Don't emit forwarder in mirror class for bridge methods #6531
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When overriding a (concrete) method in an object with a varying
signature, make sure only one static forwarder method is emitted in the
mirror class, not an additional one with the signature of the bridge.
class A { def f: Object = null }
object B extends A { override def f: String = "b" }
`typeOf[B.type].membersBasedOnFlags(BRIDGE, METHOD)` after erasure works
correctly in that it doesn't return the bridge in B, but it returns
both `A.f` and `B.f`. This commit makes it run in an earlier phase.
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changed base to 2.13.x |
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ping for review, @retronym |
retronym
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May 13, 2018
lrytz
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Aug 8, 2018
They were accidentally dropped in scala#6531. Fixes scala/bug#11057.
eed3si9n
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Aug 11, 2018
Fixes scala/bug#11061 Ref scala/bug#10812 On 2.13.x branch scala#6531 removed the forwarder for bridge methods. I would like to do same in 2.12.x since Java 11-ea started to find them ambiguous as seen in akka/akka#25449 / scala/bug#11061. To keep binary compatibility, I am still emitting the forwarder for bridge methods, but with `ACC_BRIDGE` flag.
eed3si9n
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Aug 20, 2018
Fixes scala/bug#11061 Ref scala/bug#10812 On 2.13.x branch scala#6531 removed the mirror class forwarders for bridge methods. I would like to do same in 2.12.x since Java 11-ea started to find them ambiguous as seen in akka/akka#25449 / scala/bug#11061. To keep binary compatibility, I am still emitting the forwarders for bridge methods, but with `ACC_BRIDGE` flag.
eed3si9n
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Aug 20, 2018
Fixes scala/bug#11061 Ref scala/bug#10812 On 2.13.x branch scala#6531 removed the mirror class forwarders for bridge methods. I would like to do same in 2.12.x since Java 11-ea started to find them ambiguous as seen in akka/akka#25449 / scala/bug#11061. To keep binary compatibility, I am still emitting the forwarders for bridge methods, but with `ACC_BRIDGE` flag.
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see also scala/bug#11061 |
lrytz
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Nov 27, 2018
In 2.12.6 and before, the Scala compiler emits static forwarders for bridge methods in top-level modules. These forwarders are emitted by mistake, the filter to exclude bridges did not work as expected. These bridge forwarders make the Java compiler on JDK 11 report ambiguity errors when using static forwarders (scala/bug#11061). PR scala#7035 fixed this for 2.12.7 by adding the `ACC_BRIDGE` flag to static forwarders for bridges. We decided to keep these bridges for binary compatibility. However, the new flag causes the eclipse Java compiler (and apparently also IntelliJ) to report ambiguity errors when using static forwarders (scala/bug#11271). In 2.13.x the Scala compiler no longer emits static forwarders for bridges (PR scala#6531). This PR brings the same behavior to 2.12.8. This change breaks binary compatibility. However, in the examples we tested, the Java compiler emits references to the non-bridge methods, so compiled code continues to work if a library is replaced by a new version that doesn't have forwarders for bridges: ``` $> cat T.scala class A[T] { def get: T = ??? } object T extends A[String] { override def get: String = "hi" } $> ~/scala/scala-2.12.7/bin/scalac T.scala ``` Generates two forwarders in `T.class` ``` // access flags 0x49 public static bridge get()Ljava/lang/Object; // access flags 0x9 public static get()Ljava/lang/String; ``` ``` $> javac -version javac 1.8.0_181 $> cat Test.java public class Test { public static void main(String[] args) { System.out.println(T.get()); } } $> javac Test.java ``` Generates in Test.class ``` INVOKESTATIC T.get ()Ljava/lang/String; ```
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When overriding a (concrete) method in an object with a varying
signature, make sure only one static forwarder method is emitted in the
mirror class, not an additional one with the signature of the bridge.
typeOf[B.type].membersBasedOnFlags(BRIDGE, METHOD)after erasure workscorrectly in that it doesn't return the bridge in B, but it returns
both
A.fandB.f. This commit makes it run in an earlier phase.Fixes scala/bug#10812