Ruby: Extract isArrayConstant

This predicate might be useful elsewhere.

Author: hmac

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

@@ -509,3 +509,23 @@ private module Cached {
 }
 
 import Cached
+
+/**
+ * Holds if `e` is an array constructed from an array literal.
+ * Example:
+ * ```rb
+ * [1, 2, 3]
+ * C = [1, 2, 3]; C
+ * x = [1, 2, 3]; x
+ * ```
+ */
+predicate isArrayConstant(ExprCfgNode e, ArrayLiteralCfgNode arr) {
+  // [...]
+  e = arr
+  or
+  // C = [...]; C
+  e.(ExprNodes::ConstantReadAccessCfgNode).getExpr().getValue().getDesugared() = arr.getExpr()
+  or
+  // x = [...]; x
+  exists(Ssa::WriteDefinition def | def.getARead() = e and def.assigns(arr))
+}

ruby/ql/lib/codeql/ruby/dataflow/BarrierGuards.qll

@@ -5,6 +5,7 @@ private import codeql.ruby.DataFlow
 private import codeql.ruby.CFG
 private import codeql.ruby.controlflow.CfgNodes
 private import codeql.ruby.dataflow.SSA
+private import codeql.ruby.ast.internal.Constant
 
 private predicate stringConstCompare(CfgNodes::ExprCfgNode g, CfgNode e, boolean branch) {
   exists(CfgNodes::ExprNodes::ComparisonOperationCfgNode c |
@@ -137,19 +138,7 @@ deprecated class StringConstArrayInclusionCall extends DataFlow::BarrierGuard,
   StringConstArrayInclusionCall() {
     this.getMethodName() = "include?" and
     this.getArgument(0) = checkedNode and
-    exists(ExprNodes::ArrayLiteralCfgNode arr |
-      // [...].include?
-      this.getReceiver() = arr
-      or
-      // C = [...]
-      // C.include?
-      this.getReceiver().(ExprNodes::ConstantReadAccessCfgNode).getExpr().getValue().getDesugared() =
-        arr.getExpr()
-      or
-      // x = [...]
-      // x.include?
-      exists(Ssa::WriteDefinition def | def.getARead() = this.getReceiver() and def.assigns(arr))
-    |
+    exists(ExprNodes::ArrayLiteralCfgNode arr | isArrayConstant(this.getReceiver(), arr) |
       forall(ExprCfgNode elem | elem = arr.getAnArgument() |
         elem instanceof ExprNodes::StringLiteralCfgNode
       )