRecGetData(record);
 	Buffer		buffer;
 	Page		page;
-	struct
+	union
 	{
 		HeapTupleHeaderData hdr;
 		char		data[MaxHeapTupleSize];
@@ -7415,12 +7415,12 @@ heap_xlog_insert(XLogReaderState *record)
 		data += SizeOfHeapHeader;
 
 		htup = &tbuf.hdr;
-		MemSet((char *) htup, 0, sizeof(HeapTupleHeaderData));
+		MemSet((char *) htup, 0, SizeofHeapTupleHeader);
 		/* PG73FORMAT: get bitmap [+ padding] [+ oid] + data */
-		memcpy((char *) htup + offsetof(HeapTupleHeaderData, t_bits),
+		memcpy((char *) htup + SizeofHeapTupleHeader,
 			   data,
 			   newlen);
-		newlen += offsetof(HeapTupleHeaderData, t_bits);
+		newlen += SizeofHeapTupleHeader;
 		htup->t_infomask2 = xlhdr.t_infomask2;
 		htup->t_infomask = xlhdr.t_infomask;
 		htup->t_hoff = xlhdr.t_hoff;
@@ -7469,7 +7469,7 @@ heap_xlog_multi_insert(XLogReaderState *record)
 	BlockNumber blkno;
 	Buffer		buffer;
 	Page		page;
-	struct
+	union
 	{
 		HeapTupleHeaderData hdr;
 		char		data[MaxHeapTupleSize];
@@ -7548,14 +7548,14 @@ heap_xlog_multi_insert(XLogReaderState *record)
 			newlen = xlhdr->datalen;
 			Assert(newlen <= MaxHeapTupleSize);
 			htup = &tbuf.hdr;
-			MemSet((char *) htup, 0, sizeof(HeapTupleHeaderData));
+			MemSet((char *) htup, 0, SizeofHeapTupleHeader);
 			/* PG73FORMAT: get bitmap [+ padding] [+ oid] + data */
-			memcpy((char *) htup + offsetof(HeapTupleHeaderData, t_bits),
+			memcpy((char *) htup + SizeofHeapTupleHeader,
 				   (char *) tupdata,
 				   newlen);
 			tupdata += newlen;
 
-			newlen += offsetof(HeapTupleHeaderData, t_bits);
+			newlen += SizeofHeapTupleHeader;
 			htup->t_infomask2 = xlhdr->t_infomask2;
 			htup->t_infomask = xlhdr->t_infomask;
 			htup->t_hoff = xlhdr->t_hoff;
@@ -7618,7 +7618,7 @@ heap_xlog_update(XLogReaderState *record, bool hot_update)
 	uint16		prefixlen = 0,
 				suffixlen = 0;
 	char	   *newp;
-	struct
+	union
 	{
 		HeapTupleHeaderData hdr;
 		char		data[MaxHeapTupleSize];
@@ -7780,19 +7780,19 @@ heap_xlog_update(XLogReaderState *record, bool hot_update)
 		Assert(tuplen <= MaxHeapTupleSize);
 
 		htup = &tbuf.hdr;
-		MemSet((char *) htup, 0, sizeof(HeapTupleHeaderData));
+		MemSet((char *) htup, 0, SizeofHeapTupleHeader);
 
 		/*
 		 * Reconstruct the new tuple using the prefix and/or suffix from the
 		 * old tuple, and the data stored in the WAL record.
 		 */
-		newp = (char *) htup + offsetof(HeapTupleHeaderData, t_bits);
+		newp = (char *) htup + SizeofHeapTupleHeader;
 		if (prefixlen > 0)
 		{
 			int			len;
 
 			/* copy bitmap [+ padding] [+ oid] from WAL record */
-			len = xlhdr.t_hoff - offsetof(HeapTupleHeaderData, t_bits);
+			len = xlhdr.t_hoff - SizeofHeapTupleHeader;
 			memcpy(newp, recdata, len);
 			recdata += len;
 			newp += len;
@@ -7802,7 +7802,7 @@ heap_xlog_update(XLogReaderState *record, bool hot_update)
 			newp += prefixlen;
 
 			/* copy new tuple data from WAL record */
-			len = tuplen - (xlhdr.t_hoff - offsetof(HeapTupleHeaderData, t_bits));
+			len = tuplen - (xlhdr.t_hoff - SizeofHeapTupleHeader);
 			memcpy(newp, recdata, len);
 			recdata += len;
 			newp += len;
@@ -7823,7 +7823,7 @@ heap_xlog_update(XLogReaderState *record, bool hot_update)
 		if (suffixlen > 0)
 			memcpy(newp, (char *) oldtup.t_data + oldtup.t_len - suffixlen, suffixlen);
 
-		newlen = offsetof(HeapTupleHeaderData, t_bits) + tuplen + prefixlen + suffixlen;
+		newlen = SizeofHeapTupleHeader + tuplen + prefixlen + suffixlen;
 		htup->t_infomask2 = xlhdr.t_infomask2;
 		htup->t_infomask = xlhdr.t_infomask;
 		htup->t_hoff = xlhdr.t_hoff;
diff --git a/src/backend/access/heap/tuptoaster.c b/src/backend/access/heap/tuptoaster.c
index deb3372..8464e87 100644
--- a/src/backend/access/heap/tuptoaster.c
+++ b/src/backend/access/heap/tuptoaster.c
@@ -677,7 +677,7 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 	 */
 
 	/* compute header overhead --- this should match heap_form_tuple() */
-	hoff = offsetof(HeapTupleHeaderData, t_bits);
+	hoff = SizeofHeapTupleHeader;
 	if (has_nulls)
 		hoff += BITMAPLEN(numAttrs);
 	if (newtup->t_data->t_infomask & HEAP_HASOID)
@@ -963,7 +963,7 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		 * different conclusion about the size of the null bitmap, or even
 		 * whether there needs to be one at all.
 		 */
-		new_header_len = offsetof(HeapTupleHeaderData, t_bits);
+		new_header_len = SizeofHeapTupleHeader;
 		if (has_nulls)
 			new_header_len += BITMAPLEN(numAttrs);
 		if (olddata->t_infomask & HEAP_HASOID)
@@ -986,7 +986,7 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		/*
 		 * Copy the existing tuple header, but adjust natts and t_hoff.
 		 */
-		memcpy(new_data, olddata, offsetof(HeapTupleHeaderData, t_bits));
+		memcpy(new_data, olddata, SizeofHeapTupleHeader);
 		HeapTupleHeaderSetNatts(new_data, numAttrs);
 		new_data->t_hoff = new_header_len;
 		if (olddata->t_infomask & HEAP_HASOID)
@@ -1196,7 +1196,7 @@ toast_flatten_tuple_to_datum(HeapTupleHeader tup,
 	 *
 	 * This should match the reconstruction code in toast_insert_or_update.
 	 */
-	new_header_len = offsetof(HeapTupleHeaderData, t_bits);
+	new_header_len = SizeofHeapTupleHeader;
 	if (has_nulls)
 		new_header_len += BITMAPLEN(numAttrs);
 	if (tup->t_infomask & HEAP_HASOID)
@@ -1211,7 +1211,7 @@ toast_flatten_tuple_to_datum(HeapTupleHeader tup,
 	/*
 	 * Copy the existing tuple header, but adjust natts and t_hoff.
 	 */
-	memcpy(new_data, tup, offsetof(HeapTupleHeaderData, t_bits));
+	memcpy(new_data, tup, SizeofHeapTupleHeader);
 	HeapTupleHeaderSetNatts(new_data, numAttrs);
 	new_data->t_hoff = new_header_len;
 	if (tup->t_infomask & HEAP_HASOID)
diff --git a/src/backend/catalog/toasting.c b/src/backend/catalog/toasting.c
index e73252c..a1efddb 100644
--- a/src/backend/catalog/toasting.c
+++ b/src/backend/catalog/toasting.c
@@ -447,7 +447,7 @@ needs_toast_table(Relation rel)
 		return false;			/* nothing to toast? */
 	if (maxlength_unknown)
 		return true;			/* any unlimited-length attrs? */
-	tuple_length = MAXALIGN(offsetof(HeapTupleHeaderData, t_bits) +
+	tuple_length = MAXALIGN(SizeofHeapTupleHeader +
 							BITMAPLEN(tupdesc->natts)) +
 		MAXALIGN(data_length);
 	return (tuple_length > TOAST_TUPLE_THRESHOLD);
diff --git a/src/backend/executor/nodeHash.c b/src/backend/executor/nodeHash.c
index abd70b3..4b922b9 100644
--- a/src/backend/executor/nodeHash.c
+++ b/src/backend/executor/nodeHash.c
@@ -439,7 +439,7 @@ ExecChooseHashTableSize(double ntuples, int tupwidth, bool useskew,
 	 * don't count palloc overhead either.
 	 */
 	tupsize = HJTUPLE_OVERHEAD +
-		MAXALIGN(sizeof(MinimalTupleData)) +
+		MAXALIGN(offsetof(MinimalTupleData, t_bits)) +
 		MAXALIGN(tupwidth);
 	inner_rel_bytes = ntuples * tupsize;
 
diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c
index 020558b..d24b4d8 100644
--- a/src/backend/optimizer/path/costsize.c
+++ b/src/backend/optimizer/path/costsize.c
@@ -4036,11 +4036,11 @@ set_rel_width(PlannerInfo *root, RelOptInfo *rel)
 
 	/*
 	 * If we have a whole-row reference, estimate its width as the sum of
-	 * per-column widths plus sizeof(HeapTupleHeaderData).
+	 * per-column widths plus SizeofHeapTupleHeader.
 	 */
 	if (have_wholerow_var)
 	{
-		int32		wholerow_width = sizeof(HeapTupleHeaderData);
+		int32		wholerow_width = SizeofHeapTupleHeader;
 
 		if (reloid != InvalidOid)
 		{
@@ -4078,7 +4078,8 @@ set_rel_width(PlannerInfo *root, RelOptInfo *rel)
 static double
 relation_byte_size(double tuples, int width)
 {
-	return tuples * (MAXALIGN(width) + MAXALIGN(sizeof(HeapTupleHeaderData)));
+	return tuples * (MAXALIGN(width) +
+					 MAXALIGN(SizeofHeapTupleHeader));
 }
 
 /*
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 5c4884f..1e6680c 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -2755,7 +2755,8 @@ choose_hashed_grouping(PlannerInfo *root,
 	 */
 
 	/* Estimate per-hash-entry space at tuple width... */
-	hashentrysize = MAXALIGN(path_width) + MAXALIGN(sizeof(MinimalTupleData));
+	hashentrysize = MAXALIGN(path_width) +
+		MAXALIGN(offsetof(MinimalTupleData, t_bits));
 	/* plus space for pass-by-ref transition values... */
 	hashentrysize += agg_costs->transitionSpace;
 	/* plus the per-hash-entry overhead */
@@ -2923,7 +2924,8 @@ choose_hashed_distinct(PlannerInfo *root,
 	 */
 
 	/* Estimate per-hash-entry space at tuple width... */
-	hashentrysize = MAXALIGN(path_width) + MAXALIGN(sizeof(MinimalTupleData));
+	hashentrysize = MAXALIGN(path_width) +
+		MAXALIGN(offsetof(MinimalTupleData, t_bits));
 	/* plus the per-hash-entry overhead */
 	hashentrysize += hash_agg_entry_size(0);
 
diff --git a/src/backend/optimizer/plan/subselect.c b/src/backend/optimizer/plan/subselect.c
index 78fb6b1..11c4dd9 100644
--- a/src/backend/optimizer/plan/subselect.c
+++ b/src/backend/optimizer/plan/subselect.c
@@ -974,12 +974,13 @@ subplan_is_hashable(Plan *plan)
 
 	/*
 	 * The estimated size of the subquery result must fit in work_mem. (Note:
-	 * we use sizeof(HeapTupleHeaderData) here even though the tuples will
-	 * actually be stored as MinimalTuples; this provides some fudge factor
-	 * for hashtable overhead.)
+	 * we use SizeofHeapTupleHeader here even though the tuples will actually
+	 * be stored as MinimalTuples; this provides some fudge factor for
+	 * hashtable overhead.)
 	 */
 	subquery_size = plan->plan_rows *
-		(MAXALIGN(plan->plan_width) + MAXALIGN(sizeof(HeapTupleHeaderData)));
+		(MAXALIGN(plan->plan_width) +
+		 MAXALIGN(SizeofHeapTupleHeader));
 	if (subquery_size > work_mem * 1024L)
 		return false;
 
diff --git a/src/backend/optimizer/prep/prepunion.c b/src/backend/optimizer/prep/prepunion.c
index 05f601e..b290a08 100644
--- a/src/backend/optimizer/prep/prepunion.c
+++ b/src/backend/optimizer/prep/prepunion.c
@@ -832,7 +832,8 @@ choose_hashed_setop(PlannerInfo *root, List *groupClauses,
 	 * Don't do it if it doesn't look like the hashtable will fit into
 	 * work_mem.
 	 */
-	hashentrysize = MAXALIGN(input_plan->plan_width) + MAXALIGN(sizeof(MinimalTupleData));
+	hashentrysize = MAXALIGN(input_plan->plan_width) +
+		MAXALIGN(offsetof(MinimalTupleData, t_bits));
 
 	if (hashentrysize * dNumGroups > work_mem * 1024L)
 		return false;
diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index fb7db6d..034b8dc 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -508,7 +508,7 @@ estimate_rel_size(Relation rel, int32 *attr_widths,
 				int32		tuple_width;
 
 				tuple_width = get_rel_data_width(rel, attr_widths);
-				tuple_width += sizeof(HeapTupleHeaderData);
+				tuple_width += SizeofHeapTupleHeader;
 				tuple_width += sizeof(ItemIdData);
 				/* note: integer division is intentional here */
 				density = (BLCKSZ - SizeOfPageHeaderData) / tuple_width;
diff --git a/src/backend/replication/logical/decode.c b/src/backend/replication/logical/decode.c
index 77c02ba..31487ea 100644
--- a/src/backend/replication/logical/decode.c
+++ b/src/backend/replication/logical/decode.c
@@ -765,21 +765,21 @@ DecodeMultiInsert(LogicalDecodingContext *ctx, XLogRecordBuffer *buf)
 			 * transactions.
 			 */
 			tuple->tuple.t_tableOid = InvalidOid;
-			tuple->tuple.t_data = &tuple->header;
+			tuple->tuple.t_data = &tuple->t_data.header;
 			tuple->tuple.t_len = datalen
-				+ offsetof(HeapTupleHeaderData, t_bits);
+				+ SizeofHeapTupleHeader;
 
-			memset(&tuple->header, 0, sizeof(HeapTupleHeaderData));
+			memset(&tuple->t_data.header, 0, SizeofHeapTupleHeader);
 
-			memcpy((char *) &tuple->header
-				   + offsetof(HeapTupleHeaderData, t_bits),
+			memcpy((char *) &tuple->t_data.header
+				   + SizeofHeapTupleHeader,
 				   (char *) data,
 				   datalen);
 			data += datalen;
 
-			tuple->header.t_infomask = xlhdr->t_infomask;
-			tuple->header.t_infomask2 = xlhdr->t_infomask2;
-			tuple->header.t_hoff = xlhdr->t_hoff;
+			tuple->t_data.header.t_infomask = xlhdr->t_infomask;
+			tuple->t_data.header.t_infomask2 = xlhdr->t_infomask2;
+			tuple->t_data.header.t_hoff = xlhdr->t_hoff;
 		}
 
 		/*
@@ -815,27 +815,27 @@ DecodeXLogTuple(char *data, Size len, ReorderBufferTupleBuf *tuple)
 	Assert(datalen >= 0);
 	Assert(datalen <= MaxHeapTupleSize);
 
-	tuple->tuple.t_len = datalen + offsetof(HeapTupleHeaderData, t_bits);
+	tuple->tuple.t_len = datalen + SizeofHeapTupleHeader;
 
 	/* not a disk based tuple */
 	ItemPointerSetInvalid(&tuple->tuple.t_self);
 
 	/* we can only figure this out after reassembling the transactions */
 	tuple->tuple.t_tableOid = InvalidOid;
-	tuple->tuple.t_data = &tuple->header;
+	tuple->tuple.t_data = &tuple->t_data.header;
 
 	/* data is not stored aligned, copy to aligned storage */
 	memcpy((char *) &xlhdr,
 		   data,
 		   SizeOfHeapHeader);
 
-	memset(&tuple->header, 0, sizeof(HeapTupleHeaderData));
+	memset(&tuple->t_data.header, 0, SizeofHeapTupleHeader);
 
-	memcpy((char *) &tuple->header + offsetof(HeapTupleHeaderData, t_bits),
+	memcpy((char *) &tuple->t_data.header + SizeofHeapTupleHeader,
 		   data + SizeOfHeapHeader,
 		   datalen);
 
-	tuple->header.t_infomask = xlhdr.t_infomask;
-	tuple->header.t_infomask2 = xlhdr.t_infomask2;
-	tuple->header.t_hoff = xlhdr.t_hoff;
+	tuple->t_data.header.t_infomask = xlhdr.t_infomask;
+	tuple->t_data.header.t_infomask2 = xlhdr.t_infomask2;
+	tuple->t_data.header.t_hoff = xlhdr.t_hoff;
 }
diff --git a/src/backend/replication/logical/reorderbuffer.c b/src/backend/replication/logical/reorderbuffer.c
index bcd5896..3226405 100644
--- a/src/backend/replication/logical/reorderbuffer.c
+++ b/src/backend/replication/logical/reorderbuffer.c
@@ -2014,14 +2014,12 @@ ReorderBufferSerializeChange(ReorderBuffer *rb, ReorderBufferTXN *txn,
 				newtup = change->data.tp.newtuple;
 
 				if (oldtup)
-					oldlen = offsetof(ReorderBufferTupleBuf, data)
-						+oldtup->tuple.t_len
-						- offsetof(HeapTupleHeaderData, t_bits);
+					oldlen = offsetof(ReorderBufferTupleBuf, t_data) +
+						oldtup->tuple.t_len;
 
 				if (newtup)
-					newlen = offsetof(ReorderBufferTupleBuf, data)
-						+newtup->tuple.t_len
-						- offsetof(HeapTupleHeaderData, t_bits);
+					newlen = offsetof(ReorderBufferTupleBuf, t_data) +
+						newtup->tuple.t_len;
 
 				sz += oldlen;
 				sz += newlen;
@@ -2262,27 +2260,25 @@ ReorderBufferRestoreChange(ReorderBuffer *rb, ReorderBufferTXN *txn,
 		case REORDER_BUFFER_CHANGE_DELETE:
 			if (change->data.tp.newtuple)
 			{
-				Size		len = offsetof(ReorderBufferTupleBuf, data)
-				+((ReorderBufferTupleBuf *) data)->tuple.t_len
-				- offsetof(HeapTupleHeaderData, t_bits);
+				Size		len = offsetof(ReorderBufferTupleBuf, t_data) +
+					((ReorderBufferTupleBuf *) data)->tuple.t_len;
 
 				change->data.tp.newtuple = ReorderBufferGetTupleBuf(rb);
 				memcpy(change->data.tp.newtuple, data, len);
 				change->data.tp.newtuple->tuple.t_data =
-					&change->data.tp.newtuple->header;
+					&change->data.tp.newtuple->t_data.header;
 				data += len;
 			}
 
 			if (change->data.tp.oldtuple)
 			{
-				Size		len = offsetof(ReorderBufferTupleBuf, data)
-				+((ReorderBufferTupleBuf *) data)->tuple.t_len
-				- offsetof(HeapTupleHeaderData, t_bits);
+				Size		len = offsetof(ReorderBufferTupleBuf, t_data) +
+					((ReorderBufferTupleBuf *) data)->tuple.t_len;
 
 				change->data.tp.oldtuple = ReorderBufferGetTupleBuf(rb);
 				memcpy(change->data.tp.oldtuple, data, len);
 				change->data.tp.oldtuple->tuple.t_data =
-					&change->data.tp.oldtuple->header;
+					&change->data.tp.oldtuple->t_data.header;
 				data += len;
 			}
 			break;
@@ -2660,7 +2656,7 @@ ReorderBufferToastReplace(ReorderBuffer *rb, ReorderBufferTXN *txn,
 	 */
 	tmphtup = heap_form_tuple(desc, attrs, isnull);
 	Assert(newtup->tuple.t_len <= MaxHeapTupleSize);
-	Assert(&newtup->header == newtup->tuple.t_data);
+	Assert(&newtup->t_data.header == newtup->tuple.t_data);
 
 	memcpy(newtup->tuple.t_data, tmphtup->t_data, tmphtup->t_len);
 	newtup->tuple.t_len = tmphtup->t_len;
diff --git a/src/backend/utils/adt/trigfuncs.c b/src/backend/utils/adt/trigfuncs.c
index fb79092..a8a75ef 100644
--- a/src/backend/utils/adt/trigfuncs.c
+++ b/src/backend/utils/adt/trigfuncs.c
@@ -84,9 +84,9 @@ suppress_redundant_updates_trigger(PG_FUNCTION_ARGS)
 		 HeapTupleHeaderGetNatts(oldheader)) &&
 		((newheader->t_infomask & ~HEAP_XACT_MASK) ==
 		 (oldheader->t_infomask & ~HEAP_XACT_MASK)) &&
-		memcmp(((char *) newheader) + offsetof(HeapTupleHeaderData, t_bits),
-			   ((char *) oldheader) + offsetof(HeapTupleHeaderData, t_bits),
-			   newtuple->t_len - offsetof(HeapTupleHeaderData, t_bits)) == 0)
+		memcmp(((char *) newheader) + SizeofHeapTupleHeader,
+			   ((char *) oldheader) + SizeofHeapTupleHeader,
+			   newtuple->t_len - SizeofHeapTupleHeader) == 0)
 	{
 		/* ... then suppress the update */
 		rettuple = NULL;
diff --git a/src/include/access/htup_details.h b/src/include/access/htup_details.h
index d2ad910..d3c088d 100644
--- a/src/include/access/htup_details.h
+++ b/src/include/access/htup_details.h
@@ -150,11 +150,13 @@ struct HeapTupleHeaderData
 
 	/* ^ - 23 bytes - ^ */
 
-	bits8		t_bits[1];		/* bitmap of NULLs -- VARIABLE LENGTH */
+	bits8		t_bits[FLEXIBLE_ARRAY_MEMBER];	/* bitmap of NULLs */
 
 	/* MORE DATA FOLLOWS AT END OF STRUCT */
 };
 
+#define SizeofHeapTupleHeader offsetof(HeapTupleHeaderData, t_bits)
+
 /* typedef appears in tupbasics.h */
 
 /*
@@ -498,7 +500,7 @@ do { \
  * you can, say, fit 2 tuples of size MaxHeapTupleSize/2 on the same page.
  */
 #define MaxHeapTupleSize  (BLCKSZ - MAXALIGN(SizeOfPageHeaderData + sizeof(ItemIdData)))
-#define MinHeapTupleSize  MAXALIGN(offsetof(HeapTupleHeaderData, t_bits))
+#define MinHeapTupleSize  MAXALIGN(SizeofHeapTupleHeader)
 
 /*
  * MaxHeapTuplesPerPage is an upper bound on the number of tuples that can
@@ -513,7 +515,7 @@ do { \
  */
 #define MaxHeapTuplesPerPage	\
 	((int) ((BLCKSZ - SizeOfPageHeaderData) / \
-			(MAXALIGN(offsetof(HeapTupleHeaderData, t_bits)) + sizeof(ItemIdData))))
+			(MAXALIGN(SizeofHeapTupleHeader) + sizeof(ItemIdData))))
 
 /*
  * MaxAttrSize is a somewhat arbitrary upper limit on the declared size of
@@ -579,7 +581,7 @@ struct MinimalTupleData
 
 	/* ^ - 23 bytes - ^ */
 
-	bits8		t_bits[1];		/* bitmap of NULLs -- VARIABLE LENGTH */
+	bits8		t_bits[FLEXIBLE_ARRAY_MEMBER];	/* bitmap of NULLs */
 
 	/* MORE DATA FOLLOWS AT END OF STRUCT */
 };
diff --git a/src/include/access/tuptoaster.h b/src/include/access/tuptoaster.h
index 331dd25..7d18535 100644
--- a/src/include/access/tuptoaster.h
+++ b/src/include/access/tuptoaster.h
@@ -90,7 +90,7 @@
 
 #define TOAST_MAX_CHUNK_SIZE	\
 	(EXTERN_TUPLE_MAX_SIZE -							\
-	 MAXALIGN(offsetof(HeapTupleHeaderData, t_bits)) -	\
+	 MAXALIGN(SizeofHeapTupleHeader) -					\
 	 sizeof(Oid) -										\
 	 sizeof(int32) -									\
 	 VARHDRSZ)
diff --git a/src/include/replication/reorderbuffer.h b/src/include/replication/reorderbuffer.h
index 5a1d9a0..dcfe2b3 100644
--- a/src/include/replication/reorderbuffer.h
+++ b/src/include/replication/reorderbuffer.h
@@ -28,8 +28,11 @@ typedef struct ReorderBufferTupleBuf
 
 	/* tuple, stored sequentially */
 	HeapTupleData tuple;
-	HeapTupleHeaderData header;
-	char		data[MaxHeapTupleSize];
+	union
+	{
+		HeapTupleHeaderData header;
+		char		data[MaxHeapTupleSize];
+	}	t_data;
 } ReorderBufferTupleBuf;
 
 /*
-- 
2.3.0