Fixed variadic macro usage in LL_ERRS_IF and LL_WARNS_IF and improved...

Fixed variadic macro usage in LL_ERRS_IF and LL_WARNS_IF and improved LLError::shouldLogToStderr() behavior under xcode.

indra/llcommon/llerror.cpp

@@ -664,10 +664,10 @@ namespace
 		// console log.  It's generally considered bad form to spam too much
 		// there.
 		
-		// If stdin is a tty, assume the user launched from the command line and
-		// therefore wants to see stderr.  Otherwise, assume we've been launched
-		// from the finder and shouldn't spam stderr.
-		return isatty(0);
+		// If stderr is a tty, assume the user launched from the command line or
+		// debugger and therefore wants to see stderr.  Otherwise, assume we've
+		// been launched from the finder and shouldn't spam stderr.
+		return isatty(STDERR_FILENO);
 #else
 		return true;
 #endif

indra/llcommon/llerror.h

@@ -381,8 +381,13 @@ typedef LLError::NoClassInfo _LL_CLASS_TO_LOG;
 #define LL_WARNS(...)	lllog(LLError::LEVEL_WARN, false, ##__VA_ARGS__)
 #define LL_ERRS(...)	lllog(LLError::LEVEL_ERROR, false, ##__VA_ARGS__)
 // alternative to llassert_always that prints explanatory message
-#define LL_WARNS_IF(exp, ...)	if (exp) LL_WARNS(##__VA_ARGS__) << "(" #exp ")"
-#define LL_ERRS_IF(exp, ...)	if (exp) LL_ERRS(##__VA_ARGS__) << "(" #exp ")"
+// note ## token paste operator hack used above will only work in gcc following
+// a comma and is completely unnecessary in VS since the comma is automatically
+// suppressed
+// https://gcc.gnu.org/onlinedocs/cpp/Variadic-Macros.html
+// https://docs.microsoft.com/en-us/cpp/preprocessor/variadic-macros?view=vs-2015
+#define LL_WARNS_IF(exp, ...)	if (exp) LL_WARNS(__VA_ARGS__) << "(" #exp ")"
+#define LL_ERRS_IF(exp, ...)	if (exp) LL_ERRS(__VA_ARGS__) << "(" #exp ")"
 
 // Only print the log message once (good for warnings or infos that would otherwise
 // spam the log file over and over, such as tighter loops).