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/* NSC -- new Scala compiler
* Copyright 2005-2013 LAMP/EPFL
* @author Jason Zaugg
*/
package scala.tools.nsc
package backend.jvm
import scala.tools.nsc.symtab._
/** Code shared between the erstwhile legacy backend (aka GenJVM)
* and the new backend [[scala.tools.nsc.backend.jvm.GenASM]]. There should be
* more here, but for now I'm starting with the refactorings that are either
* straightforward to review or necessary for maintenance.
*/
trait GenJVMASM {
val global: Global
import global._
import icodes._
import definitions._
val ExcludedForwarderFlags = {
import Flags._
// Should include DEFERRED but this breaks findMember.
( SPECIALIZED | LIFTED | PROTECTED | STATIC | EXPANDEDNAME | BridgeAndPrivateFlags | MACRO )
}
protected def isJavaEntryPoint(icls: IClass) = {
val sym = icls.symbol
def fail(msg: String, pos: Position = sym.pos) = {
reporter.warning(sym.pos,
sym.name + " has a main method with parameter type Array[String], but " + sym.fullName('.') + " will not be a runnable program.\n" +
" Reason: " + msg
// TODO: make this next claim true, if possible
// by generating valid main methods as static in module classes
// not sure what the jvm allows here
// + " You can still run the program by calling it as " + sym.javaSimpleName + " instead."
)
false
}
def failNoForwarder(msg: String) = {
fail(msg + ", which means no static forwarder can be generated.\n")
}
val possibles = if (sym.hasModuleFlag) (sym.tpe nonPrivateMember nme.main).alternatives else Nil
val hasApproximate = possibles exists { m =>
m.info match {
case MethodType(p :: Nil, _) => p.tpe.typeSymbol == ArrayClass
case _ => false
}
}
// At this point it's a module with a main-looking method, so either succeed or warn that it isn't.
hasApproximate && {
// Before erasure so we can identify generic mains.
enteringErasure {
val companion = sym.linkedClassOfClass
if (hasJavaMainMethod(companion))
failNoForwarder("companion contains its own main method")
else if (companion.tpe.member(nme.main) != NoSymbol)
// this is only because forwarders aren't smart enough yet
failNoForwarder("companion contains its own main method (implementation restriction: no main is allowed, regardless of signature)")
else if (companion.isTrait)
failNoForwarder("companion is a trait")
// Now either succeeed, or issue some additional warnings for things which look like
// attempts to be java main methods.
else (possibles exists isJavaMainMethod) || {
possibles exists { m =>
m.info match {
case PolyType(_, _) =>
fail("main methods cannot be generic.")
case MethodType(params, res) =>
if (res.typeSymbol :: params exists (_.isAbstractType))
fail("main methods cannot refer to type parameters or abstract types.", m.pos)
else
isJavaMainMethod(m) || fail("main method must have exact signature (Array[String])Unit", m.pos)
case tp =>
fail("don't know what this is: " + tp, m.pos)
}
}
}
}
}
}
}
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