Allow configuring number of errors logged by compiler (#199)

Author: borkaehw

README.md

@@ -41,6 +41,7 @@ If the right design principles are kept, implementing additional features should
 * [Customizable rules](docs/newdocs/phases.md#customizing-the-core-rules)
 * [Multiple Scala versions in one build](docs/newdocs/scala_versions.md#specifying-the-scala-version-to-use)
 * [Optimal handling of macros and ijars](docs/newdocs/macros.md#macros-and-ijars)
+* [Pass flags to Zinc compiler](docs/newdocs/zinc_flags.md)
 
 ## Usage
 

docs/newdocs/zinc_flags.md

@@ -0,0 +1,18 @@
+## Pass flags to Zinc compiler
+
+### Persistence Directory Path
+Use `--persistence_dir` to specify the path to save Zinc state files.
+
+### Use Persistence Directory
+Use `--use_persistence` to enable or disable the persistence directory. The default is `true`.
+
+### Maximum Error Number
+Use `--max_errors` to specify the number of errors to be shown from Zinc. The default is `10`.
+
+## Example
+In `.bazelrc` file, add the following snippet
+```sh
+build --worker_extra_flag=ScalaCompile=--persistence_dir=bazel-zinc
+build --worker_extra_flag=ScalaCompile=--use_persistence=true
+build --worker_extra_flag=ScalaCompile=--max_errors=20
+```

src/main/scala/higherkindness/rules_scala/workers/zinc/compile/ZincRunner.scala

@@ -67,6 +67,7 @@ object ZincRunner extends WorkerMain[Namespace] {
     val parser = ArgumentParsers.newFor("zinc-worker").addHelp(true).build
     parser.addArgument("--persistence_dir", /* deprecated */ "--persistenceDir").metavar("path")
     parser.addArgument("--use_persistence").`type`(Arg.booleanType)
+    parser.addArgument("--max_errors")
     parser.parseArgsOrFail(args.getOrElse(Array.empty))
   }
 
@@ -212,8 +213,12 @@ object ZincRunner extends WorkerMain[Namespace] {
     }
 
     val setup = {
+      val maxErrors: Int = worker.getString("max_errors") match {
+        case x: String if x.forall(_.isDigit) => x.toInt
+        case _                                => 10
+      }
       val incOptions = IncOptions.create()
-      val reporter = new LoggedReporter(10, logger)
+      val reporter = new LoggedReporter(maxErrors, logger)
       val skip = false
       Setup.create(lookup, skip, null, compilerCache, incOptions, reporter, Optional.empty(), Array.empty)
     }