Ensure 'legacy' is called as fallback even w/ non-standard includes

Author: eddelbuettel

inst/include/RcppArmadillo/interface/RcppArmadilloForward.h

@@ -50,15 +50,21 @@
 // See version/arma.h header for the (user and/or compilation) drive selection of these defines
 #if defined(ARMA_SELECTED_CURRENT_VERSION)
 
-    // we include Armadillo 15.0.1 here
+    // we include Armadillo 15.0.1 here -- but do it quietly
     //#pragma message("Using compilation with current Armadillo version.")
 
     // Armadillo 15.0.1 or later
     #include "current/armadillo"
 
-#elif defined(ARMA_SELECTED_LEGACY_VERSION)
+#else
+
+    // we use a catch-all else branch to provide for packages including this file directly
+    // needless to say, we recommend one of the official entry-point headers
+    #if !defined(ARMA_SELECTED_LEGACY_VERSION)
+        #pragma message("Neither 'current' nor 'legacy' version selected. Ensure you use proper entry point headers.")
+    #endif
 
-    // we include Armadillo 14.6.3 here
+    // we include Armadillo 14.6.3 here -- but do it quietly
     //#pragma message("Using fallback compilation with Armadillo 14.6.3.")
 
     // Armadillo has deprecation warnings (which RcppArmadillo suppressed at time to
@@ -73,10 +79,6 @@
 
     #include "legacy/armadillo"
 
-#else
-
-    #error "Neither 'current' nor 'legacy' version selected. Ensure you use proper entry point headers."
-
 #endif
 
 /* forward declarations */