[CSStep] Add message to list possible type variables that will be attempted next.

Author: Amritpan Kaur

lib/Sema/CSStep.cpp

@@ -369,6 +369,21 @@ StepResult ComponentStep::take(bool prevFailed) {
     log.indent(2);
     log << ")" << '\n';
     log.indent(0);
+      
+    if (CS.getTypeVariables().size() > 1) {
+      auto &log = getDebugLogger();
+      log << "(selecting next type variable to attempt from [";
+      auto typeVars = CS.getTypeVariables();
+      PrintOptions PO;
+      PO.PrintTypesForDebugging = true;
+      interleave(typeVars, [&](TypeVariableType *typeVar) {
+                     Type(typeVar).print(log, PO);
+                   },
+                   [&] {
+                     log << ", ";
+                   });
+      log << "])" << '\n';
+    }
   }
 
   if (CS.shouldAttemptFixes()) {