Better auto project ID handling. Ref #776.

* Consolidate project ID validation and normalization into Project methods
* Provide an earlier and more detailed error message when the directory
  name can't be used for the project ID

ivy/src/main/scala/sbt/StringUtilities.scala

@@ -5,6 +5,7 @@ package sbt
 
 object StringUtilities
 {
+	@deprecated("Different use cases require different normalization.  Use Project.normalizeModuleID or normalizeProjectID instead.", "0.13.0")
 	def normalize(s: String) = s.toLowerCase.replaceAll("""\W+""", "-")
 	def nonEmpty(s: String, label: String)
 	{

main/src/main/scala/sbt/Defaults.scala

@@ -923,7 +923,7 @@ object Classpaths
 		conflictWarning in GlobalScope :== ConflictWarning.default("global"),
 		conflictWarning := conflictWarning.value.copy(label = Reference.display(thisProjectRef.value)),
 		unmanagedBase := baseDirectory.value / "lib",
-		normalizedName := StringUtilities.normalize(name.value),
+		normalizedName := Project.normalizeModuleID(name.value),
 		isSnapshot <<= isSnapshot or version(_ endsWith "-SNAPSHOT"),
 		description <<= description or name,
 		homepage in GlobalScope :== None,

main/src/main/scala/sbt/Load.scala

@@ -435,17 +435,26 @@ object Load
 		val loadedDefs = new sbt.LoadedDefinitions(defDir, Nil, plugs.loader, defs, loadedProjects, defNames)
 		new sbt.BuildUnit(uri, normBase, loadedDefs, plugs)
 	}
+
 	private[this] def autoID(localBase: File, context: PluginManagement.Context, existingIDs: Seq[String]): String = 
 	{
-		import StringUtilities.{normalize => norm}
+		def normalizeID(f: File) = Project.normalizeProjectID(f.getName) match {
+			case Right(id) => id
+			case Left(msg) => error(autoIDError(f, msg))
+		}
 		def nthParentName(f: File, i: Int): String =
-			if(f eq null) Build.defaultID(localBase) else if(i <= 0) norm(f.getName) else nthParentName(f.getParentFile, i - 1)
+			if(f eq null) Build.defaultID(localBase) else if(i <= 0) normalizeID(f) else nthParentName(f.getParentFile, i - 1)
 		val pluginDepth = context.pluginProjectDepth
 		val postfix = "-build" * pluginDepth
 		val idBase = if(context.globalPluginProject) "global-plugins" else nthParentName(localBase, pluginDepth)
 		val tryID = idBase + postfix
 		if(existingIDs.contains(tryID)) Build.defaultID(localBase) else tryID
 	}
+
+	private[this] def autoIDError(base: File, reason: String): String = 
+		"Could not derive root project ID from directory " + base.getAbsolutePath + ":\n" +
+			reason + "\nRename the directory or explicitly define a root project."
+
 	private[this] def projectsFromBuild(b: Build, base: File): Seq[Project] = 
 		b.projectDefinitions(base).map(resolveBase(base))
 

main/src/main/scala/sbt/Project.scala

@@ -157,10 +157,26 @@ object Project extends ProjectExtra
 		delegates: => Seq[ProjectReference] = Nil, settings: => Seq[Def.Setting[_]] = defaultSettings, configurations: Seq[Configuration] = Configurations.default,
 		auto: AddSettings = AddSettings.allDefaults): Project =
 	{
-		DefaultParsers.parse(id, DefaultParsers.ID).left.foreach(errMsg => sys.error("Invalid project ID: " + errMsg))
+		validProjectID(id).foreach(errMsg => sys.error("Invalid project ID: " + errMsg))
 		new ProjectDef[ProjectReference](id, base, aggregate, dependencies, delegates, settings, configurations, auto) with Project
 	}
 
+	/** Returns None if `id` is a valid Project ID or Some containing the parser error message if it is not.*/
+	def validProjectID(id: String): Option[String] = DefaultParsers.parse(id, DefaultParsers.ID).left.toOption
+
+
+	/** Constructs a valid Project ID based on `id` and returns it in Right or returns the error message in Left if one cannot be constructed.*/
+	def normalizeProjectID(id: String): Either[String, String] =
+	{
+		// TODO: better attempt
+		val attempt = id.toLowerCase.replaceAll("""\W+""", "-")
+		validProjectID(attempt).toLeft(attempt)
+	}
+
+	/** Normalize a String so that it is suitable for use as a dependency management module identifier.
+	* This is a best effort implementation, since valid characters are not documented or consistent.*/
+	def normalizeModuleID(id: String): String = id.toLowerCase.replaceAll("""\W+""", "-")
+
 	def resolved(id: String, base: File, aggregate: => Seq[ProjectRef], dependencies: => Seq[ResolvedClasspathDependency], delegates: => Seq[ProjectRef],
 		settings: Seq[Def.Setting[_]], configurations: Seq[Configuration], auto: AddSettings): ResolvedProject =
 			new ProjectDef[ProjectRef](id, base, aggregate, dependencies, delegates, settings, configurations, auto) with ResolvedProject

src/sphinx/Extending/Build-Loaders.rst

@@ -175,7 +175,7 @@ project/ directory.
         val pom = pomFile(info)
         val model = readPom(pom)
 
-        val n = StringUtilities.normalize(model.getName)
+        val n = Project.normalizeProjectID(model.getName)
         val base = Option(model.getProjectDirectory) getOrElse info.base
         val root = Project(n, base) settings( pomSettings(model) : _*)
         val build = new Build { override def projects = Seq(root) }