rytz's patch for making our crazy long names a ...

rytz's patch for making our crazy long names a bit less crazy. You can
now use -Xmax-classfile-name to limit your filenames to as few as 72
characters. Watch out, nanotube gardens, we'll be stepping on your tiny
flowers before you know it. No review.

3 files changed, 19 insertions, 28 deletions

diff --git a/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala b/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
index 1670dfb94a..7405ca0b3d 100644
--- a/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
+++ b/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
@@ -57,6 +57,7 @@ trait ScalaSettings extends AbsScalaSettings with StandardScalaSettings {
   val future        = BooleanSetting    ("-Xfuture", "Turn on future language features.")
   val genPhaseGraph = StringSetting     ("-Xgenerate-phase-graph", "file", "Generate the phase graphs (outputs .dot files) to fileX.dot.", "")
   val XlogImplicits = BooleanSetting    ("-Xlog-implicits", "Show more detail on why some implicits are not applicable.")
+  val maxClassfileName = IntSetting        ("-Xmax-classfile-name", "Maximum filename length for generated classes", 255, Some(72, 255), _ => None)
   val Xmigration28  = BooleanSetting    ("-Xmigration", "Warn about constructs whose behavior may have changed between 2.7 and 2.8.")
   val nouescape     = BooleanSetting    ("-Xno-uescape", "Disable handling of \\u unicode escapes.")
   val Xnojline      = BooleanSetting    ("-Xnojline", "Do not use JLine for editing.")
diff --git a/src/compiler/scala/tools/nsc/symtab/NameManglers.scala b/src/compiler/scala/tools/nsc/symtab/NameManglers.scala
index b24a064139..dae07a29d5 100644
--- a/src/compiler/scala/tools/nsc/symtab/NameManglers.scala
+++ b/src/compiler/scala/tools/nsc/symtab/NameManglers.scala
@@ -22,15 +22,28 @@ trait NameManglers {
 
     def flattenedName(segments: Name*): NameType = compactedString(segments mkString "$")
 
-    private final val MaxFileNameLength = 255
-    private final val MaxNameLength = MaxFileNameLength - 6 // leave space for ".class"
-
-    /** "COMPACTIFY" */
+    /**
+     * COMPACTIFY
+     *
+     * The hashed name has the form (prefix + marker + md5 + marker + suffix), where
+     *   - prefix/suffix.length = MaxNameLength / 4
+     *   - md5.length = 32
+     *
+     * We obtain the formula:
+     *
+     *   FileNameLength = 2*(MaxNameLength / 4) + 2.marker.length + 32 + 6
+     *
+     * (+6 for ".class"). MaxNameLength can therefore be computed as follows:
+     */
+    private final val marker = "$$$$"
+    private final val MaxNameLength = math.min(
+      settings.maxClassfileName.value - 6,
+      2 * (settings.maxClassfileName.value - 6 - 2*marker.length - 32) + 6
+    )
     private lazy val md5 = MessageDigest.getInstance("MD5")
     private def toMD5(s: String, edge: Int) = {
       val prefix = s take edge
       val suffix = s takeRight edge
-      val marker = "$$$$"
 
       val cs = s.toArray
       val bytes = Codec toUTF8 cs
diff --git a/src/compiler/scala/tools/nsc/symtab/Names.scala b/src/compiler/scala/tools/nsc/symtab/Names.scala
index 9e0348c2e3..a046058faf 100644
--- a/src/compiler/scala/tools/nsc/symtab/Names.scala
+++ b/src/compiler/scala/tools/nsc/symtab/Names.scala
@@ -23,9 +23,6 @@ trait Names extends reflect.generic.Names {
   private final val HASH_MASK  = 0x7FFF
   private final val NAME_SIZE  = 0x20000
 
-  private final val MaxFileNameLength = 255
-  private final val MaxClassNameLength = MaxFileNameLength - 6 // leave space for ".class"
-
   final val nameDebug = false
 
   /** memory to store all names sequentially
@@ -78,26 +75,6 @@ trait Names extends reflect.generic.Names {
     else nc = nc + len
   }
 
-  private lazy val md5 = MessageDigest.getInstance("MD5")
-
-  /** "COMPACTIFY" */
-  private def toMD5(s: String, edge: Int) = {
-    val prefix = s take edge
-    val suffix = s takeRight edge
-    val marker = "$$$$"
-
-    val cs = s.toArray
-    val bytes = Codec toUTF8 cs
-    md5 update bytes
-    val md5chars = md5.digest() map (b => (b & 0xFF).toHexString) mkString
-
-    prefix + marker + md5chars + marker + suffix
-  }
-
-  def compactify(s: String): String =
-    if (s.length <= MaxClassNameLength) s
-    else toMD5(s, MaxClassNameLength / 4)
-
   /** Create a term name from the characters in cs[offset..offset+len-1].
    */
   def newTermName(cs: Array[Char], offset: Int, len: Int): TermName = {