Ruby: address review feedback

Author: nickrolfe

ruby/ql/lib/change-notes/2022-03-25-deprecate-getStringOrSymbol.md

@@ -2,4 +2,4 @@
  category: minorAnalysis
 ---
  *  Whereas `ConstantValue::getString()` previously returned both string and regular-expression values, it now returns only string values. The same applies to `ConstantValue::isString(value)`.
- *  Regular-expression values can now be accessed with the new predicates `ConstantValue::getRegExp()`, `ConstantValue::isRegExp(value)`, and `ConstantValue::isRegExpWithFlags(value, flags).
+ *  Regular-expression values can now be accessed with the new predicates `ConstantValue::getRegExp()`, `ConstantValue::isRegExp(value)`, and `ConstantValue::isRegExpWithFlags(value, flags)`.

ruby/ql/lib/codeql/ruby/ast/Constant.qll

@@ -74,7 +74,7 @@ class ConstantValue extends TConstantValue {
   /** Gets the regexp value, if this is a regexp. */
   string getRegExp() { this.isRegExpWithFlags(result, _) }
 
-  /** Holds if this is the regexp value `/s/`. */
+  /** Holds if this is the regexp value `/s/`, ignoring any flags. */
   predicate isRegExp(string s) { this.isRegExpWithFlags(s, _) }
 
   /** Holds if this is the regexp value `/s/flags` . */
@@ -125,13 +125,13 @@ module ConstantValue {
   class ConstantStringlikeValue extends ConstantValue, TStringlike { }
 
   /** A constant string value. */
-  class ConstantStringValue extends ConstantValue, TString { }
+  class ConstantStringValue extends ConstantStringlikeValue, TString { }
 
   /** A constant symbol value. */
-  class ConstantSymbolValue extends ConstantValue, TSymbol { }
+  class ConstantSymbolValue extends ConstantStringlikeValue, TSymbol { }
 
   /** A constant regexp value. */
-  class ConstantRegExpValue extends ConstantValue, TRegExp { }
+  class ConstantRegExpValue extends ConstantStringlikeValue, TRegExp { }
 
   /** A constant Boolean value. */
   class ConstantBooleanValue extends ConstantValue, TBoolean { }

ruby/ql/test/library-tests/ast/escape_sequences/EscapeSequences.ql

@@ -18,9 +18,7 @@ query predicate regexpEscapeSequenceComponents(RegExpEscapeSequenceComponent c,
 }
 
 query predicate stringlikeLiterals(StringlikeLiteral l, string value, string kind) {
-  value = l.getConstantValue().getString() and kind = "string"
-  or
-  value = l.getConstantValue().getSymbol() and kind = "symbol"
-  or
-  value = l.getConstantValue().getRegExp() and kind = "regexp"
+  exists(ConstantValue v |
+    v = l.getConstantValue() and value = v.getStringlikeValue() and kind = v.getValueType()
+  )
 }