Improve Object-getClass-test-for-primitive.ql

Tested query with Variant Analysis and had one result.

Author: Marcono1234

codeql-custom-queries-java/not-tested-queries/Object-getClass-test-for-primitive.ql

@@ -0,0 +1,28 @@
+/**
+ * Finds `Object.getClass()` calls which compare the result with
+ * a primitive type literal, e.g.:
+ * ```java
+ * obj.getClass() == int.class
+ * ```
+ *
+ * Primitives do not exist as `Object` (only their boxed representation
+ * does), therefore these checks will always fail.
+ * 
+ * @kind problem
+ */
+
+import java
+
+class PrimitiveOrVoidType extends Type {
+    PrimitiveOrVoidType() {
+        this instanceof PrimitiveType
+        or this instanceof VoidType
+    }
+}
+
+from EqualityTest eqTest, MethodAccess getClassCall
+where
+    getClassCall.getMethod().hasStringSignature("getClass()")
+    and eqTest.getAnOperand() = getClassCall
+    and eqTest.getAnOperand().(TypeLiteral).getReferencedType() instanceof PrimitiveOrVoidType
+select eqTest, "`getClass()` will never return primitive class"