Bug 83501

Summary: IBinding#getJavaElement needs better specification
Product: [Eclipse Project] JDT Reporter: Dirk Baeumer <dirk_baeumer>
Component: CoreAssignee: Jerome Lanneluc <jerome_lanneluc>
Status: VERIFIED FIXED QA Contact:
Severity: normal    
Priority: P3 CC: jeem, jerome_lanneluc, markus.kell.r, martinae
Version: 3.1   
Target Milestone: 3.1 M7   
Hardware: PC   
OS: Windows XP   
Whiteboard:
Bug Depends on:    
Bug Blocks: 92059    

Description Dirk Baeumer CLA 2005-01-23 08:47:20 EST 
The current specification is very vague when this method returns null and when
not. I expect the following behaviour:

Types:
- primitive types, including null and void: ==> null
- for wildcard types: ==> null
- for array types the Java element of the element type, or null if the 
  element type is a primitive
- for all other kind of types this method never returns null (even not for local 
  and anonymous types inside a method)
- for Raw type the Java element of the erasure
- for Parameterized types the Java element of the erasure

PackageBinding:
- never returns null

VariableBinding
- never returns null since we have IJavaElements for locals.
Comment 1 Markus Keller CLA 2005-03-22 05:44:50 EST 
Note: for parameterized types, getJavaElement() currently returns the unresolved
type. We could consider returning the resolved type in such cases in order to be
consistent with ICodeAssist#codeSelect(..) on a reference such as
    List<Integer> intList;

I don't have a specific use case for this right now; just wanted to mention the
difference before the specification is set in stone.
Comment 2 Markus Keller CLA 2005-04-20 10:20:13 EDT 
IVariableBinding#getJavaElement() should return null for an array's 'length'
field (see bug 92059).
Comment 3 Jim des Rivieres CLA 2005-04-20 23:17:34 EDT 
Revised the spec as follows.

/**
 * Returns the Java element that corresponds to this binding.
 * Returns <code>null</code> if this binding has no corresponding
 * Java element.
 * <p>
 * For array types, this method returns the Java element that corresponds
 * to the array's element type. For raw and parameterized types, this method
 * returns the Java element of the erasure.
 * </p>
 * <p>
 * Here are the cases where a <code>null</code> should be expected:
 * <ul>
 * <li>primitive types, including void</li>
 * <li>null type</li>
 * <li>wildcard types</li>
 * <li>capture types</li>
 * <li>the "length" field of an array type</li>
 * <li>array types of any of the above</li>
 * </ul>
 * For all other kind of type, method, variable, and package bindings,
 * this method returns non-<code>null</code>.
 * </p>
 * 
 * @return the Java element that corresponds to this binding, 
 * 		or <code>null</code> if none
 * @since 3.1
 */
public IJavaElement getJavaElement();

The implementation should be brought into line with this spec at the same time 
bug 92059 is addressed.
Comment 4 Philipe Mulet CLA 2005-04-21 05:08:58 EDT 
Integrated spec changes, and addressed bug 92059.
I believe resolved elements make sense there two when applicable.
Will not close this bug until this is resolved as well.
Comment 5 Jerome Lanneluc CLA 2005-04-22 12:32:52 EDT 
Changed implementation of getJavaElement() to return a resolved element when
possible. Use isResolved() to check if it is resolved.
Comment 6 Frederic Fusier CLA 2005-05-12 07:46:00 EDT 
Verified for 3.1 M7 using build I20050509-2010 + jdt.core HEAD.
(considering that ASTModelBridge tests all these cases and pass)