Just to see if my project could use some new java features - iterfaces with default methods, method references in lambdas, and such, I set the sourceCompatibility and targetCompatibility = 8 in my build.gradle and tried to build.

 

The build failed and the error is here: (I snipped away the successful stuff)

 

 

14:59:22.177 [LIFECYCLE] [class org.gradle.TaskExecutionLogger] :reobf FAILED
14:59:22.183 [iNFO] [org.gradle.execution.taskgraph.AbstractTaskPlanExecutor] :reobf (Thread[main,5,main]) completed. Took 0.793 secs.
14:59:22.189 [DEBUG] [org.gradle.execution.taskgraph.AbstractTaskPlanExecutor] Task worker [Thread[main,5,main]] finished, busy: 6.546 secs, idle: 0.098 secs
14:59:22.198 [ERROR] [org.gradle.BuildExceptionReporter]
14:59:22.206 [ERROR] [org.gradle.BuildExceptionReporter] FAILURE: Build failed with an exception.
14:59:22.215 [ERROR] [org.gradle.BuildExceptionReporter]
14:59:22.220 [ERROR] [org.gradle.BuildExceptionReporter] * What went wrong:
14:59:22.225 [ERROR] [org.gradle.BuildExceptionReporter] Execution failed for task ':reobf'.
14:59:22.230 [ERROR] [org.gradle.BuildExceptionReporter] > java.lang.IllegalArgumentException (no error message)
14:59:22.802 [ERROR] [org.gradle.BuildExceptionReporter]
14:59:22.807 [ERROR] [org.gradle.BuildExceptionReporter] * Exception is:
14:59:22.811 [ERROR] [org.gradle.BuildExceptionReporter] org.gradle.api.tasks.TaskExecutionException: Execution failed for task ':reobf'.
14:59:22.815 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeActions(ExecuteActi
onsTaskExecuter.java:69)
14:59:22.820 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.execute(ExecuteActionsTask
Executer.java:46)
14:59:22.824 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.api.internal.tasks.execution.PostExecutionAnalysisTaskExecuter.execute(PostExecuti
onAnalysisTaskExecuter.java:35)
14:59:22.827 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.api.internal.tasks.execution.SkipUpToDateTaskExecuter.execute(SkipUpToDateTaskExec
uter.java:64)
14:59:22.832 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.api.internal.tasks.execution.ValidatingTaskExecuter.execute(ValidatingTaskExecuter
.java:58)
14:59:22.836 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.api.internal.tasks.execution.SkipEmptySourceFilesTaskExecuter.execute(SkipEmptySou
rceFilesTaskExecuter.java:42)
14:59:22.841 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.api.internal.tasks.execution.SkipTaskWithNoActionsExecuter.execute(SkipTaskWithNoA
ctionsExecuter.java:52)
14:59:22.845 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.api.internal.tasks.execution.SkipOnlyIfTaskExecuter.execute(SkipOnlyIfTaskExecuter
.java:53)
14:59:22.849 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.api.internal.tasks.execution.ExecuteAtMostOnceTaskExecuter.execute(ExecuteAtMostOn
ceTaskExecuter.java:43)
14:59:22.853 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.api.internal.AbstractTask.executeWithoutThrowingTaskFailure(AbstractTask.java:289)

14:59:22.857 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.execution.taskgraph.AbstractTaskPlanExecutor$TaskExecutorWorker.executeTask(Abstra
ctTaskPlanExecutor.java:79)
14:59:22.861 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.execution.taskgraph.AbstractTaskPlanExecutor$TaskExecutorWorker.processTask(Abstra
ctTaskPlanExecutor.java:63)
14:59:22.866 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.execution.taskgraph.AbstractTaskPlanExecutor$TaskExecutorWorker.run(AbstractTaskPl
anExecutor.java:51)
14:59:22.870 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.execution.taskgraph.DefaultTaskPlanExecutor.process(DefaultTaskPlanExecutor.java:2
3)
14:59:22.874 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.execution.taskgraph.DefaultTaskGraphExecuter.execute(DefaultTaskGraphExecuter.java
:86)
14:59:22.878 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.execution.SelectedTaskExecutionAction.execute(SelectedTaskExecutionAction.java:29)

14:59:22.882 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecuter.java:61)
14:59:22.886 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.execution.DefaultBuildExecuter.access$200(DefaultBuildExecuter.java:23)
14:59:22.890 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.execution.DefaultBuildExecuter$2.proceed(DefaultBuildExecuter.java:67)
14:59:22.894 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.execution.DryRunBuildExecutionAction.execute(DryRunBuildExecutionAction.java:32)
14:59:22.899 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecuter.java:61)
14:59:22.903 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecuter.java:54)
14:59:22.907 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.initialization.DefaultGradleLauncher.doBuildStages(DefaultGradleLauncher.java:166)

14:59:22.911 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.initialization.DefaultGradleLauncher.doBuild(DefaultGradleLauncher.java:113)
14:59:22.915 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.initialization.DefaultGradleLauncher.run(DefaultGradleLauncher.java:81)
14:59:22.919 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.launcher.exec.InProcessBuildActionExecuter$DefaultBuildController.run(InProcessBui
ldActionExecuter.java:64)
14:59:22.923 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.launcher.cli.ExecuteBuildAction.run(ExecuteBuildAction.java:33)
14:59:22.927 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.launcher.cli.ExecuteBuildAction.run(ExecuteBuildAction.java:24)
14:59:22.931 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.launcher.exec.InProcessBuildActionExecuter.execute(InProcessBuildActionExecuter.ja
va:35)
14:59:22.935 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.launcher.exec.InProcessBuildActionExecuter.execute(InProcessBuildActionExecuter.ja
va:26)
14:59:22.940 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.launcher.cli.RunBuildAction.run(RunBuildAction.java:50)
14:59:22.944 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.internal.Actions$RunnableActionAdapter.execute(Actions.java:171)
14:59:22.948 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.launcher.cli.CommandLineActionFactory$ParseAndBuildAction.execute(CommandLineActio
nFactory.java:201)
14:59:22.952 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.launcher.cli.CommandLineActionFactory$ParseAndBuildAction.execute(CommandLineActio
nFactory.java:174)
14:59:22.956 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.launcher.cli.CommandLineActionFactory$WithLogging.execute(CommandLineActionFactory
.java:170)
14:59:22.960 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.launcher.cli.CommandLineActionFactory$WithLogging.execute(CommandLineActionFactory
.java:139)
14:59:22.967 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.launcher.cli.ExceptionReportingAction.execute(ExceptionReportingAction.java:33)
14:59:22.971 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.launcher.cli.ExceptionReportingAction.execute(ExceptionReportingAction.java:22)
14:59:22.975 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.launcher.Main.doAction(Main.java:46)
14:59:22.979 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.launcher.bootstrap.EntryPoint.run(EntryPoint.java:45)
14:59:22.983 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.launcher.Main.main(Main.java:37)
14:59:22.987 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.launcher.bootstrap.ProcessBootstrap.runNoExit(ProcessBootstrap.java:50)
14:59:22.991 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.launcher.bootstrap.ProcessBootstrap.run(ProcessBootstrap.java:32)
14:59:22.995 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.launcher.GradleMain.main(GradleMain.java:23)
14:59:22.999 [ERROR] [org.gradle.BuildExceptionReporter] Caused by: java.lang.IllegalArgumentException
14:59:23.003 [ERROR] [org.gradle.BuildExceptionReporter]        at org.objectweb.asm.ClassReader.<init>(ClassReader.java:170)
14:59:23.007 [ERROR] [org.gradle.BuildExceptionReporter]        at org.objectweb.asm.ClassReader.<init>(ClassReader.java:153)
14:59:23.011 [ERROR] [org.gradle.BuildExceptionReporter]        at org.objectweb.asm.ClassReader.<init>(ClassReader.java:424)
14:59:23.015 [ERROR] [org.gradle.BuildExceptionReporter]        at net.md_5.specialsource.JarRemapper.remapClassFile(JarRemapper.java:228)
14:59:23.019 [ERROR] [org.gradle.BuildExceptionReporter]        at net.md_5.specialsource.JarRemapper.remapJar(JarRemapper.java:189)
14:59:23.023 [ERROR] [org.gradle.BuildExceptionReporter]        at net.minecraftforge.gradle.tasks.user.reobf.ObfArtifact.applySpecialSource(ObfArtifact.java:36
7)
14:59:23.027 [ERROR] [org.gradle.BuildExceptionReporter]        at net.minecraftforge.gradle.tasks.user.reobf.ObfArtifact.generate(ObfArtifact.java:336)
14:59:23.031 [ERROR] [org.gradle.BuildExceptionReporter]        at net.minecraftforge.gradle.tasks.user.reobf.ReobfTask.doTask(ReobfTask.java:294)
14:59:23.035 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.internal.reflect.JavaMethod.invoke(JavaMethod.java:63)
14:59:23.039 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskFactory$StandardTaskActio
n.doExecute(AnnotationProcessingTaskFactory.java:219)
14:59:23.043 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskFactory$StandardTaskActio
n.execute(AnnotationProcessingTaskFactory.java:212)
14:59:23.047 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskFactory$StandardTaskActio
n.execute(AnnotationProcessingTaskFactory.java:201)
14:59:23.052 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.api.internal.AbstractTask$TaskActionWrapper.execute(AbstractTask.java:533)
14:59:23.056 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.api.internal.AbstractTask$TaskActionWrapper.execute(AbstractTask.java:516)
14:59:23.060 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeAction(ExecuteActio
nsTaskExecuter.java:80)
14:59:23.064 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeActions(ExecuteActi
onsTaskExecuter.java:61)
14:59:23.071 [ERROR] [org.gradle.BuildExceptionReporter]        ... 43 more
14:59:23.077 [ERROR] [org.gradle.BuildExceptionReporter]
14:59:23.081 [LIFECYCLE] [org.gradle.BuildResultLogger]
14:59:23.085 [LIFECYCLE] [org.gradle.BuildResultLogger] BUILD FAILED
14:59:23.090 [LIFECYCLE] [org.gradle.BuildResultLogger]
14:59:23.094 [LIFECYCLE] [org.gradle.BuildResultLogger] Total time: 22.516 secs

 

 

It appears that org.ow2.asm.4x is not compatible with java 8 for the :reObf task to complete properly. There is a 5.0 and 5.0.1 version available that would solve this issue, but I could not figure out how to make gradle use it. Is this a future enhancement, or will Forge always be stuck at 1.6 compatibility?

 

Java 8 is brand new, so usually not recommended to be used until some updates from now, just like Java 7 was. I'm sticking with 7u51 for now, as it works like a charm.

I was able to get Forge Gradle working fine with Java8 - at least on the command line - by adding this snippet to my build.gradle:

 

configurations.all {
    resolutionStrategy.eachDependency { DependencyResolveDetails details ->
        if (details.requested.group == 'org.ow2.asm' && details.requested.name == 'asm-debug-all' && details.requested.version == '4.1') {
            //prefer different version which contains some necessary fixes
            details.useVersion '5.0.1'
        }
    }
}

 

This makes Gradle use the Java8 compatible version of the asm lib.  I still had some issues with IntelliJ integration (didn't try eclipse).  Forge seems to work, but it gets tons of warnings because the ClassLoader isn't set up correctly.  Running ./gradlew debugClient and remote debugging from IntelliJ seems to work perfectly though.

 

I have no idea if a mod you make with this trick actually works with a binary Forge install, but it at least unblocks debugging until Forge has full support for Java8.