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, 4 deletions

diff --git a/src/mongo/s/mongos_options.cpp b/src/mongo/s/mongos_options.cpp
index a98cb444fc3..5163ca6c295 100644
--- a/src/mongo/s/mongos_options.cpp
+++ b/src/mongo/s/mongos_options.cpp
@@ -103,16 +103,16 @@ Status addMongosOptions(moe::OptionSection* options) {
         .setSources(moe::SourceAllLegacy);
 
 
-    options->addSection(general_options);
+    options->addSection(general_options).transitional_ignore();
 
 #if defined(_WIN32)
-    options->addSection(windows_scm_options);
+    options->addSection(windows_scm_options).transitional_ignore();
 #endif
 
-    options->addSection(sharding_options);
+    options->addSection(sharding_options).transitional_ignore();
 
 #ifdef MONGO_CONFIG_SSL
-    options->addSection(ssl_options);
+    options->addSection(ssl_options).transitional_ignore();
 #endif
 
     return Status::OK();