Description Steve Luich 2007-04-10 19:15:50 EDT

Build ID: M20070212-1330

Steps To Reproduce:
I discovered this bug while developing for our product Jtest in "org.eclipse.jdt.ui.actions.ChangeTypeAction".  (Jtest also uses this action) 

1.  I will attach the ".java" files, but the basic idea is that I have the following two classes:

public class ExampleBroken {
    private Map _previousTrackedVariables = new MyProperties();
    
    void method() {
        MyProperties trackedVariables= null;  //CANNOT generalize the type to "Map"
        _previousTrackedVariables = (trackedVariables == null) ? new MyProperties() : trackedVariables;  
    }
    
    private class MyProperties extends Hashtable {
    }
}

and 

public class ExampleWorks {
    private Map _previousTrackedVariables = new MyProperties();
    
    void method() {
        MyProperties trackedVariables= null;  //CAN generalize the type to "Map"
        if(trackedVariables == null){
            _previousTrackedVariables = new MyProperties();
        } else {
            _previousTrackedVariables = trackedVariables;
        }  
    }
    
    private class MyProperties extends Hashtable {
    }
}


Notice that the methods "method()" are equivalent in the two classes except that one uses the conditional expression syntax "? :" for the assignment and the other expands this into an "if-else" statement.  Still, the semantics are the same.

2.  Highlight "MyProperties" in the first line of "method()" in "ExampleBroken" in the Eclipse editor.  Right-click and select "Refactor > Generalize Declared Type".  Notice that it is unable to generalize the type.  The dialog comes up with the error message "Type of selected declaration cannot be changed". 

3.  Highlight "MyProperties" in the first line of "method()" in "ExampleWorks" in the Eclipse editor.  Right-click and select "Refactor > Generalize Declared Type".  Notice that it is able to generalize the type to "Map".  

Expected:

I expect the "Generalize Declared Type" feature to be able to generalize the type of "trackedVariables" to "java.util.Map" in both classes since the two classes are semantically the same.

Observed:

"Generalize Declared Type" only works in "ExampleWorks" but not in "ExampleBroken".


More information: