Windows, Java: uncaught exception if JAVA_HOME is undefined [duplicate of #6118]

[laszlocsomor]

Description of the problem / feature request:

Building a java_binary fails with an uncaught exception when JAVA_HOME is undefined.
Bazel should display an informative error message instead.

Bugs: what's the simplest, easiest way to reproduce this bug? Please provide a minimal example if possible.

1. Build Bazel at 2fda17d

2. Unset every environment variable except for:

   BAZEL_SH=c:\src\fake-msys\usr\bin\bash.exe
   SystemDrive=C:
   SystemRoot=C:\WINDOWS
   

   The fake MSYS is a C++ binary that prints its arguments then exits with 1.

3. Create a workspace with just a java_binary rule and a hello world Java file:

   C:\src\tmp>type build
   java_binary(
     name = "hello-java",
     srcs = ["Hello.java"],
     main_class = "Hello",
   )
   
   C:\src\tmp>type hello.java
   public class Hello {
     public static void main(String[] args) {
       System.out.println("hello Java");
     }
   }
   

4. Try building the target. You'll get an uncaught exception:

   ERROR: C:/users/laszlocsomor/_bazel_laszlocsomor/zovul4l7/external/bazel_tools/tools/jdk/BUILD:197:1: SkylarkAction external/bazel_tools/tools/jdk/platformclasspath.jar failed (Exit 1)
   warning: could not find a JDK 8 bootclasspath in external\local_jdk, falling back to --release
   Exception in thread "main" java.lang.IllegalArgumentException: external\local_jdk
           at jdk.compiler/com.sun.tools.javac.file.Locations$SystemModulesLocationHandler.update(Unknown Source)
           at jdk.compiler/com.sun.tools.javac.file.Locations$SystemModulesLocationHandler.handleOption(Unknown Source)
           at jdk.compiler/com.sun.tools.javac.file.Locations.handleOption(Unknown Source)
           at jdk.compiler/com.sun.tools.javac.file.BaseFileManager.handleOption(Unknown Source)
           at jdk.compiler/com.sun.tools.javac.file.BaseFileManager$2.handleFileManagerOption(Unknown Source)
           at jdk.compiler/com.sun.tools.javac.main.Option.process(Unknown Source)
           at jdk.compiler/com.sun.tools.javac.main.Option.handleOption(Unknown Source)
           at jdk.compiler/com.sun.tools.javac.file.BaseFileManager.handleOption(Unknown Source)
           at jdk.compiler/com.sun.tools.javac.main.Arguments.doProcessArgs(Unknown Source)
           at jdk.compiler/com.sun.tools.javac.main.Arguments.processArgs(Unknown Source)
           at jdk.compiler/com.sun.tools.javac.main.Arguments.init(Unknown Source)
           at jdk.compiler/com.sun.tools.javac.api.JavacTool.getTask(Unknown Source)
           at DumpPlatformClassPath.dumpJDK9AndNewerBootClassPath(DumpPlatformClassPath.java:141)
           at DumpPlatformClassPath.main(DumpPlatformClassPath.java:76)
   

5. Finally, set JAVA_HOME to the right value, and try building again. Now it works:

   C:\src\tmp>set JAVA_HOME=c:\Program Files\Java\jdk1.8.0_191
   
   C:\src\tmp>bazel-head.exe build //:hello-java
   ...
   INFO: Build completed successfully, 5 total actions
   

What operating system are you running Bazel on?

Windows Server 2016 (v1607)

If bazel info release returns "development version" or "(@non-git)", tell us how you built Bazel.

see above at repro instructions

[laszlocsomor]

This is a bad first-time user experience so I'm linking to #5254

[cushon]

This is a duplicate of #6118. That bug discusses a more general fix for recognizing invalid java_runtime configurations, but we could also improve the error handling in DumpPlatformClassPath in the interim.