Inlay hints wrong order for records

[gruvw]

Hello, when using the new inlay hints I just discovered that sometimes the order of the arguments was not correct.

Example:

For the moment it only happened to me when using java records syntax.

Environment

• Operating System: Ubuntu
• JDK version: 17
• Visual Studio Code version: 1.66.2
• Java extension version: v1.5.0

[FieteO]

I think this is caused by the getDeclaredFields() method not returning the fields in a particular order (called in the InlayHintVisitor).
From the javadoc:

	/**
	 * Returns a list of bindings representing all the fields declared
	 * as members of this class, interface, or enum type.
	 *
	 * <p>These include public, protected, default (package-private) access,
	 * and private fields declared by the class, but excludes inherited fields.
	 * Synthetic fields may or may not be included. Fields from binary types that
	 * reference unresolved types may not be included.</p>
	 *
	 * <p>Returns an empty list if the class, interface, or enum declares no fields,
	 * and for other kinds of type bindings that do not directly have members.</p>
	 *
	 * <p>The resulting bindings are in no particular order.</p>
	 *
	 * @return the list of bindings for the field members of this type,
	 *   or the empty list if this type does not have field members
	 */
	public IVariableBinding[] getDeclaredFields();

[jdneo]

Hi @angelozerr,

Do you have any idea how we can support inlay hints for Record class? The current problem is that getDeclaredFields() does not return fields with declared order.

[angelozerr]

No sorry I cannot help you for this topic.

[jdneo]

The correct parameter names are stored in the internal MethodBinding. But I didn't find a way to access it.

[rgrunber]

It doesn't look like there's currently a way to access it :\ , although it looks possible to add the API to MethodDeclaration (IMethodDeclaration).

The only other way I can see to do this is by getting access to the compilation unit where the record is declared, and go to the RecordDeclaration node. It has a method recordComponents() that lists the fields in order (since it just represents the record declaration). This seems tricky because the record invocation(s) and declaration can be different files.

[jdneo]

This seems tricky because the record invocation(s) and declaration can be different files.

Yes, that means we need first find the record type in the Java project, and then get its type root, which would be too expensive for displaying inlay hints.

How about we try to add the API at upstream? Before the new API is available, we disable the inlay hint for record method invocations temporarily.

[jdneo]

@rgrunber Will you add that required API at upstream?

[rgrunber]

JDT Core : eclipse-jdt/eclipse.jdt.core@master...rgrunber:param-names-api
JDT UI : eclipse-jdt/eclipse.jdt.ui@master...rgrunber:param-names-records

The JDT Core change is all that's needed to expose the necessary API. We can probably write the same code as in JDT UI.

I'll go ahead and propose these changes.

[rgrunber]

The API to do this on JDT Core has been available since https://download.eclipse.org/eclipse/updates/4.25-I-builds/I20220719-1800/ . I've also merged a change to fix the issue on Eclipse, so we should be able to go ahead and fix it in JDT-LS now.

See https://github.com/eclipse-jdt/eclipse.jdt.ui/pull/149/files for an example.

[jdneo]

Thank you @rgrunber, I'll follow up the fix at the JDT.LS side.