SERVER-27244 Status usage compile-time facilities.

There are numerous places in the codebase where `mongo::Status` or
`mongo::StatusWith< T >` objects are returned and never checked.
Many of these are innocuous, but many of them are potentially
severe bugs.  This change introduces facilities to permit
compile-time warning of unchecked `Status` and `StatusWith` usage
on clang compilers.  It introduces an `ignore` function which is
useful to state that a specific "ignored status" case was
intentional.  It not presently an error, in clang builds, to
forget to check a `Status` -- this will come in a later commit.

This also introduces a `transitional_ignore` function, which allows
for easy continual auditing of the codebase for current "whitelisted"
unchecked-status instances.  All present "ignored status" cases
have been marked `transitional_ignore`.

1 files changed, 3 insertions, 3 deletions

diff --git a/src/mongo/dbtests/counttests.cpp b/src/mongo/dbtests/counttests.cpp
index 7fd12a2ce74..9f3cf21c73b 100644
--- a/src/mongo/dbtests/counttests.cpp
+++ b/src/mongo/dbtests/counttests.cpp
@@ -51,7 +51,7 @@ public:
             WriteUnitOfWork wunit(&_opCtx);
             _collection = _database->getCollection(&_opCtx, ns());
             if (_collection) {
-                _database->dropCollection(&_opCtx, ns());
+                _database->dropCollection(&_opCtx, ns()).transitional_ignore();
             }
             _collection = _database->createCollection(&_opCtx, ns());
             wunit.commit();
@@ -87,9 +87,9 @@ protected:
             oid.init();
             b.appendOID("_id", &oid);
             b.appendElements(o);
-            _collection->insertDocument(&_opCtx, b.obj(), nullOpDebug, false);
+            _collection->insertDocument(&_opCtx, b.obj(), nullOpDebug, false).transitional_ignore();
         } else {
-            _collection->insertDocument(&_opCtx, o, nullOpDebug, false);
+            _collection->insertDocument(&_opCtx, o, nullOpDebug, false).transitional_ignore();
         }
         wunit.commit();
     }