Premature removal of --java11-test-mode

@jtorkkola When I was using the January 10 buck build, version 2019.01.10.01, and using the --java11-test-mode option, my build was working fine.

On the latest master HEAD version of buck:

buck version e1fec3196532dc58cf06461ac0f3020f63f570bc

I get the build failure message:

You're using Java 11, but Buck requires Java 8.

I am on MacOS X 10.14.3, and my environment is as such:

> java -version
java version "11.0.2" 2019-01-15 LTS
Java(TM) SE Runtime Environment 18.9 (build 11.0.2+9-LTS)
Java HotSpot(TM) 64-Bit Server VM 18.9 (build 11.0.2+9-LTS, mixed mode)

> buck --version
buck version e1fec3196532dc58cf06461ac0f3020f63f570bc

Build output:

Unable to connect to Buck daemon, restarting it...
Not using buckd because daemon failed to start.
Error: A JNI error has occurred, please check your installation and try again
Exception in thread "main" java.lang.Error: java.lang.ClassNotFoundException: com.facebook.buck.cli.bootstrapper.filesystem.BuckFileSystemProvider
	at java.base/java.nio.file.FileSystems$DefaultFileSystemHolder.getDefaultProvider(FileSystems.java:141)
	at java.base/java.nio.file.FileSystems$DefaultFileSystemHolder$1.run(FileSystems.java:111)
	at java.base/java.nio.file.FileSystems$DefaultFileSystemHolder$1.run(FileSystems.java:109)
	at java.base/java.security.AccessController.doPrivileged(Native Method)
	at java.base/java.nio.file.FileSystems$DefaultFileSystemHolder.defaultFileSystem(FileSystems.java:109)
	at java.base/java.nio.file.FileSystems$DefaultFileSystemHolder.<clinit>(FileSystems.java:103)
	at java.base/java.nio.file.FileSystems.getDefault(FileSystems.java:190)
	at java.base/java.io.File.toPath(File.java:2290)
	at java.base/java.util.zip.ZipFile$Source.get(ZipFile.java:1222)
	at java.base/java.util.zip.ZipFile$CleanableResource.<init>(ZipFile.java:726)
	at java.base/java.util.zip.ZipFile$CleanableResource.get(ZipFile.java:843)
	at java.base/java.util.zip.ZipFile.<init>(ZipFile.java:246)
	at java.base/java.util.zip.ZipFile.<init>(ZipFile.java:176)
	at java.base/java.util.jar.JarFile.<init>(JarFile.java:346)
	at java.base/jdk.internal.loader.URLClassPath$JarLoader.getJarFile(URLClassPath.java:813)
	at java.base/jdk.internal.loader.URLClassPath$JarLoader$1.run(URLClassPath.java:758)
	at java.base/jdk.internal.loader.URLClassPath$JarLoader$1.run(URLClassPath.java:751)
	at java.base/java.security.AccessController.doPrivileged(Native Method)
	at java.base/jdk.internal.loader.URLClassPath$JarLoader.ensureOpen(URLClassPath.java:750)
	at java.base/jdk.internal.loader.URLClassPath$JarLoader.<init>(URLClassPath.java:725)
	at java.base/jdk.internal.loader.URLClassPath$3.run(URLClassPath.java:493)
	at java.base/jdk.internal.loader.URLClassPath$3.run(URLClassPath.java:476)
	at java.base/java.security.AccessController.doPrivileged(Native Method)
	at java.base/jdk.internal.loader.URLClassPath.getLoader(URLClassPath.java:475)
	at java.base/jdk.internal.loader.URLClassPath.getLoader(URLClassPath.java:444)
	at java.base/jdk.internal.loader.URLClassPath.getResource(URLClassPath.java:313)
	at java.base/jdk.internal.loader.BuiltinClassLoader.findClassOnClassPathOrNull(BuiltinClassLoader.java:697)
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClassOrNull(BuiltinClassLoader.java:623)
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:581)
	at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
	at java.base/java.lang.Class.forName0(Native Method)
	at java.base/java.lang.Class.forName(Class.java:398)
	at java.base/sun.launcher.LauncherHelper.loadMainClass(LauncherHelper.java:760)
	at java.base/sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:655)
Caused by: java.lang.ClassNotFoundException: com.facebook.buck.cli.bootstrapper.filesystem.BuckFileSystemProvider
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:583)
	at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
	at java.base/java.lang.Class.forName0(Native Method)
	at java.base/java.lang.Class.forName(Class.java:398)
	at java.base/java.nio.file.FileSystems$DefaultFileSystemHolder.getDefaultProvider(FileSystems.java:131)
	... 34 more
You're using Java 11, but Buck requires Java 8.
Please follow https://buckbuild.com/setup/getting_started.html to properly setup your local environment and avoid build issues.

When I built buck on the commit immediately prior to the removal commit (fadef0fe2051e3533e111638a2f68989431154ba), I do not see the failure above. When I built buck on the commit immediately after the removal commit (99641972d9b9da9226cabdb9eb76db58524ce97a), then the error returns.

[jtorkkola]

There have been numerous breaking changes (interface, structural, behavioral) between Java 8 and 11, rendering running Java 8 Buck on Java 11 impossible. Buck is particularly badly affected since it reaches into compiler internals for some aspects of Java compilation.

[jtorkkola]

@styurin Agreed that this may be useful in the future. I don’t plan on doing this for Java 8.