SI-9319 Avoid "filename too long" errors for anon functions

retronym · retronym · commit 41ac5727134c · 2015-05-20T15:50:56.000+10:00
Under -Ydelambdafy:method, the name of the anonymous class is derived from the names of the original enclosing class and term of the function. However no effort is made to conform to the `-Xmaxclassname` setting when constructing the class name from the components. Recently, in 029cce7, I changed uncurry to selectively fallback to the old method of emitting lambdas when we detect that `-Ydelambdafy:method` would subvert specialization. As a result of this, we could now have a delambdafy translated function enclosed in an anonymous class representing an old-style function. If that function, in turn, is heavily nested, its long name now contributes a long suffix to the delambdafy class's name. This led to a "filename too long" error in `run/kmpSliceSearch.scala`. I have extract the essence of the failure in `pos/t9319.scala`. I then changed delambdafy to use the unexpanded names of the owners rather than the full name. This makes things work as expected. I haven't further protected against pathological cases, given that in 2.12.x and indylambda, we won't ever emit these classes.
diff --git a/src/compiler/scala/tools/nsc/transform/Delambdafy.scala b/src/compiler/scala/tools/nsc/transform/Delambdafy.scala
@@ -209,9 +209,9 @@ abstract class Delambdafy extends Transform with TypingTransformers with ast.Tre
         //      - reinstate the assertion in `Erasure.resolveAnonymousBridgeClash`
         val suffix = nme.DELAMBDAFY_LAMBDA_CLASS_NAME + "$" + (
           if (funOwner.isPrimaryConstructor) ""
-          else "$" + funOwner.name + "$"
+          else "$" + funOwner.unexpandedName + "$"
         )
-        val oldClassPart = oldClass.name.decode
+        val oldClassPart = oldClass.unexpandedName.decode
         // make sure the class name doesn't contain $anon, otherwise isAnonymousClass/Function may be true
         val name = unit.freshTypeName(s"$oldClassPart$suffix".replace("$anon", "$nestedInAnon"))
 
diff --git a/test/files/pos/t9319.flags b/test/files/pos/t9319.flags
@@ -0,0 +1 @@
+-Ydelambdafy:method
diff --git a/test/files/pos/t9319.scala b/test/files/pos/t9319.scala
@@ -0,0 +1,35 @@
+object Test {
+
+  // was causing "filename too long" errors under -Ydelambdafy:method
+  def main(args: Array[String]) {
+    val x = List(1)
+    (i: Int) => {
+      (i: Int) => {
+        (i: Int) => {
+          (i: Int) => {
+            (i: Int) => {
+              (i: Int) => {
+                (i: Int) => {
+                  (i: Int) => {
+                    (i: Int) => {
+                      ()
+                    }
+
+                    ""
+                  }
+                  ()
+                }
+                ()
+              }
+              ()
+            }
+            ()
+          }
+          ()
+        }
+        ()
+      }
+      ()
+    }
+  }
+}
