Major - P3 On Windows DEBUG (Unoptimized) it seems that the k32IncompatibleIndexSpec value is constructed before the k32IncompatibleIndexName variable, which it is using has been initialized, which results in an invalid BSON.
This later on leads to the following exception at startup:
2016-09-22T13:59:31.994-0400 I - [initandlisten] Assertion: 13111:field not found, expected type 2 E:\workspace\mongo\src\mongo/bson/bsonelement.h 667 2016-09-22T13:59:32.537-0400 I CONTROL [initandlisten] mongod.exe ...\src\mongo\util\stacktrace_windows.cpp(174) mongo::printStackTrace+0x5b 2016-09-22T13:59:32.537-0400 I CONTROL [initandlisten] mongod.exe ...\src\mongo\util\log.cpp(164) mongo::logContext+0xe2 2016-09-22T13:59:32.544-0400 I CONTROL [initandlisten] mongod.exe ...\src\mongo\util\assert_util.cpp(239) mongo::msgassertedWithLocation+0x183 2016-09-22T13:59:32.544-0400 I CONTROL [initandlisten] mongod.exe ...\src\mongo\util\assert_util.cpp(229) mongo::msgassertedWithLocation+0x4b 2016-09-22T13:59:32.544-0400 I CONTROL [initandlisten] mongod.exe ...\src\mongo\bson\bsonelement.h(667) mongo::BSONElement::chk+0x172 2016-09-22T13:59:32.545-0400 I CONTROL [initandlisten] mongod.exe ...\src\mongo\bson\bsonelement.h(96) mongo::BSONElement::String+0x3a 2016-09-22T13:59:32.545-0400 I CONTROL [initandlisten] mongod.exe ...\src\mongo\db\index_builder.cpp(126) mongo::IndexBuilder::_build+0xd7 2016-09-22T13:59:32.545-0400 I CONTROL [initandlisten] mongod.exe ...\src\mongo\db\index_builder.cpp(110) mongo::IndexBuilder::buildInForeground+0x5c 2016-09-22T13:59:32.545-0400 I CONTROL [initandlisten] mongod.exe ...\src\mongo\db\commands\feature_compatibility_version.cpp(274) mongo::FeatureCompatibilityVersion::setIfCleanStartup+0x2ff 2016-09-22T13:59:32.545-0400 I CONTROL [initandlisten] mongod.exe ...\src\mongo\db\db.cpp(800) mongo::`anonymous namespace'::_initAndListen+0x1df1 2016-09-22T13:59:32.545-0400 I CONTROL [initandlisten] mongod.exe ...\src\mongo\db\db.cpp(828) mongo::`anonymous namespace'::initAndListen+0x4c 2016-09-22T13:59:32.545-0400 I CONTROL [initandlisten] mongod.exe ...\src\mongo\db\db.cpp(1180) mongoDbMain+0x274 2016-09-22T13:59:32.546-0400 I CONTROL [initandlisten] mongod.exe ...\src\mongo\db\db.cpp(868) wmain+0x78 2016-09-22T13:59:32.546-0400 I CONTROL [initandlisten] mongod.exe f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl(80) invoke_main+0x34 2016-09-22T13:59:32.546-0400 I CONTROL [initandlisten] mongod.exe f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl(253) __scrt_common_main_seh+0x127 2016-09-22T13:59:32.546-0400 I CONTROL [initandlisten] mongod.exe f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl(296) __scrt_common_main+0xe 2016-09-22T13:59:32.546-0400 I CONTROL [initandlisten] mongod.exe f:\dd\vctools\crt\vcstartup\src\startup\exe_wmain.cpp(17) wmainCRTStartup+0x9
This was introduced in this commit: https://github.com/mongodb/mongo/commit/96a21e63bfc1a1cdde01c671d0867310c594ea5a