From f886b385aea32b6387384bd4c72edea275ac691a Mon Sep 17 00:00:00 2001
From: Christopher Vogt <oss.nsp@cvogt.org>
Date: Mon, 12 Sep 2016 14:10:10 +0100
Subject: better error message when you forget to extend BaseBuild

---
 stage2/BuildBuild.scala | 79 +++++++++++++++++++++++++------------------------
 1 file changed, 40 insertions(+), 39 deletions(-)

diff --git a/stage2/BuildBuild.scala b/stage2/BuildBuild.scala
index c57ce1b..5392217 100644
--- a/stage2/BuildBuild.scala
+++ b/stage2/BuildBuild.scala
@@ -21,50 +21,51 @@ trait BuildBuild extends BaseBuild{
   def managedBuildDirectory: java.io.File = lib.realpath( projectDirectory.parent )
   private object managedBuildCache extends Cache[BuildInterface]
   def managedBuild = managedBuildCache{
-    try{
-      val managedBuildFile = projectDirectory++"/build.scala"
-      logger.composition("Loading build at "++managedContext.projectDirectory.toString)
-      (
-        if(managedBuildFile.exists){
-          val contents = new String(Files.readAllBytes(managedBuildFile.toPath))
-          val cbtUrl = ("cbt:"++GitDependency.GitUrl.regex++"#[a-z0-9A-Z]+").r
-          cbtUrl
-            .findFirstIn(contents)
-            .flatMap{
-              url =>
-              val Array(base,hash) = url.drop(4).split("#")
-              if(context.cbtHome.string.contains(hash))
-                None
-              else Some{
-                // Note: cbt can't use an old version of itself for building,
-                // otherwise we'd have to recursively build all versions since
-                // the beginning. Instead CBT always needs to build the pure Java
-                // Launcher in the checkout with itself and then run it via reflection.
-                val dep = new GitDependency(base, hash, Some("nailgun_launcher"))
-                val ctx = managedContext.copy( cbtHome = dep.checkout )
-                dep.classLoader(classLoaderCache)
-                  .loadClass( "cbt.NailgunLauncher" )
-                  .getMethod( "getBuild", classOf[AnyRef] )
-                  .invoke( null, ctx )
-              }
-            }.getOrElse{
-              //new BasicBuild(managedContext)
-              ///*
+    val managedBuildFile = projectDirectory++"/build.scala"
+    logger.composition("Loading build at "++managedContext.projectDirectory.toString)
+    val build = (
+      if(managedBuildFile.exists){
+        val contents = new String(Files.readAllBytes(managedBuildFile.toPath))
+        val cbtUrl = ("cbt:"++GitDependency.GitUrl.regex++"#[a-z0-9A-Z]+").r
+        cbtUrl
+          .findFirstIn(contents)
+          .flatMap{
+            url =>
+            val Array(base,hash) = url.drop(4).split("#")
+            if(context.cbtHome.string.contains(hash))
+              None
+            else Some{
+              // Note: cbt can't use an old version of itself for building,
+              // otherwise we'd have to recursively build all versions since
+              // the beginning. Instead CBT always needs to build the pure Java
+              // Launcher in the checkout with itself and then run it via reflection.
+              val dep = new GitDependency(base, hash, Some("nailgun_launcher"))
+              val ctx = managedContext.copy( cbtHome = dep.checkout )
+              dep.classLoader(classLoaderCache)
+                .loadClass( "cbt.NailgunLauncher" )
+                .getMethod( "getBuild", classOf[AnyRef] )
+                .invoke( null, ctx )
+            }
+          }.getOrElse{
+            try{
               classLoader(context.classLoaderCache)
                 .loadClass(lib.buildClassName)
                 .getConstructors.head
                 .newInstance(managedContext)
-              //*/
-            }
-        } else {
-          new BasicBuild(managedContext)
-        }
-      ).asInstanceOf[BuildInterface]
+              } catch {
+                case e: ClassNotFoundException if e.getMessage == lib.buildClassName => 
+                  throw new Exception("You need to remove the directory or define a class Build in: "+context.projectDirectory)
+              }
+          }
+      } else {
+        new BasicBuild(managedContext)
+      }
+    )
+    try{
+      build.asInstanceOf[BuildInterface]
     } catch {
-      case e: ClassNotFoundException if e.getMessage == lib.buildClassName => 
-        throw new Exception("You need to remove the directory or define a class Build in: "+context.projectDirectory)
-      case e: Exception =>
-        throw new Exception("during build: "+context.projectDirectory, e)
+      case e: ClassCastException if e.getMessage.contains("Build cannot be cast to cbt.BuildInterface") =>
+        throw new Exception("Your Build class needs to extend BaseBuild in: "+context.projectDirectory, e)
     }
   }
   override def triggerLoopFiles = super.triggerLoopFiles ++ managedBuild.triggerLoopFiles
-- 
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