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, 1 insertions, 1 deletions

diff --git a/src/mongo/db/repl/drop_pending_collection_reaper_test.cpp b/src/mongo/db/repl/drop_pending_collection_reaper_test.cpp
index 8bafea199b9..4dcabbcdd09 100644
--- a/src/mongo/db/repl/drop_pending_collection_reaper_test.cpp
+++ b/src/mongo/db/repl/drop_pending_collection_reaper_test.cpp
@@ -132,7 +132,7 @@ TEST_F(DropPendingCollectionReaperTest,
         opTime[i] = OpTime({Seconds((i + 1) * 10), 0}, 1LL);
         ns[i] = NamespaceString("test", str::stream() << "coll" << i);
         dpns[i] = ns[i].makeDropPendingNamespace(opTime[i]);
-        _storageInterface->createCollection(opCtx.get(), dpns[i], {});
+        _storageInterface->createCollection(opCtx.get(), dpns[i], {}).transitional_ignore();
     }
 
     // Add drop-pending namespaces with drop optimes out of order and check that