Add isExpanded method

See scala/scala3#4146

Author: smarter

src/compiler/scala/tools/nsc/backend/jvm/BCodeHelpers.scala

@@ -394,7 +394,7 @@ trait BCodeHelpers extends BCodeIdiomatic with BytecodeWriters {
       debuglog(s"Potentially conflicting names for forwarders: $conflictingNames")
 
       for (m <- moduleClass.info.membersBasedOnFlags(ExcludedForwarderFlags, Flag_METHOD)) {
-        if (m.isType || m.isDeferred || (m.owner eq ObjectClass) || m.isConstructor)
+        if (m.isType || m.isDeferred || (m.owner eq ObjectClass) || m.isConstructor || m.isExpanded)
           debuglog(s"No forwarder for '$m' from $jclassName to '$moduleClass'")
         else if (conflictingNames(m.name))
           log(s"No forwarder for $m due to conflict with ${linkedClass.info.member(m.name)}")

src/compiler/scala/tools/nsc/backend/jvm/BackendInterface.scala

@@ -445,6 +445,7 @@ abstract class BackendInterface extends BackendInterfaceDefinitions {
     def isType: Boolean
     def isAnonymousClass: Boolean
     def isConstructor: Boolean
+    def isExpanded: Boolean
     def isAnonymousFunction: Boolean
     def isMethod: Boolean
     def isPublic: Boolean

src/compiler/scala/tools/nsc/backend/jvm/ScalacBackendInterface.scala

@@ -466,6 +466,7 @@ class ScalacBackendInterface[G <: Global](val global: G) extends BackendInterfac
     def isType: Boolean = sym.isType
     def isAnonymousClass: Boolean = sym.isAnonymousClass
     def isConstructor: Boolean = sym.isConstructor
+    def isExpanded: Boolean = sym.hasFlag(Flags.EXPANDEDNAME)
     def isAnonymousFunction: Boolean = sym.isAnonymousFunction
     def isMethod: Boolean = sym.isMethod
     def isPublic: Boolean = sym.isPublic