[ConstraintSystem] Convert TypeVariableOptions enum to String for use in printing.

Author: Amritpan Kaur

include/swift/Sema/ConstraintSystem.h

@@ -588,6 +588,19 @@ class TypeVariableType::Implementation {
 
   /// Print the type variable to the given output stream.
   void print(llvm::raw_ostream &OS);
+  
+private:
+  StringRef getTypeVariableOptions(TypeVariableOptions TVO) const {
+  #define ENTRY(Kind, String) case TypeVariableOptions::Kind: return String
+    switch (TVO) {
+    ENTRY(TVO_CanBindToLValue, "lvalue");
+    ENTRY(TVO_CanBindToInOut, "inout");
+    ENTRY(TVO_CanBindToNoEscape, "noescape");
+    ENTRY(TVO_CanBindToHole, "hole");
+    ENTRY(TVO_PrefersSubtypeBinding, "");
+    }
+  #undef ENTRY
+  }
 };
 
 namespace constraints {