Fix string literal printing in AST dump

Author: NalaGinrut

gcc/rust/ast/rust-ast-full-test.cc

@@ -242,7 +242,8 @@ Token::as_string () const
   // return get_token_description(token_id);
 
   // maybe fixed - stores everything as string though, so storage-inefficient
-  return str;
+  ::std::string quote = is_string_lit () ? "\"" : "";
+  return quote + str + quote;
 }
 
 ::std::string

gcc/rust/ast/rust-ast.h

@@ -213,6 +213,18 @@ class Token : public TokenTree, public MacroMatch
       }
   }
 
+  inline bool is_string_lit () const
+  {
+    switch (token_id)
+      {
+      case STRING_LITERAL:
+      case BYTE_STRING_LITERAL:
+	return true;
+      default:
+	return false;
+      }
+  }
+
   ::std::string as_string () const;
 
   virtual void accept_vis (ASTVisitor &vis) OVERRIDE;