Fix style violations in syscache lookups.

Project style is to check the success of SearchSysCacheN and friends
by applying HeapTupleIsValid to the result.  A tiny minority of calls
creatively did it differently.  Bring them into line with the rest.

This is just cosmetic, since HeapTupleIsValid is indeed just a null
check at the moment ... but that may not be true forever, and in any
case it puts a mental burden on readers who may wonder why these
call sites are not like the rest.

Back-patch to v11 just to keep the branches in sync.  (The bulk of these
errors seem to have originated in v11 or v12, though a few are old.)

Per searching to see if anyplace else had made the same error
repaired in 62148c352.

1 files changed, 7 insertions, 9 deletions

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index f6c9cf3b0ec..8e4743d1101 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -8606,7 +8606,7 @@ CloneFkReferencing(List **wqueue, Relation parentRel, Relation partRel)
 		ListCell   *cell;
 
 		tuple = SearchSysCache1(CONSTROID, parentConstrOid);
-		if (!tuple)
+		if (!HeapTupleIsValid(tuple))
 			elog(ERROR, "cache lookup failed for constraint %u",
 				 parentConstrOid);
 		constrForm = (Form_pg_constraint) GETSTRUCT(tuple);
@@ -8785,7 +8785,7 @@ tryAttachPartitionForeignKey(ForeignKeyCacheInfo *fk,
 
 	parentConstrTup = SearchSysCache1(CONSTROID,
 									  ObjectIdGetDatum(parentConstrOid));
-	if (!parentConstrTup)
+	if (!HeapTupleIsValid(parentConstrTup))
 		elog(ERROR, "cache lookup failed for constraint %u", parentConstrOid);
 	parentConstr = (Form_pg_constraint) GETSTRUCT(parentConstrTup);
 
@@ -8816,9 +8816,8 @@ tryAttachPartitionForeignKey(ForeignKeyCacheInfo *fk,
 	 */
 	partcontup = SearchSysCache1(CONSTROID,
 								 ObjectIdGetDatum(fk->conoid));
-	if (!partcontup)
-		elog(ERROR, "cache lookup failed for constraint %u",
-			 fk->conoid);
+	if (!HeapTupleIsValid(partcontup))
+		elog(ERROR, "cache lookup failed for constraint %u", fk->conoid);
 	partConstr = (Form_pg_constraint) GETSTRUCT(partcontup);
 	if (OidIsValid(partConstr->conparentid) ||
 		!partConstr->convalidated ||
@@ -16001,7 +16000,7 @@ ATExecDetachPartition(Relation rel, RangeVar *name)
 		Constraint *fkconstraint;
 
 		contup = SearchSysCache1(CONSTROID, ObjectIdGetDatum(fk->conoid));
-		if (!contup)
+		if (!HeapTupleIsValid(contup))
 			elog(ERROR, "cache lookup failed for constraint %u", fk->conoid);
 		conform = (Form_pg_constraint) GETSTRUCT(contup);
 
@@ -16346,9 +16345,8 @@ validatePartitionedIndex(Relation partedIdx, Relation partedTbl)
 
 		indTup = SearchSysCache1(INDEXRELID,
 								 ObjectIdGetDatum(inhForm->inhrelid));
-		if (!indTup)
-			elog(ERROR, "cache lookup failed for index %u",
-				 inhForm->inhrelid);
+		if (!HeapTupleIsValid(indTup))
+			elog(ERROR, "cache lookup failed for index %u", inhForm->inhrelid);
 		indexForm = (Form_pg_index) GETSTRUCT(indTup);
 		if (indexForm->indisvalid)
 			tuples += 1;