Allow passing JVM args to javac in ScipBuildTool (#728)

A canonical usage for this is passing `--add-opens` flags to the _launcher_ of javac to make sure annotation processors work.

To pass these arguments to the launcher, they have to be perfixed with -J – but arguments like this cannot be passed through the argfile that we use for javacOptions (see https://docs.oracle.com/en/java/javase/17/docs/specs/man/javac.html#command-line-argument-files) so we need to pass them to the command itself. 

For that purpose, we add a `jvmOptions` field to scip-java.json config – these options will have `-J` added to them and passed to the `javac` command.

The test to verify this behaviour relies on an [old version of lombok that requires these options](projectlombok/lombok#2681 (comment))

Additionally, a hidden option `--strict-compilation` is added to the CLI, to prevent error recovery: sometimes scip-java can just ignore javac errors and produce semanticdb artifacts regardless. This complicates testing, so I need an escape hatch).

### Test plan

- New test to ScipBuildToolSuite

scip-java/src/main/resources/scip-java/scip_java.bzl

@@ -71,11 +71,20 @@ def _scip_java(target, ctx):
         processorpath += [j.path for j in annotations.processor_classpath.to_list()]
         processors = annotations.processor_classnames
 
+    launcher_javac_flags = []
+    compiler_javac_flags = []
+    for value in compilation.javac_options:
+        if value.startswith("-J"):
+            launcher_javac_flags.append(value)
+        else:
+            compiler_javac_flags.append(value)
+
     build_config = struct(**{
         "javaHome": ctx.var["java_home"],
         "classpath": classpath,
         "sourceFiles": source_files,
-        "javacOptions": compilation.javac_options,
+        "javacOptions": compiler_javac_flags,
+        "jvmOptions": launcher_javac_flags,
         "processors": processors,
         "processorpath": processorpath,
         "bootclasspath": bootclasspath,

scip-java/src/main/scala/com/sourcegraph/scip_java/buildtools/ScipBuildTool.scala

@@ -202,7 +202,9 @@ class ScipBuildTool(index: IndexCommand) extends BuildTool("SCIP", index) {
     }
     val isSemanticdbGenerated = Files
       .isDirectory(targetroot.resolve("META-INF"))
-    if (errors.nonEmpty && !isSemanticdbGenerated) {
+    if (
+      errors.nonEmpty && (index.strictCompilation || !isSemanticdbGenerated)
+    ) {
       errors.foreach { error =>
         index.app.reporter.log(Diagnostic.exception(error))
       }
@@ -558,8 +560,11 @@ class ScipBuildTool(index: IndexCommand) extends BuildTool("SCIP", index) {
         BuildInfo.javacModuleOptions
       else
         Nil
+
+    val jvmOptions = config.jvmOptions.map("-J" + _)
+
     val result = os
-      .proc(javac.toString, s"@$argsfile", javacModuleOptions)
+      .proc(javac.toString, s"@$argsfile", javacModuleOptions, jvmOptions)
       .call(
         stdout = pipe,
         stderr = pipe,
@@ -815,6 +820,7 @@ class ScipBuildTool(index: IndexCommand) extends BuildTool("SCIP", index) {
       processorpath: List[String] = Nil,
       processors: List[String] = Nil,
       javacOptions: List[String] = Nil,
+      jvmOptions: List[String] = Nil,
       jvm: String = "17",
       kind: String = ""
   )

scip-java/src/main/scala/com/sourcegraph/scip_java/commands/IndexCommand.scala

@@ -83,6 +83,11 @@ case class IndexCommand(
         "Defaults to a build-specific command. For example, the default command for Maven command is 'clean verify -DskipTests'." +
         "To override the default, pass in the build command after a double dash: 'scip-java index -- compile test:compile'"
     )
+
+    @Hidden
+    @Description(
+      "Fail command invocation if compiler produces any errors"
+    ) strictCompilation: Boolean = false,
     @TrailingArguments() buildCommand: List[String] = Nil,
     @Hidden
     indexSemanticdb: IndexSemanticdbCommand = IndexSemanticdbCommand(),

tests/buildTools/src/test/scala/tests/ScipBuildToolSuite.scala

@@ -110,6 +110,49 @@ class ScipBuildToolSuite extends BaseBuildToolSuite {
         )
       )
 
+  checkBuild(
+    "jvm-args", {
+      // In this test we verify that JVM args and Javac options are passed
+      // correctly.
+      // Lombok modules need to be passed with -J prefix, and javacOptions should
+      // be passed unchanged
+      // For this test to work the lombok version HAS to be relatively old,
+      // so that it requires all these opens.
+      // The list is taken from here: https://github.com/projectlombok/lombok/issues/2681#issuecomment-748616687
+      val lombokModules = """
+        --add-opens=jdk.compiler/com.sun.tools.javac.code=ALL-UNNAMED
+        --add-opens=jdk.compiler/com.sun.tools.javac.comp=ALL-UNNAMED
+        --add-opens=jdk.compiler/com.sun.tools.javac.file=ALL-UNNAMED
+        --add-opens=jdk.compiler/com.sun.tools.javac.main=ALL-UNNAMED
+        --add-opens=jdk.compiler/com.sun.tools.javac.model=ALL-UNNAMED
+        --add-opens=jdk.compiler/com.sun.tools.javac.parser=ALL-UNNAMED
+        --add-opens=jdk.compiler/com.sun.tools.javac.processing=ALL-UNNAMED
+        --add-opens=jdk.compiler/com.sun.tools.javac.tree=ALL-UNNAMED
+        --add-opens=jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED
+        --add-opens=jdk.compiler/com.sun.tools.javac.jvm=ALL-UNNAMED
+        """.trim.split("\n").map(_.trim).mkString("\"", "\", \"", "\"")
+
+      s"""|/lsif-java.json
+          |{"jvmOptions": [$lombokModules], "javacOptions": ["--add-exports=java.base/sun.util=ALL-UNNAMED"], "dependencies": ["org.projectlombok:lombok:1.18.16"]}
+          |/foo/Example.java
+          |package foo;
+          |import sun.util.BuddhistCalendar;
+          |public class Example extends BuddhistCalendar {
+          |  public static void hello() {
+          |    BuddhistCalendar calendar = new BuddhistCalendar();
+          |  }
+          |}
+          |""".stripMargin
+    },
+    expectedSemanticdbFiles = 1,
+    // somehow it seems the actual compilation error from javac
+    // does not stop semanticdb-javac from producing the file.
+    // we explicitly disable this lenient mode so that if there
+    // are any compilation errors, it will be reflected in failed
+    // CLI command.
+    extraArguments = List("--strict-compilation")
+  )
+
   checkBuild(
     "basic",
     """|/lsif-java.json