Workaround for Visual Studio not expaning __VA_ARGS__ on macro invocation

Author: danpoe

src/util/invariant.h

@@ -249,6 +249,8 @@ invariant_violated_string(
 #define __this_function__ __func__
 #endif
 
+#define EXPAND(x) x
+
 #define GET_MACRO(X1, X2, X3, X4, X5, X6, MACRO, ...) MACRO
 
 #define REDIRECT(MACRO, ...)                                                   \
@@ -373,7 +375,7 @@ invariant_violated_string(
 #define DATA_INVARIANT3(CONDITION, REASON, DIAGNOSTICS)                        \
   INVARIANT3(CONDITION, REASON, DIAGNOSTICS)
 
-#define DATA_INVARIANT(...) REDIRECT(DATA_INVARIANT, __VA_ARGS__)
+#define DATA_INVARIANT(...) EXPAND(REDIRECT(DATA_INVARIANT, __VA_ARGS__))
 
 #define DATA_INVARIANT_STRUCTURED(CONDITION, TYPENAME, ...) \
   INVARIANT_STRUCTURED(CONDITION, TYPENAME, __VA_ARGS__)