Non-deterministic import order with non-standard sourceDirectory causes symbol resolution failures with recent JDKs

[fathzer]

Affected version

latest (docker image 3.9.11-eclipse-temurin-25)

Bug description

I have the following classes in a non standard tree (the files are directly in src, instead of src/main/java).

package com.test;

public enum State {
	FINISHED,
	PENDING
}

package com.test;

import javax.swing.SwingWorker;

public class Test extends SwingWorker<Void, Void> {
	
	@Override
	public Void doInBackground() throws Exception {
		Object state2 = State.FINISHED;
		return null;
	}
}

And the following pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>com.test</groupId>
	<artifactId>compile-bug</artifactId>
	<version>0.0.1</version>
	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<maven.install.skip>true</maven.install.skip>
		<maven.deploy.skip>true</maven.deploy.skip>
	</properties>

	<build>
		<sourceDirectory>src</sourceDirectory>
	</build>
</project>

When I compile this project using latest Docker maven image (currently 3.9.11-eclipse-temurin-25), I get the following error message:

docker run --rm -v $(pwd):/app -v ~/.m2:/root/.m2 -w /app maven:latest mvn clean compile

[INFO] -------------------------------------------------------------
[INFO] -------------------------------------------------------------
[ERROR] COMPILATION ERROR : 
[INFO] -------------------------------------------------------------
[ERROR] /app/src/com/test/Test.java:[9,38] cannot find symbol
  symbol:   variable FINISHED
  location: class java.util.concurrent.Future.State
[INFO] 1 error

The compiler is misleading between the Future.State imported in the superclass of Test and the State class available in the same package than Test.

I also check maven:3-eclipse-temurin-21 with the same failure.

If I do one of the following, the problem disappears:

• Use an quite old release of maven (maven:3-jdk-8)
• Put the source files in default source directory and remove the pom's build section.
• Add a import static com.test.State.*; in Test.java and replace State.FINISHED by FINISHED.

The following project contains a ready to use Maven project to reproduce the bug.

Thanks for reading!

PS: JDK 8 does not have a Future.State class (introduced in Java 19). This could explain why the compilation is working.

[desruisseaux]

Thanks for the test case. I don't think that it is a Maven bug, because I could reproduce the same behaviour by running javac directly on the command line. I think that, indeed, this is because the Future.State enumeration introduced in Java 19 take precedence over the com.Test.State enumeration. I presume that it worked with older docker images because they were bundled with a Java version older than 19.

[fathzer]

Ooops, you're right. I should have check this before posting (I've been happily using Maven for so long that I've forgotten javac even existed!).

The worst part is that I can no longer get the scenario to work with the source code in src/main/java. I probably had hallucination. I'm really sorry, it's obvious that the problem is not on maven side!