`InstanceOfPatternMatch` declares variable with conflicting name

[knutwannheden]

The InstanceOfPatternMatch declares a pattern variable with a conflicting name if a variable with that name already exists in the if body after the corresponding type cast as in the following example:

void test(Object o) {
  if (o instanceof String) {
    System.out.println((String) o);
    String string = "x";
  }
}

Currently the recipe will change this to the following illegal code:

void test(Object o) {
  if (o instanceof String string) {
    System.out.println(string);
    String string = "x";
  }
}

Fixing openrewrite/rewrite#2776 should address this issue and the corresponding test case can be enabled again.

• VariableNameUtils#generateVariableName() should consider following statements rewrite#2776

[koppor]

Same with

if ((f1 instanceof Integer) && (f2 instanceof Integer)) {

rewritten to

if ((f1 instanceof Integer integer) && (f2 instanceof Integer integer)) {

[timtebeek]

@koppor The second case should see some improvement already after

• Duplicate variable name in if statement with two different instanceof #175

[uhafner]

I have a similar (but a little bit different) example in one of my classes that cause the same problem:

private class JSONObject {
  Object getObject() {
      return new Object();
  }
}
public class A {
  void test(Object o) {
      if (o instanceof JSONObject) {
          Object jsonObject = ((JSONObject) o).getObject();
          if (jsonObject instanceof JSONObject) {
              Object result = ((JSONObject) jsonObject).getObject();
          }
      }
  }
}

This produces:

         if (o instanceof JSONObject object) {
              Object jsonObject = object.getObject();
              if (jsonObject instanceof JSONObject object) {
                  Object result = object.getObject();
              }
          }