4 files changed, 13 insertions, 3 deletions
diff --git a/indra/llcommon/tests/StringVec.h b/indra/llcommon/tests/StringVec.h
index a380b00a05..761956a012 100644
--- a/indra/llcommon/tests/StringVec.h
+++ b/indra/llcommon/tests/StringVec.h
@@ -18,6 +18,16 @@
 
 typedef std::vector<std::string> StringVec;
 
+#if defined(LL_LLTUT_H)
+// Modern compilers require us to define operator<<(std::ostream&, StringVec)
+// before the definition of the ensure() template that engages it. The error
+// stating that the compiler can't find a viable operator<<() is so perplexing
+// that even though I've obviously hit it a couple times before, a new
+// instance still caused much head-scratching. This warning is intended to
+// demystify any inadvertent future recurrence.
+#warning "StringVec.h must be #included BEFORE lltut.h for ensure() to work"
+#endif
+
 std::ostream& operator<<(std::ostream& out, const StringVec& strings)
 {
     out << '(';
diff --git a/indra/llcommon/tests/lleventfilter_test.cpp b/indra/llcommon/tests/lleventfilter_test.cpp
index fa2cb03e95..ed7cb56506 100644
--- a/indra/llcommon/tests/lleventfilter_test.cpp
+++ b/indra/llcommon/tests/lleventfilter_test.cpp
@@ -34,10 +34,10 @@
 // std headers
 // external library headers
 // other Linden headers
+#include "listener.h"
 #include "../test/lltut.h"
 #include "stringize.h"
 #include "llsdutil.h"
-#include "listener.h"
 #include "tests/wrapllerrs.h"
 
 #include <typeinfo>
diff --git a/indra/llcommon/tests/llleap_test.cpp b/indra/llcommon/tests/llleap_test.cpp
index 7197dedfbf..6fe9e3446f 100644
--- a/indra/llcommon/tests/llleap_test.cpp
+++ b/indra/llcommon/tests/llleap_test.cpp
@@ -18,6 +18,7 @@
 #include <functional>
 // external library headers
 // other Linden headers
+#include "StringVec.h"
 #include "../test/lltut.h"
 #include "../test/namedtempfile.h"
 #include "../test/catch_and_store_what_in.h"
@@ -26,7 +27,6 @@
 #include "llprocess.h"
 #include "llstring.h"
 #include "stringize.h"
-#include "StringVec.h"
 
 #if defined(LL_WINDOWS)
 #define sleep(secs) _sleep((secs) * 1000)
diff --git a/indra/llcommon/tests/llsdserialize_test.cpp b/indra/llcommon/tests/llsdserialize_test.cpp
index ae3a94c55d..730731a927 100644
--- a/indra/llcommon/tests/llsdserialize_test.cpp
+++ b/indra/llcommon/tests/llsdserialize_test.cpp
@@ -53,10 +53,10 @@ typedef U32 uint32_t;
 #include "llmemorystream.h"
 
 #include "hexdump.h"
+#include "StringVec.h"
 #include "../test/lltut.h"
 #include "../test/namedtempfile.h"
 #include "stringize.h"
-#include "StringVec.h"
 #include <functional>
 
 typedef std::function<void(const LLSD& data, std::ostream& str)> FormatterFunction;