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, 2 insertions, 2 deletions

diff --git a/src/mongo/db/introspect.cpp b/src/mongo/db/introspect.cpp
index 9ef233f11be..f3d6680b242 100644
--- a/src/mongo/db/introspect.cpp
+++ b/src/mongo/db/introspect.cpp
@@ -122,7 +122,7 @@ void profile(OperationContext* opCtx, NetworkOp op) {
             if (acquireDbXLock) {
                 autoGetDb.reset(new AutoGetDb(opCtx, dbName, MODE_X));
                 if (autoGetDb->getDb()) {
-                    createProfileCollection(opCtx, autoGetDb->getDb());
+                    createProfileCollection(opCtx, autoGetDb->getDb()).transitional_ignore();
                 }
             } else {
                 autoGetDb.reset(new AutoGetDb(opCtx, dbName, MODE_IX));
@@ -142,7 +142,7 @@ void profile(OperationContext* opCtx, NetworkOp op) {
             if (coll) {
                 WriteUnitOfWork wuow(opCtx);
                 OpDebug* const nullOpDebug = nullptr;
-                coll->insertDocument(opCtx, p, nullOpDebug, false);
+                coll->insertDocument(opCtx, p, nullOpDebug, false).transitional_ignore();
                 wuow.commit();
 
                 break;