Referencing classes in Gradle's API jar that are also in the JDK cause compilation errors in Eclipse when building with Java 9 and later

[wilkinsona]

Expected Behavior

A project that depends on Gradle's API jar should build cleanly in Eclipse when using Java 9+.

Current Behavior

Compilation fails when trying to, for example, use code in javax.xml.parsers due to the package being split between the unnamed and java.xml modules.

Context

The generated Gradle API jar contains packages and classes that are part of the JDK. These split packages cause compilation failures in Eclipse. It does not fail on the command line which, as per this mailing list discussion, is due to a bug in the JDK. When the JDK bug is fixed, similar failures will occur with javac.

This problem prevents compilation of Spring Boot's buildSrc on its current main branch in Eclipse. Our buildSrc plugins use code in various javax.xml packages and it does not compile in Eclipse with Java 17.

IMO, Gradle's API jar should not contain classes and packages that are also part of the JDK.

Steps to Reproduce

Import the project in this zip file into Eclipse. I'm using 2021-09 but I believe it'll occur in other versions of Eclipse as well. You should see two errors:

DocumentBuilderFactory cannot be resolved to a type	                                        Example.java	/java-xml-split-package/src/main/java/com/example	line 7	Java Problem
The package javax.xml.parsers is accessible from more than one module: <unnamed>, java.xml	Example.java	/java-xml-split-package/src/main/java/com/example	line 3	Java Problem

Your Environment

Build scan URL: scans.gradle.com is unavailable

I don't think this problem is environment-specific. FWIW, I'm using Eclipse 2021-09 on macOS with Temurin-17+35 (build 17+35).

[loetifuss]

Also having this issue. Our suite of Gradle plugins doesn't compile when imported with Eclipse Buildship and JDK 11. I can workaround this issue by limiting the module path of the Eclipse projects using the code below. The projects will compile now when "javax.xml" module is excluded.
Unfortunately this doesn't really help since now my Mockito tests throw ClassNotFoundExceptions for "java.beans.IntrospectionException" which is contained in the "java.desktop" module. The "java.desktop" module can't be added since it has a dependency on "javax.xml".

Is there any way to get this working in Eclipse and JDK 11? It seems to be working in Intellij IDEA.

pluginManager.withPlugin('eclipse') {
	eclipse {
		classpath {
			file {
				whenMerged {
					def jre = entries.find { it.path.contains 'org.eclipse.jdt.launching.JRE_CONTAINER' }
					jre.entryAttributes['module'] = 'true'
					jre.entryAttributes['limit-modules'] = '<ENTER_DESIRED_MODULES'
				}
			}
		}
	}
}

[infosuitemka]

Also have same issue, after finally being able to lift project baseline to Java 11. Everywhere we have custom Gradle tasks present and thus have the gradle API jar in the compile classpath. As we use the xml APIs, the java.xml module is required.

[jskov-jyskebank-dk]

I see the same problem trying to work on Gradle plugins in Eclipse targeting java 17.

Fortunately, it is possible to work around. The below works for me with Gradle 8.2.1, java 17, and Eclipse 2023-03.

// Workaround for https://github.com/gradle/gradle/issues/19577
//
// Makes a shaded copy of the gradle-api jar-file and switches the Eclipse classpath to use it.
// There is a per-root-project shaded file to allow for different shading configurations in different projects.
task makeShadedGradleApi(type: Zip) {
    def gradleVersion = project.gradle.gradleVersion
    def cacheDir = project.gradle.gradleUserHomeDir.toPath().resolve('caches').resolve(gradleVersion).resolve('generated-gradle-jars')
    def fileName = 'shaded-api-' + Integer.toHexString(project.rootDir.hashCode()) + '.jar'
    def shadedApiFile = cacheDir.resolve(fileName).toFile()
    def apiFile = cacheDir.resolve('gradle-api-' + gradleVersion + '.jar')

    archiveFile.set(shadedApiFile)
    from project.zipTree(apiFile)
    exclude "org/w3c/**/*"

    doFirst {
        logger.lifecycle("Shading $apiFile into $shadedApiFile")
    }
}

tasks.eclipseClasspath.dependsOn(makeShadedGradleApi)

eclipse {
    classpath {
        file {
            withXml {
                def cp = it.asNode()
                // Replace gradle-api library dependency with the shaded archive
                cp
                    .classpathentry
                    .findAll { e -> e.@kind == 'lib' && e.@path.contains('gradle-api') }
                    .each { e -> 
                        def c = e.clone()
                        c.@path = tasks.makeShadedGradleApi.archivePath

                        cp.remove(e)
                        cp.append(c)
                    }
            }
        }
    }
}

[infosuitemka]

I am out of the office until 31-07-2023. Please contact InfoSuite support at ***@***.*** for assistance. Note: This is an automated response to your message  "Re: [gradle/gradle] Referencing classes in Gradle's API jar that are also in the JDK cause compilation errors in Eclipse when building with Java 9 and later (Issue #19577)"( sent on 26-07-2023 13:41:00) . This is the only notification you will receive while this person is away.