eclipse java compiler gets confused by the new ACC_BRIDGE flag in forwarders #11271
Description
This bug affects Akka users that write Java code in eclipse. They get error messages in the IDE ("The method get(ActorSystem) is ambiguous").
To reproduce, download ecj-4.9.jar from http://download.eclipse.org/eclipse/downloads/drops4/R-4.9-201809060745/#JDTCORE
T.scala
class A[T] {
def get: T = ???
}
object T extends A[String] {
override def get: String = "hi"
}Test.java
public class Test {
public static void main(String[] args) {
System.out.println(T.get());
}
}With 2.12.6:
$> ~/scala/scala-2.12.6/bin/scalac T.scala
$> javac -version
javac 1.8.0_172
$> javac -cp . Test.java
$> java -jar ~/Downloads/ecj-4.9.jar -8 -cp . Test.java
$>
2.12.6 generates the following static methods in T.class:
// access flags 0x9
public static get()Ljava/lang/String;
// access flags 0x9
public static get()Ljava/lang/Object;
With 2.12.7 and current 2.12.x (2.12.8-bin-25c7215):
$> ../build/quick/bin/scalac T.scala
$> javac -cp . Test.java
$> java -jar ~/Downloads/ecj-4.9.jar -8 -cp . Test.java
----------
1. ERROR in /Users/luc/scala/scala12/sandbox/Test.java (at line 3)
System.out.println(T.get());
^^^
The method get() is ambiguous for the type T
----------
1 problem (1 error)
$>
Generated methods in T.class:
// access flags 0x49
public static bridge get()Ljava/lang/Object;
// access flags 0x9
public static get()Ljava/lang/String;
The bytecode change is exactly as intended by PR scala/scala#7035 that went to 2.12.7. The follow-up PR scala/scala#7383 that went into 2.12.x fixes a different bug and does not change anything here.
Someone predicted that something like this could happen.