VSCode doesn't show JDK Java source files when debugging JDK itself

[wkia]

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I'm building and debugging the latest version of OpenJDK on Windows 11. I'd like to debug it with VSCode, however I met the following problem:

I made changes in JDK Java sources (say added System.out.println("Hello") in src\jdk.javadoc\share\classes\jdk\javadoc\internal\tool\Main.java) and built JDK using JDK19 as boot JDK. I run my Java test using my freshly built JDK. It successfully starts and prints "Hello". Then I set a breakpoint at the line after my change in VSCode, and run the test under VSCode debugger. It starts, prints "Hello", and stops on my breakpoint, and shows source code, but I can't see my changes, because VSCode loaded jdk.javadoc\jdk.javadoc.internal.tool\Main.class instead of the changed Main.java.

I suppose, the class file was taken from java.configuration.runtimes, but I have no idea how can I force VSCode to load changed sources while debugging. Although VSCode is still able to show and debug my own Java-files, and, moreover, modified native JDK code (C/C++ sources), not Java.

BTW I've got the following pop-up message when debugger starts: "The compiled classes are not compatible with the runtime JDK."

Environment

• Operating System: Windows 11
• JDK version: 19
• Visual Studio Code version: 1.74.3
• Extension pack for Java: 0.25.7
• Java Debugger extension version: 0.47.0

Steps To Reproduce

1. Clone openjdk repository (https://github.com/openjdk/jdk.git) and build it
2. Make a little change in JDK's Java source file, e.g. add System.out.println("Hello") in src\jdk.javadoc\share\classes\jdk\javadoc\internal\tool\Main.java
3. Set a breakpoint at the changed line and try to debug it with VSCode

Current Result

VSCode stops at the breakpoint, loads *.class file, which doesn't contain my changes.

Expected Result

VSCode stops at the breakpoint, loads changed *.java files and shows them in debugger.

Additional Informations

My setting.json:

"java.configuration.runtimes": [
    {
        "default": true,
        "name": "JavaSE-19",
        "path": "c:\\work\\jdk19",
    }
],

My launch.json:

{
    "type": "java",
    "name": "(java) Debug",
    "request": "launch",
    "cwd": "${workspaceFolder}",
    "mainClass": "jdk.javadoc.internal.tool.Main",
    "javaExec": "${workspaceFolder}\\build\\windows-x86_64-server-fastdebug\\jdk\\bin\\java.exe",
    "classPaths": [
        "${workspaceFolder}/build/windows-x86_64-server-fastdebug/images/jdk/lib/jrt-fs.jar",
    ],
},

[testforstephen]

@wkia Could you try the pre-release version of Java debugger extension? See https://github.com/microsoft/java-debug/pull/463, recently we have optimized the source lookup logic to prioritize searching the project source first, then the libraries.

[wkia]

@testforstephen I've tried v0.47.2023011221 Nothing's changed. With the configuration I provided above, VSCode still shows *.class files without my changes while I'm debugging. If there is any recent version, could you explain how can I try it, please?

I also noted that if I specify source files path in java.configuration.runtimes pointing to my freshly built JDK (see below), VSCode can show my changes, but still loads *.class files, not *.java. This may be a confirmation that the plugin looks for JDK sources from runtime configuration, not workspace. Not sure if it is the solution.

"java.configuration.runtimes": [
    {
        "default": true,
        "name": "JavaSE-19",
        "path": "c:\\work\\jdk19",
        "sources": "c:\\work\\openjdk\\build\\windows-x86_64-server-fastdebug\\images\\jdk\\lib\\src.zip"
    }
],