Static assertions cleanup

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

3 files changed, 8 insertions, 16 deletions

diff --git a/src/common/checksum_helper.c b/src/common/checksum_helper.c
index 74d0cf0a2e2..8948df4da1a 100644
--- a/src/common/checksum_helper.c
+++ b/src/common/checksum_helper.c
@@ -177,15 +177,15 @@ pg_checksum_final(pg_checksum_context *context, uint8 *output)
 {
 	int			retval = 0;
 
-	StaticAssertStmt(sizeof(pg_crc32c) <= PG_CHECKSUM_MAX_LENGTH,
+	StaticAssertDecl(sizeof(pg_crc32c) <= PG_CHECKSUM_MAX_LENGTH,
 					 "CRC-32C digest too big for PG_CHECKSUM_MAX_LENGTH");
-	StaticAssertStmt(PG_SHA224_DIGEST_LENGTH <= PG_CHECKSUM_MAX_LENGTH,
+	StaticAssertDecl(PG_SHA224_DIGEST_LENGTH <= PG_CHECKSUM_MAX_LENGTH,
 					 "SHA224 digest too big for PG_CHECKSUM_MAX_LENGTH");
-	StaticAssertStmt(PG_SHA256_DIGEST_LENGTH <= PG_CHECKSUM_MAX_LENGTH,
+	StaticAssertDecl(PG_SHA256_DIGEST_LENGTH <= PG_CHECKSUM_MAX_LENGTH,
 					 "SHA256 digest too big for PG_CHECKSUM_MAX_LENGTH");
-	StaticAssertStmt(PG_SHA384_DIGEST_LENGTH <= PG_CHECKSUM_MAX_LENGTH,
+	StaticAssertDecl(PG_SHA384_DIGEST_LENGTH <= PG_CHECKSUM_MAX_LENGTH,
 					 "SHA384 digest too big for PG_CHECKSUM_MAX_LENGTH");
-	StaticAssertStmt(PG_SHA512_DIGEST_LENGTH <= PG_CHECKSUM_MAX_LENGTH,
+	StaticAssertDecl(PG_SHA512_DIGEST_LENGTH <= PG_CHECKSUM_MAX_LENGTH,
 					 "SHA512 digest too big for PG_CHECKSUM_MAX_LENGTH");
 
 	switch (context->type)
diff --git a/src/common/controldata_utils.c b/src/common/controldata_utils.c
index 2d1f35bbd18..5c654746fae 100644
--- a/src/common/controldata_utils.c
+++ b/src/common/controldata_utils.c
@@ -149,14 +149,6 @@ update_controlfile(const char *DataDir,
 	char		buffer[PG_CONTROL_FILE_SIZE];
 	char		ControlFilePath[MAXPGPATH];
 
-	/*
-	 * Apply the same static assertions as in backend's WriteControlFile().
-	 */
-	StaticAssertStmt(sizeof(ControlFileData) <= PG_CONTROL_MAX_SAFE_SIZE,
-					 "pg_control is too large for atomic disk writes");
-	StaticAssertStmt(sizeof(ControlFileData) <= PG_CONTROL_FILE_SIZE,
-					 "sizeof(ControlFileData) exceeds PG_CONTROL_FILE_SIZE");
-
 	/* Update timestamp  */
 	ControlFile->time = (pg_time_t) time(NULL);
 
diff --git a/src/common/encnames.c b/src/common/encnames.c
index 596a23b64da..2329db572bc 100644
--- a/src/common/encnames.c
+++ b/src/common/encnames.c
@@ -451,6 +451,9 @@ static const char *const pg_enc2icu_tbl[] =
 	"KOI8-U",					/* PG_KOI8U */
 };
 
+StaticAssertDecl(lengthof(pg_enc2icu_tbl) == PG_ENCODING_BE_LAST + 1,
+				 "pg_enc2icu_tbl incomplete");
+
 
 /*
  * Is this encoding supported by ICU?
@@ -469,9 +472,6 @@ is_encoding_supported_by_icu(int encoding)
 const char *
 get_encoding_name_for_icu(int encoding)
 {
-	StaticAssertStmt(lengthof(pg_enc2icu_tbl) == PG_ENCODING_BE_LAST + 1,
-					 "pg_enc2icu_tbl incomplete");
-
 	if (!PG_VALID_BE_ENCODING(encoding))
 		return NULL;
 	return pg_enc2icu_tbl[encoding];