Moved static forwarder generation behind -Xforw...

Moved static forwarder generation behind -Xforwarders option. Special
cased main so #363 continues to work. Moved test case for #1745 into
pending since it requires forwarders to work.

7 files changed, 17 insertions, 10 deletions

diff --git a/src/compiler/scala/tools/nsc/Settings.scala b/src/compiler/scala/tools/nsc/Settings.scala
index f13e1cfa21..6026186010 100644
--- a/src/compiler/scala/tools/nsc/Settings.scala
+++ b/src/compiler/scala/tools/nsc/Settings.scala
@@ -618,6 +618,7 @@ trait ScalacSettings
   val checkInit     = BooleanSetting    ("-Xcheckinit", "Add runtime checks on field accessors. Uninitialized accesses result in an exception being thrown.")
   val noassertions  = BooleanSetting    ("-Xdisable-assertions", "Generate no assertions and assumptions")
   val Xexperimental = BooleanSetting    ("-Xexperimental", "Enable experimental extensions")
+  val forwarders    = BooleanSetting    ("-Xforwarders", "Generate static forwarders in mirror classes")
   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 info on why some implicits are not applicable")
diff --git a/src/compiler/scala/tools/nsc/backend/jvm/GenJVM.scala b/src/compiler/scala/tools/nsc/backend/jvm/GenJVM.scala
index cee270e555..e77333581b 100644
--- a/src/compiler/scala/tools/nsc/backend/jvm/GenJVM.scala
+++ b/src/compiler/scala/tools/nsc/backend/jvm/GenJVM.scala
@@ -209,10 +209,17 @@ abstract class GenJVM extends SubComponent {
         }
       }
       else {
+        val lmoc = c.symbol.linkedModuleOfClass
         // add static forwarders if there are no name conflicts; see bugs #363 and #1735
-        if (c.symbol.linkedModuleOfClass != NoSymbol && !c.symbol.hasFlag(Flags.INTERFACE)) {
-          log("Adding forwarders to existing class " + c.symbol + " found in module " + c.symbol.linkedModuleOfClass)
-          addForwarders(jclass, c.symbol.linkedModuleOfClass.moduleClass)
+        if (lmoc != NoSymbol && !c.symbol.hasFlag(Flags.INTERFACE)) {
+          // forwarders were creating many issues, see #1795 for instance; so for now
+          // they are only enabled if -Xforwarders is supplied to scalac...
+          if (settings.forwarders.value) {
+            log("Adding forwarders to existing class " + c.symbol + " found in module " + lmoc)
+            addForwarders(jclass, lmoc.moduleClass)
+          }
+          // ...but we special case main so at least ticket #363 can continue to work.
+          else addForwarders(jclass, lmoc.moduleClass, _.name == nme.main)
         }
       }
 
@@ -228,6 +235,7 @@ abstract class GenJVM extends SubComponent {
         genBeanInfoClass(c)
     }
 
+
     /**
      * Generate a bean info class that describes the given class.
      *
@@ -748,9 +756,11 @@ abstract class GenJVM extends SubComponent {
     /** Add forwarders for all methods defined in `module' that don't conflict with
      *  methods in the companion class of `module'. A conflict arises when a method
      *  with the same name is defined both in a class and its companion object (method
-     *  signature is not taken into account).
+     *  signature is not taken into account).  If 3rd argument cond is supplied, only
+     *  symbols for which cond(sym) is true are given forwarders.
      */
-    def addForwarders(jclass: JClass, module: Symbol) {
+    def addForwarders(jclass: JClass, module: Symbol) { addForwarders(jclass, module, _ => true) }
+    def addForwarders(jclass: JClass, module: Symbol, cond: (Symbol) => Boolean) {
       def conflictsIn(cls: Symbol, name: Name) =
         cls.info.nonPrivateMembers.exists(_.name == name)
 
@@ -784,7 +794,7 @@ abstract class GenJVM extends SubComponent {
       if (settings.debug.value)
         log("Dumping mirror class for object: " + module);
 
-      for (m <- module.info.nonPrivateMembers; if shouldForward(m))
+      for (m <- module.info.nonPrivateMembers; if shouldForward(m) ; if cond(m))
         addForwarder(jclass, module, m)
     }
 
diff --git a/test/pending/pos/t1840/J.java b/test/files/pos/t1840/J.java
index 3914721431..3914721431 100644
--- a/test/pending/pos/t1840/J.java
+++ b/test/files/pos/t1840/J.java
diff --git a/test/pending/pos/t1840/S.scala b/test/files/pos/t1840/S.scala
index 00ab0ff3b1..00ab0ff3b1 100644
--- a/test/pending/pos/t1840/S.scala
+++ b/test/files/pos/t1840/S.scala
diff --git a/test/files/pos5/misc-pos.log b/test/files/pos5/misc-pos.log
deleted file mode 100644
index b921dd4d64..0000000000
--- a/test/files/pos5/misc-pos.log
+++ /dev/null
@@ -1,4 +0,0 @@
-A.java:3: error: illegal cyclic reference involving object A
-import static test.A.STATE.UNDEF;
-       ^
-one error found
diff --git a/test/files/pos5/t1745/J.java b/test/pending/pos5/t1745/J.java
index 8444eabb24..8444eabb24 100644
--- a/test/files/pos5/t1745/J.java
+++ b/test/pending/pos5/t1745/J.java
diff --git a/test/files/pos5/t1745/S.scala b/test/pending/pos5/t1745/S.scala
index 70210ba502..70210ba502 100644
--- a/test/files/pos5/t1745/S.scala
+++ b/test/pending/pos5/t1745/S.scala