Add reserved operator knowledge to OperatotProperties

- is-reserved-operator    return whether given op name is reserved
- reserved-operator-hint  return hint for reserved operator name

src/Raku/ast/operator-properties.rakumod

@@ -165,6 +165,30 @@ class OperatorProperties {
           !! nqp::substr(self.bracket-openers,$index,1)
     }
 
+#-------------------------------------------------------------------------------
+# Reserved operators
+
+    # Return hash with reserved operator names and optional hints for errors
+    method reserved-operators-lookup() {
+        my constant RESERVED := nqp::hash(
+          'infix:sym<=>',   "",
+          'infix:sym<:=>',  "",
+          'infix:sym<::=>', "",
+          'infix:sym<~~>',  "(consider implementing an ACCEPTS method)",
+          'prefix:sym<|>',  ""
+        )
+    }
+
+    # Return whether given operator name is reserved
+    method is-reserved-operator(str $operator) {
+        nqp::existskey(self.reserved-operators-lookup,$operator)
+    }
+
+    # Return hint to be added to error message if reserved
+    method reserved-operator-hint(str $operator) {
+        nqp::atkey(self.reserved-operators-lookup,$operator)
+    }
+
 #-------------------------------------------------------------------------------
 # Methods that can be run on both an instance and a type object.  Note that
 # when calle on a type object, an "empty" representation of that function