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removed actors #3
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I'm all in favor of nuking the old actors from orbit, but I think we should consider a more rigorous and specific compatibility policy before we start wantonly deleting everything in sight. |
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@djspiewak Additionally, isn't changing the library a non-option anyway if one takes the compatibility constraints into account? |
aloiscochard
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Sep 5, 2014
Upgrade tot Scala 2.11.0-M5
puffnfresh
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Jul 30, 2015
Under `-Ydelambdafy:method`, a public, static accessor method is
created to expose the private method containing the body of the
lambda.
Currently this accessor method has its parameters in the same order
structure as those of the lambda body method.
What is this order? There are three categories of parameters:
1. lambda parameters
2. captured parameters (added by lambdalift)
3. self parameters (added to lambda bodies that end up in trait
impl classes by mixin, and added unconditionally to the static
accessor method.)
These are currently emitted in order typelevel#3, typelevel#1, typelevel#2.
Here are examples of the current behaviour:
BEFORE (trait):
```
% cat sandbox/test.scala && scalac-hash v2.11.5 -Ydelambdafy:method sandbox/test.scala && javap -private -classpath . 'Test$class'
trait Member; class Capture; trait LambdaParam
trait Test {
def member: Member
def foo {
val local = new Capture
(arg: LambdaParam) => "" + arg + member + local
}
}
Compiled from "test.scala"
public abstract class Test$class {
public static void foo(Test);
private static final java.lang.String $anonfun$1(Test, LambdaParam, Capture);
public static void $init$(Test);
public static final java.lang.String accessor$1(Test, LambdaParam, Capture);
}
```
BEFORE (class):
```
% cat sandbox/test.scala && scalac-hash v2.11.5 -Ydelambdafy:method sandbox/test.scala && javap -private -classpath . Test
trait Member; class Capture; trait LambdaParam
abstract class Test {
def member: Member
def foo {
val local = new Capture
(arg: LambdaParam) => "" + arg + member + local
}
}
Compiled from "test.scala"
public abstract class Test {
public abstract Member member();
public void foo();
private final java.lang.String $anonfun$1(LambdaParam, Capture);
public Test();
public static final java.lang.String accessor$1(Test, LambdaParam, Capture);
}
```
Contrasting the class case with Java:
```
% cat sandbox/Test.java && javac -d . sandbox/Test.java && javap -private -classpath . Test
public abstract class Test {
public static class Member {};
public static class Capture {};
public static class LambaParam {};
public static interface I {
public abstract Object c(LambaParam arg);
}
public abstract Member member();
public void test() {
Capture local = new Capture();
I i1 = (LambaParam arg) -> "" + member() + local;
}
}
Compiled from "Test.java"
public abstract class Test {
public Test();
public abstract Test$Member member();
public void test();
private java.lang.Object lambda$test$0(Test$Capture, Test$LambaParam);
}
```
We can see that in Java 8 lambda parameters come after captures. If we
want to use Java's LambdaMetafactory to spin up our anoymous FunctionN
subclasses on the fly, our ordering must change.
I can see three options for change:
1. Adjust `LambdaLift` to always prepend captured parameters,
rather than appending them. I think we could leave `Mixin` as
it is, it already prepends the self parameter. This would result
a parameter ordering, in terms of the list above: typelevel#3, typelevel#2, typelevel#1.
2. More conservatively, do this just for methods known to hold
lambda bodies. This might avoid needlessly breaking code that
has come to depend on our binary encoding.
3. Adjust the parameters of the accessor method only. The body
of this method can permute params before calling the lambda
body method.
This commit implements option typelevel#2.
In also prototyped typelevel#1, and found it worked so long as I limited it to
non-constructors, to sidestep the need to make corresponding
changes elsewhere in the compiler to avoid the crasher shown
in the enclosed test case, which was minimized from a bootstrap
failure from an earlier a version of this patch.
We would need to defer option typelevel#1 to 2.12 in any case, as some of
these lifted methods are publicied by the optimizer, and we must
leave the signatures alone to comply with MiMa.
I've included a test that shows this in all in action. However, that
is currently disabled, as we don't have a partest category for tests
that require Java 8.
folone
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Aug 14, 2015
The log messages intented to chronicle implicit search were always being filtered out by virtue of the fact that the the tree passed to `printTyping` was already typed, (e.g. with an implicit MethodType.) This commit enabled printing in this case, although it still filters out trees that are deemed unfit for typer tracing, such as `()`. In the context of implicit search, this happens to filter out the noise of: ``` | | | [search #2] start `()`, searching for adaptation to pt=Unit => Foo[Int,Int] (silent: value <local Test> in Test) implicits disabled | | | [search #3] start `()`, searching for adaptation to pt=(=> Unit) => Foo[Int,Int] (silent: value <local Test> in Test) implicits disabled | | | \-> <error> ``` ... which I think is desirable. The motivation for this fix was to better display the interaction between implicit search and type inference. For instance: ``` class Foo[A, B] class Test { implicit val f: Foo[Int, String] = ??? def t[A, B](a: A)(implicit f: Foo[A, B]) = ??? t(1) } ``` ```` % scalac -Ytyper-debug sandbox/instantiate.scala ... | |-- t(1) BYVALmode-EXPRmode (site: value <local Test> in Test) | | |-- t BYVALmode-EXPRmode-FUNmode-POLYmode (silent: value <local Test> in Test) | | | [adapt] [A, B](a: A)(implicit f: Foo[A,B])Nothing adapted to [A, B](a: A)(implicit f: Foo[A,B])Nothing | | | \-> (a: A)(implicit f: Foo[A,B])Nothing | | |-- 1 BYVALmode-EXPRmode-POLYmode (site: value <local Test> in Test) | | | \-> Int(1) | | solving for (A: ?A, B: ?B) | | solving for (B: ?B) | | [search #1] start `[A, B](a: A)(implicit f: Foo[A,B])Nothing` inferring type B, searching for adaptation to pt=Foo[Int,B] (silent: value <local Test> in Test) implicits disabled | | [search #1] considering f | | [adapt] f adapted to => Foo[Int,String] based on pt Foo[Int,B] | | [search #1] solve tvars=?B, tvars.constr= >: String <: String | | solving for (B: ?B) | | [search #1] success inferred value of type Foo[Int,=?String] is SearchResult(Test.this.f, TreeTypeSubstituter(List(type B),List(String))) | | |-- [A, B](a: A)(implicit f: Foo[A,B])Nothing BYVALmode-EXPRmode (site: value <local Test> in Test) | | | \-> Nothing | | [adapt] [A, B](a: A)(implicit f: Foo[A,B])Nothing adapted to [A, B](a: A)(implicit f: Foo[A,B])Nothing | | \-> Nothing ```
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Don't need them.