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