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Static assertions cleanup

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Because we added StaticAssertStmt() first before StaticAssertDecl(),
some uses as well as the instructions in c.h are now a bit backwards
from the "native" way static assertions are meant to be used in C.
This updates the guidance and moves some static assertions to better
places.

Specifically, since the addition of StaticAssertDecl(), we can put
static assertions at the file level.  This moves a number of static
assertions out of function bodies, where they might have been stuck
out of necessity, to perhaps better places at the file level or in
header files.

Also, when the static assertion appears in a position where a
declaration is allowed, then using StaticAssertDecl() is more native
than StaticAssertStmt().

Reviewed-by: John Naylor <john.naylor@enterprisedb.com>
Discussion: https://www.postgresql.org/message-id/flat/941a04e7-dd6f-c0e4-8cdf-a33b3338cbda%40enterprisedb.com
This commit is contained in:
Peter Eisentraut
2022-12-08 14:30:01 +01:00
parent 2613dec4ed
commit 75f49221c2
29 changed files with 99 additions and 104 deletions
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9
src/backend/storage/lmgr/lwlock.c
View File

@@ -108,6 +108,9 @@ extern slock_t *ShmemLock;
/* Must be greater than MAX_BACKENDS - which is 2^23-1, so we're fine. */
#define LW_SHARED_MASK ((uint32) ((1 << 24)-1))
StaticAssertDecl(LW_VAL_EXCLUSIVE > (uint32) MAX_BACKENDS,
"MAX_BACKENDS too big for lwlock.c");
/*
* There are three sorts of LWLock "tranches":
*
@@ -466,12 +469,6 @@ LWLockShmemSize(void)
void
CreateLWLocks(void)
{
StaticAssertStmt(LW_VAL_EXCLUSIVE > (uint32) MAX_BACKENDS,
"MAX_BACKENDS too big for lwlock.c");
StaticAssertStmt(sizeof(LWLock) <= LWLOCK_PADDED_SIZE,
"Miscalculated LWLock padding");
if (!IsUnderPostmaster)
{
Size spaceLocks = LWLockShmemSize();

13
src/backend/storage/page/itemptr.c
View File

@@ -17,6 +17,12 @@
#include "storage/itemptr.h"
/*
* We really want ItemPointerData to be exactly 6 bytes.
*/
StaticAssertDecl(sizeof(ItemPointerData) == 3 * sizeof(uint16),
"ItemPointerData struct is improperly padded");
/*
* ItemPointerEquals
* Returns true if both item pointers point to the same item,
@@ -28,13 +34,6 @@
bool
ItemPointerEquals(ItemPointer pointer1, ItemPointer pointer2)
{
/*
* We really want ItemPointerData to be exactly 6 bytes. This is rather a
* random place to check, but there is no better place.
*/
StaticAssertStmt(sizeof(ItemPointerData) == 3 * sizeof(uint16),
"ItemPointerData struct is improperly padded");
if (ItemPointerGetBlockNumber(pointer1) ==
ItemPointerGetBlockNumber(pointer2) &&
ItemPointerGetOffsetNumber(pointer1) ==