Revert workarounds for -Wmissing-braces false positives on old GCC

We have collected several instances of a workaround for GCC bug 53119,
which caused false-positive compiler warnings.  This bug has long been
fixed, but was still seen on the buildfarm, most recently on lapwing
with gcc (Debian 4.7.2-5).  (The GCC bug tracker mentions that a fix
was backported to 4.7.4 and 4.8.3.)

That compiler no longer runs warning-free since commit 6fdd5d95634, so
we don't need to keep these workarounds.  And furthermore, the
consensus appears to be that we don't want to keep supporting that era
of platform anymore at all.

This reverts the following commits:

d937904cce6a3d82e4f9c2127de7b59105a134b3
506428d091760650971433f6bc083531c307b368
b449afb582bb9015bfbb85abc10ce122aef9ec70
6392f2a0968c20ecde4d27b6652703ad931fce92
bad0763a4d7be3005eae35d460c73ac4bc7ebaad
5e0c761d0a13c7b4f7c5de618ac38560d74d74d0

and makes a few similar fixes to newer code.

Discussion: https://www.postgresql.org/message-id/flat/e170d61f-01ab-4cf9-ab68-91cd1fac62c5%40eisentraut.org
Discussion: https://www.postgresql.org/message-id/flat/CA%2BTgmoYEAm-KKZibAP3hSqbTFTjUd47XtVcf3xSFDpyecXX9uQ%40mail.gmail.com

2 files changed, 7 insertions, 7 deletions

diff --git a/src/common/blkreftable.c b/src/common/blkreftable.c
index 6d9c1dfddbc..b935baf9ad4 100644
--- a/src/common/blkreftable.c
+++ b/src/common/blkreftable.c
@@ -265,7 +265,7 @@ BlockRefTableSetLimitBlock(BlockRefTable *brtab,
 						   BlockNumber limit_block)
 {
 	BlockRefTableEntry *brtentry;
-	BlockRefTableKey key = {{0}};	/* make sure any padding is zero */
+	BlockRefTableKey key = {0}; /* make sure any padding is zero */
 	bool		found;
 
 	memcpy(&key.rlocator, rlocator, sizeof(RelFileLocator));
@@ -300,7 +300,7 @@ BlockRefTableMarkBlockModified(BlockRefTable *brtab,
 							   BlockNumber blknum)
 {
 	BlockRefTableEntry *brtentry;
-	BlockRefTableKey key = {{0}};	/* make sure any padding is zero */
+	BlockRefTableKey key = {0}; /* make sure any padding is zero */
 	bool		found;
 #ifndef FRONTEND
 	MemoryContext oldcontext = MemoryContextSwitchTo(brtab->mcxt);
@@ -340,7 +340,7 @@ BlockRefTableEntry *
 BlockRefTableGetEntry(BlockRefTable *brtab, const RelFileLocator *rlocator,
 					  ForkNumber forknum, BlockNumber *limit_block)
 {
-	BlockRefTableKey key = {{0}};	/* make sure any padding is zero */
+	BlockRefTableKey key = {0}; /* make sure any padding is zero */
 	BlockRefTableEntry *entry;
 
 	Assert(limit_block != NULL);
@@ -521,7 +521,7 @@ WriteBlockRefTable(BlockRefTable *brtab,
 		for (i = 0; i < brtab->hash->members; ++i)
 		{
 			BlockRefTableSerializedEntry *sentry = &sdata[i];
-			BlockRefTableKey key = {{0}};	/* make sure any padding is zero */
+			BlockRefTableKey key = {0}; /* make sure any padding is zero */
 			unsigned	j;
 
 			/* Write the serialized entry itself. */
@@ -616,7 +616,7 @@ BlockRefTableReaderNextRelation(BlockRefTableReader *reader,
 								BlockNumber *limit_block)
 {
 	BlockRefTableSerializedEntry sentry;
-	BlockRefTableSerializedEntry zentry = {{0}};
+	BlockRefTableSerializedEntry zentry = {0};
 
 	/*
 	 * Sanity check: caller must read all blocks from all chunks before moving
@@ -1291,7 +1291,7 @@ BlockRefTableWrite(BlockRefTableBuffer *buffer, void *data, int length)
 static void
 BlockRefTableFileTerminate(BlockRefTableBuffer *buffer)
 {
-	BlockRefTableSerializedEntry zentry = {{0}};
+	BlockRefTableSerializedEntry zentry = {0};
 	pg_crc32c	crc;
 
 	/* Write a sentinel indicating that there are no more entries. */
diff --git a/src/common/file_utils.c b/src/common/file_utils.c
index 0e3cfede935..eaa2e76f43f 100644
--- a/src/common/file_utils.c
+++ b/src/common/file_utils.c
@@ -687,7 +687,7 @@ pg_pwritev_with_retry(int fd, const struct iovec *iov, int iovcnt, off_t offset)
 ssize_t
 pg_pwrite_zeros(int fd, size_t size, off_t offset)
 {
-	static const PGIOAlignedBlock zbuffer = {{0}};	/* worth BLCKSZ */
+	static const PGIOAlignedBlock zbuffer = {0};	/* worth BLCKSZ */
 	void	   *zerobuf_addr = unconstify(PGIOAlignedBlock *, &zbuffer)->data;
 	struct iovec iov[PG_IOV_MAX];
 	size_t		remaining_size = size;