ruby: first draft of thread-unsafe modification

Author: yoff

ruby/ql/src/queries/performance/ConstantModification.ql

@@ -0,0 +1,14 @@
+import ruby
+import codeql.ruby.ast.Expr
+import codeql.ruby.ast.Constant
+import codeql.ruby.ast.Variable
+
+predicate relevantModification(Expr e) {
+  e instanceof ClassVariableWriteAccess
+  or
+  exists(e.(ConstantAssignment).getScopeExpr())
+}
+
+from Expr e
+where relevantModification(e) and exists(e.getEnclosingCallable())
+select e