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, 4 insertions, 2 deletions

diff --git a/src/mongo/dbtests/query_stage_sort.cpp b/src/mongo/dbtests/query_stage_sort.cpp
index 40f03c7a8c4..efe7c4c5ece 100644
--- a/src/mongo/dbtests/query_stage_sort.cpp
+++ b/src/mongo/dbtests/query_stage_sort.cpp
@@ -360,7 +360,8 @@ public:
         args.nss = coll->ns();
         {
             WriteUnitOfWork wuow(&_opCtx);
-            coll->updateDocument(&_opCtx, *it, oldDoc, newDoc, false, false, NULL, &args);
+            coll->updateDocument(&_opCtx, *it, oldDoc, newDoc, false, false, NULL, &args)
+                .status_with_transitional_ignore();
             wuow.commit();
         }
         exec->restoreState();
@@ -378,7 +379,8 @@ public:
             oldDoc = coll->docFor(&_opCtx, *it);
             {
                 WriteUnitOfWork wuow(&_opCtx);
-                coll->updateDocument(&_opCtx, *it++, oldDoc, newDoc, false, false, NULL, &args);
+                coll->updateDocument(&_opCtx, *it++, oldDoc, newDoc, false, false, NULL, &args)
+                    .status_with_transitional_ignore();
                 wuow.commit();
             }
         }