Regression: Expressions broken for Remote Java Application in recent Eclipse versions

[CalculonPrime]

We have a command-line build process for our framework, not using Eclipse that generates several JARs that get deployed via Embedded Tomcat. In earlier Eclipse versions (circa 2017), I was able to create an Eclipse project, remove the "src" directory and replace it with a link to our app's source (outside the Eclipse project), and then attach to the running external Java app using a Remote Java Application launcher in Eclipse.

I also added the output JARs from the build to the project, and all the 3rd party JARs used by the app.

With all of this in place, I could set breakpoints, step line-by-line, and most importantly, evaluate expressions in the expression pane.

However, with the most recent versions of Eclipse (2023-09 and 2023-12 tested), expressions don't work. This is horrific! Having to rebuild with logging or print commands makes things much more difficult. Expressions added show no output, and I believe this is connected to what happens when I press ctrl+shift+I after selecting a variable in the code near the breakpoint, which reports,

java.lang.reflect.InvocationTargetException: Unable to evaluate the selected expression:

To perform an evaluation, an expression must be compiled in the context of a Java project's build path. The current execution context is not associated with a Java project in the workspace.
	at org.eclipse.jdt.internal.debug.ui.actions.EvaluateAction$1.run(EvaluateAction.java:270)
	at org.eclipse.jface.operation.ModalContext$ModalContextThread.run(ModalContext.java:122)

The Java project for the new Eclipses was built in the same way, with the src directory in the project linked to the external Java source. All the fixes for this problem on the web say to make sure that you're linking to the same source and libraries in the project, but as mentioned the app wasn't built with an Eclipse project in my case, as it's an external app. So this is not possible as a solution.

Am I stuck using Eclipse from 2017 or switching to IntelliJ? Why would the devs have made such a mind-boggling change that breaks an important feature? Is my take on this correct and if so would filing a bug have a chance of getting this fixed?

[iloveeclipse]

First of all you should provide a self contained example and step by step instructions how to reproduce you problem. With that one would have at least some understanding what is broken and where (Eclipse, your framework or something else).

[CalculonPrime]

The most basic example of "remote debugging" (debugging an attached Java process outside the Eclipse project) will reproduce it.

I've attached two files:
javaTestApp.tar.gz
JavaHostProject.tar.gz

The first, javaTestApp, is a standalone Java app. It contains a build.sh and run.sh to build and run the app - just javac and java commands. The app takes a number and prints its square, in a loop. Hit return without typing anything to exit. The other tar file is the Eclipse project JavaHostProject, which links to the external javaTestApp java app.

To reproduce:

• Expand both of these tar files in your /tmp directory (Linux assumed).
• Build javaTestApp from the command line using build.sh, and run it with run.sh. You can type numbers into the app to see that it works. Just leave it running. We're going to attach to it in Eclipse.
• Open Eclipse, and import the project directory /tmp/JavaHostProject. The src directory in the project is a link to the src directory in the javaTestApp (which assumes you expanded it in /tmp). You can double click on Input.java in the project to open that source file in Eclipse.
• Attach to the running javaTestApp via Run >> Debug Configurations >> Remote Java Application. The run.sh script for the external app opens debug port 8000 which is the default for Remote Java Application
• Set a breakpoint somewhere inside the loop of Input.java. I will assume you set it at the line containing the System.out.println() call that prints the variable "square".
• Type another integer into the javaTestApp you left running. This will cause Eclipse to hit the breakpoint. Try hovering over the variable "square" in the source code. This will show the correct value.
• Now go to the expressions window and type square + " ok". In working versions of Eclipse you'll see the correct output. In non-working versions, there will be no output.
• Go back to the source file and select "square" with the mouse and press ctrl+shift+I. A dialog will pop up with the correct value in it in working versions of eclipse. In non working versions, you see the error message I originally reported:

To perform an evaluation, an expression must be compiled in the context of a Java project's build path. The current execution context is not associated with a Java project in the workspace`

Note that in non-working versions of Eclipse, when you hit the breakpoint, you'll be prompted to re-enter the source link to the external java app javaTestApp/src, even though it's already in the project. This doesn't happen in working versions of Eclipse, so that issue may be related to expressions not working. Re-entering the path doesn't fix expressions, but Eclipse requires it.

Working version: Oxygen.2 Release (4.7.2)
Broken versions: Eclipse 2023-09 and 2023-12

[CalculonPrime]

Were you able to reproduce the problem? Should I file a Github Issue (as this is a discussion thread)?